Evaluation of thermal hazard characteristics of four low temperature reactive azo compounds under isothermal conditions

The polymerization reaction can lower the threshold of the required energy by the initiator to improve the efficiency of the overall process reaction. Emerging polymerization initiators are also a major focus of process improvement and technological progress. Azo compounds (azos), which used in dyeing applications, are subsequently used in polymerization reactions due to their highly exothermic reaction characteristics. Although higher heat release can promote polymerization and modify the product, heat generation may also cause process hazards.These thermal hazard parameters were studied by selecting dimethyl 2,2′-azobis(2,4-dimethylvaleronitrile) (ABVN), 2,2′-azobis(2-methyl propionate) (AIBME), 2,2′-azobis(2-methylpropionamide) dihydrochloride (AIBA), and 2,2′-azobis(isobutyronitrile) (AIBN), which are common azo initiators at present. Thermal hazards are closely related to the reaction kinetics of the substance itself. The form of the reaction, the apparent activation energy and the thermodynamic parameters of the exothermic mode were also obtained.Kinetic analysis of the actual process using the experimental data of the isothermal calorimetry model is rarely used in the evaluation of related thermal hazard characteristics. The simulation results revealed the kinetic azo models and were further applied to calculate the runaway situations of azo under specific boundary conditions.     

TRACE METALS IN SEDIMENT: SPATIAL TRENDS AND SORPTION PROCESSES1

ABSTRACT: Sediment bound trace metals are often examined for spatial trends such as downstream patterns or distance from a source. Spatial trends may indicate either differences in metal inputs, or, when considerable sediment variability exists, differences in sediment sorption processes. These two possibilities become important not only when sediment contamination is evaluated within an area, but also when regulatory agencies attempt to make equivalent among area decisions. Sediments from an urban watershed were examined for: (1) downstream trace metal trends and (2) sediment sorption relationships. Analyses determined that downstream trenda as related to metal inputs could not be recognized by analyzing the < 2mm (≤, sand) sediment size fraction. Conversely, the trace metal concentrations were found to be distinctly related to sediment characteristics. The watershed's metal concentrations are similar to those found in uncontaminated to slightly contaminated sediments in the United States.     

Chemical behavior of organic compounds in the interface of water/dual-cation organobentonite

The sorption behavior of polar of ionizable organic compounds,such as p-nitrophenol,phenol and aniline,in the water/organobentonite systems is investigated.Both adsorption and partition occur to the sorption of organic compounds to dual-cation organobentonites.The separate contributions of adsorption and partition to the total sorption of organic compounds to dual-cation organobentonites are analyzed mathematically in the first time.The factors to the contributions are also discussed.The results indicated that the contribution of adsorption and partition is related to the composition and ratio of dual-cation surfactants exchanging onto the bentonite.The sorption of organic compounds to dual-cation organobentonite is dominated by adsorption at low concentrations and by partition at high concentrations,making the organobentonites powerful sorbents for organic contaminants over wide range of concentrations.     

活性炭对二硫化碳和水的共吸附动力学行为的热重研究

用热重法研究了５种国产活性炭对水蒸汽和二硫化碳的吸附动力学行为，发现其动力学行为均遵循Ｂａｎｇｈａｍ方程和Ｅｌｏｖｉｃｈ方程所描述的规律，但Ｂａｎｇｈａｍ方程更为优越。     

苯蒸气在有机膨润土上的吸附行为研究

探讨了苯蒸气在膨润土原土、单阳离子有机膨润土及阴－阳离子有机膨润土上的吸附性能、机理及影响因素。结果表明，有机膨润土对苯蒸气有良好的吸附性能，两种阴－阳离子有机膨润土对气态苯的吸附能力大于单阳离子有机膨润土，表现出较强的协同吸附作用；有机膨润土对气态苯的吸附作用主要由分配作用所致，等温吸附线呈线性，吸附系数（Kd)与有机膨润土的有机碳含量（foc）成正相关，与温度及比表面积成负相关，吸附速率（r)与有机碳含量成正相关。有机膨润土具有较大的开发、应用潜力。     

4-氯苯酚在水溶液中的光化学反应(Ⅱ)反应的动力学研究

研究了在模拟太阳光和紫外光作用下，４氯苯酚（４ＣＰ）的光反应动力学．研究表明，紫外光的作用更为显著．４ＣＰ的反应速率与４ＣＰ起始浓度、ｐＨ值，金属离子浓度、富里酸浓度等因素有关．通入空气，能够加速４ＣＰ降解．     

新农药环境化学行为研究（V）─—三氟羧草醚（Acifluorfen）在土壤和水环境中的滞留、转化

从如下几方面研究了三氟羧草醚在土壤－水环境中的化学行为：一是土壤对该药的吸附，结果表明，吸附强度与土壤理化特性密切相关，Ｆｒｅｕｎｄｌｉｃｈ常数ｋ＿ｆ＝０．９４Ｗ＿（ＯＭ）＋０．６５Ｗ＿（ＣＬＡＹ）－９．５９ｐＨ（ｒ￣２＝０．９４）；二是吸附机理研究，发现三氟羧草醚能与碱金属以外的许多金属离子形成配合物，并证实了与Ｃｕ￣（２＋）形成的双核桥联配合物的可能性；三是实验指出它在水中避光有一定的稳定性，不易水解；四是它在＜３５０ｎｍ的光辐照下，易脱羧转化，速度较快，光解产物有较好的稳定性。     

生物法净化低浓度挥发性有机废气的动力学问题探讨

依据对生物膜填料塔净化低浓度甲苯废气过程的生物化学反应类型、过程控制因素和生物膜作用等机理问题的分析研究，定义其为一个以生物膜为有效吸附表面、以活菌体为生物反应活化中心的吸附生物化学反应过程，并据此建立了“吸附生物膜”理论及相应的动力学模式．该模式计算值与实验值之间有较好的相关性（相关系数Ｒ＞０．９５）．结果将为相关的理论研究和实际操作研究提供有益的资料．     

黄河中游泥沙对铜离子的吸持行为研究

以黄河中游泥沙和重金属Cu为研究对象，通过等温吸持实验和Tessier形态提取实验，研究了黄河中游泥沙在含量较高的条件下对铜离子的吸持特性．结果表明：黄河中游泥沙具有很强的吸持铜的能力．体系pH和泥沙理化性质对吸持具有强烈影响：当铜浓度较低时，pH是控制吸持的主要因素，不同泥沙对铜的吸持率均达到99％，泥沙吸持的空间差异很小；当铜浓度较高时，泥沙理化性质是使黄河中游泥沙吸持表现出空间差异的重要因素，碳酸盐是主要影响组份；在泥沙含量较高的条件下，单位吸持量随泥沙含量变化的规律符合“泥沙效应”规律，但吸持容量随泥沙含量升高而升高，这与泥沙含量升高导致体系pH升高有关。     

活性炭脱硫研究 (Ⅰ)SO2-N2-O2体系中SO2的氧化反应动力学

通过测定不同时间活性炭上的ＳＯ３蓄积量，以Ｌｎｇｍｕｉｒ－Ｈｉｎｓｈｅｌｗｏｏｄ方法进行了动力学方程的推导，发现整个过程可分为具有不同反应机理的两个阶段，在ＳＯ３蓄积量小的情况下，ＳＯ３对ＳＯ２和氧的吸附不产生影响；在ＳＯ３蓄积量达到一定限度后，同晟为一种阻抑物质，同时还获得了吸附平衡常数和反应速率常数。