水溶液中臭氧和溴离子的反应研究

为探明O3氧化Br-的反应机制,采用离子色谱、PDA紫外-可见光度仪研究了水中Br-被O3氧化的反应过程.离子色谱分析表明,被氧化的Br-中只有约10%被O3氧化成BrO3-.进一步研究表明,除了生成BrO3-外,Br-被O3氧化过程中还产生了Br2,Br2又与溶液中存在的Br-结合形成Br3-,并首次得到了Br3-的吸收光谱,测得Br3-的最大吸收峰λmax为260 nm,提出了Br-与O3的基元反应.该研究补充和完善了O3氧化Br-的反应机制,也为O3处理含Br-水时Br-的归趋提供了有益信息.     

零价铁去除废水中的汞

研究了零价铁(zero-valent iron,ZVI)去除废水中Hg2+的动力学特征及其影响因素,初步探讨了ZVI与Hg2+的作用机制.结果表明,ZVI对废水中Hg2+的最佳去除条件:Hg2+的初始浓度为0.10 mg·L-1、pH为5、ZVI用量为0.050 g、温度为25℃,获得Hg2+的去除率为94.5%.ZVI对废水中Hg2+有一个快速的去除过程,可用准一级反应动力学方程描述,速率常数为0.010 min-1.ZVI去除废水中Hg2+的机制主要是氧化还原反应、铁氧化物和氢氧化物的吸附和共沉淀作用,ZVI表面钝化是降低Hg2+去除率的主要原因,其钝化成分主要是FeOOH和Fe2O3-Fe3O4.胡敏酸可与ZVI还原产生的Fe2+、Fe3+结合形成Fe-HA复合物,增加可溶性铁的比例,缓解ZVI的钝化,对细铁氧化物和铁氢氧化物胶体具有稳定作用,增强对废水中Hg2+的吸附作用.     

复合生物絮凝剂CBF-1的絮凝作用机理研究

采取PAC+絮凝剂的复配方式开展高岭土悬浊液烧杯实验,考察了复合生物絮凝剂CBF-1、CBF-1溶解物及微生物絮凝剂MBF8的絮凝特性,并借助iPDA仪分析和扫描电镜、光学显微镜观察等手段,比较分析了絮凝过程及絮体特性的差异.结果表明,各复配絮凝的浊度去除效果排序为CBF-1＞ CBF-1溶解物＞MBF8,CBF-1投加量1 mg·L-1时,浊度去除率可达到97.5％;絮体强度排序为CBF-1＞ CBF-1溶解物＞MBF8,絮体恢复因子排序为MBF8＞CBF-1溶解物＞CBF-1,絮体大小排序为CBF-1＞ CBF-1溶解物＞MBF8.单独投加PAC或投加PAC+MBF8的情况下,形成的絮体形态相对规整、密实;投加PAC+ CBF-1溶解物或投加PAC+ CBF-1形成的絮体则相对无序、疏松,CBF-1作用下絮体大、沉降快.CBF-1中高电荷MBF8组分及大分子羧甲基纤维素、羧甲基多聚糖等组分具有强的电荷中和与桥联协同增效作用;CBF-1还含有纤维素、木质素等大分子量且带多种官能团的不溶性组分,在桥联和吸附过程中也起着重要作用.     

链霉菌FX645对偶氮染料红AR30的降解机制研究

从印染厂污泥中筛选到1株对偶氮染料红30(AR30)具有较强脱色降解作用的菌株Streptomyces sp.FX645.通过降解产物的紫外-可见吸收光谱、LC-MS分析及各降解产物在发酵体系中浓度随时间变化的规律,探讨了菌株FX645对AR30的可能降解途径,首先在偶氮还原酶的作用下AR30发生偶氮键的裂解,生成4-硝基-2,6-二氯苯胺与2-[(4-胺苯基)-(2-氰乙基)-氨基]乙酸乙酯,然后分别发生硝基还原、氨基酰化、氰基水解作用,生成一系列的苯胺类化合物.     

基于废陶瓷的多孔陶瓷研制及其对Ni2+的吸附性能

通过SEM、XRD、FT-IR表征及多孔陶瓷对废水中镍的去除能力,确定多孔陶瓷的制备条件:原料中田菁粉掺杂质量分数为4%,焙烧温度为800℃.SEM和孔结构表征说明,焙烧使多孔陶瓷形貌、结构发生变化;随着焙烧温度的升高,多孔陶瓷的比表面积和孔容呈现降低的趋势,而孔径呈现增大的趋势;EDS分析能表明,原废瓷粉和多孔陶瓷的主要元素组成均为Si、Al、O.SEM、XRD和FT-IR分析表明,多孔陶瓷吸附前后结构稳定.吸附Ni2+的系列实验表明,多孔陶瓷用量为10 g·L-1,吸附时间为60 min,进水pH值为6.32,进水Ni2+浓度在100 mg.L-1以内.在此条件下废水的Ni2+去除率可达89.7%,多孔陶瓷对废水中镍有较好的去除效果.以制备的多孔陶瓷处理含镍废水,考察多孔陶瓷对废水中Ni2+的吸附动力学和吸附等温线,结果表明,多孔陶瓷对Ni2+的吸附过程符合准二阶动力学模型(R2=0.999 9),Qe为9.09 mg·g-1;吸附过程可用Freundlich方程和Langmuir方程来描述,温度由20℃升高至40℃,最大吸附量Qm由14.49 mg·g-1上升至15.38 mg·g-1.     

含铬废水的处理技术及机理简述

介绍了废水中六价铬的来源及存在形态,以及处理含铬废水的物理、物化、化学及生物等各种工艺,并对各种工艺的机理和优缺点进行分析,展望含铬废水的治理前景。     

Removal of Cd2+ from water by Friedel’s salt (FS: 3CaO.Al2O3·CaCl2·10H2O): Sorption characteristics and mechanisms

The development of low-cost and efficient new mineral adsorbents has been a hot topic in recent years. In this study, Friedel’s salt (FS:3CaO·A12O3 ·CaCl2 ·10H2O), a hexagonal layered inorganic absorbent, was synthesized to remove Cd2+ from water. The adsorption process was simulated by Langmuir and Freundlich models. The adsorption mechanism was further analyzed with TEM, XRD, FT-IR analysis and monitoring of metal cations released and solution pH variation. The results indicated the adsorbent FS had an outstanding ability for Cd(Ⅱ) adsorption. The maximum adsorption capacity of the FS for Cd(Ⅱ) removal can reach up to 671.14 mg/g. The nearly equal numbers of Cd2+ adsorbed and Ca2+ released demonstrated that ion-exchange (both surface and inner) of the FS for Cd(Ⅱ) played an important role during the adsorption process. Furthermore, the surface of the FS after adsorption was microscopically disintegrated while the inner lamellar structure was almost unchanged. The behavior of Cd(Ⅱ) adsorption by FS was significantly affected by surface reactions. The mechanisms of Cd2+ adsorption by the FS mainly included surface complexation and surface precipitation. In the present study, the adsorption process was fitted better by the Langmuir isotherm model (R2 = 0.9999) than the Freundlich isotherm model (R2 = 0.8122). Finally, due to the high capacity for ion-exchange on the FS surface, FS is a promising layered inorganic adsorbent for the removal of Cd(Ⅱ) from water.     

Photocatalytic degradation of carbofuran in TiO2 aqueous solution：Kinetics using design of experiments and mechanism by HPLC/MS/MS

The photocatalytic degradation kinetics of carbofuran was optimized by central composite design based on response surface methodology for the first time. Three variables, TiO2 concentration, initial pH value and the concentration of carbofuran, were selected to determine the dependence of degradation efficiencies on independent variables. Response surface methodology modeling results indicated that the degradation efficiency of carbofuran was highly affected by the initial pH value and the concentration of carbofuran. Then nine degradation intermediates were detected by HPLC/MS/MS. The Frontier Electron Densities of carbofuran were calculated to predict the active sites on carbofuran attacked by hydroxyl radicals and photoholes. Point charges were used to elucidate the chemisorption pattern on TiO2 catalysts during the photocatalytic process. By combining the experimental results and calculation data, the photocatalytic degradation pathways of carbofuran were proposed, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain.     

LNAPLs污染物在层状非均质多孔介质中的运移试验研究

文章通过室内试验研究层状非均质多孔介质中轻非水相液体(Light Non-Aqueous Phase Liquid,LNAPL)的运移机制与分布特性。首先,在二维砂槽上进行LNAPL的入渗试验,试验过程中用数码相机进行拍照,把LANPL的扩散过程以图像的形式记录下来;然后,用AutoCAD对图片进行分析处理,得出不同时刻LNAPL的入渗锋面变化图。结果发现,介质结构突变面改变了LNAPL的迁移模式。在LNAPL由中砂进入细砂层后,由于受到毛细作用的增强,其运移速度加快;而由中砂进入粗砂,受粗砂介质阻滞作用增强的影响,LNAPL运移速度变小。当LNAPL由干砂进入湿润砂体时,由于孔隙水浮托力增大,LNAPL先产生纵向运移,随后以横向迁移的形式在地下水位上部聚积。当达到一定厚度后,LNAPL的压头足以克服浮托力,驱替孔隙水进入砂土孔隙。另外,LNAPL的厚度足够大时,方可克服饱水层受到的浮托力,在地下水位上形成LNAPL池,并因孔隙水向周围砂体排泄,LNAPL池周围的水位上升。     

钢渣湿法捕获CO_2反应机制研究

以炼钢过程中排放的固体废弃物钢渣为碳捕获剂,进行了钢渣湿法捕获烟气CO2工艺的实验研究。通过分析钢渣的组成成份及反应机理,研究液固比、反应温度、反应时间、pH值及反应产物等主要参数对钢渣湿法碳捕获状况的影响。实验证明,通过合理的设计和适当的操作,可使钢渣湿法碳捕获效率达60%以上,具有一定的应用价值。