Chen Ling,Shuai Wu,Tailu Dong,Haifan Dong,Zhengxiao Wang,Yuwei Pan,Jiangang Han
Sulfide-modified zero-valent iron (S-Fe 0 ) is regarded as a promising method to enhance the catalytic activity of Fe 0 for peroxymonosulfate (PMS) activation. However, the roles of sulfidation and the application of the sulfidation treatment method are worth to further investigation. In our study, the effects of the S/Fe ratio, Fe 0 dosage, and initial pH on sulfadiazine (SDZ) removal were investigated. The characterization of S-Fe 0 with SEM, XPS, contact angle and Tafel analysis confirmed that the formation of sulfur species on the Fe 0 surface could enhance the catalytic performance of Fe 0 . S 2− played the major role and SO 3 2- played the minor role in accelerating the conversion of Fe 3+ to Fe 2+ . EPR tests, radical quenching and quantitative determination experiments identified • OH as playing the major role and SO 4 •− also playing an important role in SDZ removal in S-Fe 0 /PMS system. Sulfidation produced no notable change in the role of • OH and SO 4 •− . A possible degradation pathway of SDZ was proposed. Effect of sulfidation on various sizes of Fe 0 was also studied which demonstrated that the smaller sizes of Fe 0 (< 8 µm) were more effective in the sulfidation method treatment. S-Fe 0 /PMS system also showed a good performance in removing antibiotics in natural fresh water.
Jie Gao,Lizhe Yang,Yingying Liu,Fengli Shao,Qianjiahua Liao,Jingge Shang
Nano scale zerovalent iron (nZVI) used in waste water treatment can be more effective when modified with sulfur. In this study, we synthesized biochar-supported sulfide-modified nZVI (S-nZVI/BC) and characterized it using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Our results reveal that sulfidation resulted in the formation of FeS on the surface of S-nZVI/BC. The Cr(VI) removal efficiency and capacity of the above composite were investigated as a function of initial solution pH/Cr(VI) concentration, reaction time, and presence of background ions (Ca 2+ and SO 4 2– ). Batch experiments revealed that solution pH had a significant impact on Cr(VI) removal capacities, with the maximum observed at pH 2.5. From a kinetic viewpoint, Cr(VI) removal was best described by a pseudo-second-order model. Importantly, the scavenger reaction was significantly promoted in the presence of SO 4 2– , being slightly inhibited by Ca 2+ and dissolved oxygen. Thus, the sulfidised nanohybrids exhibited excellent Cr(VI) removal performance, being well suited to the remediation of Cr(VI)-polluted water.
Ying Liu,Jingfeng Gao,Qian Wang,Hao Chen,Yi Zhang,Xiaoyu Fu
Whether it’s necessary to extra chemical synthesis steps to modify nZVI in peroxymonosulfate (PMS) activation process are worth to further investigation. The 56 mg/L nZVI/153.65 mg/L PMS and 56 mg/L sulfidated nZVI (S-nZVI) (S/Fe molar ratio = 1:5)/153.65 mg/L PMS) processes could effectively attain 97.7% (with k obs of 3.7817 min −1 ) and 97.0% (with k obs of 3.4966 min −1 ) of the degradation of 20 mg/L sulfadiazine (SDZ) in 1 min, respectively. The nZVI/PMS system could quickly achieve 85.5% degradation of 20 mg/L SDZ in 1 min and effectively inactivate 99.99% of coexisting Pseudomonas . HLS-6 (5.81-log) in 30 min. Electron paramagnetic resonance tests and radical quenching experiments determined SO 4 •− , HO•, 1 O 2 and O 2 •− were responsible for SDZ degradation. The nZVI/PMS system could still achieve the satisfactory degradation efficiency of SDZ under the influence of humic acid (exceeded 96.1%), common anions (exceeded 67.3%), synthetic wastewater effluent (exceeded 90.7%) and real wastewater effluent (exceeded 78.7%). The high degradation efficiency of tetracycline (exceeded 98.9%) and five common disinfectants (exceeded 96.3%) confirmed the applicability of the two systems for pollutants removal. It’s no necessary to extra chemical synthesis steps to modify nZVI for PMS activation to remove both chemical and biological pollutants.
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