Adsorption of Chromium (VI) from Aqueous Solution Using Palm Leaf-Derived Biochar: Kinetic and Isothermal Studies

In this study, biochar produced by low-temperature pyrolysis from palm leaves was treated with phosphoric acid in order to increase the sorption efficiency of Cr (VI) from aqueous solutions. Numerous characterization experiments using BET surface area, FE-SEM and FT-IR showed that the phosphoric acid-treated biochar (TBC-P) was covered with P particles. In comparison to the palm leaves and biochar, the TBC-P also had more surface oxygenated functional groups, surface area, pore size and internal structure. FTIR analysis showed that the functional groups of pretreated biochar were similar to those of biochar. Batch adsorption experiments showed that the TBC-P had a strong sorption ability to Cr (VI), with the highest removal efficiency of 99% at a low pH value of 2.0, which was significantly higher than that of the untreated biochar. The kinetic study has shown that the mechanism of the reaction was well represented by the second-order model, while isotherm data were well presented by the Langmuir model. The TBC-P was successfully regenerated using a 0.1 M HCl solution.