Ramakrishnan Kamaraj

Adsorption of herbicide 2-(2,4-dichlorophenoxy)propanoic acid by electrochemically generated aluminum hydroxides: an alternative to chemical dosing

This research article presents an in situ electrosynthesis of aluminum hydroxides by anodic dissolution of sacrificial aluminum anode and their application towards the adsorption of herbicide 2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP) from aqueous solution. Different sacrificial anode material like iron, magnesium, zinc and aluminum are tested and stainless steel is used as the cathode. The optimization of different experimental parameters like current density, pH, temperature and inter-electrode distance on the adsorption of 2,4-DP was carried out. The results showed that the maximum removal efficiency of 93.0% was achieved with aluminum as sacrificial anode at a current density of 0.10 A dm−2 and pH of 7.0. The adsorption of 2,4-DP preferably followed the Langmuir adsorption isotherm. The adsorption kinetic studies showed that the adsorption of 2,4-DP was best described using the second-order kinetic model. Thermodynamic parameters indicates that the adsorption of 2,4-DP on aluminum hydroxides was feasible, spontaneous and endothermic.

Facile one-pot electrosynthesis of Al(OH)3 – kinetics and equilibrium modeling for adsorption of 2,4,5-trichlorophenoxyacetic acid from aqueous solution

This study presents a Al(OH)3 synthesis in a facile one-pot process by an electrodissolution method. This process is a novel process, where the adsorbents are generated in an in situ, efficient and cost-effective way for removing organic pollutants. The adsorption performance of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) onto Al(OH)3 was systematically investigated and the experimental results indicated that Al(OH)3 showed an excellent adsorption capacity toward 2,4,5-T. To optimize the removal efficiency of 2,4,5-T, different experimental parameters like the effect of current density, pH, temperature, different anodes and inter-electrode distance were carried out. The results showed that the maximum removal efficiency of 86.0% was achieved at a current density of 0.10 A dm−2 and a pH value of 7.0. The adsorption kinetics could be well described by the pseudo-second-order model and the Langmuir isotherm model showed a better fit with experimental data than the Freundlich and D–R model. Moreover, thermodynamic parameters indicate that the adsorption of 2,4,5-T on aluminum hydroxides was feasible, spontaneous and endothermic. The adsorbed Al(OH)3 was characterized by different techniques, such as SEM, EDAX, XRD and FTIR measurements.

Enhanced removal of cephalosporin based antibiotics (CBA) from water by one-pot electrosynthesized Mg(OH)2: a combined theoretical and experimental study to pilot scale

This study explores the removal of cephalosporin based antibiotics (CBA), such as cefepime, cefaclor, cefuroxime, cefazolin, cefixime, cefalexin and ceftobiprole, from water using Mg(OH)2 synthesised using a facile one-pot process via an electrodissolution method. This process is a novel process, where the adsorbents are generated in situ, which is efficient and cost-effective for removing organic pollutants. The adsorption performance for CBA onto Mg(OH)2 was systematically investigated and the experimental results indicated that Mg(OH)2 showed excellent adsorption capacity towards CBA due to the high specific surface area (60.703 m2 g−1) of Mg(OH)2. To optimise the removal efficiency, the effects of contact time, concentration, pH and current density were studied. The adsorption kinetics were modelled using pseudo first and second order kinetics, and Elovich, and Weber and Morris intraparticle diffusion models. The rate constants for all these kinetic models were calculated and the results show that the second order kinetic models were best fitted to model the kinetic adsorption of CBA. Langmuir, Freundlich, D–R isotherm and Temkin models were applied to describe the equilibrium isotherm models and the isotherm constants were determined. The adsorption was studied thermodynamically, and the Gibbs free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were calculated. The pilot scale study shows that the process is technologically feasible. The adsorbed Mg(OH)2 was characterized using different techniques, such as FESEM, EDAX, XRD, BET and FTIR measurements.

OPAC (orange peel activated carbon) derived from waste orange peel for the adsorption of chlorophenoxyacetic acid herbicides from water: Adsorption isotherm, kinetic modelling and thermodynamic studies

This study presents the orange peel activated carbon (OPAC), derived from biowaste precursor (orange peel) by single step pyrolysis method and its application for the adsorption of chlorophenoxyacetic acid herbicides from the water. The OPAC exhibited the surface area of 592.471 m2 g-1, pore volume and pore diameter of 0.242 cc g-1 and 1.301 nm respectively. The adsorption kinetics and thermodynamic equilibrium modelling for all chlorophenoxyacetic acid herbicides were investigated. The various parametric effects such as pH and temperature were evaluated. A pseudo-second-order kinetic model was well fitted for all the herbicides. The Langmuir isotherm was obeyed for all the herbicides and the maximum Langmuir capacity of 574.71 mg g-1 was achieved. The thermodynamic studies revealed that the adsorption increases with increase in temperature. The results shows that the orange peel derived carbon (OPAC) as effective and efficient adsorbent material for the removal of chlorophenoxyacid herbicides from the water.