Removal of As(V) from water using galvanically coupled sacrificial metals

The Permeable reactive barriers (PRBs) is one of the sustainable methods of environmental remediation for groundwater treatment. On using iron as reactive media for PRBs, the longevity of the column is affected by the accumulation of iron corrosion products resulting in permeability reduction. Hence, in this work, iron and zinc are employed as sacrificial metals to remove 50 mg/L As(V) from aqueous solution in an oxic environment, where copper is added as a noble metal. The iron-based system followed first-order reaction kinetics with rate constants -1.65 x 10(-3) min-1 for iron and 2.95 x 10(-3) min(-1) for copper-iron. The zinc-based system followed second-order reaction kinetics with rate constants - 1.26 x 10(-4) L.mg(-1).min(-1)for zinc and 4.67 x 10(-4) L.mg(-1).min(-1) for copper-zinc. The half-life was computed to be 420.1, 234.9. 171.1, and 46.6 min for Fe, Cu-Fe, Zn, and Cu-Zn. The constant supply of adsorption sites is ensured by the continuous generation of corrosion products by sacrificial metals on galvanically coupling with copper. The effectiveness of arsenic retention can be in the order: Cu-Zn > Cu-Fe > Zn > Fe. Among the studied systems, the copper-zinc system can be suggested as the best possible reactive media for PRB in arsenic remediation of groundwater.

Automated summary

The study found that in an oxic environment, iron and zinc can effectively remove 50 mg/L As(V) from aqueous solution, with iron-based system following first-order reaction kinetics and zinc-based system following second-order reaction kinetics. The addition of copper as a noble metal also played a significant role in the arsenic retention order.