Torta de algodão como biossorvente de cobre e zinco

Abstract

The objective of this study was to evaluate the efficiency of cotton cake in the zinc and copper removal of synthetic solutions by adsorption process. The first step consisted in the preparation of the cotton cake and the metal solutions. Before the tests, the cotton cake was washed with tap water and distilled, then dried in the oven at 60ºC. The synthetic solution was prepared in concentrations of 0,1 to 1,2 meq L-1 of Cu2+ and 0.25 to 2.5 meq L-1 of Zn2+. Subsequently, an evaluation of the metals with pH adjustment of the solution and zero charge point (PCZ) test at pH 5,5 for both metals was carried out. In the next step, a test was carried out by varying the mass of cotton cake with the purpose of obtaining the optimal mass, with 3,75 g for Cu2+ and 7,5 g for Zn2+. The tests were carried out in a leachate for 24 hours with constant stirring speed of 30 rpm at 25°C. As a last step, the kinetic study and isotherms attainment were performed and verified with the results that the metal adsorption in the cotton cake occurs in a monolayer for both metals, with a maximum adsorption capacity, under the analyzed conditions of 8,01 mg g-1 for Cu+2 and 20,5 for Zn2+, with removals of 80% for both metals. In view of these results, cotton cake is a promising biosorbent in the removal of metals from aqueous solutions, being a low cost alternative for the treatment of effluents in relation to conventional adsorbents.