Anodic Oxidation as Green Alternative for Removing Diethyl Phthalate from Wastewater Using Pb/PbO2 and Ti/SnO2 Anodes

The electrochemical oxidation (EO) of diethyl phthalate (DEP) in aqueous solution was studied at Pb/PbO₂ and Ti/SnO₂ anode materials under galvanostatic‐experimental conditions. Results obtained clearly demonstrated that the anode plays a significant role for the optimization of the oxidation process, deciding the mechanisms and by‐products formed. DEP and by‐products of oxidation were also analyzed during various stages of the electrolysis reaction by HPLC and GC/MS techniques. Before the analysis by GC/MS technique, the samples were treated by solid phase microextraction (SPME) in order to concentrate the compounds from the reaction solution and identify all electrolysis intermediates. Current efficiencies (instantaneous current efficiency; ICE and total current efficiency; TCE) achieved during EO experiments were dependent on anode used and current density (20–40 mA cm^?2) at 40°C. The results obtained demonstrated that the environmental electrochemical methods can be a feasible alternative for the wastewater treatment containing hazardous phthalates.     

Adsorption behaviour of dibutyl phthalate on marine sediments

Laboratory experiments were carried out to investigate the adsorption behaviour of dibutyl phthalate (DBP) on marine sediments collected from five different sites in Victoria Harbour, Hong Kong. DBP adsorption can be well described by the Langmuir isotherm. The maximum DBP adsorption capacity (Q(max)) of the marine sediments ranges from 53 to 79 mg g(-1), which has a positive correlation with their organic content. Around 90% of the organic can be removed from the sediments with treatment by H(2)O(2) oxidation, and the Q(max) then decreases to a range between 13 and 22 mg g(-1). The black carbon content of the sediments has a much greater DBP adsorption capacity than does the natural organic matter of the sediments. The amount of DBP adsorbed on the sediments increases as the salinity of the marine water increases.     

超声波萃取-高效液相色谱法测定土壤中邻苯二甲酸酯

邻苯二甲酸酯类(PAEs)是环境激素类物质中的一类化合物。文章对土壤中6种被美国EPA列入"优先监测污染物名单"的PAEs类物质邻苯二甲酸二甲酯(DMP)、二乙酯(DEP)、二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)、二辛酯(DOP)、丁基苄基酯(BBP)邻苯二甲酸酯经超声波萃取、柱层析净化后,采用高效液相色谱法测定。对影响加标回收率的实验条件如萃取溶剂比例、萃取时间和萃取溶剂的选择等进行优化。方法回收率为94.1%～108.2%,相对标准偏差(RSD,n=7)为0.70%～2.42%,方法检出限为0.003～0.009μg/g。建立的方法样品前处理简单、快速,溶剂用量少,液相色谱法分析6种PAEs类物质仅用10 min,适用于大批量土壤样品中PAEs类物质的测定。     

Laboratory studies of some environmental variables controlling sulfur emissions from plants

Several trace sulfur gases that can have a significant influence on atmospheric chemistry are emitted from biological systems. In order to begin to address biological questions on the mechnisms of production of such gases, laboratory-scale experiments have been developed that reproduce such emissions under controlled conditions. Using a flux chamber technique, flats containing soil, or soil plus plants were sampled for the net fluxes of sulfur gases. The major sulfur gas emitted from all the plants tested (corn, alfalfa, and wheat) was dimethyl sulfide (DMS). Alfalfa and wheat also emitted lesser amounts of methanethiol, variable amounls of hydrogen sulfide, and in some experiments wheat emitted carbon disulfide. The use of a plant incubator allowed a systematic study of the effects of variables such as temperature, photon flux, and carbon dioxide levels, on these emissions. Fluxes of all the emitted sulfur gases increased exponentially with increasing air temperature, and increased with increasing photon flux up to a saturation level of \~300 E/m^–2 sec^-1. Three to four-fold changes in DMS flux were observed during light to dark or dark to light transitions. By varying the CO₂ content of the chamber flush gas, it was shown that the observed sulfur fluxes from corn and alfalfa were not related to the CO₂ concentration. Growing these crop plants through holes in a Teflon soil-covering film allowed a separate determination of soil and foliage emissions and substantiation of the light dependent uptake of COS by growing vegetation observed in previous field studies.     

Short-Term Variability of Atmospheric DMS and Its Oxidation Products at Amsterdam Island during Summer Time

A one-month experiment was performed at Amsterdam Island in January 1998, to investigate the factors controlling the short-term variations of atmospheric dimethylsulfide (DMS) and its oxidation products in the mid-latitudes remote marine atmosphere. High mixing ratios of DMS, sulfur dioxide (SO₂) and dimethylsulfoxide (DMSO) have been observed during this experiment, with mean concentrations of 395 parts per trillion by volume (pptv) (standard deviation, = 285, n = 500), 114 pptv ( = 125, n = 12) and 3 pptv ( = 1.2, n = 167), respectively. Wind speed and direction were identified as the major factors controlling atmospheric DMS levels. Changes in air temperature/air masses origin were found to strongly influence the dimethylsulfoxide (DMSO)/DMS and SO₂/DMS molar ratios, in line with recent laboratory data. Methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO₄ ^2–) mean concentrations in aerosols during this experiment were 12.2± 6.5 pptv (1, n=47) and 59 ± 33 pptv (1, n=47), respectively. Evidence of vertical entrainment was reported following frontal passages, with injection of moisture-poor, ozone-rich air. High MSA/ nss-SO₄ ^2– molar ratios (mean 0.44) were calculated during these events. Finally following frontal passages, few spots in condensation nuclei (CN) concentration were also observed.     

酞酸酯对龙须菜的生态毒理研究

研究了酞酸酯类化合物对龙须菜(Gracilaria lemaneiformis)生长的影响以及酞酸酯在龙须菜体内的积累状况。结果表明,在邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酯二异辛酯(DEHP)4种酞酸酯混合质量浓度为0.05,0.10,0.20和0.40 mg/L的暴露条件下,龙须菜的相对生长速率和叶绿素a含量均受到了明显影响。与对照组比较,在高质量浓度处理组(0.1~0.4 mg/L)中,两指标分别下降了18.4%~21.3%和10.4%~15.3%,致毒效应与酞酸酯暴露浓度呈正相关。在受控水体的暴露试验中,利用气相色谱(GC-FID)分析表明,4种酞酸酯类(DMP,DEP,DBP和DEHP)在龙须菜体内均有一定程度的积累,其残留量分别为0~0.14 mg/kg,0~0.83 mg/kg,0.11~1.89 mg/kg,0.01~10.4 mg/kg,其积累程度与酞酸酯分子结构相关,侧链较长的酞酸酯比侧链较短的积累量要大,并随处理浓度的增加和时间推移呈增加趋势。     

煤系高岭石的原始晶粒尺寸及结晶度对插层作用的影响

采用SEM、XRF、XRD和IR研究了大同、平朔和淮北煤系高岭石的结构、粒度及其特性,探讨了粒度大小对高岭石插层作用的影响及其机理。研究发现:粒度中等且结晶有序的平朔煤系高岭石插层率最高,其次为晶体粗大但结晶有序的大同高岭石,粒度最小且结晶无序的淮北高岭石插层率最低。研究认为高岭石原始晶粒粒度对高岭石插层作用有重要影响,中等粒度最有利于高岭石插层作用的进行,粒度过大或过小均不利于高岭石插层作用的进行,其原因是由于不同粒度的高岭石插层作用过程中导致的差异弹性变形引起的。结晶有序度对高岭石插层作用也有重要影响,结构无序不利于插层作用的进行。     

An FTIR product study of the photooxidation of dimethyl disulfide

The products of the 254 nm photolysis of ppm levels of DMDS have been studied as a function of the O₂ partial pressure at 760 Torr (N₂ + O₂) and 298±2 K. The major sulfur containing compounds detected were SO₂ and CH₃SO₃H (methane sulfonic acid, MSA) and the major carbon containing compounds were CO, HCHO, CH₃OH and CH₃OOH (methyl hydroperoxide). Within the experimental error limits the observed sulfur and carbon balances were approximately 100%. CH₃OOH has been observed for the first time in such a photooxidation system. Its observation provides evidence for the formation of CH₃ radicals by the further oxidation of the CH₃S radicals formed in the primary photolysis step.From the behavior of the DMDS photolysis products as a function of the O₂ partial pressure, O₃ concentration and added OH radical source it is postulated that the further reactions of CH₃SOH (methyl sulfenic acid), formed in the reaction OH + CH₃SCCH₃ CH₃SOH + CH₃S, are the main source of MSA in the 254 nm photolysis of DMDS.Some of the possible implications of the results of this study for the degradation mechanisms of other atmospherically important organic sulfur compounds, in particular DMS, are briefly considered.     

Toxic effects of several phthalate esters on the embryos and larvae of abalone Haliotis diversicolor supertexta

As the most widely used plasticizers in the world, phthalate esters (PAEs) are potential endocrine disruption compounds (EDCs). In the present study, the toxicity of dimethyl phthalate (DMP),diethyl phthalate (DEP), dibutyl phthalate (DBP), di (2-ethylhexyl) phthalate (DEHP) on embryogenesis and larvae development of the marine univalve Haliotis diversicolor supertexta was examined in laboratory. The results show that the malformation of embryos appeared during the experiment, such as embryos died or lysed, small transparent flocculent rings studded on the periphery of the embryo, and the larvae could failed to hatch. In embryo toxic test, embryos incubated at the highest concentration of DMP,DEP and DBP solutions showed significantly high abnormal rate compared with the control, while DEHP solutions displayed no significant difference. In larval toxic test, in all concentrations of DMP, DEP and DBP solutions, larval settlement rates were low significantly than that of the control. Similarly, DEHP solutions show nearly no effect on the larval settlement. The order of toxicity on embryos and larvae is DBP>DEP>DMP>DEHP. Being a simple and easy stimulation to indoor spawn, sensitive to environmental factors, and short culture time, the embryos of 1-1. diversicolor supertexta can be used to indicate toxicity of the PAEs.     

气相色谱-质谱联用法测定土壤中邻苯二甲酸酯类增塑剂

应用加速溶剂萃取,气相色谱-质谱联用法测定土壤中6种邻苯二甲酸酯类有机污染物。对邻苯二甲酸酯类污染物的提取溶剂进行了优化选择,确定二氯甲烷作为最佳提取溶剂。对色谱柱升温程序进行了优化,以使两个出峰时间较接近的目标物邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)能够达到基线分离。方法标准曲线的线性范围为0.50～20.0mg/L,线性相关系数均大于0.9970,方法检出限为67μg/kg,加标回收率为81.9%～111.4%。方法检出限较低,精密度好,简便快速,可满足大批量样品分析对质量和进度的要求。