WATER RESEARCH
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2020
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IF 9.13
Di Zhang,Feifei Wang,Youli Duan,Shenghua Chen,Aihong Zhang,Wenhai Chu
Disinfection by-products (DBPs) are associated with various adverse health effects. Diversiform advanced treatment processes have been applied for the control of DBPs, but DBPs can still be frequently detected in tap water . Tea-leaves can be made into popular beverage and is itself a porous bio-adsorbent. By simulating tea brewing process, this study evaluated the removal of DBPs from drinking water during the tea brewing process. Removal of four trihalomethanes (THMs) and four haloacetamides (HAMs) by different fermentation degree tea-leaves was investigated. Little DBPs were removed by unfermented and semi-fermented tea-leaves (i.e., Meitan turquoise bud and Dahongpao tea) with less than 5% removal of HAMs, whereas 40% HAMs can be removed by fermented tea (i.e., Jinjunmei tea and Shuixian tea). Tea soup is neutral and slightly acidic, so little DBP hydrolysis was observed under typical tea-leaf brewing process. DBPs were mainly removed by volatilization and adsorption during tea brewing. Removal difference caused by DBP volatilization is very small. The DBP removal difference of four kinds of tea-leaves may be caused by fermentation degree. The surface of unfermented Meitan turquoise bud had a smooth and regular morphology, whereas a rough, irregular, hollow and spongy surface of fermented tea (i.e., Jinjunmei and Shuixian tea) was observed. Generally, the higher the degree of tea fermentation, the more adsorption sites, and the more removal of DBPs. Finally, the model, which takes the DBP initial concentration, tea-leaf dose and brewing time into account, was established under the experimental conditions to predict the variation of DBP concentration during tea brewing, and suggestions for DBP removal were provided to reduce DBP exposure risk. The integrated toxic risk during tea brewing was also investigated, and about 30% integrated cytotoxicity and 26% genotoxicity was reduced during Jinjunmei and Shuixian tea-leaf brewing.
研究领域:
环境科学
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公共卫生
✓ 已验证
产品关联
DOI
PubMed
高影响因子
WATER RESEARCH
·
2018
·
IF 7.051
Chao Fang,Stuart W. Krasner,Wenhai Chu,Shunke Ding,Tiantao Zhao,Naiyun Gao
Haloacetamides (HAMs), an emerging class of disinfection by-products, have received increasing attention due to their elevated cyto- and genotoxicity. However, only limited information is available regarding the iodinated analogues. This study investigated the formation and speciation of iodinated haloacetamides (I-HAMs) and their chlorinated/brominated analogues during the chloramination of bromide and/or iodide-containing waters and a model compound solution over various time periods. The rapid formation of diiodoacetamide (DIAM) was observed during chloramination of three simulated samples, whereas brominated (Br-HAMs) and chlorinated haloacetamides (Cl-HAMs) increased slowly with increasing reaction time. To further understand the differences in the formation of HAMs containing different halogens, experiments with the model compound asparagine in the presence/absence of iodide were conducted. Moreover, iodine utilisation factors and iodine incorporation factors were observed to increase significantly faster and were substantially higher than those of bromine. This implied that, compared with bromide, iodide has substantially greater potential to be transformed to the corresponding HAMs during chloramination, similar to that of other classes of DBPs. That is, I-HAMs formed faster than the other species investigated, including Cl-HAMs and Br-HAMs, in the early reaction stages (0–3 h). The effect of the bromide/iodide ratio (i.e., constant iodide, increasing bromide) on I-HAM formation was also examined. With increasing bromide/iodide ratio, the formation of Br-HAMs increased and dichloroacetamide decreased, but the formation of DIAM was largely unchanged. This was consistent with the constant level of iodide in spite of the increasing bromide. Chlorine and ammonia are applied separately during chloramination in water treatment , so the effect of pre-chlorination (before adding ammonia) on the formation and speciation of I-HAMs during in situ chloramination was also evaluated. Effective mitigation of DIAM formation with in situ chloramination was achieved, and the efficiency improved with increasing pre-chlorination time, where iodide was oxidised to iodate . The HAM-associated cytotoxicity was calculated to determine the change in toxicity at different reaction times, bromide/iodide ratios, and pre-chlorination times. A similar trend as the formation of I-HAMs was observed, which increased rapidly in the first 3 h, but decreased somewhat subsequently. When the bromide/iodide ratio and pre-chlorination time was increased, the calculated toxicity of the HAMs increased (due to more formation of Br-HAMs and less Cl-HAMs) and decreased (due to less DIAM formation), respectively.
研究领域:
环境科学
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Yan Shen,Xinyi Weng,Jingsi Chen,Jiafu Li
The aldehyde addition reaction is recognized as a key pathway in the formation of haloacetamides (HAMs) in drinking water. In particular, the reaction between monochloramine and chloroaldehydes has been reported to proceed rapidly. However, the measured concentrations of haloaldehydes (HALs) in chloraminated water are often much higher than those of HAMs. This discrepancy suggests that the role of the aldehyde pathway in HAM formation may have been overestimated. In this study, two commonly detected HALs [dichloroacetaldehyde (DCAL) and trichloroacetaldehyde (TCAL)] were selected as model compounds to investigate the transformation and formation among three classes of toxic disinfection byproducts (DBPs): HALs, HAMs, and haloacetonitriles (HANs), within a chloramination system. Theoretical calculations reveal that HALs can form HAMs via two distinct reaction pathways. Quantum-level computational analyses confirm the thermodynamic feasibility of both pathways for the studied Cl-HALs. Experimental investigations of the reaction kinetics between Cl-HALs and monochloramine, conducted at room temperature under light-shielded and catalyst-free conditions, showed that the concentrations of both DCAL and TCAL remained essentially unchanged throughout the reaction. HANs and HAMs in reaction solution were not detected. These results suggest that HALs exhibit negligible reactivity with monochloramine under ambient, uncatalyzed conditions, indicating strong kinetic hindrance in practical scenarios. In general, the reaction rate between HALs and monochloramine is not as high as that reported in the published literature (3.27–8.25 ×10 −3 h −1 ), which may help explain why much higher concentrations of HALs than HAMs were generally observed in chloraminated drinking water. This finding provides new insights into the transformation and formation of HALs, HAMs, and HANs in chloraminated drinking water systems.
研究领域:
环境化学
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水处理
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毒理学
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化学反应工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）