Solar photocatalytic degradation of some hazardous water-soluble pesticides at pilot-plant scale

The technical feasibility and performance of photocatalytic degradation of six water-soluble pesticides (cymoxanil, methomyl, oxamyl, dimethoate, pyrimethanil and telone) have been studied at pilot-plant scale in two well-defined systems which are of special interest because natural solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. TiO(2) photocatalysis tests were performed in a 35L solar pilot plant with three Compound Parabolic Collectors (CPCs) under natural illumination and a 75L solar pilot plant with four CPC units was used for homogeneous photocatalysis tests. The initial pesticide concentration studied was 50 mg L(-1) and the catalyst concentrations employed were 200 mg L(-1) of TiO(2) and 20 mg L(-1) of iron. Both toxicity (Vibrio fischeri, Biofix) and biodegradability (Zahn-Wellens test) of the initial pesticide solutions were also measured. Total disappearance of the parent compounds and nearly complete mineralization were attained with all pesticides tested. Treatment time, hydrogen peroxide consumption and release of heteroatoms are discussed.     

Effect of methanol addition on water–CO2–diethanolamine system: Influence on CO2 solubility and on liquid phase speciation

The aim of this study is the characterisation of VLE and chemical equilibria for the system CO₂/diethanolamine (DEA)/H₂O/methanol. The effect of MeOH composition has been studied using four compositions (from 0 to 30 wt% of methanol with a fixed composition (30 wt%) of DEA), the measurement being made at T = 298.15 K and at various CO₂ loadings (from 0.2 to 0.8). An original experimental device was used. This device combines a FT-IR spectroscopy analysis of the liquid phase with a VLE measurement cell.The data base obtained, including the new solubility data and the liquid phase composition, allows the modelling of the system CO₂/DEA/H₂O/methanol using an electrolyte equation of state [Fürst, W., Renon, H., 1993, Representation of excess properties of electrolyte solutions using a new equation of state, AIChE J, 39(2): 335–343] representing the equilibrium properties of the system and the liquid phase speciation.     

高效液相色谱直接进样法测定水中氨基甲酸酯

采用直接进样-高效液相色谱-荧光检测,Waters Carbamate Analysis3．9×150mm色谱柱,以水-甲醇-乙腈为流动相,激发波长为339nm,发射波长为445nm定量测定水中的氨基甲酸酯。结果表明本方法的标准偏差在0．02-0．12μg／L之间,变异系数在1．07％-7．24％之间,平均回收率在89．5％-100．5％之间,检出限在0．06-0．36μg/L之间。     

化工生产中“绿色原料”——碳酸二甲酯的应用

碳酸二甲酯是一种环境友好的有机化学品。介绍了碳酸二甲酯替代光气、硫酸二甲酯、卤代甲烷等对环境危害大的原料,生产异氰酸酯、聚碳酸酯、苯甲醚等重要的化工产品,以及作为绿色溶剂在绿色化学中的应用。     

稳定性同位素稀释技术结合气相色谱-离子阱质谱法检测葡萄酒中的氨基甲酸乙酯

目的建立葡萄酒中氨基甲酸乙酯(EC)的测定方法。方法使用气相色谱-离子阱质谱法和稳定性同位素稀释技术,采用硅藻土Extrelut NT进行基质固相分散萃取净化,二氯甲烷洗脱,选择离子储存方式SIS测定。结果方法的线性范围在10~1000μg/kg,检出限为2μg/kg,定量限为6μg/kg。3个不同加标水平葡萄酒中氨基甲酸乙酯的平均回收率为88.5%~112.8%,RSD为5.8%~9.5%(n=5)。结论本方法准确可靠,可用于葡萄酒中氨基甲酸乙酯的测定。     

利用UPLC-MS/MS同时检测水中10种氨基甲酸酯类农药及代谢物

氨基甲酸酯类农药的大量使用在全球范围内受到广泛的关注,并且进入各国的优先污染物监测范围.为建立一种高通量、高灵敏度同时检测EPA531.1中规定的10种氨基甲酸酯类农药及代谢物的方法,本文建立了UPLC-MS/MS方法.地下水、地表水等清洁水样样品经过简单的0.2μm滤膜过滤之后即可进样,实际样品加标的方法回收率达到87.3-105.3％,10种氨基甲酸酯农药及代谢物检测范围为0.1-2μg/L;农业用水、生活污水、工业废水等复杂基体水样的分析需要经过一个改良的固相革取净化过程,l00mL的水样经过浓缩净化之后方法检测限达到2-40ng/L,方法回收率达到81.1-114.7％.与目前国家标准方法相比较,本方法通过质谱定性的方式避免了紫外或荧光检测器可能出现的误判现象;在定量方面,本方法极大地提高了灵敏度;同时,实现了地表水等实际环境样品的前处理过程的极大简化,减少了萃取溶剂,节约了时间和成本,适宜用于水样中氨基甲酸酯类农药及代谢物的检测.     

Carbon2Polymer: A CO2-based Route to Polyurethanes via Oxidative Carbonylation of TDA with Methyl Formate

The Carbon2Polymer project involves a multistep reaction sequence for the non-phosgene synthesis of the high-value polymer precursor toluene-2,4-diisocyanate (TDI) starting from carbon dioxide. The present study of the oxidative carbonylation revealed that for the intermediate toluene-2,4-dicarbamate (TDC) the productivity is highest with Pd@ZrO₂, followed by Pd@CeO₂. As one of the side products which are formed in parallel and consecutive reactions the methylene-bridged dimer “TDCCH2TDC” (5) has a promising potential for industrial application.     

Theoretical studies on the relative reactivities of aryl thiol,thiono and dithio carbonates and carbamates

RHF, MP2 and DFT calculations were carried out for the unhydrated and explicitly solvated (by five water molecules) putative zwitterionic complexes formed in the aminolysis of oxo {(O, O)} and thio {(O, S), (S, O) and (S, S)} carbonates [MeO? C(?Y)? Y^′Ar] and carbamates [NH₂? C(?Y)? Y^′Ar, where Y and Y^′ are O or S] with ammonia. The reorganization energy of the carbonyl carbon from an sp² to an sp³ center, i.e., the energy needed to form a zwitterionic tetrahedral intermediate, was inversely related to the experimental rate of the aminolysis of carbonates as Y and Y^′ are varied, (O, S)<(O, O)<(S, S)<(S, O). For carbamates the reorganization energy is the highest and the solvation energy is the lowest among ester, carbonate and carbamate series, which is suggestive of the difficulty of zwitterionic intermediate formation and changeover to a concerted mechanism found experimentally for the aminolysis of the carbamates.     

Comparative study of chemical absorbents in postcombustion CO2 capture

In order to reduce CO₂ emissions from a power plant, CO₂ can be captured either from the syngas that is to be burned or from the flue gases exiting the energy conversion process. Postcombustion capture has the advantage that it can be applied to retrofit existing power plants. In this paper the authors compare two primary amines (MEA and DGA) to ammonia with respect to their capability to capture CO₂ from a flue gas stream. The ammonia process captures CO₂ by formation of stable salts, which are separated from the solvent stream by filtration or sedimentation. These salts can be used commercially as fertilizers. Energy requirements are greatly reduced, since no heat is required for solvent regeneration, and no compression of the separated CO₂ is necessary. Energy, however, is required for the reduction of ammonia emissions. In order to obtain the solid ammonia salts, their solubility has to be reduced by modification of the solvent and by lowering absorption temperature. With and without separation of the salt products, ammonia proved to be an alternative solvent with high CO₂ removal efficiency. Simulation of all processes was carried out with Aspen Plus^® and compared to experimental results for CO₂ scrubbing with ammonia.     

Dietary intake of pesticides: State of Kuwait total diet study

The State of Kuwait conducted a total diet study (TDS) to determine the dietary intakes of selected pesticides. This paper reports the results of this study. A national food consumption survey was performed and core food lists for different population groups were established representing the total diet of the Kuwaiti population. Food items (table-ready) were purchased/prepared and analysed for their contents of organophosphate/organochlorine carbamate, benzimidazole and phenylurea pesticides according to the US FDA Pesticide Analytical Manual (PAM I). Dietary intakes of these pesticides are presented for 19 population groups, which range from infants to elderly adults. The intakes of selected population groups are compared with representative findings from the US FDA/TDS and data published from other countries. In general, the average daily intakes were well below acceptable limits, but higher than those reported from developed countries.