Bengal Gram Husk as Efficient and Cost-Effective Adsorbent for Pb2+ and Methylene Blue Removal in Single and Binary Systems

Abstract

The present study reported on the utilization of pulse processing waste [Bengal gram peel powder (BGPP)] for the removal of lead ions (Pb2+) and methylene blue (MB) from aqueous solution in single and binary systems. The characterization of BGPP before and after adsorption was done by various advanced techniques. Results depicted that, whereas the maximum removal of Pb2+ occurred within 60 min (∼99% removal), MB took 12 h to attain equilibrium (∼95% removal) with the optimum dose of 2.0 g/L in a single system. It is interesting to note that, at the same dose of 2.0 g/L, the equilibrium time was increased to 12 and 20 h for Pb2+ and MB, respectively, when Pb2+ and MB are present in a mixture (binary system). The optimum pH for Pb2+ and MB was 4.5 and 7.0, respectively. The equilibrium data fit well with the Freundlich model. Maximum adsorption capacity obtained was 55.58 mg/g for Pb2+ and 24.70 mg/g for MB. Kinetic data complied with a pseudo-second-order model. The results suggest that Bengal gram waste can be utilized as an ecologically friendly adsorbent and it can be used as an economical way for the removal of Pb2+ and MB in single as well as in binary systems.