Equilibrium and kinetic studies for sequestration of Cr(VI) from simulated wastewater using sunflower waste biomass

In the present work, potential of sunflower head (BSH) [an agricultural waste biomass] to remove Cr(VI) from simulated wastewater has been evaluated under different process conditions such as pH, metal concentration, adsorbent dose and contact time. A contact time of 120 min and pH 2.0 were found to be optimum. Chromium removal decreased from 90.0 to 45.2% as its concentration increased from 10 to 70 mg/L. The Cr(VI) removal increased from 31.4 to 52.4% as adsorbent dose increased from 4.0 to 20.0 g/L using a test solution having 100 mg/L Cr(VI) concentration. Adsorption isotherms were employed to evaluate the maximum adsorption capacity. Adsorption data fitted well to Langmuir isotherm and pseudo-second order model as indicated by high values of correlation coefficient (0.9882 and 0.999) respectively. The adsorption capacity calculated from Langmuir isotherm was 8.177 mg/g.