Faculty Publications
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Item SWAT Modeling and Water Quality Analysis of Meenachil River, Kerala(Springer Science and Business Media Deutschland GmbH, 2022) Sujana, P.V.; Surenjan, A.The Meenachil River is an important river serving Central Kerala. The rapid growth of population and change in land use have had an adverse effect on the river basin. A hydrological research in Meenachil River Basin (MRB) would aid in implementing an enhanced management program to prevent degradation of soil and water resources in the area. Soil and Water Assessment Tool (SWAT) modeling for streamflow has done in MRB for analyzing the water quality of the river. Using the SuFi2 algorithm in SWAT-CUP, the model was successfully calibrated and validated for Kidangoor gauging station. The model was calibrated during a ten-year period (1997–2006) and verified over a nine-year period (2007–2015). As reflected by coefficient of determination (R2) and Nash–Sutcliffe simulation efficiency (NSE) values, model predictions done remarkably efficient on monthly basis during the calibration and validation periods. The R2 and NSE for the simulated monthly streamflow are 0.79 and 0.77 for the calibration period, and 0.82 and 0.75 for the validation period. The calibrated model was used to study the effects of landscape, climate condition, and fertilizer application on sediment and nutrient loadings. From the investigation, it was observed that hydrological processes play an important role in the transport of pollutants and fertilizer which led to excessive nutrient loadings in the river. The model performs effectively, indicating that it can be used to estimate streamflow in MRB and provide knowledge about the water quality under various land scape and climate conditions. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Application of circular economy in wastewater treatment using biochar based adsorbent derived from sewage sludge(Institute of Physics, 2022) Kenchannavar, P.; Surenjan, A.The Circular Economy intends to reuse wastewater and recover resources and energy from the sludge in the wastewater sector. The conversion of sewage sludge into biochar by pyrolysis technique is a sustainable, environmentally friendly option for sewage sludge management. In the current work, biochar was produced by co-pyrolyzing sewage sludge and coconut shell, and it was then utilized as an adsorbent to eliminate methylene blue (the model pollutant) from wastewater. The sewage sludge is abundant in functional groups and metal ions, and the addition of coconut shells increased the porosity of the adsorbent. The biochar produced by mixing coconut shell and sewage sludge in the ratio1:1 showed higher adsorption capacity compared to biochar obtained from pure sewage sludge; hence the co-pyrolyzed biochar was used for further studies. The morphology and functional groups present on biochar were examined using SEM and FTIR analysis. The kinetics and mechanism of methylene blue adsorption was adequately explained by the pseudo-second-order kinetic model. Using the Langmuir isotherm model, the maximal adsorption capacity of the methylene blue dye on biochar was observed to be 31.64 mg/g. © Published under licence by IOP Publishing Ltd.Item Photocatalytic Reactor Modelling Incorporating Computational Fluid Dynamics (CFD) for Water and Air purification: A Concise Review(Springer, 2025) Pandey, P.; K, K.P.; Mohanan, S.; Surenjan, A.Photocatalysis is a potent, advanced oxidation process that is effective in converting hazardous organic contaminants into non-toxic end products, offering a sustainable solution for water and air purification. The degradation process in photocatalysis is primarily influenced by several critical factors, including the illumination source, catalyst (either in the form of a slurry or immobilized), the pH range, and reactor design. Numerous costly, time-consuming, and difficult-to-perform experiment trials are conducted in the laboratory to optimize these operating parameters. Computational fluid dynamics (CFD) can be used to surpass these limitations. CFD has several advantages compared to experimentation, such as the capability to conduct many simulations, efficient use of time, cost-effectiveness, and the ability to simulate challenging conditions (such as high temperature, high pressure, or hazardous environments) in various reactor designs. Furthermore, CFD enables the analysis of spatial and temporal variation in independent variables, including velocity variation, reactant concentrations, and light intensity, which provides insights into the reactor. CFD is a popular tool in the field of reactor design and optimization. Its applications include the analysis of flow patterns, the modelling of mass transfer phenomena, and the scaling up of reactor systems to provide efficient designs. This review aims to provide insight into the basic photocatalytic process, the correlation between the photoreactor concept, reaction kinetics, irradiation scenarios (irradiation modelling) and the photocatalytic process parameters (pollution degradation conditions, pollutant type and concentration, different hydrodynamic modelling). © The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd. 2025.Item An efficient system for electro-Fenton oxidation of pesticide by a reduced graphene oxide-aminopyrazine@3DNi foam gas diffusion electrode(Elsevier B.V., 2020) Senthilnathan, J.; Younis, S.A.; Kwon, E.E.; Surenjan, A.; Kim, K.-H.; Yoshimura, M.A stable rGO-AmPyraz@3DNiF gas diffusion electrode was prepared via modification of 3D nickel foam (3D-NiF) with aminopyrazine functionalized reduced graphene oxide (rGO-AmPyraz) for the electro Fenton (EF) process. The generation capacity of H2O2 and OH radicals by this electrode was assessed relative to 3DNiF and rGO-AmPyraz@indium tin oxide (ITO) electrodes and with/without a coated Fe3O4 plate. The rGO-AmPyraz@3DNiF electrode showed the maximum production of these radicals at 2.2 mmol h?1 and 410 ?mol h?1, respectively (pH 3) with the least leaching of Ni2+ such as < 0.5 mg L?1 even after 5 cycles (e.g., relative to 3DNiF (24 mg L?1). Such control on Ni ion leaching was effective all across the tested pH from 3 to 8.5. Its H2O2 generation capacity was far higher than that of the nanocarbon supported on commercially available ITO conductive glass. The mineralization of dichlorvos (at initial concentration: 50 mg L?1) was confirmed with its complete degradation as the concentrations of the end products (e.g., free Cl?1 (5.36 mg L?1) and phosphate (12.89 mg L?1)) were in good agreement with their stoichiometric concentration in dichlorvos. As such, the proposed system can be recommended as an effective electrode to replace nanocarbon-based product commonly employed for EF processes. © 2020 Elsevier B.V.Item CFD modelling of an immobilised photocatalytic reactor for phenol degradation(IWA Publishing, 2023) Devipriya, B.; Mohanan, S.; Surenjan, A.Photocatalysis is an advanced oxidation process, which has been gaining attention as a sustainable technology for tackling pollution. Optimum design, fabrication and scaling up of novel photocatalytic reactors are faced with problems such as fabrication cost and numerous experimental trials for optimisation. Computational fluid dynamics (CFD), a computer simulation technique can ease the process of scaling up photocatalytic reactors. The current study focuses on CFD modelling of a serpentine flow path photocatalytic reactor with curved baffles for phenol degradation. The investigation compared different reactor configurations to finalise the optimum design with maximum removal efficiency. Initially, a simple cuboidal reactor was chosen with an efficiency of 27%. However, with a serpentine flow path being introduced, the reactor displayed an improved efficiency of 42%. The addition of baffles improved flow homogeneity and degradation efficiency. The investigation showed that serpentine flow increased the residence time and fluid mixing, while the curved baffles prevented flow channelisation, which enhanced the degradation efficiency. Efficiencies corresponding to different baffle types and geometry were also compared and the final reactor design chosen was a horizontal curved baffled serpentine flow reactor with a flow rate of 0.3 L/s and improved efficiency of 43.1% for a residence time of 18.44 s. © 2023 The Authors.Item Green synthesis, characterisation, and performance evaluation of ZnO/TiO2 nanocomposite for cationic and anionic dye removal from aqueous solutions under solar irradiation(IWA Publishing, 2024) Anil, K.; Surenjan, A.Utilising plant extract for the synthesis of nanocomposite shows great potential as a viable substitute for conventional chemical method. In this study, ZnO/TiO2 composite of three different weight ratios (1:2, 1:1, and 2:1) were green synthesised using hibiscus leaf extract as the capping agent. The synthesised composites were characterised using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS), Energy Dispersive X-ray Spectrometer (EDS), and Fourier Transform Infrared Spectroscopy (FTIR). XRD results confirmed the presence of wurtzite ZnO and anatase TiO2 in the composite. FTIR and FESEM analysis confirmed the formation of the composite. The composite was used for the removal of methylene blue and methyl orange dye under solar radiation. The degradation rate constant (k) of the composite with 1:2 weight ratio was 1.9 times the k value of pure TiO2. The effect of photocatalyst amount, initial pH of the dye solution, and reusability of the catalyst was investigated. The TiO2 and ZnO/TiO2 samples indicated a bandgap of 3.14 and 2.98 eV, respectively, which suggests better photocatalytic activity and also making the composite more active in the visible region. © 2024 The Authors.Item Assessing the effectiveness of electrocoagulation, ozonation and Fenton's oxidation for the treatment of phenalkamine condensate: A comparative study(Elsevier Ltd, 2024) Aswathy, K.R.; Joshy, A.; Biju, A.; Manu, B.; Surenjan, A.This study aims to investigate the feasibility of three Advanced Oxidation Processes (AOPs), Electrocoagulation (EC), ozonation and Fenton's oxidation for the treatment of real phenalkamine condensate. Three methods were compared based on COD removal efficiency. Phenalkamines are the Mannich reaction product of cardanol, formaldehyde, and amines. These are widely used in coatings for marine and offshore constructions and as curing agents in industrial adhesives. Cardanol is a derivative obtained by thermal treatment of cashew nut shell liquid (CNSL). The effluent from the cashew nut industry consists of phenolic compounds of high persistence, and they are potentially carcinogenic and mutagenic. The phenalkamine condensate has high pH, high chemical oxygen demand (COD). Fenton oxidation showed the highest COD removal efficiency, with maximum efficiency of 80 % and 94 % achieved after the first stage and five stage Fenton's oxidation respectively at optimized operating conditions. In comparison, EC process and ozonation resulted maximum COD removal efficiency of 54.26 % and 30.64 % respectively at optimum reaction conditions. This study revealed that Fenton's oxidation is the most effective method for the treatment of phenalkamine condensate. © 2023 Elsevier LtdItem Photocatalytic degradation of metformin on a rectangular baffled reactor: CFD modeling and validation investigation(Elsevier B.V., 2024) Pandey, P.; Mohanan, S.; Surenjan, A.Solar-irradiated photocatalysis is an advanced oxidation process (AOP) commonly used for water purification due to its excellent potential to break down a diverse range of persistent organic compounds into non-toxic byproducts. Reactor design is crucial in the photocatalysis process's efficiency, effectiveness, and scalability. Computational fluid dynamics (CFD) is an effective tool to study and comprehend reactor designs, reduce system cost, design time, and optimise reactor performance. This investigation focuses on designing and developing a rectangular baffled photocatalytic reactor that can effectively degrade metformin (MTF). The experimental study optimized the value of pH and catalyst dosage for efficient removal. The photoreactor demonstrated an efficiency of 58.14 % and was validated. The CFD results, including velocity profile and mass fraction of metformin, strongly agreed with the experimental results with an R2 value of 0.9826. The combination of various baffle sizes and spacing configurations was modeled and analyzed to develop a rectangular baffled photocatalytic reactor with maximum removal efficiency. The inclusion of baffles increased the flow path, improved mixing and enhanced the degrading efficiency. The investigation findings indicated the highest degradation efficiency of 78.03 % with the seven number of baffles. © 2024Item CFD Modeling and Analysis of the Effect of Baffles in an Immobilized Annular Photocatalytic Reactor for Ethylene Degradation(Springer, 2025) Sandesh, V.H.; Mohanan, S.; Surenjan, A.In recent years, the adverse effect of indoor air pollution on human well-being has become a topic of concern. Although conventional treatment approaches have demonstrated success in pollutant degradation, they often prove inadequate when dealing with persistent pollutants. Photocatalysis is a sustainable technique which can degrade such pollutants without harmful by-products. The study focuses on the photocatalytic degradation of ethylene in an annular photocatalytic reactor with different baffle configurations using computational fluid dynamics. The results indicate that the use of Longitudinal baffles in reactors has improved the reactor efficiency owing to the flow uniformity and Longer flow path length. Different baffle configurations were modeled using ANSYS Fluent, and the flow, species concentration, distribution, and reaction rates were studied. The novel design of a four-baffled reactor was found to have an efficiency of 68.96% for a hydraulic retention time of 5.597 s and a flow rate of 58.34 L/min. © The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd. 2025.Item Exploring the potential of cashew nut shell biochar for chlorpyrifos pesticide removal(Elsevier B.V., 2025) Pandey, P.; Kenchannavar, P.; Surenjan, A.India generates over 620 million metric tons of agricultural waste yearly. Agricultural wastes have limited economic worth and are underutilized. Agro-waste recycling into circular economy products is essential for environmental health. In small-scale cashew industries, shell waste generation is 67.5 % of the seed weight. Cashew nut shells (CNS), a residual product of the industry, are burned following the extraction of pulp and oils, resulting in negative environmental impacts. This study focuses on the application of CNS biochar for the removal of chlorpyrifos, a highly toxic organophosphate pesticide. Prepared biochar was analyzed using SEM, BET, and FTIR. After adsorption, the specific surface area of biochar decreased from 111.62 m²/g to 14.00 m²/g. For an initial chlorpyrifos concentration of 15 mg/L, the highest removal efficiency of 94.2 % was obtained with a 120-minute contact time, a biochar dose of 0.5 g/L and a pH of 6. Adsorption studies demonstrated a maximum adsorption capacity of 31.34 mg/g, with results following the Langmuir isotherm and pseudo-second-order kinetics, indicating monolayer chemisorption. The findings highlight CNS biochar as a promising alternative to conventional adsorbents, offering an environmentally friendly solution for water purification. © 2025 Elsevier B.V.