Enhanced removal of nitrobenzene with lignosulfonate modified zero valent iron: removal kinetic, reaction mechanism, and application feasibility

The reductive capacity of zero valent iron (ZVI) is extremely restricted by the surface passivation. To address this issue, ball-milling lignosulfonate modified ZVI (LS-ZVI) was prepared and used to determine the reactivity, electron utilization efficiency and application feasibility towards nitrobenzene (ArNO 2 ) removal. The results showed that LS-ZVI could completely remove ArNO 2 within 40 min with aniline conversion percentage of ∼95%, while ArNO 2 reduction by ZVI was negligible within 180 min. Electrochemical evidence, H 2 production, and characterization analysis collectively illuminated that the enhanced ArNO 2 reduction by LS-ZVI was attributed to the increased Fe 0 exposure that endowed it with excellent electron transfer ability. The inhibited H 2 production indicated that the electron utilization efficiency of LS-ZVI towards ArNO 2 was close to 100%. Moreover, ArNO 2 removal was slightly inhibited under higher solution pH. Except for the obvious inhibitory effect of high concentration NO 3 − , the effects of co-existing ions (Cl − , NO 3 − , SO 4 2− , Ca 2+ , and Mg 2+ ) were little. The presence of Ni(II) had a negligible effect on ArNO 2 removal, while high concentration of Cd(II) and Cr(VI) could obviously inhibit ArNO 2 reduction. In addition, the excellent reusability of LS-ZVI and the complete ArNO 2 removal in groundwater suggested the feasibility of LS-ZVI in practical field remediation.