Pd-Ni/GC电极电化学还原水中三氯甲烷的研究

通过电沉积法在玻碳板(GC)电极上负载钯镍双金属,并利用正交实验对其进行循环伏安(CV)研究. CV结果表明,钯镍双金属比钯、镍单金属具有更大的氢吸附峰值,可以在- 500 mV(以Hg/Hg2SO4 为参比电极)左右获得- 24.83 mA的氢吸附峰.扫描电镜分析(SEM)表明,镍的加入改变了钯颗粒在GC表面的分布形态,钯镍双金属颗粒形貌明显不同于钯、镍单金属颗粒,钯镍双金属颗粒粒径介于钯、镍单金属颗粒粒径之间.实验考察了脱氯电流、脱氯时间对三氯甲烷去除率的影响.三氯甲烷的去除率随脱氯电流的增大而增大,随脱氯时间的延长而提高.在优化条件下制备的Pd-Ni/GC电极在0.5 mA、180 min的脱氯条件下对三氯甲烷的去除率为42.53%.可以推测,随着脱氯时间的继续延长,三氯甲烷去除率可得到进一步提高.     

EDTA催化Fe3+/H2O2降解水中孔雀石绿

以孔雀石绿(malachite green, MG)为目标物,在pH=7的中性条件下,考察EDTA对Fe3 /H2O2降解水中孔雀石绿的影响,发现EDTA很大程度地促进了Fe3 /H2O2对孔雀石绿的降解. EDRA的加入可以使MG的脱色率由43%升至98.3%.在本实验条件下, EDTA的投加量增加5倍时, MG的脱色率上升40%.随着H2O2投量的增加, MG的脱色率显著上升.随着温度的升高, MG的脱色率显著上升.叔丁醇的加入抑制了EDTA对Fe3 /H2O2降解孔雀石绿的催化效果.总量相同H2O2的多次投加并未获得明显优于一次投加的去除效果. EDTA催化Fe3 /H2O2降解水中孔雀石绿并不遵循简单的羟基自由基机理,同时存在的中间价态铁的物种起着主要的氧化作用.随着反应的进行, EDTA被部分降解.     

氢气还原海绵铁去除水体中硝酸盐的研究

利用小球烧结和氢气还原工艺制备了粒径1mm～5mm的多孔性球形海绵铁,对球形海绵铁去除水体中硝酸盐的效率及去除动力学进行了研究。结果表明:溶液初始pH值对硝酸盐去除效率的影响显著,初始pH值小于3时,硝酸盐的去除率随溶液初始pH的增加而逐渐降低;初始pH值大于3时,硝酸盐的去除率又随之升高。硝酸盐浓度低于10mgN/L时,硝酸盐去除率随着硝酸盐初始浓度的增加而增加,硝酸盐的残余量保持在0.4mgN/L左右;硝酸盐浓度高于20mgN/L时,硝酸盐的去除率随初始硝酸盐浓度的增加而略有降低。球形海绵铁去除硝酸盐为一级动力学反应,反应级数为0.970～1.378,表观反应速率常数为0.314h-1～0.536h-1。海绵铁还原硝酸盐的主要产物为氨氮,随着还原反应的进行,溶液pH值快速增加,氨氮以分子态氨的形式从水中逸出。进行归纳总结和对比,并以多环芳烃的提取为例列举了各方法的应用步骤,从而为其他环境样品其他有机物分析预处理提供参考。     

河湖疏浚底泥与固废物好氧堆肥研究

研究了不同比例的河湖底泥与固废物混合物在堆肥过程中温度、pH值、含水率、有机质、全氮和碳氮比[ρ(C)∶ρ(N)]等的变化特征.结果表明:含水率保持在60%左右有利于堆肥的腐熟,过高的含水率延长堆肥的腐熟时间;底泥堆肥有机质质量分数不应低于15%;ρ(C)∶ρ(N)保持在25～30:1.添加猪粪和稻壳效果较好,未屑分解较慢,加入尿素等无机氮肥有利于堆肥的腐熟.     

《循环经济促进法》有效实施的思考和建议

颁布实施《循环经济促进法》,是落实党中央提出的实现循环经济较大规模发展战略目标的重要举措。该法实施一年来取得了积极效果,循环经济的理念逐步深入人心,有利于循环经济发展的制度环境初步形成,全国范围内循环经济试点稳步扎实推进,技术、标准、信息化网络等循环经济基本工作得到加强。与此同时,一些深层次问题也开始显现,需要尽早重视和解决。     

氧化处理水中典型酚类污染物研究进展

环境激素是一类能干扰人类和动物正常内分泌的外源性物质,对生物体的生理过程产生很大的危害。本文介绍了水处理中,典型酚类污染物氧化剂降解技术的机理、特点、应用以及局限性,主要介绍了Fenton试剂、O3、二氧化氯等氧化剂及高铁酸钾新型氧化剂在酚类废水处理中的应用。并指出了复合氧化剂、新型氧化剂与其他水处理技术的联合应用将是酚类废水氧化处理的发展方向。     

混凝法深度处理焦化废水的研究

针对焦化厂二级生化出水CODcr、色度不达标问题,研究采用PAC和PFS对焦化厂二级生化出水进行深度处理研究。研究确定了各混凝剂的最佳投药量和最适pH值,对比了各混凝剂在最佳混凝条件下的处理效果,以及在最佳投药量条件下最佳pH值。结果表明：PAC最佳投药量为6g/L,PFS最佳投药量为5.5g/L;在最佳投药量的条件下,对CODcr去除较好的是PAC,去除率为44.83%;对色度去除率两者相同,都为80%;二者最佳pH值均为7。     

大气环境质量现状评价模型存在的问题及改进——以沈阳大气指数模型为例

文章分析了几类大气环境质量现状评价模型各自存在的问题,针对这些问题,选择了较典型的沈阳大气指数模型,首先对原模型中参数进行修正,使其成为与当前执行的环境空气质量标准相对应的综合指数模型,其次,基于概率统计思想对模型进行改进,得到不同保证率下的大气环境质量现状评价模型,最后,运用SPSS软件进行实证分析,改进后模型得到的评价结果更能准确反映区域实际大气环境质量现状。     

Isolation and characteristics of a novel biphenyl-degrading bacterial strain, Dyella ginsengisoli LA-4

A novel biphenyl-degrading bacterial strain LA-4 was isolated from activated sludge. It was identified as Dyella ginsengisoli according to phylogenetic similarity of 16S rRNA gene sequence. This isolate could utilize biphenyl as sole source of carbon and energy, which degraded over 95 mg/L biphenyl within 36 h. The major metabolites formed from biphenyl, such as 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) and benzoic acid, were identified by LC-MS. The crude cell extract of strain LA-4 exhibited the activity of 2,3-dihydroxybiphenyl 1,2-dioxygenase (2,3-DHBD) and the kinetic parameters were Km= 26.48 μmol/L and Vmax= 8.12 μmol/mg protein. A conserved region of the biphenyl dioxygenase gene bphA1 of strain LA-4 was amplified by PCR and confirmed by DNA sequencing.     

Induction of chemotaxis to sodium chloride and diacetyl and thermotaxis defects by microcystin-LR exposure in nematode Caenorhabditis elegans

Apart from the liver disruption, embryotoxicity and genotoxicity, microcystin (MC)-LR also could cause neurotoxicity. Nematode Caenorhabditis elegans was explored as a model to study the neurotoxicity. In the present study, we provided evidence to indicate the neurotoxicity on chemotaxis to NaCl and diacetyl, and thermotaxis from MC-LR exposure to C. elegans. As a result, higher concentrations of MC-LR caused significantly severe defects of chemotaxis to NaC1 and diacetyl, and thermotaxis. The neurotoxicity on chemotaxis to NaCl and diacetyl, and thennotaxis from MC-LR exposure might be largely mediated by the damage on the corresponding sensory neurons (ASE, AWA, and AFD) and interneuron AIY. The expression levels of che-1 and odr-7 were significantly decreased (P<0.01) in animals exposed to MC-LR at concentrations lower than 10 μg/L, whereas the expression levels of ttx-1 and ttx-3 could be significantly (P<0.01) lowered in animals even exposed to 1 μg/L of MC-LR. Moreover, both the chemotaxis to NaCl and diacetyl and the thermotaxis were more significantly reduced m MC-LR exposed mutants of che-1(p674), odr-7(ky4), ttx-1(p767), and ttx-3(ks5) than those in exposed wild-type N2 animals at the same concentrations.