不同硅铝比的ZSM-5型沸石分子筛吸附水中Cu2+离子的研究

考察了3种不同硅铝比的ZSM-5沸石分子筛（25H、38H和50H,25、38和50为硅铝比）对水中Cu²⁺的吸附过程及其影响因素。结果表明,3种材料均能有效吸附去除水中Cu²⁺离子,动力学符合假二阶动力学模型,吸附等温线符合Langmuir吸附等温式。3种材料吸附速率及吸附容量顺序为：25H＞50H＞38H,其中,25H最大吸附容量达到12.83 mg/g。投加量由0.8 g/L增加至2.0 g/L,材料对Cu²⁺吸附去除率由87.0%增加至97.5%。考察水中常见阳离子对吸附的干扰作用,结果表明,干扰离子的影响顺序为：Pb²⁺> K⁺> Na⁺ > Mg²⁺;随着干扰离子浓度的增大,材料对Cu²⁺的去除率显著下降。硅铝比及晶粒形貌均对沸石分子筛吸附Cu2+有较大影响,小的孔径不利于Cu²⁺的吸附,低硅铝比有利于Cu²⁺在分子筛上的吸附。     

Photocatalytic degradation of gaseous toluene over Ag-doping TiO₂ nanotube powder prepared by anodization coupled with impregnation method

In this work, Ag-doping TiO₂ nanotubes were prepared and employed as the photocatalyst for the degradation of toluene. The TiO₂ nanotube powder was produced by the rapid-breakdown potentiostatic anodization of Ti foil in chloride-containing electrolytes, and then doped with Ag through an incipient wetness impregnation method. The samples were characterized by scanning electron microscope, high-resolution transmission electron microscopy, X-ray diffraction, surface photovoltage measurements, X-ray photoelectron spectroscopy and N₂ adsorption. The nanotubular TiO₂ photocatalysts showed an outer diameter of approximately 40 nm, fine mesoporous structure and high specific surface area. The photocatalytic activity of Ag-doping TiO₂ nanotube powder was evaluated through photooxidation of gaseous toluene. The results indicated that the degradation efficiency of toluene could get 98% after 4 h reaction using the Ag-doping TiO₂ nanotubes as the photocatalyst under UV light illumination, which was higher than that of the pure TiO₂ nanotubes, Ag-doping P25 or P25. Benzaldehyde species could be observed during the photocatalytic oxidation monitored by in situ FTIR, and the formed benzaldehyde intermediate during reaction would be partially oxidized into CO₂ and H₂O.     

A/O和A2/O工艺对膜生物反应器处理焦化废水影响的研究

为提高膜生物反应器对焦化废水的处理效果,采用A/O和A2/O两种工艺的膜生物反应器处理焦化废水,通过对比处理效果、分析膜污染情况,寻求膜生物反应处理焦化废水的最优工艺。实验结果表明：A2/O工艺系统对酚、NH3-N、COD的去除率分别为99%、90%和95%;A/O工艺系统对酚、NH3-N和COD的去除率分别为97%、75%和93%。A2/O膜生物反应器系统对焦化废水中NH3-N的去除效果明显优于A/O膜生物反应器系统,其反硝化率为50%-70%。对膜污染分析表明不同工艺对膜污染的影响不显著,A2/O工艺膜通量衰减59%,A/O工艺膜通量衰减56%。研究表明在膜生物反应器中,A2/O工艺对焦化废水的去除效果要优于A/O工艺。     

底灰动态吸附焦化和造纸废水研究

分析了底灰的化学组成、矿物组成和比表面积等基本理化性质;采用动态吸附柱法研究了底灰处理焦化和造纸废水的性能,探讨了进水流量和吸附柱高度对吸附效果的影响.结果表明,底灰不仅有吸附作用,还具有一定的混凝作用;颗粒态有机碳(POC)较易被混凝除去,焦化废水中POC占总有机碳(TOC)的17%,而造纸废水中POC仅占TOC的2.3%,因此底厌对焦化废水COD的去除效果比造纸废水好;底灰对焦化废水色度的去除率要高于COD;接近吸附饱和时,底灰对造纸废水OM275的去除率仍有约27%,说明造纸废水中苯环类物质相比于其他有机物较易被去除.     

光电芬顿氧化法深度处理垃圾渗滤液研究

采用光电芬顿氧化法对北京市某垃圾填埋场已经生化处理后的垃圾渗滤液进行深度处理,分别考察了电流强度和铁的不同价态等因素对渗滤液总有机碳（TOC）、化学需氧量（COD）以及色度去除效果的影响,并对阳极氧化、电芬顿和光电芬顿不同反应过程进行了对比。通过分析渗滤液UV-Vis光谱(200～500 nm)变化和渗滤液中有机污染物的分子量变化,发现光电芬顿反应可以明显改善渗滤液生化性。深入研究了反应过程中铁价态的变化规律。试验结果发现,以高比表面积的活性炭纤维(ACF)为阴极的光电芬顿反应可以有效降解垃圾渗滤液,在pH为3,Fe²⁺ 浓度为1 mmol/L,电流为0.5 A,O₂通入量为250 mL/min条件下降解360 min,垃圾渗滤液TOC和COD去除率分别达到78.9%和62.8%,色度完全去除。     

硫自养反硝化去除地下水中硝酸盐氮的研究

研究实际地下水硫自养反硝化动力学过程,考察季节因素(温度)对动力学的影响,实验结果表明,地下水升流式硫自养滤柱反硝化动力学符合1/2级动力学模型,其反应速率常数受温度的影响很大,用阿仑尼乌斯方程计算硫自养反硝化活化能为80.38 kJ/mol。硫自养反硝化产生的硫酸根与反硝化掉的硝酸根离子呈线性相关。在地下水不经任何预处理的条件下,硫自养反硝化仍能有效地脱除地下水中的硝酸盐,反应器出水的pH值仍维持在中性范围。     

Impacts of a strong cold front on concentrations of HONO,HCHO, O3, and NO2 in the heavy traffic urban area of Beijing

Much rain and strong winds caused by a cold front occurred in Beijing during the period of Sep. 27 to Oct. 4, 2004 and led to sharp drops in maximum and mean concentrations of HONO, HCHO, O₃, and NO₂, i.e., the maximum concentrations were reduced by 5.9, 21.3, 45.6, and 44.4 ppb, respectively, and the mean concentrations were decreased by 4.0, 5.5, 30.3, and 32.3 ppb, respectively. For daily HO_x production rates HONO photolysis was the largest contributor and over 90% contributions were from photolysis of HONO and HCHO. Large number and area percentages of soot aggregate from PM10, and high correlations between concentrations of PM10 and chemical formation of HONO suggested that heterogeneous reactions of NO₂ on surfaces of soot aggregate could be a key source of HONO in the heavy traffic areas of Beijing during the night and should be considered in air quality simulations for such areas.     

胶团强化超滤中表面活性剂结构差异对苯酚增溶性能的影响研究

在胶团强化超滤(MEUF)技术处理有机物废水中,采用多因素正交实验研究了3种不同类型的阳离子型表面活性剂,即疏水链长度相同,而亲水基头不同;亲水基头相同,而疏水链长度不同的表面活性剂,分析基团差异对于苯酚增溶的影响。结果表明,十六烷基氯化吡啶(CPC)对于苯酚的去除效果最好,其次是十八烷基三甲基溴化铵(OTAB),最后是十六烷基三甲基溴化铵(CTAB)。综合去除效果和经济性两方面考虑,在单因素超滤实验中选择OTAB来重点研究表面活性剂浓度和电解质浓度两个操作参数对于苯酚增溶的影响。     

饮用水质安全保障的研究与技术发展趋势:Ⅱ.基于微界面过程的水质净化技术

非均相介质体系下的复杂界面是污染物赋存与水质净化过程的载体,微界面反应过程是强化水质净化过程的手段与途径。设计构建针对不同污染物与净化目标的高效界面,阐明基于微界面过程的水质转化与净化机制,建立微界面水质净化过程调控方法,是饮用水质安全保障研究的重要内容。本文从非均相体系下微界面水质过程调控、微界面尺度物质相互作用强化、特殊功能的高效界面构建、非稳态条件下界面反应抑制等角度,综合论述了微界面水质过程调控、强化与控制的重要科学问题与饮用水质净化技术方向。     

乙酰甲胺磷对斜生栅藻的毒性及细菌降解研究

采用血球计数法测定斜生栅藻细胞数目,研究了乙酰甲胺磷对斜生栅藻的毒性作用,并通过藻类培养液中接种经过筛选得到的乙酰甲胺磷高效降解菌测定其对乙酰甲胺磷毒性的去除影响。研究结果表明,乙酰甲胺磷对斜生栅藻的抑制中浓度(EC50)大于159 mg/L,急性毒性为低毒。但进一步研究发现,在7 d后,EC50为174.68 mg/L,明显低于24 h的1 128.57 mg/L,存在亚慢性毒性。通过藻类培养液接种高效降解菌Y-6,乙酰甲胺磷对藻类的生长抑制程度减轻。