ZnO纳米颗粒对SBR活性污泥活性的影响

建立了模拟的SBR反应器,并研究了ZnO纳米颗粒(ZnO-NPs)对SBR活性污泥活性的影响.结果表明低浓度(10mg/L)ZnO-NPs对活性污泥活性无明显抑制作用.较高浓度下,ZnO-NPs对活性污泥沉降性能?呼吸速率?EPS和SMP产量及其组成?有机物降解效率等具有明显影响.20,50,100mg/L ZnO-NPs使COD去除率分别降低8.1%, 19.5%和27.7%,使污泥沉降性能分别降低24.2%,35.0%和36.0%,使MLVSS/MLSS比值分别降低8.0%,14.7%和21%,使活性污泥呼吸速率抑制率达到54.0%, 79.0%和80.3%;使EPS产量分别降低29.0%,49.9%和65.4%,使SMP产量分别升高48.9%,102.6%和203.0%.研究表明,较高浓度ZnO-NPs能够抑制污泥代谢,降低活性污泥生物量,显著抑制活性污泥活性.     

Full scale amendment of a contaminated wood impregnation site with iron water treatment residues

Iron water treatment residues are a free by-product with high concentration of iron oxides Iron water treatment residues has a large potential for arsenic sorption Soils are highly contaminated by arsenic at wood preservation sites Iron water treatment residues were added to hot spots contaminated with arsenic The addition led to significant decrease in leaching of arsenic from the contaminated soil Iron water treatment residues (Fe-WTR) are a free by-product of the treatment of drinking water with high concentration of iron oxides and potential for arsenic sorption. This paper aims at applying Fe-WTR to a contaminated site, measuring the reduction in contaminant leaching, and discussing the design of delivery and mixing strategy for soil stabilization at field scale and present a cost-effective method of soil mixing by common contractor machinery. Soil contaminated by As, Cr, and Cu at an abandoned wood impregnation site was amended with 0.22% (dw) Fe-WTR. To evaluate the full scale amendment a 100 m² test site and a control site (without amendment) were monitored for 14 months. Also soil analysis of Fe to evaluate the degree of soil and Fe-WTR mixing was done. Stabilization with Fe-WTR had a significant effect on leachable contaminants, reducing pore water As by 93%, Cu by 91% and Cr by 95% in the upper samplers. Dosage and mixing of Fe-WTR in the soil proved to be difficult in the deeper part of the field, and pore water concentrations of arsenic was generally higher. Despite water logged conditions no increase in dissolved iron or arsenic was observed in the amended soil. Our field scale amendment of contaminated soil was overall successful in decreasing leaching of As, Cr and Cu. With minor improvements in the mixing and delivery strategy, this stabilization method is suggested for use in cases, where leaching of Cu, Cr and As constitutes a risk for groundwater and freshwater.     

TiO2光电催化中光生电子降解对苯醌的行为研究

通过施加外加偏压把TiO2/Ti薄膜阳极产生的光生电子转移到阴极,并对其在阴极的电化学行为进行了研究.用水杨酸探针法对阴极溶液中产生的活性氧自由基进行了检测,探讨了pH值、恒电流值和连接类型等因素对阴极室溶液中对苯醌降解效果的影响.实验结果表明,在酸性条件下,转移至阴极的光生电子可将溶液中的溶解氧还原生成H2O2,再进而生成·OH;在pH值为2.0、恒电流为3.5mA和阳离子膜作为反应器双室连接类型的条件下,在60min内,阴极溶液中对苯醌的降解率可达到82.3%.     

铁锰双金属氧化物对过硫酸氢钾降解酸性橙7的催化效果

为了发挥均相体系中过渡金属元素对PMS(过硫酸氢钾)的催化效果,同时解决存在的金属离子污染的问题,以AO7(酸性橙7)为目标污染物,研究了采用溶胶-凝胶法(sol-gel method)制备Fe-MnO_x(铁锰双金属氧化物)催化剂催化PMS的效果及降解机理. 结果表明:ρ(Fe-MnO_x)由50 mg/L升至200 mg/L后,35 min时AO7降解率由53.74%升至96.65%;继续升高ρ(Fe-MnO_x),AO7降解率提升效果不明显. 随着ρ(PMS)₀(PMS初始质量浓度)的升高,AO7的降解率变化趋势与之相同;而随着ρ(AO7)₀(AO7初始质量浓度)的升高,AO7降解率有所下降. 分别投加EA(乙醇)、TBA(叔丁醇)这2种捕获剂来验证体系氧化物种时发现,55 min时AO7降解率分别为79.40%和91.33%,氧化体系的主要氧化物种为·SO₄-(硫酸根自由基)和少量·OH(羟基自由基). XRD(X射线衍射)和XPS(X射线光电子能谱)结果显示,Fe-MnO_x催化剂中的Fe、Mn主要以Fe3+、Mn2+、Mn4+ 3种形式存在,Fe、Mn、O 3种元素中,Fe3+、Mn2+、Mn4+、O2-和表面羟基氧的摩尔比分别为20.49%、26.46%、5.60%、32.51%和14.91%. 研究显示,Fe-MnO_x催化剂具有金属离子溶出量低、催化性能良好等优良性能,能够有效催化PMS生成自由基,对水中的污染物具有良好的降解效果.      

镧铁羟基氧化物修饰还原氧化石墨烯复合电极材料电吸附除磷效能及机理研究

污水处理厂尾水中低浓度PO₄^3-的排放是水体中总磷的主要来源,是导致水体富营养化的重要原因之一,对其开展深度去除的应用基础性研究具有重要的理论意义和实践价值.复合金属氧化物材料表现出较好PO₄^3-吸附能力,但仍然存在吸附速率较慢的问题.本研究采用溶剂热、复合薄膜压片法制备了镧铁羟基氧化物（LaFeO_xH_y）修饰还原氧化石墨烯（rGO）复合电极材料（LaFe-rGO）,LaFe-rGO复合电极材料显著提高了对PO₄^3-的吸附速率,5 min可达到吸附平衡,在1.2 V电压下对PO₄^3-的最大吸附量为108.69 mg·g^-1.提出了基于晶格氧提供活性位点及LaFe-rGO双电层电容电促吸附除磷机理,LaFe-rGO复合电极材料中晶格氧La-O与Fe-O同时对PO₄^3-吸附提供吸附位点,PO₄^3-与材料中的La/Fe键合以形成内球表面复合物La/Fe-PO₄,掺杂在rGO表面上的LaFeO_xH_y增加了电极材料电容并提高了其电化学活性,促进了LaFe-rGO复合电极材料对PO₄^3-的吸附.     

ZnO纳米粒子通过线粒体通路抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性的作用研究

氧化锌(ZnO)纳米粒子已被发现具有生物毒性,氧化应激被认为是最重要的因素之一。前期实验证实,ZnO纳米粒子能显著减少锰超氧化物歧化酶(Mn SOD)蛋白的表达,降低Mn SOD活性。本文通过检测乳酸脱氢酶(LDH)释放、线粒体活性氧(ROS)水平和膜电位(Δφm)、延迟整流钾电流变化和Na~+/K~+-ATP酶的表达及活性等变化,检测ZnO纳米粒子对小鼠光感受器细胞的细胞毒作用。结果表明,ZnO纳米粒子可显著增强小鼠光感受器细胞中LDH的释放、增加线粒体内ROS水平并下调Δφm、阻断延迟整流钾电流,同时降低Na~+/K~+-ATP酶的表达及活性,从而对小鼠视网膜光感受器细胞产生细胞毒作用,提示ZnO纳米粒子可通过线粒体通路引起氧化应激,从而抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性,产生细胞毒性,导致细胞死亡。本文的研究结果有助于理解ZnO纳米粒子引起细胞毒性的作用机理。     

Enzymatic nitrous oxide emissions from wastewater treatment

Nitrous oxide (N₂O), a potent greenhouse gas, is emitted during nitrogen removal in wastewater treatment, significantly contributing to greenhouse effect. Nitrogen removal generally involves nitrification and denitrification catalyzed by specific enzymes. N₂O production and consumption vary considerably in response to specific enzyme-catalyzed nitrogen imbalances, but the mechanisms are not yet completely understood. Studying the regulation of related enzymes’ activity is essential to minimize N₂O emissions during wastewater treatment. This paper aims to review the poorly understood related enzymes that most commonly involved in producing and consuming N₂O in terms of their nature, structure and catalytic mechanisms. The pathways of N₂O emission during wastewater treatment are briefly introduced. The key environmental factors influencing N₂O emission through regulatory enzymes are summarized and the enzyme-based mechanisms are revealed. Several enzymebased techniques for mitigating N₂O emissions directly or indirectly are proposed. Finally, areas for further research on N₂O release during wastewater treatment are discussed.

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Mn-Ce/Ti-PILC催化剂低温脱硝性能研究

以钛基柱撑黏土(Ti-PILC)为载体,采用浸渍法制备了Mn-Ce/Ti-PILC催化剂,并考察了其脱硝性能。在n(Ti)∶m(黏土)为15 mmol/g、焙烧温度为400 ℃、Mn-Ce负载量(w)为12%和6%、空速为120 000 h^-1的条件下,Mn-Ce/Ti-PILC在宽温度窗口180~260 ℃的NO转化率可达90%以上,N₂选择性可达80%以上;220 ℃时NO转化率接近100%,N₂选择性达86%左右。柠檬酸和Mo的掺杂可进一步提高Mn-Ce/Ti-PILC的脱硝性能。Ti-PILC载体结构有助于活性组分分散,且Ti与Mn-Ce之间可形成强相互作用。Ce的加入可降低催化剂酸性位点强度。     

磁性粒子/介孔碳的合成及其吸附性能

以介孔分子筛SBA-15为模板,采用三氯化铁和蔗糖同步浇铸的方法,利用纳米刻蚀技术合成了Fe-Fe3O4磁性纳米粒子/介孔碳复合体(简称磁性粒子/介孔碳)。XRD分析和高分辨透射电子显微镜表征结果表明,磁性粒子/介孔碳中含有强磁性粒子——Fe3O4和α-Fe。在初始罗丹明B质量浓度为200 mg/L的溶液中加入于碳化温度为800 oC下制得的磁性粒子/介孔碳1 mg/L,吸附190 min后,平衡吸附量为329 mg/g。吸附后的磁性粒子/介孔碳在乙醇中的脱附率可达93.7%。通过外加磁场可将吸附后的磁性粒子/介孔碳与溶液分离。     

Cu2O/PTCDI复合材料的制备及其光催化活性

] 以p型半导体氧化亚铜（Cu₂O）与n型半导体苝二酰亚胺（PTCDI）为原料,通过原位还原的方法制备了Cu₂O/PTCDI复合材料,并考察了其对亚甲基蓝的光催化降解活性。实验结果表明：与纯Cu₂O及PTCDI自组装体相比,Cu₂O/PTCDI复合材料的光催化活性与稳定性都有所提升; PTCDI自组装体质量分数为90%的Cu₂O/PTCDI复合材料对亚甲基蓝的降解率可达70%。Cu₂O和PTCDI自组装体的有效复合降低了光生电子和空穴的复合率,同时改善了Cu₂O和PTCDI自组装体的光催化活性。