Pyrolysis chars derived from rice wastes were chemically activated and used in W(VI) oxyanion adsorption assays in synthetic and mining wastewaters. For comparison purposes, a commercial activated carbon (CAC) was also used. Different experimental conditions were tested in the adsorption assays: solid/liquid ratio (S/L), initial pH, contact time, and initial W concentration. The porous carbon P2C+KOH presented the overall best performance in both media, due to its high surface area (2610 m2 g−1), mesopore volume (1.14 cm3 g−1), and neutral pHpzc (6.92). In the synthetic wastewater, the highest uptake capacity of P2C+KOH (854 mg g−1) was found in the assays with an S/L 0.1 g L−1, an initial pH 2, and an initial W concentration of 150 mg L−1, for 24 h. This value was almost 8 times higher than the one obtained for CAC (113 mg g−1). In the mining wastewater, P2C+KOH showed an even higher uptake capacity (1561 mg g−1) in the assay with the same experimental conditions, which was almost 3 times higher than for CAC (561 mg g−1). These results suggest that P2C+KOH seems to be an efficient alternative to CAC in the W(VI) adsorption from liquid effluents.
- Activated carbons
- Rice wastes