Santhi Raju Pilli

Biosorption of Cr(VI) on immobilized Hydrilla verticillata in a continuous up-flow packed bed: prediction of kinetic parameters and breakthrough curves

abstract In this work, biomass of Hydrilla verticillata, a waste weed was used in its immobilized form to remove hexavalent chromium from aqueous solutions. The powdered biomass was entrapped in polyvinyl alcohol and packed bed studies were carried out using beads of immobilized H. verticillata. Bed height, influent Cr(VI) concentrations, and influent flow rate were variable parameters for the present study. The overall performance of the biosorbent was satisfactory as very high Cr(VI) uptake (45.83 mg g−1) was observed. Three different models—Bed depth service time (BDST), Yoon–Nelson, and Thomas—were studied and fitted to the experimental data. The correlation coefficient values were all above 0.96, whereas the BDST model fitted the data best. From the Thomas model, Thomas rate constant, K Th was calculated and found to be 0.0215 L mg−1 h−1. The data obtained from the Yoon–Nelson model indicated that τ (148 min at 5 mg L−1) values were very similar to experimental (140 min at 5 mg L−1) results. Desorpti...

Performance of different ionic liquids to remove phenol from aqueous solutions using supported liquid membrane

AbstractAn experimental study was carried out for the removal of phenol from aqueous solutions using supported liquid membranes containing ionic liquid (IL) as the carrier solvent. The commercial grade ILs namely: [CYPHOS® 101], [CYPHOS® 102], [CYPHOS® 103], [CYPHOS® 104], [Aliquat 336®], and [C8MIM][PF6] were used as membrane phase in this work. The effect of various parameters such feed phase pH, operation time, and stirring speed on the removal of phenol has been investigated using the six different ILs. Supported ionic liquid membrane (SILM) through vacuum immobilization method was used for the removal of phenol. The maximum permeation rate of 75.63% was achieved over an experimental run of 24 h at pH 4. High permeation rate was obtained by [CYPHOS® 104] among all the six ILs studied. The order of the permeation rates followed: [CYPHOS® 104] > [CYPHOS® 103] > [CYPHOS® 102] > [CYPHOS® 101] > [C8MIM][PF6] > [Aliquat 336®]. The operational stability and performance of the supported liquid membranes were ...

Ionic Liquids as Green Solvents for the Extraction of Endosulfan from Aqueous Solution: A Quantum Chemical Approach

Abstract This work presents a judicious screening of 986 possible ionic liquid (IL) combinations for the removal of Endosulfan using COSMO-RS (Conductor-like Screening Model for Real Solvents) model. Initially, benchmarking studies have been carried out for α-Endosulfan, β-Endosulfan, Endosulfan sulfate, Endosulfan-alcohol, Endosulfan lactone, and Endosulfan ether by comparing COSMO-RS experimental and predicted octanol–water partition coefficients. Thereafter, COSMO-RS selectivity predictions were done on 986 ionic liquid combinations at infinite dilution. The order of selectivity for the five cation groups were found to be as follows: [TBP] > [TIBMP] > [TBMP] > [C2DMIM] > [BEPYR] > [DPPYR] > [C4DMIM] > [C8MPY] > [BTNH] > [BETNH]. Highest selectivity was obtained for phosphonium based IL namely: [TBP][TOS] (212.5). Anions such as [C8H17SO4], [Br], [Sal], [TOS], [MDEGSO4], and [DEC] contributed high selectivities because of the absence of sterical shielding effect around their charge centers. Further capacity and the performance index (PI) values were calculated and predicted along with selectivity. The increasing order of performance index values were found to follow: [TBP][Sal] (1.71+E5) > [DPPYR][Br] (1.07+E6) > [C2DMIM] (1.01+E6) > [C8MPY][Cl] (1.6+E5) > [BETNH][DEC] (1.2+E5).