A machine learning-assisted prediction of potential biochar yield subjected to the physicochemical properties of biomass Tanushka Florence Panicker, Deepraj Sarkar, Rajashree Krishna, Ranjeet Kumar Mishra, Srinivas Kini Manjeshwar, Abhishek Sharma Fuel, 2026 The thermochemical process of slow pyrolysis is commonly employed to convert organic waste into biochar. This study utilised Pearson correlation for feature selection and applied seven machine learning models, such as Random Forest Regression, Decision Tree Regression, Bagging Regression, Extreme Gradient Boost Regression, Support Vector Regression, Gradient Boost Regression, and Extra Tree Regressor, to predict biochar yield based on 13 selected variables. Partial dependence analysis provided insights into the relationships between feature variables. RFR, GBR, XGBR, BaggingR and ETR demonstrated superior performance, achieving R 2 values above 0.90 for the test set and over 0.90 for the training set. Partial dependence plots revealed that pyrolysis conditions have a more substantial influence on the biochar yield than biomass components. Interestingly, temperature was found to be a crucial element in maximising the biochar yield. This study signifies the effectiveness of integrating approaches based on machine learning frameworks to optimise thermochemical conversion processes, demonstrating their potential for efficient pyrolysis testing and predictive process modelling, thereby promoting sustainable biochar production.
Production and characterisation of char derived from pyrolysis of waste residue for removal of nitrates from wastewater Yashasvi Trivedi, Abhishek Sharma, Manisha Sharma, Ranjeet Kumar Mishra, Jyeshtharaj B Joshi, Akhilendra Bhushan Gupta, Achintya Bezbaruah, Kalpit Shah Environmental Research Communications, 2026 This study presents an innovative valorisation pathway for two challenging waste streams, Refuse-Derived Fuel (RDF) and biosolids, by converting them into highly efficient adsorbents for nitrate removal from wastewater. Chars produced via pyrolysis at 500 °C and 700 °C were structurally modified using ZnCl 2 at varying impregnation ratios (1:1, 2:1, 3:1), significantly enhancing their adsorption uptake capacity and functional groups, as confirmed by surface area determination by Brunauer-Emmett-Teller (BET, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). analysis. The batch adsorption experiments were conducted under varying conditions of pH, temperature, initial nitrate concentration, and adsorbent dosage. Among the samples, RDF-derived char (RDF500-2) demonstrated a maximum adsorption capacity of 160 mg g −1 at optimal conditions (pH 7, 35 °C, adsorbent dose 5 g l −1 ), outperforming various conventional low-cost adsorbents. Adsorption followed pseudo-second-order kinetics and was best described by the Sips isotherm model (R 2 = 0.99), indicating a mixed monolayer-multilayer chemisorption mechanism. Thermodynamic parameters confirmed the process as spontaneous and exothermic. Importantly, the modified RDF and biosolid chars were enriched with additional −COOH and −C=O groups, which were responsible for nitrate binding, demonstrating tailored surface chemistry for environmental applications. The present study introduces sustainable, circular-economy-based adsorbents derived from problematic urban and industrial wastes and offers a low-cost solution for decentralised nitrate removal. These results contribute to a new direction in waste-to-resource innovation, aligning with environmental remediation and waste minimisation policies.
Treatment of Landfill Leachate Using an Advanced Microwave Reactor Coupled with a Batch and Continuous Algal Photobioreactor Binay Kumar Tripathy, Ranjeet Kumar Mishra, Mathava Kumar ACS Omega, 2026 Landfill leachate poses a significant environmental challenge due to its high concentrations of organic pollutants, nutrients, and toxic metals. This study presents a hybrid microwave-coagulation-algal (M-C-A) photobioreactor system that operates in batch and continuous-flow modes for effective leachate treatment. The hybrid system integrates microwave-assisted removal, coagulation, and algal bioremediation to enhance pollutant removal efficiency. Furthermore, the microwave pretreatment achieved 83.6% ammonia removal at 95 °C, thereby reducing leachate toxicity and enhancing the subsequent biological treatment. Coagulation using FeCl3 further removed 76% of the COD and 90% of the turbidity. The pretreated leachate was further subjected to algal photobioreactor treatment, during which optimal growth occurred at a 50% leachate dilution, resulting in 77% total nitrogen (TN) removal and 17% total phosphorus (TP) removal. In the continuous-flow algal sequencing batch reactor (ASBR), the maximum TN and TP removal rates were 23.50 and 2.66 g/m3/d, respectively. The heavy metals Zn2+ and Pb2+ were removed, with Fe removal reaching up to 92%. The harvested algal biomass exhibited a calorific value of 16.50 MJ/kg, indicating its potential for biofuel production. Finally, the integrated M-C-A system demonstrated efficient removal of organic matter, nutrients, and metals, while enabling biomass valorization. The continuous flow operation ensures scalability and operational stability, making it a promising sustainable technology for managing landfill leachate and recovering resources.
Catalytic co-pyrolysis of teak wood sawdust and polystyrene: Effect of process parameters on yield and properties of pyrolysis oil Tanushka Florence Panicker, Ranjeet Kumar Mishra Energy Nexus, 2026 • Waste biomass and plastics were co-pyrolysed for pyrolysis oil production. • The maximum pyrolysis oil (51.58 wt.%) was found to be 30 wt.% PS blending. • The use of catalysts at 5 and 10 wt.% promoted selectivity for aromatic hydrocarbons. • Characterisation of char confirmed enhanced properties by blending PS. The present study explores the thermo-catalytic co-pyrolysis of waste teak wood sawdust (TWS) and polystyrene (PS) using a semi-batch reactor. The experiments were performed at varying temperatures (450-550 °C), biomass-to-plastic ratios (10-50 wt.%), and catalyst loadings (5-20 wt.% of CaO and MgO). The physicochemical analysis of TWS and PS revealed HHV values of 19.50 and 43.18 MJ kg -1 , and oxygen contents of 45.40% and 0.43%, respectively. TGA results showed major biomass degradation occurring between 150-550 °C, while the FTIR analysis identified key functional groups, including C-H, C=C, -OH, and C=O. Thermal pyrolysis at 500 °C produced a 46.05% liquid yield, while the addition of 30 wt.% PS increased yield by 5.53%. The resultant pyrolytic oil exhibited an improved carbon content (81.37%) and a higher heating value (37.85 MJ kg -1 ). The GC-MS analysis demonstrated a 59.69% increase in hydrocarbon yield at 30 wt.% PS while acids and ketones reduced by 4.58% and 9.74%, respectively. The addition of CaO (5 wt.%) and MgO (10 wt.%) enhanced the deoxygenation, aromatisation, and cracking reactions, resulting in selectivity towards aromatic hydrocarbons. The catalytic pyrolytic oil yielded 62% total hydrocarbons, with the aromatic fraction accounting for 56% of the total. The NMR study further confirmed the shifting of the hydrogen from oxygen-containing compounds towards aromatic structures. Furthermore, blending PS at a dynamic ratio decreased the char yield, whereas adding catalysts increased it. The catalytic char showed increased ash content and demonstrated alkaline pH. Overall, the thermo-catalytic co-pyrolysis has significant potential to contribute to the circular economy by converting waste into renewable fuels and chemicals.
Thermal degradation behaviour and kinetic analysis of effluent treatment plant sludge towards sustainable bioenergy potential Gaurav Singh, Ranjeet Kumar Mishra, Neeraj Kumar Energy Nexus, 2026 Effluent treatment plant sludge (ETPS) is a significant byproduct of the pulp and paper industry and has been investigated to assess its thermal degradation behaviour, kinetic parameters, and bioenergy recovery potential. Physicochemical characterisation revealed lower moisture content (4.40 wt.%), a higher volatile content (67.79 wt.%), and a significant ash fraction (19.22 wt.%), rich in catalytically active alkali metals. Thermogravimetric analysis at 10–30 °C/min showed three distinct stages: dehydration (30–150 oC), active devolatilization (150–700 oC), and char stabilisation (>700 oC), with decomposition temperatures shifting higher at elevated heating rates due to kinetic effects. Furthermore, to capture the complex, multi-step reactions, eight iso-conversional kinetic models (KAS, OFW, FM, DAEM, STM, TM, VZM, and AVIC) were employed. The activation energy varied (139–350 kJ/mol) with conversion (0.1–0.8), confirming heterogeneous decomposition behaviour. The apparent average activation energies (185–225 kJ/mol) indicate moderate to high energy requirements influenced by inorganic interactions. Master plot analysis revealed a shift from diffusion-controlled mechanisms at early conversions to nucleation and interfacial reactions at higher conversions. Lastly, thermodynamic analysis indicated that ETPS pyrolysis is endothermic (ΔH > 0), non-spontaneous (ΔG>0), and disorder-promoting (ΔS>0), requiring continuous heat supply. These results demonstrate the technical feasibility of ETPS valorisation through pyrolysis while highlighting the need for process optimisation to overcome ash-related operational challenges.
Co-pyrolysis behaviour and kinetic analysis of waste mango seeds and low-density polyethylene for their bioenergy potential Soham Basu, Sampath Chinnam, Ranjeet Kumar Mishra, M. Srinivas Kini Bioresource Technology Reports, 2026 The increased accumulation of agricultural residues and plastic waste highlights the need for sustainable conversion methods. This study investigates the pyrolysis behaviour and kinetic characteristics of waste mango seeds (MS), low-density polyethylene (LDPE) and their co-pyrolysed blends (10–30 wt%) for bioenergy recovery. Thermogravimetric analysis revealed multistage degradation between 200 and 600 °C, with higher heating rates shifting the decomposition peaks towards higher temperatures due to thermal lag. Kinetic characteristics using KAS, OFW, FM, TG, DAEM, and VZ models revealed average activation energies of 208–215 kJ/mol for MS and 179–219 kJ/mol for LDPE. Co-pyrolysis exhibited strong synergistic effects: MS + LDPE-20 wt% blend showed reduced activation energy (105.93 kJ/mol), indicating enhanced degradation, while 10 wt% blend demonstrated the highest activation energy (268.67 kJ/mol), suggesting improved stability. Thermodynamic evaluation confirmed all reactions were endothermic and non-spontaneous. The MS + LDPE-20 wt% blend demonstrated optimal energy efficiency, reduced activation energy, and enhanced product yield, thereby supporting co-pyrolysis as a viable strategy for sustainable energy production. • Co-pyrolysis of mango seed and LDPE enhances bioenergy recovery efficiency. • MS + LDPE 20 wt% shows the lowest activation energy (105.93 kJ/mol). • Activation energy varies 83–269 kJ/mol across blends and models. • Thermogravimetric data reveal multi-stage degradation (200–600 °C). • Reactions are endothermic and non-spontaneous with a positive entropy shift.
Life cycle assessment of industrial wastes and wastewater Yash Misra, Ranjeet Kumar Mishra, Ravi Sankannavar, D. Jaya Prasanna Kumar Integrated Biotechnological Solutions for the Treatment of Industrial Wastewater for A Healthy and Sustainable Environment, 2025
