Scientific Reports
·
2016
·Vol. 6
·期 1
·1-11
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IF 5.228
Yu Lei,Tang Qing-wen,Zhang Yu-jia,Chen Rong-ping,Liu Xin,Qiao Wei-chuan,Li Wen-wei,Ruan Hong-hua,Song Xin
In this work, the effect of cultivation factors on the flocculation efficiency (FE) of bioflocculant P-GS408 from Klebsiella oxytoca was optimized by the response surface methodology. The most significant factor, i.e . culture time, was determined by gray relational analysis. A total of 240 mg of purified P-GS408 was prepared from 1 liter of culture solution under the optimal conditions. GC-MS analysis results indicated that the polysaccharide of P-GS408 mainly contains Rhamnose and Galactose, and the existence of abundant hydroxyl, carboxyl and amino groups was evidenced by FTIR and XPS analyses. With the aid of Fe 3+ , the FE of kaolin solution by P-GS408 could achieve 99.48% in ten minutes. Functional groups of polysaccharide were involved in the first adsorption step and the zeta potential of kaolin solution changed from −39.0 mV to 43.4 mV in the presence of Fe 3+ and P-GS408. Three-dimensional excitation-emission (EEM) fluorescence spectra demonstrates that the trivalent Fe 3+ and Al 3+ can bind efficiently with P-GS408, while those univalent and divalent cations cannot. With the help of SEM images, FTIR, zeta potential and EEM spectra, we proposed the P-GS408 flocculation mechanism, which consists of coordination bond combination, charge neutrality, adsorption and bridging, and net catching.
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Materials Today Energy
·
2017
·
IF 0
Ge Ma,Zhen Chen,Zhihong Chen,Mingliang Jin,Qingguo Meng,Mingzhe Yuan,Xin Wang,Jun-Ming Liu,Guofu Zhou
In this work, we have prepared a series of efficient visible-light-driven WO 3 /Fe(III) nanofiber photocatalysts by electrospinning and impregnation method. The physical and optical properties of the prepared photocatalysts were characterized by field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the nitrogen adsorption analysis. Under the irradiation of visible light , all the prepared WO 3 /Fe(III) nanofiber photocatalysts exhibit much higher activity for degrading methyl orange (MO) solution than the pristine WO 3 nanofibers, and reaches 94.6% under visible light irradiation for 3 h when the relative grafting amount of Fe(III) ions was 0.003 by mass percentage. Grafting of Fe(III) ions on the surface of WO 3 nanofiber could enhance its visible-light absorption and reduce the photo-generated electron-hole pairs recombination due to the interfacial charge transfer (IFCT) effect, and thus improve its photocatalytic activity , which were further verified by the ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence (PL) and the ns-level time-resolved fluorescence decay spectrum measurements.
研究领域:
材料科学
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光催化化学
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纳米技术
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环境功能材料
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物理化学
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JOURNAL OF HAZARDOUS MATERIALS
·
2015
·
IF 4.529
Zhouwei Miao,Xiaogang Gu,Shuguang Lu,Mark L. Brusseau,Ni Yan,Zhaofu Qiu,Qian Sui
In this study, the effects of reducing agents on the degradation of tetrachloroethene (PCE) were investigated in the Fe(II)/Fe(III) catalyzed sodium percarbonate (SPC) system. The addition of reducing agents, including hydroxylamine hydrochloride, sodium sulfite, ascorbic acid and sodium ascorbate, accelerated the Fe(III)/Fe(II) redox cycle, leading to a relatively steady Fe(II) concentration and higher production of free radicals. This, in turn, resulted in enhanced PCE oxidation by SPC, with almost complete PCE removal obtained for appropriate Fe and SPC concentrations. The chemical probe tests, using nitrobenzene and carbon tetrachloride, demonstrated that HO was the predominant radical in the system and that O 2 − played a minor role, which was further confirmed by the results of electron spin resonance measurements. PCE degradation decreased significantly with the addition of isopropanol, a HO scavenger, supporting the hypothesis that HO was primarily responsible for PCE degradation. It is noteworthy that Cl − release was slightly delayed in the first 20 min, indicating that intermediate products were produced. However, these intermediates were further degraded, resulting in the complete conversion of PCE to CO 2 . In conclusion, the use of reducing agents to enhance Fe(II)/Fe(III) catalyzed SPC oxidation appears to be a promising approach for the rapid degradation of organic contaminants in groundwater.
研究领域:
环境化学
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水处理
·
修复技术
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JOURNAL OF HAZARDOUS MATERIALS
·
2022
·
IF 14.224
Ying Cai,Jinhong Fan,Zhigang Liu
This study constructed a FeS-based Fenton-like process to explore the degradation of TTC in the presence of copper ions . The acidic condition of pH 3 was more favorable to the H 2 O 2 decomposition and TTC degradation , and it was slightly enhanced by Cu(II). The production of •OH from H 2 O 2 was revealed through radical scavenging and benzoic acid probe experiments, and the ratio of H 2 O 2 decomposition to •OH production was about 1–1.5, which is comparatively consistent with the theoretical ratio. FeS-based Fenton process was proved to be a homogenous system, the slow release of Fe(II) source and the autocatalytic cycle of Fe(III) to Fe(II) resulting from the reductive species of TTC and dissolved S(-II) improved the production of •OH and the degradation of TTC, which was proved by comparing TTC degradation, TOC removal, H 2 O 2 decomposition and Fe(II) concentration with different iron sources (FeS, Fe(II) and Fe(III)) and external addition of dissolved S(-II). The possible degradation pathways of TTC were subsequently inferred according to the detected products by LC-MS. Understanding these autocatalytic processes is essential to reveal the transformation of redox-active substances in environments and may have potential significance in applying FeS-based Fenton-like process for the treatment of wastewater containing reductive organic matters.
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CHEMICAL ENGINEERING JOURNAL
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2022
·
IF 16.744
Sitao Wang,Zhijie Liu,Bolun Pang,Yuting Gao,Santu Luo,Qiaosong Li,Hailan Chen,Michael G Kong
Antibiotics are widely used to treat or prevent infectious diseases in human and veterinary medicine. Excessive residues in the aquatic environment lead to increasingly prominent antibiotic pollution; therefore, it is urgent to develop sustainable strategies for rapidly degrading antibiotics. In this study, a highly synergetic effect for norfloxacin (NOR) remediation is achieved by coupling underwater bubble plasma formation with a Fe (III)–S (IV) system due to the efficient utilization of reactive species in chain reactions. The degradation rate using synergetic approach can reach 76.4% within 50 min discharge, and further increases significantly to 94.4% after 5 h post-discharge. The effects of pulsed peak voltage and Fe (III)/S (IV) dosage on NOR removal are characterized. The existence of hydroxyl radicals ( • OH) and sulfate radicals (SO 4 •− ) are proved by electron spin resonance spectrometer (ESR) during degradation. Furthermore, radical scavenger experiments demonstrate that • OH and SO 4 •− play a crucial role in degradation. Underwater bubble plasma provides the oxic and acidic liquid environment for the Fe (III)–S (IV) system to accelerate the self-perpetuating chain reactions. These reactions not only introduce SO 4 •− and generate more • OH during plasma-on, but also induce their regeneration and further prolong the degradation process during plasma-off through plasma-generated effects. Finally, the degradation intermediates of NOR are identified, and a possible degradation pathway is proposed. The possible contribution weight of each approach on the degradation rate is speculated. These new findings offer promising applications for developing a technology with real potential for the treatment of organic compounds in industrial wastewater treatment.
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MATERIALS RESEARCH BULLETIN
·
2022
·
IF 5.6
Qianyu Wei,Qiuhu Lin,Zezhen Zhang,Lili Wu,Chaocan Zhang
Polyvinylidene fluoride (PVDF)/polyhexamethylene guanidine (PHMG)/tannic acid (TA) coatings have some degree of hydrophilicity but lack stability. To improve the hydrophilicity and stability of antimicrobial PVDF/PHMG/TA membranes, Fe(III) is introduced into the composite system. As a weakly acidic hydrophilic nanoion, Fe(III) can enhance the hydrophilicity and resistance to contamination of the membranes. Furthermore, the stability can be enhanced because a three-dimensional cross-linked coating structure is formed by the complexation of Fe(III), TA and PHMG. This work investigates the effects of different tannic acid concentrations and pH conditions on the hydrophilicity, anti-pollution and stability of the modified coatings. The surface morphology of the membranes was analyzed by field-emission scanning electron microscopy. Additionally, the hydrophilicity and the antipollution performance were evaluated based on the water contact angle, submerged oil contact angle, emulsion flux and flux recovery rate. The stability was evaluated by the changes in flux recovery rate and water contact angle before and after emulsion scouring and ultrasonic treatment. The results show that the modified membranes have favorable hydrophilicity and stability after the addition of Fe(III). The water contact angle can be reduced to 19°, the pure water flux can reach 13,850 L·m −2 ·h −1 , and the emulsion flux can reach 2650 L·m −2 ·h −1 . Moreover, 99.68% flux recovery was achieved after 7 days of deionized water flushing, and the water contact angle remained almost unchanged.
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JOURNAL OF FLUORESCENCE
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2022
·Vol. 32
·期 5
·1743-1754
·
IF 2.525
Xu Ouwen,Wan Shuyu,Yang Jing,Song Hanyang,Dong Luzheng,Xia Ji,Zhu Xiashi
In this work, an “on-off-on” fluorescent probe based on Ni-MOF functionalized Nitrogen-doped carbon quantum dots (Ni-MOF-NCDs) was developed. Ni-MOF-NCDs was characterized by FT-IR, TEM, SEM, and XPS. The presence of Fe (III) will reduce the fluorescence intensity of Ni-MOF-NCDs and “turn off” the fluorescence signal at emission peak of 390 nm, while the signal can be “turn on” after the addition of ascorbic acid (AA). The Ni-MOF-NCDs was established as an “on-off-on” fluorescent probe for the detection of Fe (III) and AA with the linear ranges of 0.029-8.0 µg/mL and 0.263-18.0 µg/mL, respectively. The method has been successfully applied to the detection of water samples and foods with satisfactory recovery. The experimental results showed that Ni-MOF-NCDs not only had the fluorescence properties of NCDs, but also had the adsorption performance of Ni-MOF.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Xiaomeng Zhang,Yang Zong,Longqian Xu,Yunfeng Mao,Deli Wu
Abiotic humification can be facilitated by iron-containing minerals or oxides, but most studies have focused on well-crystallized and stable iron phases, the catalytic effect of which is generally unremarkable. In the present study, we report an enhanced abiotic integrated polyphenol-Maillard humification reaction catalysed by Mg/Fe-layered double hydroxide (Mg/Fe-LDH) with high surface reactivity. The results demonstrated that Mg/Fe-LDH could effectively promote the humification reaction at a lower dosage compared with Fe 2 O 3 . As an iron-chelating ligand, catechol rapidly induced iron dissolution from Mg/Fe-LDH through the formation of an Fe(III)-catechol complex, which strengthened the catalytic effect of Fe(III). The photochemical behaviour of Fe(III)-catechol complex and its impact on the Fe(III)-catalysed humification process were investigated. Under light irradiation, environmentally persistent free radicals (EPFRs) originated from the Fe(III)-catechol complex were formed and stabilized in the presence of Mg/Fe-LDH particles, which inhibited the oxidation of catechol and the humification process. Hence, the formation of humic substances (HS) catalysed by Mg/Fe-LDH was more efficient under darkness. Iron redox cycling and generation of reactive oxygen species (ROS), HO• and O 2 •- , were also involved. According to transformation products (TPs) analysis, ortho -aminophenol was proposed to be a key product in the humification reaction. Self-coupling of catechol radical and ortho -aminophenol radical, ring cleavage were likely to occur in the Fe(III)-catalysed humification process. Higher relative abundance of CHO products was observed in the presence of Mg/Fe-LDH by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), suggesting that iron is effective on promoting C–C bonds formation. The above results provide more comprehensive insights into Fe(III)-catalysed humification and a guidance to improve the efficiency of HS formation and carbon sequestration in organic wastes utilization.
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WATER RESEARCH
·
2023
·
IF 12.8
Wenyu Liu,Li Long,Zhe Yang,Li Wang,Qimao Gan,Shenghua Zhou,Pulak Sarkar,Hao Guo,Chuyang Y. Tang
Nanofiltration technology has been applied in a variety of water treatment scenarios. However, conventional thin-film composite (TFC) membranes fail to remove emerging organic micropollutants (OMPs) efficiently. Here we applied thin-film nanocomposite membrane with an interlayer (TFNi) of Fe (III)-tannic acid to remove various types of OMPs, such as endocrine disrupting chemicals (EDCs), pharmaceutically active compounds (PhACs), and perfluoroalkyl substances (PFASs). Compared to the pristine TFC membrane, TFNi membrane exhibited crumpled morphology and its rejection layer was denser, better cross-linked and possessed smaller average pore size with narrower distribution. Significant enhancement in water-OMPs selectivity of PhACs and PFASs was observed. The mechanism lies in the effects of interlayer in improving the membrane permeance to water and meanwhile reducing the permeance to some OMPs by enhancing size exclusion effects. This work confirms the effectiveness of using TFNi membrane to simultaneously enhance the OMPs rejection and water permeance. The unraveled mechanism might inspire the future development of high-performance nanofiltration membranes targeting OMPs removal.
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Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Zhengheng Yang,Xiaoming Ma,Hongbo Zhou,Jinxing Ma,Yuxin Ding,Di He
For more than a century, coagulation-precipitation using Fe(II) and Fe(III) are ubiquitous in wastewater treatment , however, a systematic understanding of the underlying mechanism and their performance toward chelated heavy metals (e.g. Cu II -EDTA) is still lacking. In this study, we therefore investigate the efficiency of Fe(II) and Fe(III) salts coagulation-precipitation, the properties (coagulation and crystallization behavior) of in-situ formed iron (oxy)hydroxides and explore the reaction mechanism using a suite of characterization techniques. Our results reveal that no matter Fe(II) and Fe(III) exhibited an exceptional removal performance for Cu(II) in terms of kinetics and iron dosage along with pH. Impressively, under optimal condition, over 95 % of chelated Cu(II) was removed within 10 min from Fe(II) while about 85 % from Fe(III) dosing. The highly reductive structural Fe(II) existing on mixed-valent iron bearing mineral results in reductive decomplexation of Cu II -EDTA in the Fe(II) coagulation-precipitation process in compare with replacement decomplexation in the Fe(III) coagulation-precipitation process, and then released free metal ions (Cu(I) and Cu(II)) can be removed by adsorption and coprecipitation . In addition, the in-situ formed Fe(III) (oxy)hydroxides were amorphous 2-line ferrihydrite with stable flocs and better sedimentation behavior than crystalline lepidocrocite from Fe(II) dosing, and these factors are crucial to the subsequent retention of heavy metals. The elucidation of this study has highlighted the great potential of using in-situ formed iron (oxy)hydroxides for cost-effective treatment of chelated heavy metal-bearing industrial wastewaters .
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FOOD CHEMISTRY
·
2023
·
IF 8.8
Zheng Guo,Han-Yi Zheng,Zhong-Ying Huang,Yue-Zhen Liu,Yao-Hua Liu,Yun Chen,Jing Gao,Yong Hu,Chao Huang
A ternary deep eutectic solvent (DES) consisting of choline chloride, lactic acid, and urea in a molar ratio of 1:2:2 was used to pretreat chamomile residue, followed by carbon dots (CDs) preparation using a one-pot solvothermal method . The CDs prepared under the suitable conditions had a high quantum yield of 47.34% and could be used as a bifunctional fluorescent probe for the detection of tartrazine and Fe(III). The concentration of tartrazine or Fe(III) had a good linear relationship with the fluorescence intensity of CDs that the determination coefficient ( R 2 ) was 0.9957 and 0.9943, and the limit of detection (LOD) was 40 nM and 119 nM, respectively. After verifying the different fluorescence quenching mechanisms of CDs by these two substances, a quantitative analysis was performed on real samples with recoveries of 90.70%∼104.29%. Overall, this study provided a promising technology for chemical conversion from low-cost chamomile residue to attractive bifunctional fluorescent probe.
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TALANTA
·
2018
·
IF 4.244
Hao Zhang,Chen Nie,Jiahui Wang,Ruifang Guan,Duxia Cao
Organic-inorganic hybrid fluorescent microspheres (OI-FMs) without typical fluorophores were prepared. Fluorescence quantum yield of OI-FMs is up to 70.0% after being heated in an oven at 120 °C (named as OI-FMs-120). Interestingly, OI-FMs-120 shows different detection performances in different solvents. It can be used for qualitative and quantitative detection of Fe 3 + with a detection limit of 37.8 nM in absolute ethanol. While in aqueous solution, it can be applied as an ON-OFF-ON fluorescent probe . Fluorescence of the probe is quenched by Hg 2 + and later recovered by biothiols. The detection limit is as low as 34.9 nM for Hg 2 + , 91.0 nM for Cys, 0.12 μM for Hcy and 0.13 μM for GSH in aqueous medium, respectively.
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