Faculty Publications
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Item Effect of media characteristics on performance of upflow aerobic biofilters(2008) Srinikethan, G.; Shrihari, S.; Pradeepan, V.S.Laboratory studies were conducted to assess the influence of media related factors such as porosity, pore size, particle size and specific surface area on the performance of upflow aerobic biofilters (ABFs). Three simple models of 8 litre capacity upflow submerged ABFs packed with support media of size 40 mm, 20 mm and 10 mm respectively were installed. The hydraulic retention time (HRT) was maintained as 12 hours. The study was carried out for a period of 90 days. The reactor performance indicated that the aerobic biofilter (ABF-3), associated with media of lowest porosity, pore size, particle size and highest specific surface area, demonstrating the highest BOD and COD removal efficiency of 93.32 % and 85.01 % respectively.Item Removal of remazol brilliant blue dye from dye-contaminated water by adsorption using red mud: Equilibrium, kinetic, and thermodynamic studies(2012) Ratnamala, G.M.; Shetty K, K.V.; Srinikethan, G.Utilization of industrial solid wastes for the treatment of wastewater from another industry could help environmental pollution abatement, in solving both solid waste disposal as well as liquid waste problems. Red mud (RM) is a waste product in the production of alumina and it poses serious pollution hazard. The present paper focuses on the possibility of utilization of RM as an adsorbent for removal of Remazol Brilliant Blue dye (RBB), a reactive dye from dye-contaminated water. Adsorption of RBB, from dye-contaminated water was studied by adsorption on powdered sulfuric acid-treated RM. The effect of initial dye concentration, contact time, initial pH, and adsorbent dosage were studied. Langmuir isotherm model has been found to represent the equilibrium data for RBB-RM adsorption system better than Freundlich model. The adsorption capacity of RM was found to be 27.8 mg dye/g of adsorbent at 40 °C. Thermodynamic analysis showed that adsorption of RBB on acid-treated RM is an endothermic reaction with ?H0 of 28.38 kJ/mol. The adsorption kinetics is represented by second-order kinetic model and the kinetic constant was estimated to be 0.0105 ± 0.005 g/mgmin. Validity of intra-particle diffusion kinetic model suggested that among the mass transfer processes during the dye adsorption process, pore diffusion is the controlling step and not the film diffusion. The process can serve dual purposes of utilization of an industrial solid waste and the treatment of liquid waste. © Springer Science+Business Media Dordrecht 2012.Item Isotherm, kinetics, and process optimization for removal of Remazol Brilliant Blue dye from contaminated water using adsorption on acid-treated red mud(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ratnamala, G.M.; Shetty K, K.V.; Srinikethan, G.Red mud, which is a waste product from alumina production, has been utilized after activation with concentrated sulphuric acid treatment for removal of Remazol Brilliant Blue (RBB) dye from dye-contaminated water to investigate its potential as a low-cost adsorbent. The activation has enhanced the surface area of red mud from 20.2 to 32.28 m2/g, thus enhancing its adsorption capacity. The effect of initial dye concentration, contact time, initial pH and adsorbent dosage on percentage removal of dye using concentrated sulphuric acid-treated red mud (CATRM) was investigated. The ranges of these variables for optimization were selected based on batch studies. Acidic pH favoured adsorption and 300 min contact time was found to be suitable for attainment of equilibrium under shaking conditions of 145 rpm. Langmuir isotherm model has been found to represent the equilibrium data for RBB-CATRM adsorption system better in comparison with Freundlich model. The adsorption capacity of CATRM was found to increase with the increase in temperature, and at 40°C, it was found to be 125 mg dye/g of CATRM. The adsorption kinetics was represented by second-order kinetic model, and the kinetic constant was estimated to be 0.0063 g/mg min. Factors affecting the adsorption process were optimized by response surface methodology based on experiments designed as per central composite design. The effects of individual variables and their interaction effects on dye removal were determined. The results of the study showed that dye removal efficiency of almost 100% can be obtained with optimal conditions of initial dye concentration at 105 mg/l, red mud dosage of 2.05 g/l, initial pH of 1 and temperature of 31.65°C. pH and temperature were found to have high interaction effect on adsorption. © 2015 Balaban Desalination Publications. All rights reserved.Item Simultaneous adsorption of Remazol brilliant blue and Disperse orange dyes on red mud and isotherms for the mixed dye system(Springer Verlag service@springer.de, 2017) Ratnamala, R.; Shetty K, K.V.; Srinikethan, G.The paper presents the adsorption of Remazol brilliant blue (RBB) and Disperse orange 25 (DO25) dyes from aqueous solution of the mixture of dyes onto concentrated sulphuric acid-treated red mud (ATRM). First-order derivative spectrophotometric method was developed for the analysis of RBB and DO25 in mixed dye aqueous solution to overcome the limitations arising due to interference in the zero-order spectral method. The optimum conditions to maximize RBB adsorption favoured the adsorption of RBB, and those for DO25 favoured DO25 adsorption from the mixed dye aqueous solutions. Presence of a second dye always inhibited the adsorption of a target dye. The uptake and percentage adsorption of each of the dyes onto ATRM from the aqueous solution of the mixture of dyes decreased considerably with increasing concentrations of the other dye showing the antagonistic effect. Monocomponent Langmuir isotherm fitted the mixed dye adsorption equilibrium data better than the monocomponent Freundlich isotherm. However, monocomponent models are suitable for the fixed concentration of the other dye. Modified Langmuir isotherm model adequately predicted the multi-component adsorption equilibrium data for RBB-DO25-ATRM adsorption system with a good accuracy and is more generic from the application point of view. © 2017, Springer-Verlag Berlin Heidelberg.Item Surface treated Pteris vittata L. pinnae powder used as an efficient biosorbent of Pb(II), Cd(II), and Cr(VI) from aqueous solution(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2018) Prabhu, S.G.; Srinikethan, G.; Hegde, S.Biosorption is a surface-dependent phenomenon. Surface modifications by chemical treatment methods could either improve or reduce the biosorption capacity of potential biosorbents. In the present work, pristine Pteris vittata L. pinnae (PPV) powder was treated separately with sodium hydroxide (NaOH), calcium chloride (CaCl2), and nitric acid (HNO3). The pristine and treated biosorbents were used to assess the biosorption of Pb(II), Cd(II), and Cr(VI) as a function of pH. Kinetics and adsorption isotherms were studied. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope combined with energy dispersive x-ray (SEM-EDX) spectroscopic techniques were used to characterize the biosorbents before and after chemical treatments. The possible functional groups contributing to the metal sorption were identified. Results revealed favorable biosorption of Pb(II), Cd(II), and Cr(VI) described by pseudo-second order kinetics. NaOH-treated P. vittata (NPV) showed higher biosorption capacity for Pb(II) and Cd(II) compared to that of PPV. ATR-FTIR studies indicated that -OH, -COOH, and -NH2 groups were mainly involved in Cr(VI) and -OH in Pb(II) and Cd(II) biosorption. The enhanced efficiency of NPV and CaCl2 treated P. vittata (CPV) in the uptake of Pb(II) and Cd(II) compared to PPV can be associated with their altered physicochemical characters. © 2018, © 2018 Taylor & Francis Group, LLC.Item Kinetic and equilibrium modeling of biosorption of nickel (II) and cadmium (II) on brewery sludge(IWA Publishing 12 Caxton Street London SW1H 0QS, 2019) Kulkarni, R.M.; Shetty K, K.; Srinikethan, G.In the current study, utilization of industrial waste brewery sludge for the biosorption of nickel (II) and cadmium (II) has been explored. The suitable conditions for the effective removal of Ni (II) and Cd (II) from aqueous solutions were examined. The kinetic evaluation showed that the biosorption process using the sludge followed pseudo-second order kinetics. In the presence of a metal co-ion, competitive and preferential biosorption was observed. The Langmuir model and Freundlich model were able to describe the sorption equilibrium for biosorption of Ni (II) and Cd (II) ions in single and dual metal systems. The effects of co-ion concentrations onto mono-component isotherm parameters (Langmuir and Freundlich) were studied and the inhibitory effect of co-ion concentration was observed. The effective reusability of biomass was assessed by three cycles of sorption-desorption. The sludge, owing to its high biosorption intensity and large availability from the local supply, is a better biosorbent for the treatment of Ni (II) and Cd (II) contaminated water. © IWA Publishing 2019 Water Science & Technology.Item Spontaneous Cr(VI) and Cd(II) biosorption potential of native pinnae tissue of Pteris vittata L., a tropical invasive pteridophyte(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2019) Prabhu, S.G.; Srinikethan, G.; Hegde, S.Heavy metal pollution is a prevalent and critical environmental concern. Its rampancy is attributed to indiscriminate anthropogenic activities. Several technologies including biosorption have been continuously researched upon to overcome the limitations of the conventional method of treatments in removal of heavy metals. Biosorption technology involves the application of a biomass in its nonliving form. Pteris vittata L., a pteridophyte, considered as an invasive weed was investigated in the present study as a potential decontaminant of toxic metals, Cr(VI) and Cd(II). The adsorption capacity of the biosorbent for Cr(VI) and Cd(II) under equilibrium conditions was investigated. The morphology, elemental composition, functional groups, and thermal stability of the biosorbent before and after metal loading were evaluated. At 303 K and an equilibrium time of 120 min, the maximum loading of Cr(VI) on the biosorbent was estimated to be 166.7 mg/g at pH 2 and Cd(II) to be 31.3 mg/g at pH 6. Isotherm models, kinetic studies, and thermodynamic studies indicated the mechanisms, chemisorption, ion exchange and intraparticle diffusion, controlling the Cr(VI) and Cd(II) uptake, respectively. The interactive effect of multi-metal ions in binary component systems was synergistic for Cd(II) uptake. The results validate the toxic metal removal potency of the biosorbent. © 2019, © 2019 Taylor & Francis Group, LLC.Item Continuous fixed-bed adsorption of reactive azo dye on activated red mud for wastewater treatment-Evaluation of column dynamics and design parameters(Springer Science and Business Media Deutschland GmbH, 2023) Mavinkattimath, R.G.; Shetty K, V.; Srinikethan, G.Continuous adsorption of Remazol Brilliant Blue (RBB) dye in water onto sulfuric acid activated red mud (CATRM) in a fixed bed column was investigated. Breakthrough curves were obtained experimentally by varying the bed height (Z), influent flow rate (Q), and dye concentration(C0). The adsorption efficiency in the removal of RBB was favored at lower C0, higher Z, and lower Q. The maximum adsorption capacity of the activated red mud bed in the column was obtained at C0 = 70 mg/L, Z = 8 cm, and Q = 5 mL/min and found to be 106 mg/g. Important parameters of column dynamics and design such as mass transfer zone (MTZ) and length of unused bed (LUB) were evaluated from the breakthrough curves. The MTZ and LUB have varied with varying Z, which indicated the existence of nonideal conditions. Thomas model was found to be valid to predict the column dynamics and the model parameters were evaluated. Bed depth service time (BDST) model parameters were evaluated to facilitate the determination of packed bed height for the design of packed bed adsorption column. The bed could be regenerated with NaOH solution with desorption efficiency decreasing from 83.8 to 55.72% from the first to third cycle. A fixed bed of CATRM can be effectively used for continuous dye removal from industrial wastewater. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.