Adsorption study of chromium(VI) by dried biomass of tea leaves

Heritage Institute of Technology, Anandapur, Kolkata-700 107, India E-mail: sonalihazra.das@heritageit.edu Manuscript received online 28 January 2019, accepted 25 March 2019 Chromium contamination has increased in the last few years in industrial effluents. Environmental Protection Act has set an enforceable Criteria Maximum Concentration (CMC) level of total chromium in freshwater as 16 µg/L. The aim of this study was to investigate the CrVI adsorption on used and dried tea leaves (Camellia sinensis). The parameters used to study the adsorption behaviour of chromium on tea leaves were pH of the reaction mixture, initial chromium concentration, dried biomass of tea leaves and agitation speed. The batch kinetic studies showed that adsorption had increased with increase in dried biomass and decrease in pH. No significant variation in the removal efficiency was seen with the increase in agitation speed. Response Surface Methodology was used as a tool of varying multiple experimental parameters simultaneously to get the output. Maximum removal efficiency (84.57%) was obtained after 24 h at pH 5.7; initial chromium concentration of 19.9 mg/ L, agitation of 4.2 rpm and dried biomass of 1.5 g. Successful adsorption by tea leaves had been further confirmed by Scanning Electron Microscope, which showed the appearance of smoother surface after adsorption