Role of Artificial Intelligence in Advancing Sustainable Development, Circular Economy, and Economic Growth in India’s Chemical Industry under Union Budget 2026–27

Pranav Mishra^†, Utkarsha Zarbade^† and Satyajit Bhattacharjee^*,†

^†Department of Chemical Engineering, Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh 495009, India

Abstract. The integration of Artificial Intelligence (AI) in the chemical industry is transforming the sector toward sustainable development, circular economy practices, and economic growth in India. AI-driven technologies such as predictive analytics, smart manufacturing, process automation, and waste optimization are improving production efficiency, reducing energy consumption, and minimizing environmental impact. In the framework of a circular economy, AI supports resource recovery, recycling, waste management, and the reuse of industrial by-products, thereby promoting efficient utilization of raw materials and reducing industrial pollution. These advancements directly contribute to the goals of sustainable development by encouraging green chemistry, lowering carbon emissions, conserving natural resources, and supporting environmentally responsible industrialization. The Government of India through the Union Budget 2026–27 is expected to strengthen the adoption of AI and digital technologies in chemical manufacturing by increasing investments in innovation, research and development, renewable energy, and industrial infrastructure. Budget initiatives focusing on “Make in India,” green hydrogen, clean energy transition, and smart industrial ecosystems can accelerate the modernization of India’s chemical sector while generating employment and enhancing global competitiveness. Furthermore, the combination of AI, circular economy principles, and sustainability strategies can help Indian chemical industries achieve long-term economic resilience and environmental balance. Thus, AI acts as a bridge connecting technological advancement, sustainable industrial practices, and national economic policies, paving the way for a greener and more efficient future for the Indian chemical industry.

GreenScore AI: A Circular Economy-Based Sustainability Scoring and Resource Optimization Framework for Smart Farming

Ashmitha S^†

^†Department of Agricultural Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore 641003, India

Abstract. Sustainable agriculture is challenged by the need to balance productivity with efficient resource use and environmental conservation. This research presents GreenScore AI, an artificial-intelligence-driven framework designed to assess and enhance sustainability in smart farming through circular economy principles. The proposed system evaluates key agricultural parameters such as water consumption, energy usage, waste generation, and crop productivity to generate a comprehensive sustainability score. GreenScore AI not only quantifies farm performance but also provides intelligent, data-driven recommendations to optimize resource utilization and minimize waste. (continued overleaf)

This paper presents an integrated decision-support methodology for evaluating and optimizing urban waste-management systems in the Indian context. The proposed framework combines five complementary analytical layers: life-cycle assessment for environmental quantification, system dynamics for long-term, feedback-rich simulation, artificial-intelligence-based forecasting for waste-generation prediction, fuzzy TOPSIS for technology ranking under uncertainty, and reinforcement learning for adaptive policy sequencing. The framework is designed around Indian municipal realities, including high organic fractions, variable collection efficiency, monsoon effects, festival-linked waste spikes, legacy dumpsites, dependence on the informal sector, and limited municipal finance. Recent policy and empirical research are incorporated to continue the expansion of the Swachh Bharat Mission–Urban 2.0, to address India’s approximately 150,000 tonnes per day of urban waste generation, and to address global projections that municipal solid waste may increase substantially by 2050. The methodology supports comparative assessment of sanitary landfilling, composting, anaerobic digestion, material recovery, waste-to-energy, refuse-derived fuel systems, and biomining of legacy waste. By coupling environmental, economic, technical, social, and policy variables, the framework provides a reproducible, transparent, and adaptive basis for sustainable waste-management planning in Indian cities.

The proposed methodology involves pyrolytic synthesis of biochar from Parthenium hysterophorus under optimized temperature and residence time conditions, followed by chemical activation to enhance surface area, porosity, and functional group density. Characterization of the synthesized biochar will be conducted using BET surface area analysis, FTIR spectroscopy, SEM-EDX, XRD, and TGA to establish structure–property correlations. Batch adsorption experiments will investigate the effect of pH, contact time, adsorbent dosage, and initial pollutant concentration on removal efficiency in both single and multi-pollutant systems. Adsorption kinetics, equilibrium isotherm modeling, and thermodynamic studies will be performed to elucidate the underlying adsorption mechanisms. This study aims to demonstrate that Parthenium-derived biochar serves as a high-performance adsorbent in complex multi-pollutant systems, offering a scalable and economically viable solution for industrial wastewater treatment. The dual-benefit approach of invasive weed valorization and pollutant remediation positions this work as a meaningful contribution toward sustainable water management.

Natural Lotus Wax-Modified Commercial Sponges for Efficient Oil Absorption

Santhra Krishnan P.^†, Sriharitha Rowthu^‡ and Sreeram K. Kalpathy^†

^†Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India  ·  ^‡Department of Materials Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382055, India

Abstract. Oil-contaminated water streams continue to pose significant environmental and resource recovery challenges, necessitating the development of sustainable, cost-effective treatment technologies. Commercial cleaning sponges are inexpensive, widely available, and possess highly interconnected porous networks, making them attractive candidates for absorbent-based water remediation. However, their intrinsic amphiphilicity and large pore sizes often permit the rapid penetration of both water and oil, limiting separation selectivity. In this work, a simple, material-efficient surface modification strategy based on the deposition of natural lotus wax is proposed to regulate capillary-driven liquid transport in commercially available sponges. Pristine and wax-modified sponges will be evaluated in terms of pore morphology, pore size distribution, wettability, absorption performance, and liquid infiltration behavior. Static and dynamic contact angle measurements and time-dependent uptake experiments will be employed to investigate wetting transitions and transport kinetics. Pore characteristics will be quantified through image analysis, while the infiltration behavior of water and oil will be interpreted using capillary pressure and Washburn infiltration concepts to establish relationships between pore architecture, surface energy, and liquid transport dynamics. The study aims to elucidate how natural wax deposition alters pore geometry and surface wettability, thereby affecting liquid invasion in highly interconnected porous networks. It is anticipated that even low wax loadings will significantly retard water penetration while preserving rapid oil uptake, thereby improving oil–water selectivity without extensive modification of the underlying sponge structure. By combining an inexpensive commercial substrate with a bio-derived surface treatment, the proposed approach is expected to provide a scalable and environmentally benign route for selective oil removal from contaminated water streams, further contributing to a mechanistic understanding of capillary transport in porous absorbents and supporting the development of materials for circular water management and resource recovery applications.

In this study, EC with iron electrodes was optimized for sludge dewatering by systematically varying key operational parameters, including applied voltage, electrode spacing, and reaction time. The dewatering performance was evaluated using specific resistance to filtration (SRF) and moisture content reduction. To enhance process efficiency and promote resource recovery, the EC-treated sludge was further converted into iron-loaded biochar (Fe–BC) via thermochemical treatment. The synthesized Fe–BC was reutilized as an additive in subsequent EC cycles to improve floc formation, electrical conductivity, and overall dewatering efficiency. The impact of Fe–BC addition on energy consumption, treatment time, and dewatering performance was systematically investigated. Furthermore, the reusability of Fe–BC was assessed over multiple cycles to determine its performance stability and functional lifespan. Changes in physicochemical properties of Fe–BC after repeated use were analyzed to understand the mechanisms governing its effectiveness. The results demonstrate that Fe–BC significantly enhances EC performance while reducing energy requirements, with a gradual decline observed beyond a certain number of reuse cycles.

Reactive Transport Modelling in Porous Media using COMSOL-MATLAB-PHREEQC

C. Bersha Angelin Christal^† and Swapna Singha Rabha^†

^†Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Abstract. The interaction between pore structure, permeability, pressure gradients, and transport mechanisms such as advection, diffusion, and mechanical dispersion governs fluid flow in porous media. In reactive transport systems, dissolved chemical species undergo geochemical phenomena such as mineral dissolution, precipitation, ion exchange, and aqueous speciation while moving across interconnected pore spaces. Understanding subsurface processes is made easier by Reactive Transport Modelling (RTM) in porous media. In practice, RTM uses one of the Operator Splitting (OS) approaches, known as the Sequential Non-Iterative approach, which solves the equations of transport and reactions separately rather than simultaneously. This study presents a coupled framework integrating COMSOL Multiphysics, MATLAB, and PHREEQC to solve RTM problems. The coupling approach uses COMSOL’s transport-solving capabilities with PHREEQC’s geochemical equilibrium and kinetic calculations, with MATLAB serving as a data exchanger and OS interface. The benchmark problem used is a 2D axisymmetric problem: pesticide transport and reaction in soil. The effective saturation plotted along with the velocity field helps us understand the rate and direction at which the pesticides move through the soil. After pesticide infiltration, the concentration of aldicarb reaches a steady state as the plume gets concentrated around the source, while aldicarb sulfoxide affects a larger soil volume, exhibiting a distinct ring-band pattern after 10 days. The benchmark study reveals that the coupled framework can accurately capture the evolution of contaminated plumes in soil. The developed methodology can be further extended towards applications in geological CO₂ sequestration; understanding these coupled processes is critical for predicting long-term storage stability, mineral trapping mechanisms, porosity evolution, and environmental consequences of carbon capture and storage (CCS) technologies.

Ongoing studies are focused on investigating the degradation of representative PAHs under blue-light irradiation in the presence of hydrogen peroxide, where TiO₂ is expected to generate reactive oxygen species capable of oxidizing PAHs into less harmful products. The active photocatalytic platform enhanced catalyst–pollutant interactions, leading to efficient degradation of representative PAHs. At an initial concentration of 10 ppm, TiO₂-functionalized pectin micromotors achieved ≈100% degradation of anthracene and ≈70% degradation of naphthalene after 24 h of blue-light irradiation. These findings demonstrate the effectiveness of bio-based photocatalytic micromotors for degrading persistent organic pollutants and highlight their potential as sustainable and environmentally friendly materials for coal mine wastewater remediation.

ZnFe₂O₄/TiO₂/rGO Nanocomposites for the Efficient Photocatalytic Degradation of Polycyclic Aromatic Hydrocarbons

Chinthalapudi Naga Lakshmi^†, A. Hariharan^† and Swathi Sudhakar^*,†

^†Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Abstract. There is growing global interest in advancing wastewater treatment methods to effectively remove polycyclic aromatic hydrocarbons, which are persistent, toxic, and carcinogenic contaminants. Conventional techniques are ineffective at removing these compounds. Photocatalysis is one of the best oxidation techniques utilising solar energy, degrading these persistent compounds into non-harmful products; however, heterogeneous photocatalytic degradation of water pollutants presents a considerable challenge due to its complex nature. In this work, we synthesized ZnFe₂O₄/TiO₂/rGO nanocomposites for the photocatalytic degradation of naphthalene under visible light irradiation. XRD analysis confirmed the formation of cubic-phase zinc ferrite and tetragonal-phase titanium dioxide in the composite. Morphological analysis revealed the successful integration of the ZnFe₂O₄/TiO₂ nanocomposite with rGO nanosheets, resulting in a well-defined heterojunction. This heterojunction facilitates efficient exciton separation and transport, suppresses charge carrier recombination, and enhances the generation of reactive oxygen species, thereby playing a crucial role in the photocatalytic degradation of naphthalene. The ZnFe₂O₄/TiO₂/rGO nanocomposites showed improved photocatalytic performance compared to bare ZnFe₂O₄ and TiO₂ nanoparticles. The increased efficiency resulted from their narrow bandgap, improved visible-light absorption, and enhanced charge-carrier separation and transport.

Co₃O₄ Nanostructures for Supercapacitors: Toward Circular Electrode Design

Chrisma Rose Babu^†,§, E. I. Anila^§, Sreeram K. Kalpathy^‡,† and Tiju Thomas^‡,†

^†Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India  ·  ^‡Centre for Resource Efficiency, Recyclability and Circularity in Energy Transition (CRRET), School of Sustainability, Indian Institute of Technology Madras, Chennai 600036, India  ·  ^§Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore 560029, India

Abstract. Cobalt is a critical metal widely used in energy storage technologies, and its recovery from various electronic waste streams, especially batteries, offers a promising route toward circular resource utilization. In the present work, we have used a commercially available cobalt precursor to synthesize Co₃O₄ nanostructures for supercapacitor applications. (continued overleaf)

Pharmaceutical wastewater containing micro-pollutants is an important environmental problem because these pollutants tend to persist in the environment. Membrane-based separation processes are regarded as a convenient and compact means of treating wastewater. The main aim of this research study was to separate the pharmaceutical active compound nystatin by applying the membrane technique. To achieve this, graphene oxide (GO) and magnetite graphene oxide (MGO) were synthesized, and MGO was then incorporated onto a polysulfone-based hollow fiber membrane to improve its separation performance. Membranes of varying MGO loadings were analyzed using FT-IR, Raman spectroscopy, XRD, XPS, FE-SEM, HR-TEM, EPR, DSC, and TGA techniques. Among all the membranes used, M-4, which contained 0.03% MGO, displayed the highest effectiveness, with a permeability of ≈71.34 L/m²h·bar at 1 bar pressure, nystatin rejection of 98%, and a MWCO of ≈1531 Da. The improved membrane performance was mainly attributed to enhanced membrane morphology and hydrophilicity, which contributed to high permeation flux and improved separation efficiency.

Water Recovery from Saline Water using Hydrophobic Polyvinylidene Fluoride (PVDF) Hollow Fiber Membrane Based Direct Contact Membrane Distillation (DCMD)

Vishal B. Gohil^†, Mrinmoy Mondal^† and Puyam S. Singh^†

^†Membrane Science and Separation Technology Division, CSIR-CSMCRI, Bhavnagar 364021, India

Abstract. Direct contact membrane distillation (DCMD) is a thermally driven desalination technique that has gained increasing attention for high-salinity water treatment due to its ability to operate at low temperatures while delivering high separation efficiency and effectively utilizing low-grade heat sources. In this study, a PVDF hollow fiber membrane engineered with a sandwich tri-layer porous morphology was employed to enhance vapor transport and reduce mass-transfer resistance. The membrane exhibited a hydrophobic surface with a water contact angle of 115°, ensuring stable operation without pore wetting. DCMD performance was evaluated using a 3.5 wt% NaCl feed solution, achieving an average permeation flux of 7.5 L/m²h and a salt rejection exceeding 99.7% with a hot saline water stream at 80°C and a cold distillate stream at 18°C. The system demonstrated stable long-term operation over a continuous 10-hour run, confirming the suitability of the PVDF hollow fiber structure for energy-efficient and reliable desalination applications.

Enhanced Primary Treatment and Hybrid Wastewater Treatment Systems for Domestic Sewage

Md Sarfraz Ahmad^*,† and Dr. Maithili Mohanty^†

^†Department of Civil Engineering, National Institute of Technology Rourkela, Sundargarh, Odisha 769008, India

* Corresponding author · 525ce6007@nitrkl.ac.in

Abstract. One of the most recent advancements in the enhancement of pollutant removal in municipal wastewater treatment is Chemically Enhanced Primary Treatment (CEPT). By treating the primary stage of wastewater treatment with coagulants and flocculants, there is an increase in the removal of suspended solids and particulate organic matter, along with an overall improvement in treatment efficiency and organic load reduction provided to subsequent downstream biological treatment processes.

Glucoside-Assisted Enhancement of CO₂ Hydrate Formation Kinetics: Molecular Dynamics Investigation

Ramkhelavan Kanaujiyaa^†, Tarak K. Patra^† and Atanu K. Metya^*,‡

^†Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India  ·  ^‡Department of Chemical and Biochemical Engineering, IIT Patna, Patna 801106, India

* Corresponding author · ch21d030@smail.iitm.ac.in

Abstract. Gas hydrates, or clathrate hydrates, are crystalline compounds in which water molecules form hydrogen-bonded cages that encapsulate guest gases such as CO₂ and CH₄ under high-pressure, low-temperature conditions. Naturally occurring in deep-sea sediments and permafrost, these hydrates also hold promise for technological applications, including gas storage, separation, transportation, greenhouse gas sequestration, wastewater treatment, desalination, and flow assurance in oil and gas pipelines. However, their inherently slow formation kinetics remain a major limitation for large-scale carbon capture and storage. In this work, molecular dynamics (MD) simulations are employed to examine the impact of glucoside-based additives – caprylyl glucoside, decyl glucoside, lauryl glucoside, and their sulphonated derivatives – on CO₂ hydrate nucleation and growth. The influence of pressure, temperature, and additive concentration is systematically investigated to provide molecular-level insights into glucosides as kinetic hydrate promoters. Our results demonstrate that glucoside-based promoters significantly enhance hydrate formation and growth, advancing the understanding of hydrate–promoter interactions and underscoring their potential for efficient, sustainable CO₂ capture and storage strategies.

A Novel Wave Powered Maritime Surveillance System

Suman Kumar^† and Abdus Samad^*,†

^†Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai, India

* Corresponding author · samad@iitm.ac.in

Abstract. Unmanned coastal surveillance systems (UCSSs) powered by ocean wave energy can be deployed along coasts where close observation is needed to prevent infiltration or detection of unknown objects that could threaten a country’s security. Existing systems generally use solar power, which requires a large battery. A wave energy converter (WEC) extracts energy from ocean surface waves and reduces the battery requirements of a UCSS. This study describes a WEC, Sindhuja-I, that supplied power to a UCSS. The Sindhuja-I is portable and can be deployed at 10 m to any water depth in the sea. The UCSS was designed and tested in the wave basin facility at IIT Madras, and system performance was recorded under different wave conditions. A few objects were detected and identified using an image-processing strategy. The WEC produced varying power, reaching up to 20 W, while the camera consumed around 2 W under different laboratory test conditions.

Among various CO₂ capture methods, amine-based CO₂ absorption remains a widely used technology in industry, with efficiency depending on factors such as operating conditions, the type of amine used, and the effectiveness of gas–liquid contact. Structured packings offer excellent mass transfer efficiency, low pressure drop, good wettability, and high capacity compared to random packings for effective gas–liquid contact, but are also more sensitive to maldistribution, which reduces gas–liquid mass transfer, making it important to improve mass transfer in structured packing. This work focuses on developing a multiphase Eulerian CFD model to predict the hydrodynamics, mass transfer, and CO₂ absorption in monoethanolamine (MEA) for an in-house structured packed column. The computational domain consists of a packed column of 28 cm height and 5 cm diameter, equipped with structured packing of 4.979 cm diameter to enhance gas–liquid contact; the liquid phase consists of aqueous MEA solution filled to a height of 28 cm, with a binary gas mixture of 28.2 wt% CO₂ and 71.8 wt% N₂ introduced from the bottom at 0.021 m/s. The governing momentum, energy, and species transport equations are solved using OpenFOAM v8.0, beginning with an investigation of hydrodynamics followed by detailed modelling of CO₂ absorption in MEA, where CO₂ reacts with MEA to form carbamate (CO₂ + H₂O + 2 MEA ⇌ MEACOO⁻ + MEAH⁺). Mass transfer between gas and liquid phases is incorporated through a Sherwood number correlation, Sh = f(Re, Sc), and the predicted CO₂ loading and capture efficiency at different gas velocities are validated against in-house experimental data; the effective interfacial area across the column is estimated from the gradient of the liquid volume fraction. Unlike the porous media approach commonly used in the literature, which fails to capture the realistic flow distribution across packings that strongly influences mass transfer, the present work employs in-house realistic structured packing geometry, allowing the flow behaviour within the packing elements to be observed, and the resulting CFD predictions of product formation are compared with those obtained using the porous media approach.

Sustainable MEA-Based CO₂ Capture: Mass Transfer and Solvent Stability Analysis

Praveen Kumaar R^† and Swapna Singha Rabha^†

^†Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, India

Abstract. Post-combustion CO₂ capture using aqueous monoethanolamine (MEA) is one of the most mature technologies for reducing industrial carbon emissions. However, long-term operation is often limited by solvent degradation and corrosion, leading to reduced process efficiency, increased solvent consumption, and higher operational waste generation. From a circular energy perspective, improving solvent stability and extending solvent lifetime are essential for enhancing the sustainability of carbon capture systems. In this study, CO₂ absorption experiments were conducted in both semi-batch and continuous modes to investigate capture performance, mass transfer behaviour, solvent degradation, and corrosion in MEA-based systems under realistic operating conditions. Experiments were carried out in a stainless-steel packed column (5 cm diameter, 1 m height) using 10–30 wt% MEA solutions over a range of temperatures and inlet CO₂ concentrations. Initial CO₂ absorption efficiencies of 80–90% and CO₂ loadings of 0.45–0.50 mol CO₂ mol⁻¹ MEA were achieved; with prolonged operation, capture capacity declined by 25–35% due to solvent aging and degradation. (continued overleaf)

Energy-Based Screening of Advanced Solid Adsorbents for Sustainable CO₂ Capture Applications

Paridhi Goel^†, Praveen Kumaar R.^† and Swapna Singha Rabha^*,†

^†Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

* Corresponding author · srabha@iitm.ac.in

Abstract. Adsorption-based carbon capture has emerged as a promising alternative to conventional amine absorption, offering several advantages. In conventional temperature-swing adsorption (TSA) processes, regeneration is typically performed at a constant heating temperature, which often results in excessive thermal driving forces, irreversible heat transfer, and poor energy utilization; the large regeneration energy requirement during the desorption step remains a major challenge limiting the large-scale deployment of adsorption systems. The present work proposes a simplified thermodynamic framework for analyzing regeneration energy requirements in adsorption-based CO₂ capture systems, introducing the concept of pinch-based thermal management to define optimized desorption conditions during the regeneration of solid adsorbents. The model is employed to analyze different heating strategies, with the baseline constant-temperature case first validated against reported literature results; the validated model is then employed to evaluate various heating strategies and their influence on regeneration energy demand, desorption duration, and thermodynamic efficiency. The model framework is further extended to compare the regeneration behavior of various solid adsorbents such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), zeolitic imidazolate frameworks (ZIFs), and amine-functionalized silica adsorbents. The expected outcome of this work is the identification of adsorbent materials and regeneration strategies that offer lower specific energy consumption and improved thermodynamic performance, providing a simple yet effective platform for screening emerging adsorbents from an energy perspective and enabling a more performance-oriented evaluation rather than one based solely on adsorption capacity.

Multiscale Modeling Framework for Electrically Heated Steam Methane Reforming Reactor

T. Bhumana^†, S. De^‡, A. P. van Bavel^§, A. N. R. Bos^§ and H. Goyal^*,†

^†Indian Institute of Technology Madras, India  ·  ^‡Shell India Markets Private Limited, Bangalore, India  ·  ^§Shell Global Solutions International B.V., Amsterdam, Netherlands

* Corresponding author · goyal@iitm.ac.in

Abstract. The increasing availability of affordable renewable electricity offers a significant opportunity to decarbonize energy-intensive chemical processes. Among various electricity-to-heat technologies, including microwave and induction heating, Joule heating has emerged as a promising option owing to its high thermal efficiency, rapid thermal response, and scalability. While experimental studies have demonstrated the feasibility of electrically heated catalytic reactors, the development of computational design frameworks for reactor optimization and scale-up remains limited. In this work, a two-dimensional axisymmetric computational fluid dynamics (CFD) model is developed to investigate the coupled electro-thermal-species transport behavior in a Joule-heated steam methane reforming (SMR) reactor, incorporating the heterogeneous reaction kinetics proposed by Xu and Froment. (continued overleaf)

Scalable Azo-Dye Based Carbon Quantum Dot for Optical Management

Ayush George^† and Abhay Vijay Kotkondawar^*,†

^†Department of Chemistry, Institute of Chemical Technology–Indian Oil Odisha Campus, Bhubaneswar, India

* Corresponding author · av.kotkondawar@iocb.ictmumbai.edu.in; abhay.kotkondawar@gmail.com

Abstract. Azo dyes are a versatile class of organic compounds widely recognized for their intense coloration, photophysical properties, and broad applications in industrial and biomedical fields. The current investigation explores their potential as carbon dot precursors through a facile solvothermal synthesis approach, transforming the azo dye precursor under solvothermal conditions to facilitate carbonization and the formation of organic solvent-soluble carbon quantum dots (green-yellow CQDs). The developed method produced CQDs with a reaction yield of approximately 68% and exhibited strong fluorescence emission in the visible region. The physicochemical properties of the synthesized CQDs were comprehensively characterized using FT-NMR, HR-TEM, XPS, UV-DRS, and photoluminescence (PL) spectroscopy. Low-resolution TEM images revealed the formation of colloidal assemblies with average sizes ranging from 50 to 70 nm, while HR-TEM analysis indicated that the individual CQDs distributed within these assemblies possessed average particle sizes below 1.5 nm. The synthesized CQDs displayed pronounced fluorescence emission around 483 nm along with a high fluorescence quantum yield in DMF solution. Furthermore, a CQD-based luminescent film was fabricated using a poly(methyl methacrylate) (PMMA) matrix and successfully integrated onto a blue LED chip to construct a down-conversion light-emitting device; the Commission Internationale de l’Éclairage (CIE) chromaticity coordinates of the fabricated LED were determined to be approximately (0.27, 0.32). The excellent optical properties, solvent processability, and tunable fluorescence characteristics of azo-dye-derived CQDs highlight their potential applications in optical management, light-emitting devices, sensing, and advanced photonic technologies.

Assessing the Impact of Particle Size and Constituent Ratios of Mixed Household Waste on Syngas Production: A Hybrid Analysis

Srijan Sanjeev Shahane^†, Rohan Dutta^† and Vikranth Volli^*,†

^†School for Climate Action, Anant National University, Ahmedabad, Gujarat 382115, India

Abstract. India has complex waste management challenges due to its mixed waste streams. Thermochemical conversion pathways are effective for extracting value from this waste as gaseous or liquid fuels, with efficiency and product formation determined by process temperature and feedstock composition. In this ongoing study, the characteristics of a mixed feedstock and their impact on syngas production and quality in a high-temperature gasification system are explored. The feedstock consisted of mixed sawdust, low-density polyethylene (LDPE) garbage bags, and kraft paper bags, shredded and mixed in different ratios. For sawdust mixtures, moisture and volatile matter were 7.2–7.36% and 85–86.9%, respectively, with ash content between 1.4–2.1%; for kraft paper, these parameters were 4.478%, 89.1%, and 6.86%, respectively; and for the garbage bag sample, they were 0.395%, 87.96%, and 9.36%, respectively, with ash content attributable to fillers and additives. The results of the proximate analysis show that both particle size and feedstock composition influence output and reaction kinetics; moisture and volatile matter, along with particle size and mixture ratios, play a role in determining the quality of syngas produced. These findings will aid in identifying ideal feedstock pre-treatment conditions for chemical recycling.

Valorization of Waste Biomass to Hard Carbon Anodes for Sodium-Ion Batteries

Nithyasree Manohar^†,‡,§ and Nitin Muralidharan^*,†,‡,§

^†EMERGE Research Group, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India  ·  ^‡Centre for Resource Efficiency, Recyclability, and Circularity in Energy Transition, Indian Institute of Technology Madras, India  ·  ^§School of Sustainability, Indian Institute of Technology Madras, Chennai, India

* Corresponding author · muralidharan@iitm.ac.in

Abstract. The rising demand for cost-effective and sustainable energy storage solutions has necessitated the exploration of alternative battery technologies beyond traditional lithium-ion batteries. Sodium-ion batteries (SIBs) have emerged as a viable alternative for large-scale energy storage systems due to the natural abundance, extensive geographical distribution, and low cost of sodium resources. Among the numerous anode candidates, hard carbon has attracted considerable interest due to its high reversible capacity, suitable working potential, and compatibility with sodium-ion storage mechanisms. In this study, banana peduncle, an abundant agricultural waste biomass, is used as a sustainable precursor for the synthesis of hard-carbon anode materials. The biomass is initially subjected to acid hydrolysis to remove impurities and partially decompose lignocellulosic components, followed by potassium hydroxide (KOH) activation to develop a porous structure and increase the availability of active sites; the activated precursor is subsequently carbonized under an inert atmosphere to obtain hard carbon with a disordered microstructure favorable for sodium-ion storage. Structural and morphological characteristics of the synthesized materials are investigated using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The combined acid hydrolysis, chemical activation, and thermal carbonization processes are expected to produce hard carbon with enlarged interlayer spacing, abundant defect sites, and hierarchical porosity, facilitating sodium-ion diffusion and storage. This work presents a cost-effective, environmentally sustainable approach to valorize banana peduncle waste into high-value hard carbon materials and highlights its potential as an anode material for next-generation sodium-ion batteries.

DFT Study on Conversion of Lignin-Derived Compounds in Supercritical Water, Methanol, and Ethanol Environments

Praveen Kumar Reddy Annapureddy^† and Nanda Kishore^*,†

^†Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India

Abstract. The transformation of lignin-derived compounds into high-value chemicals is a crucial step in the development of sustainable biomass-based energy systems and circular bioeconomies. The thermodynamic feasibility of two representative lignin-derived conversion pathways – conversion of ferulic acid to cinnamic acid and guaiacol to cyclohexanone – was investigated in supercritical methanol and supercritical ethanol. Thermodynamic parameters such as the change in Gibbs free energy (ΔG) and change in enthalpy (ΔH) were determined at different temperature and pressure conditions mimicking supercritical processing. The calculated Gibbs free energy values for both reactions were negative under all investigated conditions, indicating thermodynamically favourable reaction behaviour regardless of the solvent environment; however, the values for supercritical methanol and ethanol were relatively more negative than for supercritical water, implying increased thermodynamic favourability and improved stabilisation of reactants and products in alcohol-based supercritical media. (continued overleaf)

Performance Evaluation of a Pilot-Scale Two-Column VPSA System for Post-Combustion CO₂ Capture Using Zeolite 13X Beads

R. Harish Ragavendran^†,‡, Parthiban V^†,§, Satyanarayanan Seshadri^†,§,‖ and Swapna Singha Rabha^†,§,‡

^†The Energy Consortium, Indian Institute of Technology Madras, Chennai, India  ·  ^‡Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, India  ·  ^§School of Sustainability, Indian Institute of Technology Madras, Chennai, India  ·  ^‖Department of Applied Mechanics & Biomedical Engineering, Indian Institute of Technology Madras, Chennai, India

Abstract. Post-combustion carbon capture is considered one of the promising approaches for reducing industrial CO₂ emissions and supporting sustainable energy transition strategies. In the present study, a pilot-scale Vacuum Pressure Swing Adsorption (VPSA) system integrated within a mobile containerized unit was experimentally investigated for cyclic CO₂ capture using zeolite 13X beads as the adsorbent material. The zeolite bead size ranged from 1.5–2.5 mm, and the adsorption columns possessed an internal diameter of 0.45 m with a total height of 1.5 m and a packed bed height of 0.70 m. The VPSA system consisted of two adsorption columns operated alternately under adsorption and vacuum desorption conditions to ensure continuous cyclic operation. A simulated flue gas mixture containing air and CO₂ in an 80:20 ratio was supplied from the bottom of the packed bed at a total flow rate of 125 SLPM using a compressor. During adsorption, selective adsorption of CO₂ occurred within the zeolite 13X packed bed, while regeneration was achieved using a vacuum pump under desorption conditions; the adsorption process exhibited exothermic characteristics, with bed temperatures reaching nearly 110°C during cyclic operation. System performance was evaluated over five consecutive adsorption–desorption cycles through breakthrough analysis, adsorption capacity, CO₂ production rate, pressure drop characteristics, and cyclic stability studies. The experimental investigation demonstrated stable VPSA operation with effective CO₂ separation under industrially relevant operating conditions, highlighting the potential of zeolite 13X-based packed bed systems for post-combustion carbon capture applications.

Production of Biofuel from Algal Biomass by Aqueous Phase Reforming

Taanisha Mukhopadhyay^† and Dr. Gourisankar Roymahapatra^*,‡,§

^†Department of Chemical Engineering, IIEST Shibpur, Howrah, India  ·  ^‡Department of Metallurgy and Materials Science Engineering, IIEST Shibpur, Howrah, India  ·  ^§Department of Applied Science and Humanities, Haldia Institute of Technology (Autonomous), Haldia 721657, West Bengal, India

* Corresponding author · grm.chem@gmail.com

Abstract. With the growth of the human population, the need for sustainable energy resources has increased substantially; large-scale utilisation of fossil fuels would leave few viable energy resources for future generations, making renewable and clean sources of energy – Green Energy Resources – essential. Biological hydrogen (H₂) production (BHP) enhancement through the use of nanoparticle (NP) supplements in the growth media has recently emerged as a promising approach; nanoparticles, including metal and metal oxide NPs, have shown significant improvement in BHP. (continued overleaf)

Machine Learning-Based Battery Second-Life Classification for Sustainable Electric Vehicle Ecosystems

Amartya R. Nair^†, Aditya V. Padwalkar^† and Anupam Sharma^*,†

^†School of Engineering, Chanakya University, Bengaluru, Karnataka, India

* Corresponding author · anupam.s@chanakyauniversity.edu.in

Abstract. The rapid growth of electric vehicles (EVs) has led to a significant increase in lithium-ion batteries, posing both environmental challenges and resource wastage concerns. Many batteries are removed from EV applications when their State of Health falls below 70%, yet they still have sufficient usable capacity for secondary applications such as stationary energy storage. This paper proposes an AI-driven Smart Battery Second-Life Decision System that enables classification of used EV batteries into reuse, repurpose, or recycle pathways. The system senses key battery parameters, including voltage, current, temperature, and internal resistance, using an embedded hardware platform; these inputs are processed through a machine learning model trained to estimate battery health metrics such as State of Health (SoH) and Remaining Useful Life (RUL). Based on predictive analytics, the system performs automated decision-making to determine optimal second-life utilization: batteries with higher health are redirected for reuse in EV or mobility applications, moderately degraded batteries are repurposed for stationary storage such as solar energy systems, and critically degraded batteries are sent for recycling. The proposed solution contributes to circularity in the battery industry by extending battery lifecycle, reducing waste, and improving resource efficiency, while enabling scalable and cost-effective decision intelligence for sustainable battery management in emerging EV ecosystems.

Deep Eutectic Solvent Electrolytes for Sustainable Lithium–Sulphur Batteries

Dipshikha Jana^†, Bibhas Kumar Nayak^† and Kshetramohan Sahoo^*,†

^†Department of Chemical Engineering, National Institute of Technology, Rourkela-769008

* Corresponding author · sahook@nitrkl.ac.in

Abstract. The rapid shift to green and renewable energy demands efficient storage solutions which must also be sustainable. Lithium–sulphur (Li–S) batteries are attractive options due to their high theoretical energy density, low cost, and sulphur abundance. However, conventional electrolytes suffer from polysulfide shuttle, instability, and environmental concerns. This work explores deep eutectic solvent (DES)-based electrolytes as greener alternatives, offering low volatility, non-toxicity, and improved solvation behaviour. We focus on designing and optimizing DES formulations to mitigate electrolyte–electrode interaction challenges, aiming to enhance cycle life, stability, and efficiency. The study aims to advance Li–S batteries as a sustainable option for large-scale renewable energy storage.

Recovery of Active Cathode Material from Spent Mobile Lithium-ion Batteries using a Custom-made Ternary Deep Eutectic Solvent

Appurva K^*,†, Rajesha P M^†, P Hemanth^†, V M Aravind^†, Raju K Gupta^† and Sudhir H Ranganath^†

^†Bio-INvENT Lab, Department of Chemical Engineering, Siddaganga Institute of Technology, Tumakuru, Karnataka, India  ·  Department of Chemical Engineering, Indian Institute of Technology Kanpur, U.P., India  ·  Department of Sustainable Energy Engineering, Indian Institute of Technology Kanpur, U.P., India  ·  Chandrakanta Kesavan Centre for Energy Policy and Climate Solutions, Indian Institute of Technology Kanpur, U.P., India  ·  Tvastra InnoTech Solutions Pvt. Ltd., Tumakuru, Karnataka, India

* Corresponding author · 1si23ch038@sit.ac.in

Abstract. Lithium-ion batteries (LiBs) are integral to modern technology, powering a broad array of devices, including mobile phones, laptops, electric vehicles, and systems for renewable energy. However, their widespread utilisation presents considerable environmental and social challenges, notably due to the reliance on scarce and hazardous materials that necessitate energy-intensive extraction and processing methods. Recycling of LiBs emerges as a viable strategy to address these issues, offering a method to reclaim valuable metals and reduce the demand for the extraction of fresh raw materials. Furthermore, recycling initiatives have the potential to generate economic opportunities and foster innovation within the battery sector. Conventional recycling methods, including pyrometallurgical and hydrometallurgical processes, are energy-intensive and hazardous. To address this, we developed a novel Ternary Deep Eutectic Solvent (TDES), which is green and composed of Hydrogen Bond Donors and Acceptors in a specific molar ratio. This solvent offers several advantages, such as low freezing points, high thermal stability, low volatility, and tunability. Spent mobile phone batteries were dismantled under water to safely recover active cathode material (ACM), which contained Li, Co, Ni, and Mn. The TDES achieved rapid leaching of the ACM at 90°C within 30 minutes and at a significantly lower operating temperature (90°C) than traditional methods (700°C). High extraction efficiencies of ~99% were achieved for Li⁺, Co²⁺, Ni²⁺, and Mn²⁺. Subsequent stage-wise selective precipitation allowed recovery of high-purity metal oxides of Nickel, Manganese and Cobalt and Lithium is selectively precipitated as Lithium carbonate. Kinetic analysis indicated that leaching was controlled by both liquid-film diffusion and product-layer diffusion for Li and Co. The same TDES was applied to LiNi_0.85Co_0.1Al_0.05O₂ (NCA), yielding extraction efficiencies of ~68% Ni, ~64% Co, ~92% Al, and ~70% Li, aligning with elemental analysis. Further optimisation of metal recovery from NCA systems is under current investigation. Overall, the developed TDES demonstrates strong potential as a sustainable and efficient medium for LIB recycling.

Direct Electrochemical Extraction of Lithium Metal from Black Mass Leach Liquor

Lakshmi Narayana Manickavasagam^†,‡, Abraham Samuel Thangadurai^†,‡ and Nitin Muralidharan^*,†,‡

^†EMERGE Research Group, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, India  ·  ^‡Centre for Resource Efficiency, Recyclability & Circularity in Energy Transitions, Indian Institute of Technology Madras, Chennai, India

Abstract. Electrification of transport and grid-scale energy storage has resulted in the manufacturing and utilization of billions of Li-ion batteries. With increasing electrification to meet net-zero demands, the number of batteries required is also increasing exponentially year by year, and at this rate, millions of tonnes of spent or dead lithium batteries and thousands of tonnes of production scrap would be generated in the next few years. (continued overleaf)

Sustainable Benign Route to Utilize Spent Lead-Acid Batteries for Producing PbCl₂ Electrodes for Next-Generation Li-Ion Batteries

Andrews Cyril A^†, K. K. Sahu^‡ and Srijan Sengupta^*,§

^†Centre for Circularity, School of Sustainability, Indian Institute of Technology Madras, India  ·  ^‡CSIR–National Metallurgical Laboratory, Jamshedpur, India  ·  ^§Department of Materials, Rishabh Centre for Research and Innovation in Clean Energy, IIT Jodhpur, India

Abstract. In response to the rising demand for energy storage, researchers are prioritizing improving lithium-ion batteries’ specific energy and volumetric energy capacity. Lead (Pb) stands out as a promising anode option due to its high gravimetric capacity of 569 mAh/g and volumetric capacity of 6452 mAh/g, offering significant potential to enhance the performance of these batteries. Upgrading from discarded lead-acid batteries (LABs) to more contemporary lithium-ion batteries will be an alternative approach to meeting growing demand; LABs have a high lead content, resulting in the highest recovery rate during extraction. Pyrometallurgical processes remain the primary method for lead recycling; however, they pose several drawbacks, including harmful environmental impacts, such as the emission of lead dust and sulfur dioxide (SO₂), and high energy consumption. A few recently developed environmentally friendly hydrometallurgical processes operating at near-ambient temperatures have shown great potential for recovering lead from spent lead-acid batteries; direct dissolution of lead through brine leaching offers a promising, clean recovery pathway for recovering lead chloride from lead-acid batteries. In this work, LAB paste material was separated and dissolved in brine solution to produce PbCl₂ through crystallization, a green recycling technique that transforms waste into resources for active anode material in lithium-ion batteries. A novel strategy is explored to use recovered lead halide (PbCl₂) with two-stage lithiation, offering superior electrochemical performance as a replacement for pristine Pb in the negative electrode.

Efficient Xtraction and Treatment for Recovery of Advanced Critical-Materials and Technologies (EXTRACT)

Abraham Samuel Thangadurai^† and Nitin Muralidharan^*,†

^†EMERGE Research Group, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Abstract. The global scramble to secure tech metals, battery minerals, and rare earths is encountering a significant bottleneck, and current extraction routes – large, environmentally destructive mines or reliance on risky overseas supply chains – are no longer sufficient. This challenge is addressed by the EXTRACT (Efficient Xtraction and Treatment for Recovery of Advanced Critical-materials and Technologies) programme, through the development of integrated hydrometallurgical methodologies for the efficient extraction, purification, and valorization of critical materials from complex feedstocks, primarily end-of-life lithium-ion batteries and spent electronic assemblies. The approach uses smart chemical recycling, green solvents, and cleaner processes to recover high-purity critical materials from commonly overlooked sources such as low-grade ores, old electronics, and industrial waste, substantially reducing the energy and toxic waste normally associated with metal refining. (continued overleaf)

The results reveal that the microstructures of SG-2800 and SG-3000 are strongly dependent on the graphitization temperature. The SG graphitized at 3000 °C has a perfectly ordered layered structure with a high degree of graphitization, as found from the XRD and Raman studies. SG-3000 is explored as an anode material for a lithium-ion battery (LIB) application. The maximum reversible capacity of 305 mAh g⁻¹ at a current rate of 0.1C was obtained along with 94% capacity retention even after 100 cycles. These findings highlight the potential of lignite coal as an inexpensive and scalable precursor for producing high-performance synthetic graphite suitable for advanced LIB applications.

Hierarchical Flower-like Nanosheet-Stacked Ni-based Bimetallic Metal–Organic Framework Electrode for High-Energy Hybrid Supercapacitors

Kajal Samdhyan^*,†, Shiwani Khokhar^†, Prakash Chand^*,‡ and Hardeep Anand^†

^†Department of Chemistry, Kurukshetra University, Kurukshetra, Haryana 136119, India  ·  ^‡Department of Physics, National Institute of Technology, Kurukshetra, Haryana 136119, India

Abstract. Bimetallic MOFs stand out as the most promising approach since they combine the synergistic effect of two metals. Doping nickel (Ni) with a dopant is a common practice to modify the electrical and chemical properties of the resulting Ni-MOF. For doping, the size of the dopant should be comparable to nickel, which minimizes the lattice distortion and maintains the structural integrity of the MOF material. The ionic radii of Co²⁺ and Ni²⁺ are very similar, with Co²⁺ having an ionic radius of ≈79 pm and Ni²⁺ ≈83 pm. The incorporation of cobalt into the nickel framework improves both the electrochemical activity and structural properties of the material, making it more suitable for applications such as supercapacitors and batteries. The outstanding electrochemical performance of these hybrid materials can be attributed to (i) the synergistic effect between the metals, which enhances electrical conductivity; (ii) the presence of mesopores, which facilitates the easy diffusion of electrolyte; and (iii) a large surface area and pore volume, which provide significantly more electroactive sites. The flower-like morphology provides a larger surface area compared to the pristine Ni-BDC, facilitating more active sites for electrochemical reactions. Flower-like structures composed of nanosheets can be synthesized by incorporating 0.05 M cobalt solution into synthesized Ni-BDC. The optimized Co@Ni-BDC demonstrated remarkable electrochemical performance, delivering impressive specific capacitances of 2753.3 F/g at a current density of 3 A/g. The retention remained impressively high for Co@Ni-BDC, with 84% capacity retention even after 5000 cycles.

Optimization using central composite design identified the ideal pretreatment conditions (508 W, 4 min, 7.87 wt% biomass, 0.87 MSC) that resulted in maximum saccharification yield (RSY of 601 mg g⁻¹ and GY of 231 mg g⁻¹). The optimized cellulose-rich SCL biomass was further converted to LA using a g-C₃N₄-O 50% photocatalyst, which increased the LA yield to 345.39 mg g⁻¹ while reducing the formic acid yield to 30.45 mg g⁻¹. Furthermore, techno-economic analysis (TEA) revealed that the estimated net production cost of LA was $3.32 kg⁻¹, with an ROI of 14.43% and a payback period of 6.93 years; sensitivity analysis revealed that raw material costs and LA market price significantly influenced the economic viability. Overall, this work demonstrates a sustainable and economically feasible strategy for producing lactic acid from sugarcane leaf biomass through integrated microwave pretreatment and photocatalysis.

Towards Agricultural Circularity: Biomass-Derived Biodegradable Mulch Sheets with Potential for Photocatalytic Soil Remediation

R. Janani^† and Vidya K. Shetty^*,†

^†Department of Chemical Engineering, National Institute of Technology Karnataka, Surathkal, Mangaluru, India

Abstract. Agricultural mulching sheets are widely adopted for enhancing crop productivity, offering benefits such as weed control and moisture retention in soil. However, commercial mulching sheets made from synthetic polymers such as low-density polyethylene, polybutylene adipate terephthalate, and polybutylene succinate contribute to secondary pollution in the form of micro/nano plastics in the soil after use. The present work focuses on the development of biodegradable cellulose-based mulching sheets made from agricultural residues such as sugarcane bagasse, corn husk, rice straw, and banana peduncle as environmentally sustainable alternatives, with the additional objective of in-situ photocatalytic soil remediation. The biomass-derived fibers are subjected to alkaline treatment, bleaching, and homogenization to produce micro-cellulose-rich pulp (MCP); the fiber morphology and hydrodynamics of the MCP are further optimized by the inclusion of biopolymer binders such as polyvinyl alcohol and sodium alginate, which enhance dispersion, consistency, and mechanical integrity during sheet formation. Among the tested precursors, corn husk and sugarcane bagasse show improved homogeneity and processability. The key innovation of the present work is the integration of MCP with a metal-free, soil-friendly photocatalyst, which endows the sheets with soil remediation functionality by photocatalytically degrading pesticide residues present on the soil surface. In summary, this work establishes a sustainable material framework for the development of photocatalyst-integrated cellulose-based mulches with enhanced environmental functionality, advancing both agricultural practice and environmental preservation.

Surface functionalization of natural fibres has proven to be an effective approach for enhancing their strength, stiffness, and interfacial bonding characteristics while retaining their inherent biodegradability. In this study, surface modification of single jute fibres was performed using hydroxyapatite (HAP), a natural calcium mineral commonly used in bone tissue repair surgeries; earlier reports have shown that HAP has excellent biocompatibility and mechanical performance, and could therefore act as an eco-friendly interface modifier for natural fibres. Surface modification using stearic acid in jute fibre was also carried out to impart moisture resistance and enhance interfacial properties; stearic acid is a biocompatible saturated fatty acid whose incorporation in several matrices has shown an improvement in hydrophobic character. The presence of HAP and stearic acid on the surface of jute fibres was confirmed by FTIR analysis and SEM images, and studies on both HAP- and stearic-acid-coated jute fibres have shown a significant enhancement in tensile strength and thermal properties. Overall, HAP and stearic acid surface modification will help improve the interfacial fibre–matrix bond, thereby broadening the scope of application of natural fibres in composite systems.

Vortex-Induced Vibration Response of a Buoyancy-Assisted Deep-Water Marine Riser Subjected to Varying Currents

Anu Sugathan^† and K. G. Vijay^*,†

^†Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai, India

* Corresponding author · vijaykg@iitm.ac.in

Abstract. This study investigates the sensitivity of vortex-induced vibration (VIV) response in a buoyancy-assisted deep-water drilling riser subjected to sheared currents. The riser is modelled as a tensioned Euler–Bernoulli beam with coupled cross-flow (CF) and in-line (IL) responses, while hydrodynamic forcing is represented using a wake oscillator model validated against the experimental results of Trim et al. A 1200 m riser fitted with buoyancy modules over the upper 300 m is analysed alongside a bare-riser configuration for various shear parameters. The results indicate that increasing shear reduces the global coherence and amplitude of the CF response, with an overall reduction of approximately 57% between the lowest and highest shear cases; in contrast, the IL response exhibits a non-monotonic trend, increasing at intermediate shear before decreasing at high shear levels, with enhanced multi-frequency behaviour also observed with increasing shear. Compared with the CF response, the IL response shows greater sensitivity to shear in terms of both vibration amplitude and the location of peak response. The effectiveness of buoyancy modules in suppressing VIV is found to depend strongly on the shear profile, being most effective under low-shear conditions and less effective at higher shear levels. These findings highlight that riser designs based on a single representative current profile may not provide conservative predictions across varying operating conditions; therefore, shear-aware VIV assessment using a representative range of current profiles is recommended for buoyancy-assisted deep-water drilling risers.

Coal-Incorporated Polymer Composites as Circular Economy Alternatives to Wood-Plastic Composites

Shubham Jaiswal^† and Ethayaraja Mani^*,†,‡,§

^†Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India  ·  ^‡Centre of Excellence in Biodegradable Packaging, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India  ·  ^§School of Sustainability, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India

* Corresponding author · ethaya@iitm.ac.in

Abstract. The global wood-plastic composite market, valued at approximately USD 10 billion and growing rapidly, faces persistent challenges due to its reliance on wood flour as a primary filler. This material is inherently flammable, prone to biological decay, and degrades under high heat. Meanwhile, large-scale coal preparation plants generate millions of tonnes of coal fines and reject material annually, which are typically treated as low-value waste with limited use. This study introduces coal-incorporated polymer composites as a circular-economy solution that addresses the performance gaps of conventional wood-plastic composites and valorizes an abundant domestic industrial by-product. Following detailed characterization, we will modify the coal to improve its compatibility with plastics. These tailored fillers will then be blended at varying loadings using standard molding techniques. The resulting composites will be evaluated for structural strength, thermal resilience, and fire resistance. Leveraging coal’s carbon-rich structure, we anticipate improved flame retardancy and heat tolerance, reducing dependence on expensive chemical additives. Additionally, this waste-derived filler offers clear economic benefits through its low cost and local availability. Ultimately, this research aims to convert industrial coal refuse into valuable structural materials, lowering disposal burdens, fostering sustainable manufacturing, and supporting national resource efficiency objectives.

From Recycling to Second-Life: Assessing Challenges and Policy Gaps in the Electric Vehicle Battery Reverse Supply Chain

Bindhu A.^†,‡ and Arshinder Kaur^†,‡

^†Centre for Circularity, Indian Institute of Technology Madras, Chennai, India  ·  ^‡Department of Management Studies (DoMS), Indian Institute of Technology Madras, Chennai, India

Abstract. This paper presents a review of reverse supply chains (RSCs) for used electric vehicle batteries. It integrates existing knowledge across battery recycling, battery reuse, second-life applications, material recovery, and policy frameworks. The review highlights multi-dimensional uncertainties in return quality, quantity, costs, and regulation that determine an efficient RSC or used electric vehicle batteries. While recycling shows strong technical feasibility, its industrial scalability remains limited, and the logistics costs dominate the economics. Second-life deployment at 70–80% residual capacity, although it is established, in reality is constrained by liability, standardised state-of-health assessment, and pricing. Policy analysis shows insufficiently regulated global regulations. The paper concludes by identifying research gaps in integrating scalable supply chain logistics, adopting regulation, and viable second-life business models.