Journal of Water Process Engineering
·
2025
·
IF 6.7
Yueli Chen,Huilin Huang,Runying Luo,Aiping Zhang
Landfill leachate contains high levels of refractory organic compounds that pose significant environmental risks. The treatment of landfill leachate through advanced oxidation processes (AOPs) is an effective method for removing these compounds. However, the presence of chloride ions (Cl − ) might lead to the formation of chlorinated organics. In this study, we compared the formation of chlorinated organics during the removal of refractory organic compounds from landfill leachate treated by a membrane bioreactor (MBR) through UV/H 2 O 2 and UV/PDS processes with different oxidant dosages. The relationship between the formation of chlorinated organics and the concentration of organics was explained via ultraviolet visible spectra, three-dimensional excitation and emission matrix spectra, and total organic carbon. The results revealed that the concentration of chlorinated organics increased with increasing oxidant dosage. Under the oxidant dosage of 40 mM and a reaction time of 90 min, the cumulative concentration of the 4 chlorinated organics in the UV/H 2 O 2 process reached 482.8 μg/L, and those of the 8 chlorinated organics reached 34,370.2 μg/L in the UV/PDS process. Concentrations of chloroacetaldehyde, chloroacetic acid and trichloroacetic acid produced in the UV/H 2 O 2 process and concentrations of chloroacetaldehyde, dichloroacetaldehyde and dichloroacetonitrile produced in the UV/PDS process were significantly and positively correlated with the concentrations of aromatic organic compounds. In the UV/H 2 O 2 and UV/PDS processes, the concentration of Cl − affects the conversion of reactive chlorine species, such as Cl • and Cl 2 •– , and the reactive species, such as HO • , SO 4 •– , Cl • and Cl 2 •– generated in the process react with organic compounds to form intermediates through hydrogen extraction, addition and electron transfer processes that gradually open ring structures to form small molecules. Cl • and Cl 2 •– further react with these small-molecule intermediates to form chlorinated organics through chlorine substitution. The toxicity evaluation of chlorinated organics revealed that haloacetaldehydes were the main source of chlorinated organic toxicity in both the UV/H 2 O 2 and UV/PDS processes. This study provides theoretical support for reducing the formation of chlorinated organics during refractory organic compound removal processes from landfill leachate via advanced oxidation processes such as UV/AOPs.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS ES&T Engineering
·
2022
·
IF 0
Shaoxiong He,Enya Wu,Mingjie Shen,Haodong Ji,Lixi Zeng,Mingshan Zhu
Fluorinated liquid crystal monomers (LCMs) have been identified as emerging persistent and bioaccumulative chemicals with non-negligible environmental concentrations. Herein, 12 fluorinated LCMs including highly detected 4-ethoxy-2,3-difluoro-4′-(trans-4-propylcyclohexyl)biphenyl (EDPB) were selected as target fluorinated LCMs to investigate their structure–reactivity relationships by the ultraviolet/peroxydisulfate (UV/PDS) treatment. EDPB with biphenyl and ethoxy showed the highest first-order degradation rate constant of 1.93 h–1, while that of fluorinated LCMs with ethoxy (1.10–1.26 h–1) and biphenyl (0.45–0.56 h–1) and without biphenyl or ethoxy (0.27–0.30 h–1) decreased sequentially. HO• and SO4•– were identified as the main oxidative species in the UV/PDS treatment. Theoretical calculation suggested that biphenyl and ethoxy can significantly alter the electron distribution of LCM molecules, providing more attackable sites for HO• and SO4•– on LCMs with biphenyl or ethoxy. Oxalic acid, cyclohexane, and bicyclohexane were the main degradation products of fluorinated LCMs even though their degradation pathways were determined by their different molecular structures. Toxicity estimation revealed that fluorinated LCMs with high acute toxicity and developmental toxicity could be decomposed into some final products with less toxicity. This study is expected to fill knowledge gaps in the structure–activity relationships of fluorinated LCMs by the UV/PDS treatment.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Boqiang Li,Baiyang Chen,Zongsu Wei
UV/peroxydisulfate (UV/PDS) process is known to be highly efficient for degrading micropollutants from water by generating sulfate (SO 4 •− ) and hydroxyl radicals (HO • ). Reliable analyses of short-lived SO 4 •− and HO • are therefore critical for understanding reaction mechanisms and optimizing operating conditions. Currently, alcohols are commonly used as quenchers to distinguish radicals based on the assumption that they exclusively react with target radicals without other influences. However, this study for the first time reveals a series of unexpected effects that challenge this conventional wisdom because: 1) adding alcohols altered the decomposition rates of PDS by replacing the reactions between SO 4 •− and HO • with PDS by the reactions between secondary reactive species and PDS; and 2) SO 4 •− preferably reacted with alcohols to generate nonnegligible level of hydrogen peroxide (H 2 O 2 ) under oxygen-rich conditions, which subsequently led to indirect formation of HO • . Additionally, the formation of H 2 O 2 was substantially impacted by the types of alcohols, dosages, dissolved oxygen, and solution pH. Using probe tests as tools, we found that the actual SO 4 •− levels after dosing alcohols were only slightly different from assumed/expected levels, whereas the actually HO • levels were 43.7, 3364.9, and 12.5 times higher than assumed/expected conditions for samples dosed with methanol, iso-propanol, and tert-butanol, respectively. These unanticipated effects thus suggest that cautions are needed when using alcohols to qualitative and quantitative determine HO • and SO 4 •− in UV/PDS process.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 30
·17627-17634
·
IF 3.119
Shoufeng Tang,Jiachen Tang,Deling Yuan,Zetao Wang,Yating Zhang,Yandi Rao
Humic substances are polyelectrolytic macromolecules; their presence in water leads to many environmental problems without effective treatment. In this work, the elimination of humic acid (HA), a typical humic substance, has been examined through ultraviolet (UV) activation systems in the presence of peroxydisulfate (PDS) and peroxymonosulfate (PMS), respectively. The results indicated that 92.9% and 97.1% of HA were eliminated with rate constants of 0.0328 ± 0.0006 and 0.0436 ± 0.0011 min−1 with 180 and 60 min treatment times at pH 6 and 3 when adding 3 and 1 mmol L−1 oxidant during UV/PDS and UV/PMS, respectively; the corresponding electric energies per order were 0.0287 and 0.0131 kW h m−3. The HA removal was systematically investigated by varying different reaction parameters, including radical scavengers, persulphate dose, solution pH, and initial HA concentration, and by addition of various common ions. Moreover, the decomposition details were identified through the changes in the dissolved organic carbon, unique UV absorbances, and UV spectroscopic ratios. Furthermore, the destruction mechanism was verified by fluorescence spectroscopy, demonstrating that the HA structure was decomposed to small molecular fractions in the two UV/persulphate systems. In addition, the purification of HA by the two UV/persulphate processes was assessed in actual water matrices.
研究领域:
环境科学
·
水处理技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Sui-Qin Yang,Rui-Qiu Ye,Yu-Hong Cui,Zheng-Qian Liu,Kai Sun,Yu-Ze Yu
Advanced oxidation processes for the treatment of organic pollutants in wastewater suffer from difficulties in mineralization, potential risks of dissolved residues, and high oxidant consumption. In this study, radical-initiated polymerization is dominated in an UV/peroxydisulfate (PDS) process to eliminate organic pollutant of pharmaceutical metoprolol (MTP). Compared with an ideal degradation-based UV/PDS process, the present process can save four fifths of PDS consumption at the same dissolved organic carbon removal of 47.3%. Simultaneously, organic carbon can be recovered from aqueous solution by separating solid polymers at a ratio of 50% of the initial chemical oxygen demand. The chemical structure of products was analyzed to infer the transformation pathways of MTP. Unlike previous studies on simple organic pollutants that the polymerization can occur independently, the polymerization of MTP is dependent on the partial degradation of MTP, and the main monomer in polymerization is a dominant degradation product (4-(2-methoxyethyl)-phenol, denoted as DP151). The separated solid polymers are formed by repeated oxidation and coupling of DP151 or its derivatives through a series of intermediate oligomers . This proof-of-concept study demonstrates the advantage of polymerization-dominated mechanism on dealing with large organic molecules with complex structures, as well as the potential of UV/PDS process for simultaneous organic pollution reduction and organic carbon recovery from aqueous solution.
研究领域:
环境科学
·
水处理工程
·
药学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Ruijie Xie,Jianping Cao,Xiaowen Xie,Dongxue Lei,Kaiheng Guo,Hong Liu,Yuxuan Zeng,Haibao Huang
Chlorobenzene is a typical chlorinated volatile organic compound (CVOC), and the degradation of chlorobenzene frequently produces high-toxic byproducts such as dioxins in the treatment process. To prevent this, complete oxidation of chlorobenzene into harmless CO 2 is highly desirable. Wet scrubber coupled with advanced oxidation processes (AOPs) for gaseous VOCs treatment has been widely reported, but their mineralization capacity and mechanism are still poorly understood. Herein, this study developed an efficient technology for chlorobenzene oxidation via wet scrubbing process coupled with UV/peroxydisulfate (PDS), with UV/H 2 O 2 as comparison. The mineralization efficiency of chlorobenzene was much higher in UV/PDS (75.4%) than that in UV/H 2 O 2 (42.0%), although the removal efficiencies in both AOPs were similar at 90–97%. Sulfate radical (SO 4 •− ) was predominant for the initial oxidation of chlorobenzene, forming the intermediates that were favorable for the mineralization process. Then, O 2 and HO • played important roles on the formation of CO 2 in the complete oxidation of chlorobenzene in UV/PDS. The role of O 2 was further comfirmed by the result that high-toxic dimeric products, rather than CO 2 , were generated in UV/PDS in the absence of O 2 . The possible pathway on chlorobenzene oxidation was proposed based on the evolution of intermediates and Density Functional Theory (DFT) calculation. Carbon cation radical was formed from the initial oxidation of chlorobenzene by SO 4 •− , followed by the ring-opening and more CO 2 yields via the synergetic effect of SO 4 •− , O 2 and HO • . This study not only provides an environment-friendly method to improve the VOC removal efficiency, but also gets a deep understanding of the different functions of SO 4 •− , HO • and O 2 on the mineralization process.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Water Process Engineering
·
2025
·
IF 6.7
Youwei Yang,Jianxing Wang,Yan Gao,Xuekun Tang,Chunying Wang,Xianping Luo
ZnFe 2 O 4 catalysts synthesized via hydrothermal (ZFO-H) and sol-gel (ZFO-S) methods were employed to activate peroxodisulfate (PDS) under UV light for the efficient conversion of low-concentration NH 4 + -N into environmentally benign N 2 , offering a promising solution for advanced wastewater treatment. Characterization revealed that the sol-gel-derived ZFO-S exhibited uniform agglomeration, smooth surfaces, and an 80% reduction in surface hydroxyl density (as indicated by the FTIR peak area at 3320 cm -1 ), outperforming both hydrothermally prepared and commercial ZnFe₂O₄ (ZFO-H and ZFO-M, respectively). This study addresses the critical challenge of ammonia nitrogen removal in wastewater, where conventional methods often struggle with low efficiency or secondary pollution. Mechanistic studies demonstrated that ZnFe 2 O 4 facilitated electron transfer at Zn sites to activate PDS, generating reactive species dominated by singlet oxygen ( 1 O 2 ), which drove NH 4 + -N oxidation. Density functional theory (DFT) calculations further elucidated the reaction pathway, highlighting preferential adsorption of NH 3 at oxygen sites on the ZnFe 2 O 4 (311) surface, followed by sequential dehydrogenation and coupling to form N 2 . Under optimal conditions (pH >9.25, 10 mM PDS, 25°C, 3 h), 97.40% of initial 50 mg/L NH₄ + -N was converted to N₂, with negligible NO 3 − byproduct formation (< 6%), demonstrating high feasibility for practical wastewater remediation. The reduced surface hydroxyl groups and lower work function of ZFO-S enhanced electron transfer, underscoring its superior catalytic activity. This work provides a novel strategy for designing hydroxyl-regulated photocatalysts tailored for wastewater treatment and advances the mechanistic understanding of persulfate-based ammonia nitrogen remediation in engineered water systems.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Qi Lu,Qi Han,Hongnan Liu,Li Feng,Yongze Liu,Ziwen Du,Liqiu Zhang
Dissolved black carbon (DBC) released from biochar, is an essential group in the dissolved organic matter (DOM) pool and is widely distributed in aquatic environments. In various advanced oxidation processes (AOPs), DBC exhibits enhanced free radical scavenging compared to typical DOM, attributed to its smaller molecular weight and more compacted aromatic structure; however, the molecular-level transformations of DBC in different AOPs , such as UV/H 2 O 2 , UV/PDS, and UV/Chlorine, remain unclear. This study employed a DBC derived from wheat biochar for experimentation. Characterization involved ultraviolet-visible (UV–Vis) spectroscopy and fluorescence excitation-emission-matrix (EEM) spectroscopy, revealing the transformation of DBC through diminished SUVA 254 values and reduced intensity of three-dimensional fluorescence peaks. Further insights into the transformation were gained through Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). After each UV-AOP treatment, a conspicuous augmentation in the oxygen content of DBC was observed. The detailed oxygenation processes were elucidated through mass difference analysis, based on 23 types of typical reactions. Results indicated that oxygenation reactions were most frequently detected in all three UV-AOP treatments. Specifically, the hydroxylation (+O) predominated in UV/H 2 O 2 , while the di-hydroxylation (+2O) prevailed in UV/PDS. UV/Chlorine treatments commonly exhibited tri-hydroxylation (+3O), with the identification of 1194 Cl-BPs of unknown structures. This study contributes to a comprehensive understanding of the molecular transformations of DBC induced by various free radicals in different UV-AOP processes, leading to a better understanding of the different fates of DBC in UV-AOP processes. In addition, the identification of DBC as a precursor of by-products will also contribute to the understanding of how to inhibit the generation of by-products.
研究领域:
环境科学
·
化学工程
·
分析化学
·
水处理
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）