摘要

Heavy metal contamination, especially contamination involving Pb(II), is a major environmental problem faced by modern society; hence, research on bio-adsorbents with a low cost and high efficiency for removal of Pb(II) from water is highly desirable. Herein, a novel carbon-silica bio-sorbent prepared by carbonization of rice husk with sulfuric acid followed by ammonium persulfate oxidation was successfully applied to highly efficient Pb(II) removal. The synthetic adsorbent was characterized by scanning electron microscopy, Nitrogen (N-2) sorption, Fourier transform infrared and X-ray photoelectron spectroscopy techniques. Batch experiments with varying solution pH, contact time, temperature and ionic strength were carried out to evaluate the adsorption performance. Adsorption equilibrium was achieved within 30 min, and adsorption kinetics were best fit by the pseudo-second-order model. The experimental data fitted the Langmuir isotherm better than the other two isotherms. Thermodynamic studies suggested that the adsorption process was spontaneous and endothermic. Furthermore, desorption results showed that adsorption performance can be retained at levels up to 80 % after being used four times. Overall, waste rice husk-derived carbon-silica composite bio-sorbent is an attractive candidate for the removal of Pb(II) from aqueous systems.