Enhanced Cr(VI) elimination from water by goethite-impregnated activated carbon coupled with weak electric field

A weak electric field (WEF, 2 mA cm -2) was employed to promote Fe(III)/Fe(II) cycle on goethite-impregnated activated carbon (FeOOH@AC) filled in a continuous -flow column for enhanced Cr(VI) elimination from water. Surficial analysis and Cr species distribution showed that alpha-FeOOH of 0.2-1 mu m was successfully synthesized and evenly loaded onto AC. Electron transfer from WEF to alpha-FeOOH was facilitated with AC as electron shuttles, thereby boosting Fe(III) reduction in the alpha-FeOOH. The generated Fe(II) reduced Cr(VI) and the resultant Cr(III) subsequently precipitated with OH- and Fe(III) to form Cr(OH)3 and (Cr chi Fe1-chi)(OH)3. Therefore, the WEFFeOOH@AC column exhibited a much lower Cr(VI) migration rate of 0.0018 cm PV -1 in comparison with 0.0037 cm PV -1 of the FeOOH@AC column, equal to 104 % higher Cr(VI) elimination capacity and 90 % longer column service life -span. Additionally, under different Cr(VI) loadings by varying either seepage velocities or influent Cr(VI) concentrations, the WEF-FeOOH@AC column maintained 1.0-1.5 folds higher Cr(VI) elimination and 0.9-1.4 folds longer longevity than those of the FeOOH@AC column owing to the interaction between FeOOH@AC and WEF. Our research demonstrated that WEF-FeOOH@AC was a potential method to promote Cr (VI) elimination from water and offer an effective strategy to facilitate Fe(III)/Fe(II) cycle in iron oxides.