Adsorption of PtCl62− from Hydrochloric Acid Solution by Chemically Modified Lignin Based on Rice Straw

Abstract

A novel adsorbent with the properties of selective adsorption based on rice straw was used to adsorb PtCl62− from hydrochloric acid solution by batch sorption. Many influencing factors for PtCl62− adsorption, such as initial concentration of PtCl62−, adsorption time, and concentration of hydrochloric acid, were optimized. The results suggested that the saturation adsorption capacity of PtCl62− was 218.8mgg−1 and the equilibrium adsorption time was 120min. The adsorbent had excellent selectivity on PtCl62− when the concentration of hydrochloric acid was lower than 0.5molL−1. The adsorption fitted well with the Langmuir isotherm model and pseudo-second-order kinetics model. The adsorption mechanism was investigated by FT-IR and X-ray photoelectron spectroscopy analyses and it indicated that PtIV was reduced to PtII by hydroxy groups and then coordinated with N through ion exchange between Cl− and PtCl42−.