Enhanced debromination of 4-bromophenol by the UV/sulfite process: Efficiency and mechanism

Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we systematically studied the debromination efficiency and mechanism of para-bromophenol(4-BP) by a recently developed UV/sulfite process. 4-BP underwent rapid degradation with the kinetics accelerated with the increasing sulfite concentration, pH(6.1–10) and temperature, whereas inhibited by dissolved oxygen and organic solvents. The apparent activation energy was estimated to be 27.8 kJ/mol. The degradation mechanism and pathways of 4-BP were explored by employing N_2O and nitrate as the electron scavengers and liquid chromatography/mass spectrometry to identify the intermediates. 4-BP degradation proceeded via at least two pathways including direct photolysis and hydrated electron-induced debromination. The contributions of both pathways were distinguished by quantifying the quantum yields of 4-BP via direct photolysis and hydrated electron production in the system. 4-BP could be readily completely debrominated with all the substituted Br released as Br-, and the degradation pathways were also proposed. This study would shed new light on the efficient dehalogenation of brominated aromatics by using the UV/sulfite process.     

气相组分对氨吸收同步脱除模拟烟气SO2 和NOx 的影响

在pH值5.9～6.1,吸收液浓度≥1 mol·L-1的条件下,分析了模拟烟气的NOx氧化度、O2和SO2浓度,以及添加液相S(Ⅳ)氧化抑制剂Na2S2O3对SO2、NOx吸收脱除效率的影响.结果表明,氨可高效吸收脱除SO2和NO2,但对NO的吸收脱除效率几乎为0,因此,NO氧化是其吸收脱除NOx的前提.吸收液S(Ⅳ)浓度是影响NO2脱除效率的关键因素,气相O2浓度越高或SO2浓度越低,吸收液S(Ⅳ)浓度降低越快,继而使NO2吸收脱除效率降低越快.通过添加S(Ⅳ)氧化抑制剂S2O23-到吸收液,可在一定程度上抑制其氧化,从而延缓NO2吸收脱除效率的降低.     

锰氧化菌Pseudomonas sp. QJX-1对氧四环素的去除作用与机制

氧四环素（Oxytetracycline,OTC）的大量使用可能导致环境中抗性基因的生成和传播.锰氧化菌及其催化产生的生物锰氧化物（Biogenic manganese oxides,BMO）在自然界中广泛存在,但对其去除OTC的过程与机制仍不明确.因此,本研究探讨了锰氧化菌Pseudomonas sp. QJX-1对微量（5 μg·L^-1）OTC的去除作用与机制.结果表明,微量的OTC可以促进QJX-1的生长及其对Mn²⁺的氧化.QJX-1及其催化生成的BMO对OTC的去除效果较好,在第168 h时对OTC的去除率达到99%.转录组结果表明,OTC会导致细菌的pstA、pstB、pstC、urtA和urtD等ABC转运蛋白编码基因表达上调,说明OTC可能是通过ABC转运蛋白泵出QJX-1体内进而让BMO更有效地接触OTC,从而达到OTC被吸附、氧化去除的目的.RT-qPCR结果表明,微量的OTC促进了细菌多铜氧化酶基因cumA的表达,提高了BMO的生成速率,增强了对OTC的去除效果.     

高强UV/SO32-体系高效降解一氯乙酸

为有效解决饮用水中卤代乙酸（HAAs）污染问题,选取水中典型HAAs一氯乙酸（MCAA）作为目标污染物,系统研究了高强UV/SO₃^2-体系对其降解效能及影响因素.结果表明,高强UV/SO₃^2-体系可高效降解MCAA,50s内初始浓度为50 μmol/L的MCAA可被完全降解.与已报导的还原法降解MCAA的文献相比,本研究中MCAA降解速率提高了1000倍以上.提高SO₃^2-浓度、溶液初始pH以及紫外光强均有利于体系中MCAA降解率的提高.水中共存物质研究表明,NH₄⁺可促进MCAA降解,而NO₃^-、HCO₃^-、NOM均会抑制MCAA降解,其中,HCO₃^-影响较小.     

氨法烟气脱硫产物亚硫酸盐氧化的研究进展

在氨法烟气脱硫工艺中,将副产物亚硫酸盐氧化成硫酸盐一直是氨法脱硫工艺工业化的瓶颈,也是该领域研究的热点问题。介绍了亚硫酸盐的传统氧化法和高级氧化法,以及国内外亚硫酸盐氧化动力学的研究进展,并对目前研究中出现的问题和今后发展前景进行了分析。     

Catalytic oxidation of calcium sulfite in solution/aqueous slurry

Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfudzation(FGD) residue.Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously.Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L,manganese is 10^-4 mol/L, and oxygen is of 0.2-0.4 atm.     

硫酸、亚钠生产中烟气中水净化洗涤水的循环-硫化处理与综合利用

针对化工厂硫酸、亚硫酸钠生产过程中烟气中水净化系统存在的酸性废水未能利用问题,在净化洗涤水处理综合利用工业实验改进与完善的基础上,将净化洗涤水自身的水质特性、系统循环特点与经典硫化沉淀水处理技术应用有机结合,并形成循环-硫化沉淀酸水处理技术措施,克服烟气中水洗涤净化水处理过程中存在的沉淀分离不够稳定等问题,不但使酸性废水得到高效循环利用,而且使经除杂等处理后的含酸17%以上的酸水,作为补充水用于硫酸干吸系统浓酸的稀释;而且使酸水中所含有价金属酸泥经分步沉淀、分类分离回收后送至冶炼厂提炼,使硫酸烟气中水净化洗涤系统酸性废水得到综合利用并实现其净化酸水系统少排或零排放。     

均相/非均相体系中亚硫酸钙非催化氧化过程

将空气鼓入一个装有亚硫酸钙溶液 浆液且混合良好的鼓泡搅拌反应器中,反应器是有效容积为1000mL的五口烧瓶,空气连续鼓入反应器中实现亚硫酸钙的强制氧化.实验结果表明,对于亚硫酸钙的非催化氧化过程,均相体系与非均相体系之间既紧密联系,又具有不同的反应特征.均相体系中仅存在气 液传质和氧化反应过程,而非均相体系远比均相体系复杂,同时存在溶解 氧化 结晶过程,该过程对非均相体系的氧化过程产生巨大影响.以上2种体系的主要差别表现为氧化速率相差2个数量级,非均相体系更有利于氧化过程的进行.     

亚铵法麦草浆黑液的回收与污染治理新技术的研究

通过对亚铵法麦草浆黑液性质的研究 ,提出了蒸发浓缩 +生物活性有机肥生产的新技术路线 ,并结合生产实践对该技术加以研究、归纳 ,并进行了经济分析。实践证明 ,运用该技术不仅能实现亚铵法麦草浆黑液的回收和污染治理达标 ,而且能为企业带来可观利润 ,使企业走上可持续发展之路。     

铁矿石烧结烟气脱硫灰处理含铬废水

在分析铁矿石烧结烟气脱硫灰成分的基础上,利用脱硫灰中的亚硫酸盐还原废水中的Cr(Ⅵ),再加碱中和,通过沉淀去除铬。在初始废水pH 1.0、脱硫灰加入量0.06 g/mg(以Cr(Ⅵ)计)、振荡转速160 r/min、振荡时间25 min、中和pH 7.5的最佳工艺条件下处理模拟含铬废水,Cr(Ⅵ)质量浓度由10.00 mg/L降至0.18 mg/L,去除率达98.2%。最佳工艺条件下处理3种实际含铬废水,处理后出水的Cr(Ⅵ)和总铬的质量浓度及pH均满足GB 8978—1996《污水综合排放标准》。实现了对脱硫灰的综合利用、化害为利和以废治废的目标。