Efficient removal of arsenic from aqueous solution by continuous adsorption onto iron-coated cork granulates

Abstract

The search for low-cost technologies for arsenic removal from water is in high demand due to its human toxicity, even at low concentrations. Adsorption can be a cost-effective water treatment technique if applied with inexpensive materials. Arsenic continuous removal by adsorption onto an alternative modified biosorbent, iron-coated cork granulates (ICG), was investigated in this work. Results showed that most experimental parameters of breakthrough curves (BTC) depend on flow rate, bed height, pH, and initial arsenic concentration. The temperature did not significantly affect arsenate removal in continuous mode; however, the adsorption capacity was affected in batch mode. The thermodynamic parameters suggest that the adsorption process is spontaneous and endothermic. The maximum adsorption capacity of ICG for As(V) removal at pH 3 was 4.2 ± 0.3 mg g−1, calculated by Yan model fit (R2 = 0.981), and for As(III) at pH 9 was 1.6 ± 0.2 mg g−1 (R2 = 0.994). ICG were able to treat As(V) from 100 µg L−1 to under 10 µg L−1 and 50 µg L−1 for 895 and 1633 bed volumes, and As(III) for 569 and 861 bed volumes, respectively, both at pH 7. The application of ICG in arsenic oxyanions remediation was found to be effective under various conditions.