Journal of Environmental Sciences
·
2019
·
IF 3.556
Shijin Dai,Yilin Zheng,Youcai Zhao,Yu Chen,Dongjie Niu
Hazardous waste dechlorination reduces the potential of creating dioxins during the incineration process. To investigate the salt effect on waste dechlorination, molten hydroxides with a low melting temperature were utilized for the pre-dechlorination and decomposition of chlorine-containing organic wastes (COWs) including trichlorobenzene (TCB), perchloroethylene , hexachlorobenzene and chlordane . The results showed that a eutectic mixture of caustic sodium and potassium hydroxides (41 wt.% NaOH and 59 wt.% KOH) led to a low melting point below 300°C and a relatively high chlorine retention efficiency (CRE) with TCB as a representative COWs. The amounts of hydroxides, reaction time, and temperature all had notable influence on CRE. When the mass ratio of hydroxides to TCB reached 30:1, approximately 98.1% of the TCB was destroyed within 2.5 hr at 300°C with CRE of 71.6%. According to the residue analysis , the shapes of reaction residues were irregular with particles becoming swollen and porous. The benzene ring and C–Cl bonds disappeared, while carboxyl groups formed in the residues. The stripped chlorine was retained and condensed to form chloride salts, and the relative abundance of the chloride ions associated with the mass of TCB in residues increased from 0 to 75.0% within the 2.5 hr reaction time. The observed concentration of dioxins in residues was 5.6 ngTEQ/kg. A reaction pathway and possible additional reactions that occur in this dechlorination system were proposed. Oxidizing agents may attack TCB and facilitate hydrogenation/dechlorination reactions, making this process a promising and environmentally friendly approach for chlorine-containing organic waste treatment .
研究领域:
环境科学
·
化学工程
·
废物管理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 10
·3209-3218
·
IF 6.177
Meng Tian,Jing Qian,Jiawei Hou,Yadi Bai,Hai-Ying Jiang,Jingyun Ren
Free silver ions (Ag+) in the solution exhibit enhanced photocatalytic dechlorination processes of organic chloride, including 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP), over copper phenylacetylene (PhC2Cu) under visible light irradiation. The concentration of AgNO3 remarkably affects the dechlorination activity of PhC2Cu. With the optimal concentration of 2 mM AgNO3, PhC2Cu showed the best photocatalytic performance, and the dechlorination rate of PhC2Cu was 2.3-fold enhanced under visible light irradiation for 80 minutes. This deep mechanism study demonstrated that free Ag+ in the solution, but not the deposited Ag particles on the surface of PhC2Cu, plays the most imported role in promoting the photocatalytic dechlorination process by forming the insoluble salt of AgCl.
研究领域:
环境科学
·
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL POLLUTION
·
2024
·
IF 7.6
Fangyuan Peng,Yingyang Wang,Yi Lu,Zhaoguang Yang,Haipu Li
The increasing demand for trichloroisocyanuric acid (TCCA) in swimming pool disinfection highlights the need to evaluate its applicability in terms of disinfection by-product (DBP) formation. Nevertheless, there is limited understanding of DBP formation and control during TCCA disinfection, particularly concerning the effects of various management parameters. This study aimed to fill this knowledge gap by comprehensively investigating DBP formation during TCCA chlorination, with a particular focus on assessing the contribution and interaction of influencing factors using Box-Behnken Design and response surface methodology. Results indicated that the concentrations of trichloroacetaldehyde, chloroform, dichloroacetic acid, trichloroacetic acid, and dichloroacetonitrile produced by TCCA disinfectant were 42.5%, 74.0%, 48.1%, 94.7% and 42.6% of those by the conventional sodium hypochlorite disinfectant, respectively. Temperature exhibited the most significant impact on chloroform formation (49%), while pH played a major role in trichloroacetaldehyde formation (44%). pH 2 emerged as the primary contributor to dichloroacetic acid (90%) and trichloroacetic acid (93%) formation. The optimum water quality conditions were determined based on the minimum total DBPs (pH = 7.32, Temperature = 23.7 °C, [Cl − ] = 437 mg/L). Chlorine dosage and contact time exhibited greater influence than precursor concentration on chloroform, dichloroacetonitrile, trichloroacetaldehyde, trichloroacetic acid, and total DBPs. Although the interaction between water quality parameters was weak, the interaction between disinfection operating parameters demonstrated substantial effects on DBP formation (8.56–19.06%). Furthermore, the DBP predictive models during TCCA disinfection were provided for the first time, which provides valuable insights for DBP control and early warning programs.
研究领域:
环境科学
·
水处理
·
化学工程
·
公共卫生
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Cong Li,Feng Luo,Haojie Duan,Feilong Dong,Xiaoyang Chen,Mingbao Feng,Zuoran Zhang,Leslie Cizmas,Virender K. Sharma
This paper presents the degradation of chloramphenicol (CAP) by chlorine and chlorine dioxide (ClO 2 ) in tap water in a pilot-scale water distribution system (WDS) containing loops of three different pipe materials (stainless steel, ductile iron , and polyethylene). Greater degradation of CAP was seen with chlorine than with chlorine dioxide. After 180 min in the ductile iron loop of the WDS, the percent degradation of CAP by 2.0 mg/L of chlorine or ClO 2 was 76% and 52%, respectively. The degradation of CAP by chlorine in the WDS was investigated under various conditions, including chlorine concentrations of 1.0–4.0 mg/L, and varying pipe materials, flow velocity, and temperature. Degradation of CAP under different conditions could be fitted by first-order kinetics, and the determined first-order rate constants ( k , min −1 ) increased with an increase in chlorine concentration, flow velocity, and temperature. The degradation of CAP in different pipes followed the order stainless steel loop > ductile iron loop > polyethylene loop. Identified oxidized products of the chlorination of CAP were in agreement with proposed reaction pathways, which were also theoretically confirmed by quantum chemical calculations. Formation of three disinfection byproducts (chloroform, bromodichloromethane, and dibromochloromethane) was observed, with increases of 7.7, 0.76, and 0.39 µg/L, respectively, after 160 min.
研究领域:
环境科学
·
公共卫生
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Sciences
·
2022
·
IF 6.796
Shuang Zhang,Yi-Li Lin,Tian-Yang Zhang,Chen-Yan Hu,Zhi Liu,Zheng-Yu Dong,Meng-Yuan Xu,Bin Xu
In this study, the formation of iodinated trihalomethanes (I-THMs) was systematically evaluated and compared for three treatment processes - (i) chlorination, (ii) monochloramine, and (iii) dichloramination - under different pH conditions. The results demonstrated that I-THM formation decreased in the order of monochloramination > dichloramination > chlorination in acidic and neutral pH. However, the generation of I-THMs increased in the dichloramination < chlorination < monochloramination order in alkaline condition. Specifically, the formation of I-THMs increased as pH increased from 5 to 9 during chlorination and monochloramination processes, while the maximum I-THM formation occurred at pH 7 during dichloramination. The discrepancy could be mainly related to the stability of the three chlor (am) ine disinfectants at different pH conditions. Moreover, in order to gain a thorough insight into the mechanisms of I-THM formation during dichloramination, further investigation was conducted on the influencing factors of DOC concentration and Br − /I − molar ratio. I-THM formation exhibited an increasing and then decreasing trend as the concentration of DOC increased from 1 to 7 mg-C/L, while the yield of I-THMs increased with increasing Br − /I − molar ratio from 5:0 to 5:10. During the three processes mentioned above, similar I-THM formation results were also obtained in real water, which indicates that the excessive generation of I-THMs should be paid special attention during the disinfection of iodide-containing water.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 10
·9480-9489
·
IF 2.914
Dai Shijin,Zheng Yilin,Zhao Youcai,Li Qiang,Niu Dongjie
Chlorine-containing organic waste (COWs) is a big threat for the waste incineration because of the dioxin generation and equipment corrosion. Recently, dechlorination and detoxification of COWs is emergent in order to lower the environmental risk and treatment costs. In this study, base-catalyzed decomposition processes with different hydroxides, hydrogen donors, and catalysts were conducted for pre-treatment of COWs to reduce organic chlorine content, with the TCB as a model compound and industrial rectification residues for verification. Results showed that maximum chlorine retention efficiency (CRE) of four alkalis followed the order of KOH > NaOH–KOH > NaOH > Mg(OH) 2 , which were 98.3%, 93.4%, 97.2%, and 1.5%, respectively, and could be expressed as an apparent first-order reaction. The differences were resulted from the varying ionic potentials of the metal cations. Hydrogen donors (glycol, glycerol, paraffin oil, and PEG 200) acted as effective dechlorination regents follow the order of PEG > glycol > paraffin oil > glycerol. In addition, Fe, Ni, Cu, and activated carbon catalysts increased the CRE by 68.9% to 92.4%, 91.9%, 89.2%, and 73.3%, respectively. Residue analysis through X-ray diffraction and Fourier transform infrared spectroscopy revealed that KCl, sodium oxalate, and phenol were the main products and a plausible stepwise dechlorination pathway was proposed. The effectiveness of three optimized combinations including NaOH/PEG, KOH/PEG, and NaOH–KOH/PEG (with the Fe catalyst) was confirmed by using them for dechlorinating rectification residues, and they restrained 98.2%, 91.2%, and 94.6% of the chlorine, respectively. The organochlorine content decreased from 19.2 to 1.8% within 180 min, while inorganic chorine content increased from 1.5 to 18.9%, indicating the potential for COWs dechlorination.
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
APPLIED CATALYSIS A-GENERAL
·
2015
·
IF 3.942
Cen Tang,Yanxia Jin,Jiqing Lu,Xiaonian Li,Guanqun Xie,Mengfei Luo
A series of Mg catalysts supported on SiO 2 were prepared by an incipient wetness impregnation method and tested for gas phase dehydrochlorination of 1,1,2-trichloroethane. It was found that these catalysts were very active and selective for the reaction. The catalytic performance depended on the Mg loading rather than the Mg precursors as the catalysts using Mg(NO 3 ) 2 ·6H 2 O and MgCl 2 ·6H 2 O as the precursors showed the similar performance. A catalyst containing 10 wt.% of Mg showed the best performance with a steady state TCE conversion of 92% and cis -dichloroethene selectivity of 91%. Moreover, characterizations of the catalysts revealed the formation of Cl-containing Mg species on the surface during the reaction. The analyses of the compositions of the stable catalysts under working conditions indicated a Cl/Mg ratio of 1, suggesting that Mg(OH)Cl could be the active sites for the reaction.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
WASTE MANAGEMENT
·
2023
·
IF 8.1
Yang Ren,Hongyun Hu,Chengyang Cao,Guangzhao Guo,Xiaodong Zeng,Chan Zou,Xian Li,Hong Yao
Disposal of automobile shredder residue (ASR) via pyrolysis enables the recovery of valuable products; however, the production of hazardous pollutants and low-value products is inevitable due to its high chlorine content. In this work, chlorine evolution behavior and the conversion mechanism during ASR pyrolysis between 480 and 600 °C were systematically studied. The experimental results for organic chlorine (Org-Cl) showed that released chlorinated gases were complex, and HCl only accounted for 35% of the gas phase products, while short-chain hydrocarbons with carbon atoms between two and four accounted for 52%. Chlorine was predominantly retained in the char, and Org-Cl was the primary contributor to the residual chlorine, accounting for over 50% of the char. The content of inorganic chlorine (InO-Cl) was low in the raw sample but significantly increased in the char. Through the distinction between organic and inorganic chlorine content in char, it was confirmed that Org-Cl could be converted to InO-Cl due to complex secondary reactions with metallic compounds. The conversion was favored by increasing the Org-Cl content and the temperature. Our findings clarified the evolution mechanism of chlorine and the transformation from Org-Cl to InO-Cl, thus providing guidance for chlorine regulation and the efficient recycling of metal resources.
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
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2024
·
IF 2
Yueheng Wang,Ziyu Zhuang,Yanfei Fan,Dandan Gao,Dongdong Li
Ammonium ion is of the same charge as alkali ions and with similar ionic radius as potassium, rubidium, and cesium ions. Solid solutions are very common between ammonium and alkali salts, which is of great interest for understanding the geology, soil, and environment fate of these elements. In this study, the solid–aqueous equilibrium in the NH4Cl + RbCl + H2O and NH4Cl + CsCl + H2O systems was determined at 298.15 K. For each system, two incontinuous solid solutions, i.e. (NH4,Rb)Cl(α) and (Rb,NH4)Cl(β), or (Cs,NH4)Cl(α) and (NH4,Cs)Cl(β), presented, and their composition and structure were studied using Schreinemakers’ wet residues analysis, XRD, and Raman characterization. The equilibrium between these solid solutions and aqueous solutions were well modeled using an integrated solution equilibrium calculator program, in which a Pitzer-Simonson-Clegg model and a subregular model were implemented for describing the nonideality of aqueous phase and solid solution. According to the experimental and thermodynamic modeling results, NH4Cl can dissolve RbCl and CsCl in the solid state (NH4,Rb)Cl(α) or (NH4,Cs)Cl(β) with limited solid solubilities of 0.18 or 0.051 in mole fraction, respectively. RbCl or CsCl can also dissolve NH4Cl in the solid state (Rb,NH4)Cl(β) or (Cs,NH4)Cl(α) with limited solid solubilities of 0.37 and 0.095 in mole fraction, respectively.
研究领域:
化学
·
环境科学
·
地质学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2024
·
IF 10.8
Yi-Hsueh Chuang,Chia-Shun Chou,Yi-Lin Chu
Chlorination of ammonia or chloramine-containing waters induces breakpoint chlorination reactions, producing a hydroxyl radical (•OH), but enhances the formation of undesirable N-nitrosamines. The prevailing view attributes •OH formation to a nitrosyl intermediate derived from the hydrolysis of dichloramine, but this pathway is unlikely at neutral or acidic pH. This study reveals a novel mechanism where •OH is generated via interactions between trichloramine (NCl3) and dichloramine (NHCl2), which also form nitrosation agents. Our experiments demonstrated that the NCl3–NHCl2 interaction degrades micropollutants with kinetics 2–3 times faster than breakpoint chlorination. Using electron paramagnetic resonance, we detected •OH in the NCl3–NHCl2 reaction. Micropollutant removal was unimpaired under low dissolved oxygen (O2(aq)) conditions, aligning with negligible O2(aq) changes during the NCl3–NHCl2 reaction and suggesting O2(aq) does not participate in •OH formation. Using benzene as a probe in 18O-labeled H2O, we confirmed water contributes to the oxygen source of •OH in NCl3–NHCl2 interactions, through which parallel reactions occur, leading to the formation of one mole of •OH alongside 1.92 mol of N2. A kinetic model developed in this study accurately predicted •OH and N2 and demonstrated the NCl3–NHCl2 interaction as the primary pathway for •OH formation in breakpoint chlorination, providing new insights into breakpoint chemistry.
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
SEPARATION AND PURIFICATION TECHNOLOGY
·
2020
·
IF 5.774
Jie Yang,Yulin Zhang,Yinan Bu,Baiyang Chen,Juan Li
According to an earlier study, electrodialysis (ED) can efficiently separate most organic halogenated micropollutants from inorganic halogens (i.e., halides and oxyhalides) in water, with only a few micropollutants being poorly-recovered. To optimize the ED process and to gain in-depth knowledge of the mechanisms responsible for their low recoveries, this study designed some experiments to examine the fates and transports of three hard-to-separate organic halogen compounds. Results show that the dominant mechanism responsible for the loss of trichlorophenol (TCP) is migration and retention in the ion exchange membrane (IEM), the dominant mechanism for the loss of trichloroacetic acid (TCAA) is ion exchange with the IEM, and the dominant mechanism for the loss of trichloroacetonitrile (TCAN) is volatilization and chemical decomposition during the ED process. Optimizing specific operating conditions (e.g., sealing, voltage, and membrane type, etc.) can improve recovery of these micropollutants to 70.4–95.8% while maintaining 90.4–99.5% removal of chloride. Even though TCAN underwent hydrolysis, we recovered 82.0% chlorine from TCAN and its hydrolytic products. These results may help not only better understand the fates and transports of organic micropollutants during the ED process, but also help facilitate application of electrodialysis technique for measuring total organic halogen.
研究领域:
环境科学
·
水处理技术
✓ 已验证
DOI
高影响因子
GEOCHIMICA ET COSMOCHIMICA ACTA
·
2023
·
IF 5
Ziyan Han,Hejiu Hui,Haizhen Wei,Weiqiang Li
The Moon is depleted in volatile elements and compounds, and lunar samples exhibit a wide range of Cl isotopic compositions , which is believed to result from the volatilization of metal chlorides (e.g., NaCl, KCl, and FeCl 2 ). However, the Cl isotopic fractionation behavior during volatilization is not well constrained, particularly for metal chlorides. Furthermore, the effect of metal chloride evaporation on metal isotopes is poorly known. In the present study, we performed NaCl and KCl sublimation experiments to study Cl and K isotopic fractionations at temperatures ranging from 923 K to 1061 K and at pressures of 7×10 –5 bar to 1 bar in an N 2 atmosphere. The isotope fractionation factors of 37/35 Cl( α gas–solid ) from NaCl sublimation experiments are 0.9985±0.0002, 0.9958±0.0004, and 0.99807±0.00004 at 1, 10 –2 , and 7×10 –5 bar, respectively. Those of 41/39 K( α gas–solid ) and 37/35 Cl( α gas–solid ) from KCl sublimation experiments are 0.99884±0.00004 and 0.9988±0.0003 at 1 bar, 0.9977±0.0002 and 0.9972±0.0003 at 10 –2 bar, and 0.9989±0.0002 and 0.9989±0.0001 at 7×10 –5 bar, respectively. Chlorine and K isotopes fractionate more at 10 –2 bar than at 7×10 –5 bar and 1 bar. The saturation index in all the sublimation experiments was >95%, which resulted in near-equilibrium isotopic fractionation at the sublimation interface. Therefore, the isotopic fractionation was controlled by mass transfer processes in the gas and solid phases. The isotopic fractionation at 10 –2 bar was controlled by the chemical diffusion of sublimated gas in an N 2 atmosphere with almost no convection effect, (i.e., Pe number close to zero), whereas the isotopic fractionation at 1 bar was suppressed by atmospheric convection with a turbulence factor of 0.4±0.1 (i.e., Pe number >1). The extremely high sublimation rate and the very slow diffusion in the sublimating solid at 7×10 –5 bar suppressed isotopic fractionations. Based on our experimental results, calculations using Cl/K and Na/K in lunar materials reveal that degassing of KCl contributed very little (<0.2‰) to the K isotopic fractionation (>0.58‰) during lunar magma ocean degassing. The Cl isotopic fractionation factor from lunar samples is similar to our results at 10 –2 bar. This similarity of Cl isotope fractionation indicates that there may have been a transient atmosphere above the lunar magma ocean.
研究领域:
地球化学
·
行星科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）