Removal of Pb2+ from Aqueous Solution using Thach Khoan Kaolin from Phu Tho Province

Abstract

Kaolin sample (mixture of halloysite and kaolinite) from Thach Khoan, Phu Tho province was studied to remove Pb2+ ions from an aqueous solution. The SEM-EDS and TEM analysis showed that in the kaolin sample, tubular halloysite and plate kaolinite minerals coexist, similar to the results from previous studies. The various treatment conditions such as contact time, solution pH, the adsorbent weight, and initial concentration of Pb2+ were examined and evaluated using batch adsorption experiments. The results showed that under experimental conditions of pH0 = 5.31 and a temperature of 25 °C, with 0.7 g of Thach Khoan kaolin material, the Pb2+ adsorption can reach equilibrium after about 50 minutes and efficiency reached 90.75%. The adsorption process follows the Langmuir adsorption isotherm model with the maximum monolayer adsorption capacity of 3.79 mg/g and follows the pseudo-second-order kinetic equation. This result indicated that unmodified Thach Khoan kaolin with a mixture of tabular halloysite and plate kaolinite minerals has a significant potential in removing heavy ions from aqueous solution.