Effect of substituents in hydroxyl radical-mediated degradation of azo pyridone dyes: Theoretical approaches on the reaction mechanism

Understanding the degradation behavior of azo dyes in photocatalytic wastewater treatment is of fundamental and practical importance for their application in textile-processing and other coloration industries. In this study, quantum chemistry, as density functional theory, was used to elucidate different degradation pathways of azo pyridone dyes in a hydroxyl radical (HO^?)-initiated photocatalytic system. A series of substituted azo pyridone dyes were synthesized by changing the substituent group in the para position of the benzene moiety, ranging from strong electron-donating to strong electron-withdrawing groups. The effect of dye molecular structure on the photocatalytic degradation reaction mechanism was analyzed and quantification of substituent effects on the thermodynamic and kinetics parameters was performed. Potential energy surface analysis revealed the most susceptible reaction site for the HO^? attack. The calculated reaction barriers are found to be strongly affected by the nature of substituent group with a good correlation using Hammett σ_p constants and experimentally determined reaction rates. The stability of pre-reaction complexes and transition state complexes were analyzed applying the distortion-interaction model. The increased stability of the transition state complexes with the distancing from the substituent group has been established.     

Air Pollution and Heat Exposure Study in the Workplace in a Glass Manufacturing Unit in India

Air pollution in the workplace environment due to industrial operation have been found to cause serious occupational health hazard. Similarly, heat stress is still most neglected occupational hazard in the tropical and subtropical countries like India. The hot climate augments the heat exposure close to sources like furnaces. In this study an attempt is made to assess air pollution and heat exposure levels to workers in the workplace environment in glass manufacturing unit located in the State of Gujarat, India. Samples for workplace air quality were collected for SPM, SO₂, NO₂ and CO₂ at eight locations. Results of workplace air quality showed 8-hourly average concentrations of SPM: 165–9118 μg/m³, SO₂: 6–9 μg/m³ and NO₂: 5–42 μg/m³, which were below the threshold limit values of workplace environment. The level of CO₂ in workplace air of the plant was found to be in the range 827–2886 μg/m³, which was below TLV but much higher than the normal concentration for CO₂ in the air (585 mg/m³). Indoor heat exposure was studied near the furnace and at various locations in an industrial complex for glass manufacturing. The heat exposure parameters including the air temperature, the wet bulb temperature, and the globe parameters were measured. The Wet Bulb Globe Temperature (WBGT), an indicator of heat, exceeded ACGIH TLVs limits most of the time at all the locations in workplace areas. The recommended duration of work and rest have also been estimated.     

温度对酚试剂分光光度法测定空气中甲醛的影响

GB/T 18204.26《公共场所空气中甲醛测定方法》中的酚试剂分光光度法,其方法原理是空气中甲醛与酚试剂反应生成嗪,嗪在酸性溶液中被高铁离子氧化形成蓝绿色化合物。根据颜色深浅,比色定量。两步反应在室温较低时作用不完全。吸光度随时间延长而逐渐加大。文章经过不同室温实验提出,在室温低于23℃时,两步反应应在恒温水浴43℃保温10min。室温达到23℃时可不必加热。     

华北山区温度推算模式和应用

利用华北山区气象站观测的温度与其所在纬度、经度和高度，分山区建立宏观地面气温场方程。采用１：２０万地形图，以１０＇经、纬度为步长，判读其高度值，代入已建立好的方程中，经地形项订正，推算华北山区年、月平均温度、年较差和ΣＴ＇≥１０℃，其精度达极显著水平。计算结果使我们对华北山区热量资源有了新的认识，最后求算华北山区的主要水果最优品质种植上限高度。     

方轧件在椭圆孔型中轧制温度场的三维有限元分析

应用MARC/autoforge有限元软件对方轧件在椭圆孔型中的轧制温度场进行了热力耦合模拟.研究了模拟过程中的传热边界条件,分析了轧制前和轧制过程中轧件中温度场的分布和变化规律.模拟计算结果和实验结果的比较说明二者基本是相符的.     

pH均值计算述评及验证

pH值是水化学中常用和最重要的检验项目之一，pH均值的计算已引起环境科学工作者的重视，并提出了很多有见地的计算方法。对这些计算方法作一简要归纳和评述，并通过实测进行验证。     

Institutional and cost implications of multi-project baselines

Starting from a theoreticalnotion of capacity building this paperfocuses on the implications ofmulti-project baselines for costs andinstitutions. Availability of data and thelevel of data aggregation determine to alarge extent the cost of derivingmulti-project baselines. For localinstitutions this implies that theircapacity development needs are linked todecisions made on strictness of baselines.The initial higher costs of multi-projectcalculations in the development stage areeasily offset once more projects will usesuch a baseline. This paper argues theseinitial demands are not as high asexpected. Multi-project approaches willreduce transaction costs, especially forsmall-scale projects, will reducevalidation costs and likely reduce humanresource demands in other stages of theproject cycle.     

大理市西洱河环境容量测算初探

从环境容量利用与管理的角度出发，在科学评价环境质量现状的基础上，根据环境功能区的质量目标，通过建立污染源一环境质量的输入响应关系，确定大理市西洱河的环境容量。     

浅谈清洁生产审核中经济效益的核算方法

根据财务管理学理论，结合清洁生产审核工作实际，分析各地清洁生产审核中的经济效益核算方法的差异，提出简洁实用的核算方法。     

产品生命周期环境成本核算实例研究

针对项目层次环境成本核算技术存在的2大缺陷，构建了产品生命周期环境成本核算模型。以红矾钠产品生命周期为例，通过企业的实地调查，以直接计算法、费用当量法进行拟合，得到了红矾钠产品（产量2.28万t/a)生命周期环境成本为，直接计算法：5084.48万元；费用当量法：4941.43万元。分析了环境成本核算对可持续发展决策和管理的作用和意义。