Faculty Publications
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Item An optimization study on microwave irradiated, decomposition of phenol in the presence of H2O2(2009) Prasannakumar, B.R.; Iyyaswami, I.; Murugesan, T.Background: Removal of phenol from industrial waste waters involves basic techniques namely extraction, biodegradation, photocatalytic degradation, etc. Among the available processes, the oxidation of phenols using H2O2 is a suitable alternative because of low cost and high oxidizing power. The application of an oxidation process for the decomposition of stable organic compounds in waste water leads to the total degradation of the compounds rather than transferring from one form to another. Since oxidation using Fenton's reagent ismore dependent on pH, in this present work it was proposed to use H2O2 coupled with microwave irradiation. The effects of initial phenol concentration, microwave power and the irradiation time on the amount of decomposition were studied. Results: In the present work experiments were conducted to estimate the percentage degradation of phenol for different initial concentrations of phenol (100, 200, 300, 400 and 500 mg L-1), microwave power input (180, 360, 540, 720 and 900 W) for different irradiation times. The kinetics of the degradation process were examined through experimental data and the decomposition rate follows first-order kinetics. Response surface methodology (RSM) was employed to optimize the design parameters for the present process. The interaction effect between the variables and the effect of interaction on to the responses (percentage decomposition of phenol) of the process was analysed and discussed in detail. The optimum values for the design parameters of the process were evaluated (initial phenol concentration 300 mg L-1, microwave power output 668 W, and microwave irradiation time 60 s, giving phenol degradation 82.39%) through RSM by differential approximation, and were confirmed by experiment. Conclusion: The decomposition of phenol was carried out using H2O2 coupled with microwave irradiation for different initial phenol concentrations, microwave power input and irradiation times. The phenol degradation process follows first-order kinetics. Optimization of the process was carried out through RSM by forming a design matrix using CCD. The optimized conditions were validated using experiments. The information is of value for the scale up of the oxidation process for the removal of phenol from wastewater. © 2008 Society of Chemical Industry.Item Rapid removal of cobalt (II) from aqueous solution using cuttlefish bones; Equilibrium, kinetics, and thermodynamic study(2013) Sandesh, K.; Suresh Kumar, R.; JagadeeshBabu, P.E.The objective of this study is to assess the adsorption potential of cobalt (II) using cuttlefish bones. The bones were treated with 0.01 N HCl to enhance the heavy metal uptake. The adsorbent was characterized using scanning electron microscope and energy dispersive X-ray spectrometer. An adsorption study was conducted in a batch system to optimize process variables such as initial concentration of cobalt (II), pH, sorbent loading, particle size, process temperature, and contact time. The optimal pH was found to be 9. The kinetic data followed the pseudosecond-order kinetic model, and the equilibrium time was found to be 20 min. In the first minute of the adsorption process, 50% of the cobalt (II) was adsorbed by the cuttle bones. Adsorption isotherms were expressed by the Langmuir and Freundlich adsorption models. The Langmuir adsorption model fits the experimental data reasonably well compared with the Freundlich model. The maximum adsorption capacity of this new sorbent was found to be 76.6 mg g-1 at 40 °C. Thermodynamic parameters, including the Gibbs free energy (?Go), enthalpy (?Ho), and entropy (?So), indicated that the adsorption of cobalt (II) by cuttlefish bones was feasible and endothermic at a temperature range of 20-40 °C. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.Item Low cost Fenton's oxidative degradation of 4-nitroaniline using iron from laterite(IWA Publishing 12 Caxton Street London SW1H 0QS, 2016) Amritha, A.S.; Manu, B.The present study aims to establish the use of iron (Fe) from larerite in the case of Fenton's oxidation process which is a simple and cost-effective method for degradation of nitro compounds in effluents and in surface or ground water. 4-nitroaniline (4-NA) degradation by Fenton's oxidation method is the subject of the present study so as to optimize pH, hydrogen peroxide/iron (H/F) ratio at different initial concentrations of 4-NA. The optimum pH obtained was 3. The present study has also established optimum H/F ratio for the different initial concentrations of 4-NA for both conventional and use of Fe from laterite. The maximum removal efficiency of 99.84% was obtained for an H/F ratio of 100 for 0.5 mM initial concentration of 4-NA. The study establishes the use of Fe extracted from locally available laterite soil (LS) as a replacement of Fe salts so as to reduce the cost of the process. © 2016 IWA Publishing.Item Degradation of nitroaromatic compounds: a novel approach using iron from laterite soil(Springer Verlag, 2018) Amritha, A.S.; Manu, B.The Fenton’s oxidation process has been found to be a simple and economical method for the treatment of nitroaromatic compounds in water. In the present study, the iron extracted from the laterite soil was used as a catalyst and optimization of pH, hydrogen peroxide concentration and iron concentration was studied for different initial concentrations of 2-nitroaniline (2-NA), 3-nitroaniline (3-NA) and 4-nitroaniline (4-NA). The optimum pH obtained was 2.5 for 2-NA and 3-NA and 3 for 4-NA. The maximum removal efficiency obtained was 85.3%, 84.3% and 98.7% for 0.5 mM initial concentration at a hydrogen peroxide concentration of 3.5 mM, 4.5 mM and 5 mM for 2-NA, 3-NA and 4-NA, respectively, with a constant iron concentration of 0.05 mM. © 2018, The Author(s).Item Melanin nano-pigments for heavy metal remediation from water(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2019) Thaira, H.; Raval, K.; Manirethan, V.; Mohan Balakrishnan, R.M.Melanins are water insoluble polyphenol compounds. The metal ion chelating property of natural melanin is exploited for removal of heavy metals from contaminated water. We optimized biosynthesis of melanin from marine bacterium using different growth media, media components, and operating conditions. Optimized medium yielded 513 mg/L melanin at 36 h of incubation, which was 3.15 times higher than the yield before optimization. Particle size analysis of the biosynthesized melanin indicated a size of 32 ± 0.98 nm. Preliminary investigation indicated that melanin nanoparticles could adsorb different heavy metals such as chromium, selenium, and lead from very low initial concentrations. © 2018, © 2018 Taylor & Francis.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 Mixed Surfactant-Based Reverse Micellar Extraction Studies of Bovine Lactoperoxidase(John Wiley and Sons Inc, 2021) Karanth, S.; Iyyaswami, I.The suitability of reverse micellar extraction for recovery of bovine lactoperoxidase (LP) from aqueous solution was evaluated using systems formed by ionic and nonionic surfactant mixtures. The influence of ionic surfactant concentration, organic solvent, and pH on the extraction of LP into the reverse micellar phase was studied. The Tween® series surfactants with Aerosol-OT (bis-(2-ethylhexyl) sulfosuccinate) showed better extraction of LP in the reverse micelles (RM) compared to the Triton® and Span® series of surfactants. Complete extraction of LP from an aqueous phase of initial concentration 25 mg L?1 occurred with the RM formed by 90 mM Aerosol-OT/8 mM Tween® 80 in isooctane. The optimal pH, ionic strength, and positively charged ionic surfactant concentration for back extraction were also studied and a maximum of 95.5% back extraction efficiency and 66% LP activity recovery was obtained for a pH of 10.5,1 M KCl and 60 mM cetyltrimethylammonium bromide system. © 2021 AOCSItem Photocatalytic degradation of ciprofloxacin & norfloxacin and disinfection studies under solar light using boron & cerium doped TiO2 catalysts synthesized by green EDTA-citrate method(Elsevier B.V., 2021) Manjunatha, M.; Chandewar, P.R.; Mahalingam, H.The presence of antibiotic residues in water bodies is an emerging global concern due to its potential development of antimicrobial resistance. Hence, it is essential to develop photocatalysts that not only degrade the antibiotics but can also simultaneously disinfect. Four different boron and cerium doped TiO2 photocatalysts, synthesized by the EDTA-citrate method, are studied for the degradation of two common fluoroquinolone-based antibiotics: ciprofloxacin (CIP) and norfloxacin (NOR) under sunlight. The catalysts are characterized by SEM, TEM, Raman spectroscopy, XPS, DRS, BET surface area and particle size analyzer. At optimized conditions, the synthesized catalysts showed 90–93% degradation for both CIP and NOR. The effects of catalyst loading and initial concentration are studied, and the reaction is found to be pseudo-first-order. The degradation is analyzed by COD reduction and LC–MS, and the by-products of degradation determined. The recycle studies showed that the catalysts are stable up to three consecutive runs. The scavenging experiments indicated e? and OH? as the dominant species responsible for the photocatalytic activity. The disinfection studies using these catalysts under solar light gave 95–99.99% efficiency for E.coli confirming that they are very efficient and can be further exploited for large scale treatment. © 2020 Elsevier B.V.