Removal efficiency of Cd from aqueous solution by H2O2 and KMnO4 modified biochar derived from orange and pea shells

Abstract

Finding an effective and environmentally acceptable adsorbent is crucial because wastewater containing cadmium poses a major risk to the water environment. Biochar is a cheap and environmentally friendly adsorbent for Cd that is produced during the pyrolysis of biomass. Many modification techniques have been employed to increase the adsorption capacity of biochar because it has a low adsorption ability when it is unmodified due to its poorly porous structure and lack of surface functional groups. In this study, two types of biochars (orange shell biochar and pea shell biochar) and their modifiers by H2O2 and KMnO4 were prepared. A batch experiment was carried out to evaluate their removing efficiencies for Cd from a polluted solution. The results showed the adsorption ability of Cd by the above prepared biochar increased with increasing of their used doses and the highest removal efficiency was noticed due to application of 1 and 2 g biochars L-1. KMnO4-modifed biochars were better in removing of Cd than H2O2-modified biochars and also than the unmodified ones. The highest removing percentages of Cd were 91.75% and 93.10% due to the use of KMnO4-modifed pea biochar at levels of 1 and 2 g biochars L-1. In view of our results, the H2O2 and KMnO4 modification of orange shell and pea shell biochars can be considered as a promising and cost operative sorbent to remove Cd from water/wastewater