FePMo12催化电化学反应降解染料废水的研究

采用IR和XRD等方法对自制磷钼酸铁(FePMo12)杂多酸进行表征,表明杂多阴离子具有Keggin结构.将FePMo12负载于修饰后的4分子筛(4A)上制备FePMo12/APTES-4A催化剂填充于电化学反应器中,考察电化学氧化体系对酸性大红3R染料废水的脱色效果.结果表明,FePMo12/APTES-4A催化剂对酸性大红3R模拟废水具有良好的催化效果,当活性组分负载量为3%时,在pH为4,槽电压为22 V,曝气量为0.08 m3·h-1,极板间距为3.0 cm反应条件下,90 min后脱色率达到75.3%,COD和TOC去除率分别达到65.4%和46.0%.加入支持电解质Na2SO4和NaCl后,NaCl对电催化降解染料废水有促进作用,而Na2SO4的加入使得废水的脱色效率降低.采用可见-紫外光谱对反应过程中间产物进行分析,表明染料分子中的共轭体系已基本被破坏.     

A review of environmental characteristics and effects of low-molecular weight organic acids in the surface ecosystem

Low molecular weight organic acids （LMWOAs） are prevalent on the earth＇s surface. They are vital intermediate products during metabolic pathways of organic matter and participate in the tricarboxylic acid cycle during life activities. Photochemical reactions are pivotal for LMWOAs＇ origination and play a large role in determining their diversity and their ultimate fate. Within the long time that organic matter is preserved in sediments, it can be decomposed and converted to release organic and inorganic pollutants as well as C, N, and P nutrients, which are of potential ecological risk in causing secondary pollution to lake water. The sediment pool is a comprehensive and complex compartment closely associated with overlying water by various biochemical processes, during which LMWOAs play critical roles to transport and transform elements. This article elucidates geochemical behaviors of LMWOAs in the surface environment in details, taking natural water, soil, and aerosol as examples, focusing on reviewing research developments on sources and characteristics, migration and mineralization of LMWOAs and relevant environmental effects. Simultaneously, this review article depicts the categories and contents of LMWOAs or their contribution to DOC in environmental media, and evaluates their importance during organic matter early diagenesis. Through concluding and discussing the conversion mechanisms and influencing factors, the next research orientations on LMWOAs in lake ecosystems are determined, mainly concerning relationships with hydrochemical parameters and microorganisms, and interactions with pollutants. This will enrich the knowledge on organic matter degradation and related environmental effects, and help reconstruct a theoretical framework for organic compound succession and influencing factors, providing basic data for lake eutrophication and ecological risk assessment, conducive to better control over water pollution and proper management of water quality.     

Effects of ozonation and coagulation on effluent organic matter characteristics and ultrafiltration membrane fouling

Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.     

低分子量有机酸对三峡水库消落区土壤中汞赋存形态及其活性的影响

为研究植物根系分泌物的主要成分——低分子量有机酸对土壤汞的活化作用,利用室内模拟实验,通过分析不同浓度的柠檬酸、酒石酸和草酸溶液对三峡库区消落带土壤中汞赋存形态的影响及其随培养时间的变化特征,探究了低分子量有机酸对汞迁移能力和生物有效性的作用.结果表明,柠檬酸可增强土壤汞的迁移能力,而草酸和酒石酸则表现出软弱的抑制作用.3种低分子量有机酸均能明显地增强土壤中汞的生物有效性,整体活化效果为:柠檬酸酒石酸≈草酸.有机酸对土壤中汞形态的作用随其浓度的增加而增强,且当浓度为15 mmol·L~(-1)(柠檬酸)、10 mmol·L~(-1)(酒石酸和草酸)时开始趋于稳定.在15 mmol·L~(-1)柠檬酸培养的土壤中,汞形态分布的变化随培养时间的延长而愈加显著,直到14d时才基本停止,此时胃酸溶解态汞增加最为明显,其主要来自于部分被活化的强络合态汞.     

HPSEC-UV-TOC联用技术测定有机物相对分子质量分布

采用在线高效凝胶色谱仪(HPSEC)和紫外检测器以及TOC检测仪联用测定有机物相对分子质量分布.通过同步测定样品中大范围相对分子质量区间的UV254和TOC,更深入和准确地了解有机物的结构特性,特别是一些不含共轭双键和芳香度的有机物.结果显示,TOC检测仪能够简单快捷地检测出水中所有有机物的相对分子质量分布,包括蔗糖、海藻酸钠等对紫外响应较低的亲水性有机物;样品进样量与TOC响应线性正相关,进样量越大,响应越强;离子强度从0升至0.2mol.L-1,峰面积仅减小1.2%,离子强度对有机物相对分子质量分布测定影响较小;样品pH值在中性或酸性时不影响测定结果,pH值为碱性时,TOC响应异常;采用流动相配定的样品较超纯水配定的样品,相对分子质量分布曲线中干扰峰明显减小,出峰效果更好;该联用技术可以很好地表征湘江原水及其4种亲疏水性组分的相对分子质量分布.     

筑坝蓄水对不同水深浮游微生物群落结构和种间互作模式的影响

微生物群落之间通过直接或间接的关系相互作用,在生态过程中发挥重要作用,然而目前对于水库微生物种间互作模式的关注仍然较少.选择江苏省横山水库为研究区域,分别采集表层及深层水样,探究浮游微生物群落结构和分子生态网络对水深变化的响应规律,并辨识不同水深处浮游微生物群落的关键物种.结果发现,表层浮游微生物丰富度及均匀度均高于深层,且不同深度浮游微生物群落结构具有显著差异.水深通过改变环境异质性间接对浮游微生物群落产生影响,其中总有机碳（TOC）、硝酸盐（NO^-₃）、铵盐（NH⁺₄）和磷酸盐(PO₄^3-)等指标对浮游微生物群落结构影响最为显著.此外,深层浮游微生物分子生态网络的节点数和边数均显著高于表层,且深层浮游微生物群落中关键物种数目和种类均显著高于表层,表明深层浮游微生物群落网络规模更大,但表层浮游微生物群落种间协同合作关系和网络连通性更强.上述结果将为水库微生物群落种间相互作用研究提供科学依据,对预测水库生态系统中微生物的生态规律及全球物质循环影响具有重要意...     

北京市生物源一次气溶胶数浓度变化特征及影响因素

生物源一次气溶胶（PBAP）,是大气颗粒物的重要组成部分,不论微生物死活,对空气质量和人类健康均会产生影响,同时对大气化学以及气候变化都有重要影响.基于流式细胞仪分析技术,结合碘化丙啶（PI）和SYBR （SYBR Green I）双荧光探针,对北京城区大气环境中死的和活的PBAP进行了识别和定量分析,并探究气象因子和空气污染因子对其影响.结果发现,北京城区死的和活的PBAP数浓度中值夏季（1.03×10⁶个·m^-3和7.43×10⁵个·m^-3）高于冬季（7.34×10⁵个·m^-3和6.18×10⁵个·m^-3）,且两者呈现明显的同步变化趋势.统计学结果分析发现,PBAP数浓度与气象条件和空气质量等环境影响因子相关性并不显著,与温度和湿度呈现弱正相关关系,与O₃、最大风速和日照时数呈现弱负相关关系.PBAP数浓度与细颗粒物PM_2.5浓度相关性较弱,与粗颗粒物（PM_2.5-10）浓度呈现明显的正相关关系.静稳天气和沙尘长距离传输都可以提升北京城区PBAP的数浓度水平.     

整体式分子筛基催化剂制备及其微波催化燃烧VOCs

以整体式蜂窝状分子筛为载体,制备铜锰铈负载型催化剂,研究其微波辐照下对VOCs （甲苯、丙酮、乙酸乙酯）的催化活性及其稳定性,探究影响催化剂活性的因素,并通过测试床层温度分布进行分析.研究表明,微波功率1.3kW、催化剂体积300mm×300mm×300mm,固定床温度>300℃条件下,催化剂对初始浓度200~2000mg/m³的5m³/h VOCs气体的降解效率为80%~92%.温度是VOCs氧化降解的条件,但当床层温度超过了300℃（VOCs完全燃烧温度）之后,升温对VOCs降解效率的影响不再明显.表征可知,尖晶石态铜锰铈单金属氧化物及其复合氧化物是主要的催化活性组分.VOCs在催化剂表面进行准一级反应而被催化氧化;高温对催化剂结构有一定影响,但重复性试验证实了催化剂的高活性和良好的稳定性.     

载体平衡离子对MnOx/ZSM-5催化NH3-SCR性能影响

采用不同平衡离子（H⁺、Na⁺和NH₄⁺）的ZSM-5改性分子筛制备MnO_x/ZSM-5催化剂,研究平衡离子对氨选择催化还原（NH₃-SCR）反应活性的影响.NH₃-SCR反应结果表明,NH₄-ZSM-5为载体时,催化剂表现出优异的低温SCR活性,而H-ZSM-5为载体的催化剂则在高温范围对NO_x具有较高的转化率.XRD、TEM、BET、Raman、H₂-TPR、XPS等表征结果显示,平衡离子可明显影响MnO_x在催化剂中的分散位置以及氧化还原性质.MZ-NH₄催化剂中活性组分MnO_x分散在载体外表面,颗粒尺寸较大,主要以Mn³⁺形式存在,对NO具有较强的氧化能力,进而促进“快速SCR”反应的进行.而H-ZSM-5为载体时,MnO_x主要被限域在载体孔道内形成限域催化剂,主要以Mn⁴⁺形式存在.活性研究和表征结果证明,活性组分分散在催化剂外表面,更有利于低温SCR反应的进行.