Hexavalent Chromium removal from simulated and real effluents using Artocarpus heterophyllus peel biosorbent - Batch and continuous studies

Cr(VI) removal was studied with Artocarpus heterophyllus peel as a biosorbent in batch and continuous mode. Parameters influencing the maximum removal efficiency like biosorbent dose, contact time, pH, temperature, agitation speed, initial chromium concentration have been optimized in batch studies. Cr(VI) removal was observed to be 99.92 percentage and the residual Cr(VI) concentration was 0.036 mg/L with 50 mg/L initial concentration, 0.3 g of biosorbent at 100 rpm, pH 2.0 and 35 degrees C. Elemental analysis, Porosity and surface area of the biosorbent were determined using CHNS analysis and Mercury Intrusion Porosimetry (MIP) respectively. The characteristics and interaction of the sorbent before and after treatment with Cr(VI) were analyzed using Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometry (SEM-EDXS), Electron Spin Resonance (ESR) spectrometry, X-ray Photoelectron Spectroscopy (XPS) and Atomic Adsorption Spectroscopy (AAS). Adsorption-coupled reduction was observed to be the predominant mechanism behind Cr (VI) removal. Isotherm and kinetic analysis were performed, Q(o) value was found to be 64.47 +/- 3.7 mg/g and pseudo-second-order model fitted better than the other models analyzed. Thermodynamic parameters revealed that the process was thermodynamically feasible and endothermic. Effect of co-existing ions was also done to check the feasibility of Artocarpus heterophyllus biosorbent in removing Cr(VI) from real effluents. Continuous column studies at different feed flow rates, initial feed Cr(VI) concentration and Column bed height were optimized using simulated and tannery effluents. Considerable performances were noted from Desorption regeneration experiments with simulated Cr(VI) solution up to 3 consequent runs. Results of the present study depicted that AH biosorbent can be utilized for removal of Cr(VI) from simulated and real effluents. (C) 2018 Elsevier B.V. All rights reserved.