MINERALS ENGINEERING
·
2020
·
IF 3.795
Yang Cao,Xian Xie,Xiong Tong,Dongxia Feng,Jinfang Lv,Yumeng Chen,Qiang Song
This paper systematically analyzed the effects of Fe(II) ions on the cassiterite surface to promote the adsorption of salicylhydroxamic acid (SHA). The interaction behavior and mechanisms re investigated using micro-flotation experiments, adsorption experiments, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The micro-flotation tests revealed that the Fe(II) ions had a strong activation effect on the cassiterite, and the recovery reached the maximum at pH values of 7–8. The results of the adsorption experiment showed that the adsorption capacity of SHA on the mineral surface significantly improved after Fe (II) ion activation; this result was confirmed by the zeta potential test. In addition, the zeta potential results indicated that the positively charged Fe species absorbed on the cassiterite surface led to positive changes in the mineral surface potential and an increase in the number of active sites, thereby increasing the SHA adsorption. The XPS and FTIR results demonstrated that the Fe(II) ions activated the cassiterite through the interaction of terminal oxygen atoms with Fe species on the cassiterite surfaces, and redox reactions and displacement reactions occurred between Fe 2+ and Sn 4+ . SHA was chemisorbed on the cassiterite surface, allowing the anions to react readily with the Fe species to form Fe-SHA complexes. Therefore, the Fe(II) ion-activated cassiterite surfaces enhanced the strength and stability of the SHA chemisorption. Based on the results, an adsorption model of the Fe(II) ion-activated cassiterite surface in the SHA system was established.
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Scientific Reports
·
2020
·Vol. 10
·期 1
·1-11
·
IF 3.998
Dong Zijun,Chen Guanhan,Li Mu,Sun Feiyun,Jiang Chengchun,Bharti Bandna
Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts. Herein, iopamidol (IPM), one typical compound of ICM, was found to be rapidly degraded by ferrous activated persulfate oxidation (Fe(II)/PS) as compared with PS or Fe(II) alone. With a persulfate concentration of 1 mmol L −1 , n(Fe(II))/n(PS) of 1:10, and a pH of 3.0, 78% IPM was degraded within 60 min, with a degradation rate of 0.1266 min −1 . It was demonstrated that IPM degradation and deiodination were favored by a high temperature, while affected positively by acidic and neutral conditions. Radical quenching experiments and Electron Paramagnetic Resonace (EPR) spectra showed that the combined effects of SO 4 − · and · OH contributed dominantly to degrade IPM, while the · OH played an essential role during the degradation reaction. Through the Discrete Fourier Transform quantum chemical calculation, the possible reaction pathways for the oxidation of IPM by · OH are as follows: IPM-TP651-TP667-TP541-TP557, IPM-TP651-TP525-TP557, IPM-TP705-TP631-TP661, and IPM-TP705-TP735. The obtained results showed that IPM could be degraded effectively by Fe(II)/PS system, giving a promising technique for IPM removal from water.
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Arabian Journal of Chemistry
·
2020
·
IF 4.762
Zijun Dong,Feng Wang,Xiulan Song,Miao Zhang,Chengchun Jiang,Feiyun Sun,Mu Li
Iodoform (CHI 3 ) is one of the disinfection by-products (DBPs) that is formed in the pre-oxidation and disinfection processes of drinking water treatment. In this study, Fe(II)-activated persulfate oxidation (Fe 2+ /PS) was employed to degrade iodoform, the effects of initial reactants concentration, reaction parameters, kinetics model were investigated, and the underlying mechanisms of CHI 3 degradation in Fe 2+ /PS oxidation process was unveiled. The results showed that the mole ratio Fe 2+ /PS of 1:5, initial PS concentration of 15 μmmol/L, and pH of 3.0 were identified as the optimum operating parameters. In addition, a relatively higher temperature could enhance CHI 3 removal and deiodination. The kinetic model has two different reaction steps: a fast one during the first ten minutes of reaction; then followed by a much slower one. Suppression of the reaction by TBA and MeOH showed that the combined effects of SO 4 − · and ·OH contributed to the degradation of CHI 3 , but ·OH played a dominant role. The degradation pathways and the products of total liberated iodine species demonstrate that the applicability of the Fe 2+ /PS oxidation process for CHI 3 degradation. These results indicated that the Fe 2+ /PS oxidation process is an effective advanced oxidation process for CHI 3 removal in water treatment.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 24
·期 31
·24318-24326
·
IF 2.741
Fu Xiaori,Brusseau Mark L.,Zang Xueke,Lu Shuguang,Zhang Xiang,Farooq Usman,Qiu Zhaofu,Sui Qian
This work demonstrates the impact of hydroxylamine hydrochloride (HAH) addition on enhancing the degradation of trichloroethene (TCE) by the citric acid (CA)-chelated Fe(II)-catalyzed percarbonate (SPC) system. The results of a series of batch-reactor experiments show that TCE removal with HAH addition was increased from approximately 57 to 79% for a CA concentration of 0.1 mM and from 89 to 99.6% for a 0.5 mM concentration. Free-radical probe tests elucidated the existence of hydroxyl radical (HO • ) and superoxide anion radical (O 2
•- ) in both CA/Fe(II)/SPC and HAH/CA/Fe(II)/SPC systems. However, higher removal rates of radical probe compounds were observed in the HAH/CA/Fe(II)/SPC system, indicating that HAH addition enhanced the generation of both free radicals. In addition, increased contribution of O 2
•- in the HAH/CA/Fe(II)/SPC system compared to the CA/Fe(II)/SPC system was verified by free-radical scavengers tests. Complete TCE dechlorination was confirmed based on the total mass balance of the released Cl − species. Lower concentrations of formic acid were produced in the later stages of the reaction for the HAH/CA/Fe(II)/SPC system, suggesting that HAH addition favors complete TCE mineralization. Studies of the impact of selected groundwater matrix constituents indicate that TCE removal in the HAH/CA/Fe(II)/SPC system is slightly affected by initial solution pH, with higher removal rates under acidic and near neutral conditions. Although HCO 3
− was observed to have an adverse impact on TCE removal for the HAH/CA/Fe(II)/SPC system, the addition of HAH reduced its inhibitory effect compared to the CA/Fe(II)/SPC system. Finally, TCE removal in actual groundwater was much significant with the addition of HAH to the CA/Fe(II)/SPC system. The study results indicate that HAH amendment has potential to enhance effective remediation of TCE-contaminated groundwater.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2024
·
IF 10.8
Na Zhang,Ying Liu,Zhenchen Wan,Yanting Zhang,Wenjing Xie,Peng Zhang,Man Tong,Songhu Yuan
Reactive oxygen species (ROS) production in O2-perturbed subsurface environments has been increasingly documented in recent years. However, the constraining conditions under which abiotic and/or biotic mechanisms predominate for ROS production remain ambiguous. Here, we demonstrate that the ROS production mechanism, biotic and abiotic, is determined by sediment redox properties and sediment compositions. Upon the oxygenation of 10 field sediments, the cumulative H2O2 concentrations reached up to 554 μmol/kg within 2 h. The autoclaving sterilization experiments showed that H2O2 could be produced by both biotic and abiotic processes depending on the redox conditions. However, only the abiotic process could produce significant levels of •OH, and the production yield was closely related to the sediment components, particularly sediment Fe(II) and organic matter. Fe(II) bound with organic matter led to high yields of H2O2 and •OH production. Sediment oxygenation contributed to the appearance of H2O2 in groundwater, with the abiotic mechanism producing higher instantaneous H2O2 concentrations than the biotic mechanism. These findings reveal that the redox conditions, compositions, and texture of sediments collectively control abiotic and biotic mechanisms for ROS production, which assists the identification of ROS production hotspots and the understanding of ROS distribution and utilization in the subsurface.
研究领域:
环境科学
·
地球化学
·
微生物学
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Water Supply
·
2021
·Vol. 22
·期 1
·208-219
·
IF 1.033
Fu Xiaori,Wei Xinyan,Zhang Wei,Yan Wupeng,Wei Peng,Lyu Shuguang
The addition of hydroxylamine hydrochloride (HAH), ascorbic acid (ASC), sodium ascorbate (SAS) to the OA-Fe(II)/SPC system could promote the generation of HO • by accelerating Fe(II)/Fe(III) recycles and H 2 O 2 decomposition. The enhancement of HAH on HO • generation surpasses ASC and SAS in the OA-Fe(II)/SPC system. The generation of O 2 •− was also enhanced by HAH, ASC and SAS, and more significant promotion of O 2 •− generation was observed with ASC and SAS addition. More effective benzene removal was achieved in an OA-Fe(II)/SPC system with suitable HAH, ASC and SAS addition, compared to the parent system. Excessive HAH, ASC or SAS had a negative effect on benzene removal. Results of scavenger tests showed that HO • is indeed the dominant free radical for benzene removal in every system, but the addition of HAH, ASC and SAS increased the contribution of O 2 •− to benzene degradation. HAH, ASC and SAS enhanced OA-Fe(II)/SPC systems could be well utilized to acidic and neutral conditions, while HCO 3 − , high concentration of HA and alkaline conditions were not favorable to benzene removal. Moreover, the addition of HAH, ASC and SAS are conducive to benzene removal in actual groundwater, and HAH was the optimal reducing agent for the enhancement of the OA-Fe(II)/SPC system. Benzene removal performance in an RA-OA-Fe(II)/SPC system was investigated. HAH is more conducive to HO • generation than ASC and SAS. Significant promoted generation of O 2 •− was observed with ASC and SAS addition. HAH, ASC and SAS weakened negative effects of the solution matrix on benzene removal. HAH, ASC and SAS are conducive to benzene removal in actual groundwater.
研究领域:
环境化学
·
高级氧化技术
·
水处理
·
污染物降解
·
修复技术
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Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Zhenhua Xin,Renjie Chen,Chuanjin Lin,Bin Dong,Zuxin Xu
The aggregation and separation of magnetic biochar (MBC) are the bottlenecks in its application for the removal of hexavalent chromium (Cr(VI)) from aquatic media. To solve this problem, MBC and Fe(II)–sodium alginate (SA) hydrogel were combined to form SA–Fe(II)–MBC beads (SA–Fe–C), which were used for Cr(VI) removal and immobilization from aqueous solutions. SEM and XPS revealed that the 3D network structure of SA–Fe(II) hydrogel effectively prevented the aggregation of MBC. The experimental maximum Cr(VI) removal capacity of SA–Fe–C beads was 30.03 mg/g at pH 4. The spontaneous process of Cr(VI) removal by SA–Fe–C beads was best described by a pseudo-second-order model and dominated by chemical adsorption. Toxicity characteristic leaching procedure extraction showed that SA–Fe–C beads exhibited excellent immobilization capacity for Cr. The mechanism whereby SA–Fe–C beads removed and immobilized Cr(VI) from solution was found to involve: (1) adsorption, (2) reduction of Cr(VI) to trivalent chromium (Cr(III)) by Fe(II) and hydroxyl groups, and (3) co-precipitation of Cr(III) with Fe(II) to form chromite. In addition, the beads demonstrated excellent regeneration capability and reusability, showing promising potential for heavy metal removal from contaminated water.
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MINERALS ENGINEERING
·
2025
·
IF 5
Qinbo Cao,Yan Yan,Heng Zou,Haiyu Zhang,Dianwen Liu,Shuming Wen
The S 2 O 8 2− /Fe 2+ system can be used to depress PbS, where the activation of S 2 O 8 2− leads to the generation of SO 4 • − radicals that oxidize PbS. However, a high S 2 O 8 2− /Fe 2+ dosage is needed for PbS depression (0.15 mol/L). In this study, ultrasonication was employed to improve the depression ability of S 2 O 8 2− /Fe 2+ . The flotation and contact angle results implied that 120-kHz ultrasonication enhanced the depression ability of S 2 O 8 2− /Fe 2+ for PbS, resulting in a decrease in the S 2 O 8 2− /Fe 2+ dosage. Ultrasonication induced hot spots (5000 K) in the PbS slurry and on the PbS surface. These hot spots may cause the thermal activation of S 2 O 8 2− to generate SO 4 • − radicals, facilitating the oxidation of PbS. Thus, the ultrasound-assisted treatment increased the oxidation level of PbS. The XPS study revealed that ultrasonication favored the oxidation of S 2− on the PbS surface to SO 4 2− , such that the surface was covered with PbSO 4 and the hydrophobicity of PbS was lowered. However, ultrasonication did not considerably increase the oxidation state of the CuFeS 2 surface; thus, CuFeS 2 could still be floated and separated from PbS. This study provides a novel strategy for separating PbS–CuFeS 2 mixtures.
研究领域:
矿物加工工程
·
化学工程
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2025
·
IF 11.3
Hongyan Wei,Shoushu Wei,Qingze Chen,Yixuan Yang,Xun Liu,Shiqin Long,Jing Liu,Jianxi Zhu,Runliang Zhu
Metastable ferrihydrite nanoparticles and clay minerals always coexist as heteroaggregates in nature due to their abundance, opposite charge, and large interface energy. However, the impact of clay minerals on the transformation of ferrihydrite under anoxic conditions remains elusive. This study systematically investigated the effect of distinct clay minerals on the Fe(II)-catalyzed transformation of ferrihydrite and clarifying the underlying nanoscale mechanisms for the first time. Our results demonstrated that clay minerals could affect the production and recrystallization of labile Fe(III) (an active Fe(III) intermediate species formed by oxidation of Fe(II) at the ferrihydrite surface) by dispersing ferrihydrite aggregates. This modulation led to different transformation rates, higher crystallinity of formed lepidocrocite, and enhanced goethite formation in the heteroaggregates. Importantly, montmorillonite can accommodate Fe(II) and labile Fe(III) within its interlayer spaces, which further led to the inhibited crystallization of Fe(II) to magnetite and long-term preservation of labile Fe(III). Additionally, clay minerals served as templates for forming dendritic goethite and hexagonal magnetite nanoplates. Our findings provide new insights into the complicated roles of clay minerals in controlling the ferrihydrite transformation and other iron (oxyhydr)oxides formation, which is significant for predicting the bioavailability of iron and the fate of other coexisting contaminants.
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WATER RESEARCH
·
2014
·
IF 5.323
Jingu Shi,Zhihui Ai,Lizhi Zhang
In this study we demonstrate Fe@Fe 2 O 3 core–shell nanowires can improve Fenton oxidation efficiency by two times with rhodamine B as a model pollutant at pH > 4. Active species trapping experiments revealed that the rhodamine B oxidation enhancement was attributed to molecular oxygen activation induced by Fe@Fe 2 O 3 core–shell nanowires. The molecular oxygen activation process could generate superoxide radicals to assist iron core for the reduction of ferric ions to accelerate the Fe(III)/Fe(II) cycles, which favored the H 2 O 2 decomposition to produce more hydroxyl radicals for the rhodamine B oxidation. The combination of Fe@Fe 2 O 3 core–shell nanowires and ferrous ions (Fe@Fe 2 O 3 /Fe 2+ ) offered a superior Fenton catalyst to decompose H 2 O 2 for producing OH. We employed benzoic acid as a probe reagent to check the generation of OH and found the OH generation rate of Fe@Fe 2 O 3 /Fe 2+ was 2–4 orders of magnitude larger than those of commonly used iron based Fenton catalysts and 38 times that of Fe 2+ . The reusability and the stability of Fe@Fe 2 O 3 core–shell nanowires were studied. Total organic carbon and ion chromatography analyses revealed the mineralization of rhodamine B and the releasing of nitrate ions. Gas chromatograph-mass spectrometry was used to investigate the degradation intermediates to propose the possible rhodamine B Fenton oxidation pathway in the presence of Fe@Fe 2 O 3 nanowires. This study not only provides a new Fenton oxidation system for pollutant control, but also widen the application of molecular oxygen activation induced by nanoscale zero valent iron .
研究领域:
环境科学
·
材料科学
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Polymers
·
2016
·Vol. 8
·期 11
·389
·
IF 2.944
Lihua Guo,Xinyu Jing,Shuoyan Xiong,Wenjing Liu,Yanlan Liu,Zhe Liu,Changle Chen
A series of alkyl- and aryl-substituted iminopyridine Fe(II) complexes1a–7aand Co(II) complexes2b,3b,5b, and6bwere synthesized. The activator effect, influence of temperature, and, particularly, the alkyl and aryl substituents’ effect on catalytic activity, polymer molecular weight, and regio-/stereoselectivity were investigated when these complexes were applied in isoprene polymerization. All of the Fe(II) complexes afforded polyisoprene with high molecular weight and moderatecis-1,4 selectivity. In contrast, the Co(II) complexes produced polymers with low molecular weight and relatively highcis-1,4 selectivity. In the iminopyridine Fe(II) system, the alkyl and aryl substituents’ effect exhibits significant variation on the isoprene polymerization. In the iminopyridine Co(II) system, there is little influence observed on isoprene polymerization by alkyl and aryl substituents.Keywords:iminopyridine;Iron(II);Cobalt(II);isoprene polymerization;selectivity
研究领域:
化学
·
高分子科学
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Chuanyu Chen,Simeng Xia,Fan Chen,Ting Peng,Lin Deng,Huiying Wu,Zhou Shi
The Fe(II)/peracetic acid (PAA) process shows significant potential for the removal of organic pollutants due to the rapid reaction between Fe(II) and PAA. However, the slow reduction from Fe(III) to Fe(II) leads to the continuous or excess dosing of Fe(II) during practical application. In this study, epigallocatechin gallate (EGCG), a typical reagent extracted from green tea, was used to enhance the degradation of coumarin (COU) by Fe(II)/PAA for the first time. A complete elimination of COU (25 μM) was achieved in the presence of 50 μM Fe(II), 300 μM PAA, and 25 μM EGCG, exhibiting a k obs value of 0.108 min −1 , which was 27 times higher than that observed with Fe(II)/PAA (0.004 min −1 ). Further, Fe(II)/EGCG/PAA demonstrated remarkable pH tolerance, with a COU removal efficiency exceeding 80 % across a pH range of 3–9. Mechanisms investigations revealed that •OH played a dominant role in COU degradation by Fe(II)/EGCG/PAA (accounting for 98.2 %). The increase in EGCG concentration from 10 to 100 μM resulted in a decreased formation of •OH yield and an enhanced generation of RO•. These findings highlight the capability of EGCG to improve the oxidation capacity of Fe(II)/PAA and modulate reactive species formation. The outstanding oxidation capacity and environmental friendliness of Fe(II)/EGCG/PAA process render it a potential strategy to eliminate organic pollutants in actual water treatment.
研究领域:
环境科学
·
化学
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