Related Experiment Video
Updated: Oct 4, 2025

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron OxyHydroxides, Trace Elements, and Bacteria
Published on: December 19, 2017
Humic acid addition sequence and concentration affect sulfur incorporation, electron transfer, and reactivity of
Liangfeng Duan1, Yinshun Dai1, Lijiao Shi1
1Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, 266237, China.
Abstract:
Nanoscale zero-valent iron (nZVI) is extensively used in field remediation and can be sulfidated in situ with sulfide or sulfate-reducing bacteria to enhance its performance. Humic acid (HA) widely exists in nature, but its influence on both the sulfidation process of nZVI and the reactivity of sulfidated nZVI (S-nZVI) has been rarely reported. Herein, we first synthesized S-nZVI by one-pot (S1-nZVI) and two-step (S2-nZVI) approaches with adding HA before (pre-added) or after (post-added) FexSy generation, respectively. Then, we evaluated their reactivity on Cr(VI) removal and analyzed the effects of HA on sulfidation regarding electron transfer resistance, sulfur incorporation, and structure characterization. Pre-added HA inhibited the Cr(VI) removal by S1-nZVI more seriously than by S2-nZVI and nZVI, and stronger inhibition was observed at higher HA concentrations. The inhibitory effect can be attributed mainly to the adsorbed HA increasing the impedance of the material and the free HA impeding the generation and deposition of FexSy. Different from the inhibition of pre-added HA at all studied HA concentrations, the Cr(VI) removal by both S1-nZVI and S2-nZVI with post-added HA was enhanced at specific HA concentrations. The reason for this phenomenon was that the dispersion and specific surface area of S-nZVI were improved, thereby offsetting the inhibition from both impedance increase and sulfur loss. This work suggests that the presence of HA can affect the sulfidation process and the property of S-nZVI, which is conducive to evaluating the performance of S-nZVI produced both by injection and in situ in the subsurface contaminant remediation.
More Related Videos
09:34Synthesis and Characterization of Fe-doped Aluminosilicate Nanotubes with Enhanced Electron Conductive Properties
Published on: November 15, 2016
06:53Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Related Concept Videos
Sulfur Assimilation
Formation of Complex Ions
Preparation and Reactions of Sulfides
Preparation and Reactions of Thiols
Precipitation and Co-precipitation
Electrophilic Aromatic Substitution: Sulfonation of Benzene