Sorption\nof Lead(II), Cadmium(II), and Copper(II)\nIons from Aqueous Solutions Using Tea Waste

Abstract

In the present study, the sorption\nability of three metal ions,\nlead, cadmium, copper, from aqueous solution by tea waste was investigated.\nSorption of the evaluated toxic metals by tea waste was pH-dependent,\nand kinetic data for three metal ions not only indicated a quick sorption\nprocess but also were excellently represented by the pseudo-second-order\nmodel with all correlation coefficients <i>R</i>² > 0.97. In addition, the sorption processes of three metal ions\nby tea waste in different temperatures could be described satisfactorily\nby both Langmuir and Freundlich isotherms. According to calculated\nresults by the Langmuir equation, the maximum removal capacities of\nPb­(II), Cd­(II), and Cu­(II) were 33.49, 16.87, and 21.02 mg/g, respectively.\nFourier transform infrared (FT-IR) analysis of the tea waste samples\nladen with different metals indicated that multiple functional groups\nwere involved in the sorption of metal ions, and the carboxyl group\n(CO) and bonded–OH group were primary binding sites\nin lead and cadmium removal, while the −CN stretching and the\ncarboxyl group were primary binding sites in copper removal. All the\nresults reported strongly implied the potential of tea waste as an\neconomic and excellent bioadsorbent for removal of metal ions from\ncontaminated waters.