Hexavalent chromium removal using agricultural waste rye husk

The adsorption of Cr(VI) on rye husk (RH) was studied at varying Cr(VI) concentrations, adsorbent dose, contact time, and pH. Maximum Cr(VI) was sequestered from the solution within 140 min and the maximum removal of 5.0 mM Cr(VI) was about 68% at pH of 3.0 for 0.5 g RH. The removal of Cr(VI) was maximum (80.0%) when the initial pH of the solution was kept at 3.0. The Cr(VI) adsorption capacity of RH samples was calculated as 0.435 mmol/g at pH 3.0 from Langmuir isotherm. The adsorption kinetics data were evaluated with first-order reversible and pseudo-second-order kinetics models.