The Removal of Cd²⁺, Cu²⁺ and Pb²⁺ from Aqueous Solution with Palygorskite: The Effects of Humic Acid

Abstract

To investigate the impact of Humic acid (HA) on Palygorskite (PAL) as the adsorbent for heavy metal ions, this study was carried out to solve the existing dispute in the effects of HA on PAL sorption capacity. The sorption properties of PAL and HA-loaded PAL (HA/PAL) for Cd 2+ , Cu 2+ , Pb 2+ in batch experiments were evaluated. PAL and HA/PAL effects on metal ion elimination were examined under various test settings (time, dosage and starting concentration) were compared. The sorption efficiency of PAL was significantly higher than that of HA/PAL. The N 2 sorption-desorption and FTIR results showed that HA successfully adhered to the PAL surface without changing its crystal structure but reducing its specific surface area. Cd 2+ , Cu 2+ , and Pb 2+ for PAL and Cd 2+ and Cu 2+ for HA/PAL were modelled by pseudo-first-order kinetics; the pseudo-second-order rate conformed to Cu 2+ for PAL and Pb 2+ for HA/PAL. the Langmuir linear fitting was consistent with Cd 2+ , Cu 2+ and Pb 2+ for PAL and HA/PAL. Pb 2+ for PAL and Cd 2+ , Pb 2+ for HA/PAL were consistent with the Freundlich isotherm. The results proved that HA was not conducive to improving the adsorption performance of PAL.