Abstract
Batch scale studies were conducted to investigate biosorption potential of sodium hydroxide treated pistachio shell (PS) biomass for methylene blue (MB). Fourier transform infrared spectroscopy analysis confirmed interaction between acidic oxygen surface groups and MB nitrogen atoms. Scanning electron microscopy, wide angle X-ray diffraction (WXRD) technique, energy dispersive X-ray spectroscopy and N-2 adsorption/desorption isotherm studies were carried out to evaluate surface morphology, surface area and pore size of biomass. Optimum MB biosorption (92.12%) was observed at pH 5.63. A drastic decrease in biosorption from 21.6 to 2.75mg/g was observed with increase in ionic salt (NaCl) concentration from 0.05 to 0.25M. Contact time study showed increase in biosorption capacity from 5.75 to 23.07mg/g with MB concentration (25-100mg/L). Equilibration time ranged between 60 and 240min. Biosorption was endothermic and physical process obeying pseudo second order kinetics model. Isotherm studies revealed applicability of Sips model. The MB recovery was 99.8% with 0.15M oxalic acid (OA) within 15min. Regeneration study confirmed almost constant recovery rate for four consecutive cycles.