Nitrate Removal by Acid-Washed Sulfur Modified Iron (SMI) and Zero Valent Iron (ZVI)

Sulfur Modified Iron (SMI) and Zero Valent Iron (ZVI) have been extensively studied for its ability to reduce different contaminants, including nitrate in groundwater. Although nitrate reduction with ZVI was reported as early as 1964, research projects using the materials as an alternative for nitrate removal have emerged only recently. Therefore, further investigations are still need to maximize the efficiency of nitrate removal using SMI and ZVI. In current work, we determined the mixing ratio, effects of acidification of SMI and ZVI, and need of pH controlling to obtain the highest nitrate removal rate, increasing amount of less expensive compound, ZVI, than SMI. In the results, nitrate removal by only ZVI or SMI was 32.53% and 0.69%, respectively. Although SMI:ZVI(1:4; g/g) was the best mixing ratio for the highest nitrate removal rate, it did not improve the removal rate compared to it when we used only ZVI or SMI. However, the acidified SMI and ZVI (1:4; g/g) with 0.5 N-HCl for 8 hr increased nitrate removal from 32% to 87%. Through the test, we found that using SMI and ZVI (1:4; g/g) acidified is an appropriate method to remediate nitrate-contaminated groundwater with the highest efficiency, increasing ratio of cheaper compound ZVI. Although SMI and ZVI showed the higher nitrate removal rate in low pH in other works, in case of using acidified SMI and ZVI, pH controlling did not affect the nitrate removal rate.