Faculty Publications
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Item Highly efficient solar light-driven BiOX (X=Br/Cl/I) and BiOY heterojunction (Y=Br/Cl) nano photocatalysts in suspended and immobilised forms for malachite green dye wastewater treatment(Springer Science and Business Media Deutschland GmbH, 2023) Mishra, S.; Manjunatha, M.; Mahalingam, H.A novel BiOY (Y = Br/Cl) heterojunction nanocatalyst was synthesised chemically and compared with three different BiOX (X = Br/Cl/I) nanocatalysts as well as a physical admixture of BiOBr/BiOCl catalysts in the photocatalytic degradation of malachite green dye wastewater under solar irradiation in both suspended and immobilised forms using polysulfone as the substrate. Catalyst characterisation was done by a particle size analyser, SEM/EDX, XRD, FTIR, and DRS. In the suspended form, BiOBr showed 100% degradation within 70 min, BiOCl showed 99.3%, and BiOI showed 11.2% degradation within 120 min, and it is found to follow pseudo-first-order kinetics. In the immobilised form, BiOBr showed 89.1%, and BiOCl showed 83.4% degradation within 180 min under sunlight. The degradation measured by TOC reduction for these catalysts in suspended form was 67.4%, 57%, and 40%, affirming BiOBr as the best among these catalysts. The performance of the immobilised chemically synthesised BiOY and physical admixture catalysts were 88% and 14%, respectively. The enhanced activity in the chemically synthesised immobilised BiOBr/Cl catalyst can be attributed to the effective charge separation at the heterojunction interface. These photocatalysts are very active under solar light and hence suitable for the efficient degradation of other recalcitrant organic contaminants. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Utilization of torrefied rice husk and deoiled cashew nut shell cake biomass waste for removal of hazardous Reactive Violet 5 dye(Springer, 2025) Suriyakumar, S.; Mahalingam, H.; Sudhakar, R.D.Torrefied biomass is a renewable, sustainable, carbon–neutral fuel that is replacing coal in many areas. This organic source has increased surface area and porosity, making it an effective adsorbent. Only a very few works have been reported in the literature on exploring the use of torrefied biomass and its ash as inexpensive adsorbents for the removal of dyes. In this work, rice husk and deoiled cashew nut shell cake in its torrefied and ash forms have been employed as adsorbents for Reactive Violet 5 dye removal. Thus, four adsorbents were synthesized and characterized by BET, SEM, XRD, and FTIR. The optimum parameters for maximum dye removal efficiency were 0.8 g/L adsorbent dosage, pH 2.0, and 40-min contact time for batch experiments using 100 mL of 10 ppm dye solution. The maximum adsorption capacity of torrefied rice husk, torrefied deoiled cashew nut shell cake, torrefied rice husk ash, and torrefied deoiled cashew nut shell cake ash were 108.58 mg/g, 88.38 mg/g, 68.0 mg/g, and 29.97 mg/g, respectively. Torrefied rice husk exhibited the best fit with the Freundlich isotherm, whereas other adsorbents fitted best with the Langmuir isotherm. The non-linear pseudo-second-order model gave the best fit. The intraparticle diffusion model showed that adsorption involves multiple diffusion stages. The thermodynamic parameters indicated that the process was spontaneous, feasible, and exothermic. These eco-friendly materials can be efficiently used in dye removal, thus paving the way for torrefied biomass or its ash to be used as low-cost adsorbents for large-scale wastewater treatment. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.