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Studies on the photodegradation of Mefenacet in different water samples

CHU Mingjie,YUE Yongde,HUA Rimao,TANG Feng,

环境科学学报 , 2005,
Abstract: To study the effect of different waters on the photodegradation of Mefenacet, the photolysis of Mefenacet in pure water, natural water and buffer was studied. It indicated that in natural water samples, under the high-pressure mercury lamp(HPML) and xenon lamp(XL), the photo-half-lives of Mefenacet ranged samely as: paddy water > river water > lake water > river water(reservoir water) > redistilled water. The photo-half-lives under XL ranged from 607.80?min to (1016.40)?min, and under HPML ranged from 12.31?min to 18.53?min respectively. At room temperature, Mefenacet hydrolyzed easily in solution of pH=11.92. Under HPML, in buffers of pH=1.98 and 11.92, it photodegraded faster than in pure water, and the half-lives were 6.04?min(pH=1.98), 6.51?min(pH=11.92) and 6.75?min(redistilled water) respectively. Detecting the photoproducts by HPLC-MS indicated that a Metabolic pathway of mefenacet initiated by hydrolysis of amido groups and ether groups.
Adsorption of mefenacet on sepiolite and attapulgite

- , 2015,
Abstract: 吸附是农药在土壤环境中行为和归宿的重要过程,农药在土壤矿物上的吸附直接影响其在土壤中的迁移、转化和生物利用等过程。了解农药在土壤中的吸附,对于预测和评价农药对土壤、地下水存在的潜在危害,开展土壤修复具有十分重要的意义。本研究通过批量平衡试验,研究了苯噻酰草胺在海泡石和凹凸棒石中的吸附行为及机理。结果表明:苯噻酰草胺在海泡石和凹凸棒石中的吸附分为快速反应阶段和慢速平衡阶段,吸附平衡时间约为6 h。其吸附动力学曲线符合准二级动力学方程,线性方程和Freundlich吸附等温方程能较好地描述其在海泡石和凹凸棒石中的吸附行为,海泡石对苯噻酰草胺的吸附容量高于凹凸棒石。傅立叶变换红外光谱(FTIR)和X-射线衍射(XRD)分析显示:苯噻酰草胺在海泡石和凹凸棒石中的吸附不仅发生在其表面层,还进入了其内层。机理分析推测:苯噻酰草胺主要是通过氢键、电荷转移和电荷-偶极键形式吸附在黏土矿物中。
Adsorption is an important process in governing the fate of pesticides in soil system. Adsorption on minerals was shown to control the transport, transformation and biological processes of pesticides. It was also of great significance in evaluating the potential effects on soil and groundwater and developing soil chemical remediation. In this study, sepiolite and attapulgite were selected as absorbent. Batch equilibrium experiments were performed to study the adsorption characteristics and adsorption mechanisms of mefenacet on sepiolite and attapulgite.It was indicated that the adsorption process of mefenacet on the two clay minerals could be divided into two phases:rapid adsorption stage and slow adsorption equilibrium stage,and equilibrium phase was 6 h.Its adsorption behavior could be described by Pseudo-second-order kinetics. The adsorption isotherms of mefenacet on the two clay minerals were well fitted by Linear equation and Freundlich equation. The adsorption capacity of mefenacet on sepiolite was larger than on attapulgite. FTIR spectroscopy and XRD analysis indicated that mefenacet could enter the interlayer of sepiolite and attapulgite. Hydrogen bonds, charge transfer and charge-dipole might exist between mefenacet and sepiolite or attapulgite.
Sorption and Desorption Behavior of the Herbicide Mefenacet on Soils

LIU Zhen yu,GUO Hui qin,HE Huan,YANG Shao gui,SUN Cheng,

环境科学 , 2009,
Abstract: 采用批量平衡实验方法,研究了除草剂苯噻草胺在5种不同性质土壤中的吸附与解吸行为,并探讨了土壤有机质及溶液pH值对吸附的影响.结果表明,线性方程与Freundlich方程均能较好地拟合苯噻草胺在土壤中的吸附等温线.计算得到苯噻草胺在5种土壤中的碳标化分配系数Koc在849.5~1?818.8 L·kg-1之间,说明土壤对苯噻草胺有较强的吸附能力.苯噻草胺在土壤中的分配系数Kd、Freundlich常数Kf以及Kf(1/n)与土壤有机质含量均呈显著正相关.通过过氧化氢去除有机质后,土壤对苯噻草胺的吸附大大降低,说明土壤有机质是影响苯噻草胺在土壤中吸附的主要因素.对于同种土壤而言,苯噻草胺的吸附量随pH值的增大而减小.解吸实验表明,苯噻草胺在土壤中的解吸过程具有一定的滞后性,推测其在土壤中的迁移能力较差.
Effect of herbicide mefenacet pollution on antioxidant enzyme and ATPase of Sphingobacterium multivorum Y1
除草剂苯噻草胺污染对多食鞘氨醇杆菌(Sphingobacterium multivolum)抗氧化酶和ATP酶的影响

YE Yangfang,MIN Hang,LU Zhenmei,

环境科学学报 , 2006,
Abstract: The effect of exposed to mefenacet in short term on the activities of superoxide dismutase (SOD), catalase (CAT) and ATPase of Sphingobacterium multivorum Y1 capable of degrading mefenacet was studied. The results showed that mefenacet induced obviously SOD activity in S. multivorum Y1, especially to those in exponential phase, and also greatly stimulated CAT activity. The stimulation process of CAT activity was similar to that of SOD activity at different growth phases in S. multivorum Y1 by mefenacet. The level of ATPase activity increased after application of mefenacet, but there existed no good correlation with the growth phase of bacteria. It was feasible definitely to use antioxidant enzyme combined with ATPase as a biomarker for pollution stress of these chemicals in soil environment.
Sorption and cosorption of the nonionic herbicide mefenacet and heavy metals on soil and its components
Zhenyu Liu,Huiqin Guo,Huan He,Cheng Sun,
Zhenyu Liu
,Huiqin Guo,Huan He,Cheng Sun

环境科学学报(英文版) , 2012,
Abstract: Sorption and cosorption of the nonionic herbicide mefenacet and two typical metals (copper and silver) on black soil and its components (kaolinite and humic acid) were investigated. It was found that because of their different valences and properties, Cu2+and Ag+ presented different effects on the sorption of mefenacet. Due to the competition of Cu2+, along with the shells of dense water formed by its surface complexation, for sorption surface area with mefenacet, the addition of Cu2+ decreased the sorption amount of mefenacet on soil and its components, especially on humic acid. However, the addition of Ag+ significantly enhanced the sorption of mefenacet, which was attributed to the softness of the cation that weakened the hydrophilicity of the local region around Ag+-complexed functionalities, and thus mitigated the competitive sorption of water. In addition, the sorption of mefenacet on soil with or without the two metals was generally decreased with increasing pH, which was caused by the hydrolysis of carbonyl and carboxyl groups on the surface of the sorbents, π-π interaction between mefenacet and the soil organic matter, and so on. On the other hand, the presence of mefenacet seemed to have little effect on the sorption of Cu2+ and Ag+, indicating that Cu2+ and Ag+ might be sorbed strongly on the tested sorbents and the mefenacet added was too low in concentration to affect the sorption of the metals.
Phylogenetic analysis of a mefenacet-degrading bacterium and studies on its degradation characteristics

YE Yangfang,MIN Hang,DU Yufeng,XU Jing,

环境科学学报 , 2004,
Abstract: 自污水处理厂好氧活性污泥中分离到1株Y1菌株,该菌株具有较强的降解酰胺类除草剂苯噻草胺的能力.基于部分16SrDNA和生理生化特性分析,鉴定该菌为多食鞘氨醇杆菌(Sphingobacteriummultivolum).Y1菌株能有效地降解除草剂苯噻草胺,在1周内的降解率约为90%.其最适生长温度为28℃,最佳降解温度为32℃;在pH值为5~9范围内能保持对苯噻草胺的降解能力.Y1菌株经苯噻草胺诱导后具有一条相对分子量约为100k的特异性蛋白条带,而且在诱导1年的菌株中,该条带更明显.
Characterization of a strain of Sphingobacterium sp.and its degradation to herbicide mefenacet
Yang-fang Ye,Hang Min,Yu-feng Du,
YE Yang-fang
,MIN Hang,DU Yu-feng

环境科学学报(英文版) , 2004,
Abstract: A bacterium(designated strain Y1) degrading acetanilide herbicide mefenacet was isolated from aerobic sludge. Based on the analyses of partial 16S rRNA gene, cellular fatty acid and BIOLOG-GN, and general physiological and biochemical characteristics, strain Y1 was identified as Sphingobacterium multivolum. Strain Y1 was able to degrade mefenacet used as sources of carbon and energy. Degradation of mefenacet was accompanied by producing the metabolites N-methylaniline and an unidentified compound with molecular weight 205, indicating a metabolic pathway of mefenacet initiated by hydrolysis of amido bond.
Monitoring impact of mefenacet treatment on soil microbial communities by PCR-DGGE fingerprinting and conventional testing procedures
YE Yang-fang,MIN Hang,L Zhen-mei,
YE Yang-fang
,MIN Hang,Lü Zhen-mei

环境科学学报(英文版) , 2006,
Abstract: The effect of acetanilide herbicide mefenacet on soil microbial commun ities was studied using paddy soil samples with different short-term treatments. The culturable bacteria(plate counts), dehydrogenase activity and changes in co mmunity structure (denaturing gradient gel electrophoresis(DGGE) analysis) were used for biological community assessments. Mefenacet was a significant stimulus to cultural aerobic bacteria and dehydrogenase activity while Sphingobacterium m ultivorum Y1, a bacterium efficiently degrading the mefenacet, only induced the increasing colony-forming unit(CFU) of bacteria but little effect on dehydrogena se activity during the whole experiment. The degree of similarity between the 16 S rDNA profiles of the communities was quantified by numerically analyzing the D GGE band patterns. Similarity dendrograms showed that the microbial community st ructures of the mefenacet-treated and non-treated soils were not significantly d ifferent. But supplement of S. multivorum Y1 could increase the diversity of the microbial community in the mefenacet-polluted paddy soil. This work is a new at tempt to apply the S. multivorum Y1 for remediation of the mefenacet-polluted en vironments.
Interactions between photodegradation components
Yadollah Abdollahi, Azmi Zakaria, Khamirul Matori, Kamyar Shameli, Hossein Jahangirian, Majid Rezayi, Tahereh Abdollahi
Chemistry Central Journal , 2012, DOI: 10.1186/1752-153x-6-100
Abstract: From the validated model demonstrated that the component had interaction with irradiation time under 180 min of the time while the interaction with pH was above pH 9. Moreover, photocatalyst and p-cresol had interaction at minimal amount of photocatalyst (< 0.8 g/L) and 100 mg/L p-cresol.These variables are interdependent and should be simultaneously considered during the photodegradation process, which is one of the advantages of the response surface methodology over the traditional laboratory method.Advanced oxidation processes (AOPs) are physicochemical procedures, which designed to remove environmental organic and inorganic pollution. Photocatalysis, the current interest of AOPs, is applied for decontamination the pollutions [1-4]. The photocatalysis, under suitable light illumination, produces hydroxyl radical (●OH) and hole (h+) which are powerful and non-selective oxidants to degrade a variety of organic compounds [5-7]. Since the photocatalytic degradation (photodegradation) is dependent on several parameters including irradiation time, pH, photocatalyst and pollution concentration, it need to study the relationship between the variables during the process [8,9]. In the design of experiments, the independent variables are controlled to determine the relationship to an observable phenomenon [10]. The single variable (one-variable-at-a-time) method considers the photodegradation process as a projection while the multivariate method generalizes the observation of the photodegradation [11]. Therefore, the multivariate, which, increases the dimension of the system and produces more generalized results is preferred in comparing with the single variable approach. Recently the semi-empirical methods were used as an efficient technique to apply multivariate modeling for the photodegradation by response surface methodology (RSM) [12-18], however, no study has yet been conducted on the parameters interaction. This work looks at the parameters interaction of p-cresol ph
Journal of the Chilean Chemical Society , 2012, DOI: 10.4067/S0717-97072012000300025
Abstract: the photochemical behavior of nimodipine (nimo) and felodipine (felo), photolabile drugs widely used as antihypertensive calcium channel blockers, is studied in constrained media. specifically, we are interested in the kinetic analysis of 4-aryl-1,4-dihydropyridine photodegradation processes when they are incorporated in biological-mimicking systems like micelles or liposomes. in order to establish if the nature of the head of surfactant (ionic or nonionic) could be important modulating the photo-reactivity of these drugs, we studied the photodegradation of nimo and felo incorporated in micelles formed with sodium dodecyl sulfate (sds, anionic), dodecyl-pyridinium chloride (dpc, cationic) and mono lauryl sucrose ester (mls, nonionic) as surfactants. additionally, the results of the photodegradation of these compounds in liposomes were also included. the results clearly indicate that both dihydropyridines studied, nimo and felo, are located near to the interface, but the surface charge of micelles does not affect neither, the photodegradation rate constant nor the photodegradation products profile. the absence of singlet oxygen generation in micellar media is consistent with the proposition of these 4-aryl-1,4-dihidropyridines located near to the interface of the micelle, where a polar environment is sensed. in addition, the ethanol preferential location on membranes and dihydropyridine enhanced photodegradation by alcohol presence are interesting results to consider in future research.
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