Effects of relative humidity on the characterization of a photochemical smog chamber

A linear relationship between k_NO2→HONO and relative humidity in smog chamber is found in this work.     

O_3-Ca(OH)_2体系处理苯酚废水

研究了苯酚在新型臭氧氧化体系O_3-Ca(OH)_2体系中的降解与矿化效果。实验结果表明:苯酚及TOC的去除率都随着Ca(OH)_2用量(小于2 g/L)、进气臭氧质量浓度(小于75 mg/L)、进气流量(小于3.0 L/min)的增大以及初始苯酚质量浓度的减小而增加,但受反应压力和液相温度的影响较小;当Ca(OH)_2用量大于3 g/L时,苯酚和TOC的去除率在30 min和55 min时分别达到了100%左右;Ca~(2+)的存在实现了羟基自由基清除剂CO_3~(2-)的实时分离去除,从而强化了臭氧氧化过程中苯酚的降解与矿化。这表明,O_3-Ca(OH)_2体系是一种处理难降解有机废水的高效臭氧氧化新体系。     

汽车工业区大气挥发性有机物(VOCs)变化特征及来源解析

挥发性有机物(volatile organic compounds,VOCs)作为臭氧和细颗粒物的重要前体物已日益受到关注.鲜有针对汽车工业区大气VOCs 长期观测的报道.2019-01-01～2019-12-31 期间在上海某汽车工业园区边界,采用在线气相色谱仪对79 种VOCs 组分定量检测,分析大气VOCs 组成...     

低浓度CS2废气的光降解研究及工艺设计

利用185～253.7 nm紫外光联合降解低浓度二硫化碳废气.结果表明,在一定的气体浓度、流速以及湿度下,该技术能够有效降解二硫化碳使其浓度低于人的嗅阈值,同时研究也发现,该技术对苯乙烯和甲苯二甲苯等有机废气也有同样的处理效果,具有很好的工业化应用前景.     

Evidence of singlet oxygen and hydroxyl radical formation in aqueous goethite suspension using spin-trapping electron paramagnetic resonance (EPR)

The generation of reactive species in an aqueous goethite suspension, under room light and aeration conditions, was investigated using the electron paramagnetic resonance (EPR) technique employing spin trap agents. The trap reagents, including 5,5-dimethylpyrroline N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP), were used for the detection of OH radicals (OH) and singlet oxygen (¹O₂), respectively. On the addition of DMPO to the goethite suspended solution, a DMPO-OH adduct was formed, which was not decreased, even in the presence of the OH scavenger, mannitol. This result implied a false positive interpretation from the DMPO-OH EPR signal. In the presence of TEMP reagent, a TEMP-O signal was detected, which was completely inhibited in the presence of the singlet oxygen scavenger, sodium azide. With both DMPO-OH and TEMP-O radicals in the presence and absence of radical scavengers, singlet oxygen was observed to be the key species formed in the room-light sensitized goethite suspension. In the goethite/H₂O₂ system; however, both OH and singlet oxygen were generated, with significant portions of DMPO-OH resulting from both OH and singlet oxygen. In fact, the DMPO-OH resulting from OH should be carefully calculated by correcting for the amount of DMPO-OH due to singlet oxygen. This study reports, for the first time, that the goethite suspensions may also act as a natural sensitizer, such as fulvic acids, to form singlet oxygen.     

上海某水厂的污泥调质研究

本文针对上海某水厂污泥调质后脱水性能不好、泥饼的含固率不高等问题,开展了污泥调质的优化实验。研究表明,4种调质方式中采用"PAM+Ca(OH)2"联合调质的污泥脱水性能最好,药剂费用适中,滤液pH从7上升至10左右;PAM单独调质在经济上最优,干污泥产生量最少,但污泥比阻值最高,且脱水污泥的资源化难度大。结合水厂已有设施,建议采用PAM与石灰联合调质方式,投加剂量分别为PAM投加2.0‰、Ca(OH)2加入5.0%。     

铈离子光催化降解茜素绿的性能和机理简

主要研究了简单铈离子（Ce³⁺）在紫外光（UV）的作用下对蒽醌染料茜素绿（AG）的光催化降解效果和反应机理。结果表明,UV/Ce³⁺体系能够有效降解AG,初始反应速率随AG浓度的倒数值和Ce³⁺浓度的增加而线性增加,随初始溶液pH的增加先降低后增加,在酸性条件下有很高的TOC去除率。荧光探针实验表明,反应过程中可以产生·OH自由基。UV/Ce³⁺体系对其他类型染料和对硝基苯酚都有较好的降解效果。     

Comparison of Diuron degradation by direct UV photolysis and advanced oxidation processes

The rates of Diuron elimination by some advanced oxidation processes (AOPs) such as Fe(III)/UV, Ferrioxalate/UV, Fe(III)/H(2)O(2)/UV, Ferrioxalate/UV/H(2)O(2) and Fe(III)/H(2)O(2) have been compared. Experiments have been conducted at pH=2.3+/-0.1 with a batch reactor equipped with a low-pressure mercury lamp emitting mainly at 253.7nm. Data obtained under the following experimental conditions ([H(2)O(2)](0)=10(-3)M, [Diuron](0)=5x10(-5)M and [Fe(III)](0)=10(-3)M) have shown that rates of Diuron oxidation were higher with the systems Fe(III)/H(2)O(2)/UV and Ferrioxalate/UV/H(2)O(2) than with Fe(III)/UV and Fe(III)/H(2)O(2). On the other hand, Fe(III)/UV was found to be very efficient in mineralization of Diuron solution in comparison to direct UV photolysis. The experimental results showed that radical ()OH is the major pathway in the process of Diuron degradation.     

长沙大气中VOCs研究

应用大气采样罐采样技术和色谱-质谱联用（GC-MS）技术,对2008年长沙市大气中76种挥发性有机物（VOCs）的组分及其质量浓度水平进行测试,比较了各组分对臭氧产生的影响潜势,同时对其主要来源进行简单分析.结果表明,长沙大气总VOCs在上午和下午的浓度分别是38.4×10-9（体积分数）和22.7×10-9（体积分数）,下午大气中VOCs浓度显著低于上午;季节变化呈现VOCs冬季浓度远高于夏季VOCs浓度,组分中以卤代烃最高,烷烃、芳烃次之,烯烃最低,OH消耗速率最高的物质是间、对二甲苯（10.71×10-9 C,碳单位体积比,下同）;其次为1,2,4-三甲苯（6.04×10-9 C）和1,3,5-三甲苯（2.23×10-9 C）.芳烃对大气O3生成贡献最大（66%）,其次是烯烃（26%）,烷烃最低（8%）.高浓度的异戊烷和丙烷说明了机动车排放和液化石油气是VOCs来源之一,苯/甲苯的特征比值接近0.8,远高于机动车尾气排放特征比值0.5;说明溶剂和涂料挥发是其主要来源之一.     

对氯苯甲酸用于测量OH#方法探讨1.机理研究

对氯苯甲酸被用于臭氧氧化过程中羟基自由基的测量,为了检验对氯苯甲酸是否在测量过程中出现误差,进行了臭氧氧化对氯苯甲酸的间歇实验和半连续实验.结果表明,中性条件下间歇试验中,对氯苯甲酸可以强烈促进臭氧分解,它促进臭氧分解的能力比典型的促进剂甲酸和甲醇高10倍.半连续试验的结果进一步表明,臭氧氧化对氯苯甲酸时,可以形成中间产物过氧化氢,过氧化氢能和臭氧反应,形成大量的OH.,从而改变O3/OH.的链式反应,导致采用对氯苯甲酸测量OH.时出现误差.