Removal of zinc from contaminated groundwater by zero-valent iron permeable reactive barrier

The possibility of using zero-valent iron (ZVI) as permeable reactive barrier (PRB) to remove zinc from a contaminated groundwater was investigated. Batch equilibrium tests were carried out. The effects of many parameters such as contact time between adsorbate and adsorbent (0-240 min), initial pH of the solution (4-8), sorbent dosage (1-12 g/100 ml), initial metal concentration (50-250 mg/l), and agitation speed (0-250 rpm) were studied. The best values of these parameters that achieve the maximum removal efficiency of Zn+2 (=91%) were 3 h, 5, 10 g/100 ml, 50 mg/l, and 200 rpm, respectively. Langmuir isotherm model gives better fit for the sorption data of Zn+2 ion by ZVI than Freundlich model under the studied conditions. Finite difference method and COMSOL Multiphysics 3.5a software, which is based on finite element method, were used to simulate the one-dimensional equilibrium transport of zinc through sandy aquifer with and without presence of PRB. The predicted and experimental results proved that the PRB plays a potential role in the restriction of the contaminant plume migration. A reasonable agreement between these results was recognized with root mean squared error not exceeded the 0.1487.