Biosorption of Cu(II), Ni(II), Zn(II) and Pb(II) ions from aqueous solution by Sophora japonica pods powder

Background Biosorption of Cu (II), Ni(II), Zn(II) and Pb(II) ions from aqueous solutions onto Sophora japonica pods powder has been studied using batch adsorption technique. The biosorption studies were determined as a function of pH, contact time, initial metal ion concentration, biosorbent dosage and temperature. Results The kinetic study showed that the biosorption of the Cu(II), Ni(II), Zn(II) and Pb(II) ions followed pseudosecond- order kinetic model. Experimental data obtained were analyzed with Langmuir, Freundlich, Dubinin–Radushkevich and Temkin isotherm models and in each case the Langmuir model appears to have better regression coefficients. Thermodynamic parameters: DG°, DH° and DS° were calculated indicating that the biosorption of Cu(II), Ni(II), Zn(II) and Pb(II) ions is spontaneous and endothermic process. Conclusions The results of the study showed that Sophora japonica pods powder can be efficiently used as a low-cost alternative for the removal of Cu(II), Ni(II), Zn(II) and Pb(II) ions from aqueous solutions.