纳米铁协同超声降解氯苯的研究

报道了纳米铁协同超声波降解一氯代苯 (CB)的研究。探讨了有效声强、pH、CB初始浓度对降解效果的影响。比较了纳米铁协同超声波和单纯超声波对CB的降解效果和降解速率 ,反应 2 0min时 ,纳米铁协同超声波的降解率达到95 % ,而单纯超声波的降解率仅为 1 0 8%。上述两者都符合准一级反应动力学 ,超声波降解CB的准一级速率动力学常数k=6× 1 0 -3 min-1 ,而协同作用降解CB的准一级动力学常数k =1 6 3× 1 0 -1 min-1 ,提高了 2 7倍。     

4,5-二甲基-2-噻唑偶氮重氮氨基偶氮苯固相萃取光度法测定环境样品中锌的研究

研究了新试剂4,5-二甲基-2-噻唑偶氮重氮氨基偶氮苯(DMTDAA)与锌的显色反应,在pH=10的硼砂—氢氧化钠缓冲介质中,TritonX-100存在下,DMTDAA与锌反应生成2∶1稳定络合物,体系最大吸收波长λmax=530nm,摩尔吸光系数ε=1.12×105L.mol-1.cm-1,样品中的锌用强阴离子交换固相萃取柱固相萃取预分离和富集后用该方法测定,结果令人满意。     

低浓度苯系物在室温下的MnOx/Al2O3催化O3氧化

采用固定床连续流动反应器,研究在室温下MnOx/Al2O3催化剂催化臭氧(O3)氧化.结果表明,在室温下,MnOx/Al2O3催化剂具有良好的催化O3分解和催化臭氧氧化苯系物的性能,Mn的最佳负载量为5%.当入口O3和苯系物浓度分别为70,15 mg/m3时,苯、甲苯、对二甲苯和O3的转化率分别为75%,84%,88%,90%.随着入口O3浓度的升高,苯系物转化率先升高然后基本不变,而O3转化率略有下降;随着入口苯系物浓度的升高,苯系物转化率明显降低,O3转化率略有下降.苯系物及O3转化率皆随催化反应时间的延长而缓慢降低.苯系物催化氧化反应中生成的芳香醛、芳香酸和甲酸等中间产物在催化剂表面的堆积是导致催化剂活性降低的主要原因.     

北京市大气中BTEX工作日与非工作日的浓度变化

对2006年北京市大气中苯系物(BTEX)在工作日和非工作日的浓度变化进行研究.结果表明,BTEX在非工作日的平均浓度比工作日低4.8%,其中"五一"和"十一"假期BTEX的浓度分别为54%和13.2%.BTEX在非工作日浓度降低的主要原因是因为非工作日机动车使用量的减少.在工作日BTEX浓度峰值与上下班交通高峰有关,而在非工作日浓度从下午到夜间维持在一个较高浓度.BTEX各物质之间的比值在工作日和非工作日差别不大,但是各物质之间在非工作日的相关性比工作日好.苯和甲苯在工作日和非工作日都具有较好的相关性,乙苯和二甲苯之间在非工作日的相关性比工作日高.     

煤矸石堆放场周围玉米作物中苯并(a)芘污染特征

以焦作矿区演马矿煤矸石堆放场周围农田玉米为研究对象,对玉米中苯并(a)芘污染特征进行了分析研究.在矸石堆周围布设三条采样线采集玉米样品,玉米样品经提取、浓缩、净化处理后采用高效液相色谱(HPLc)法对其中苯并(a)芘含量进行检测分析.结果表明,研究区玉米作物叶子中苯并(a)芘污染水平较高,达46.7%,茎和籽均未出现苯并(a)芘污染现象,且玉米各部位苯并(a)芘含量与距矸石堆距离呈反比.进一步指出矿区企业应加强对周围环境生态的预防保护,以确保企业的可持续发展.     

苯并[a]芘和二苯并[a,h]蒽的土壤降解特性及其影响因素

实验室条件下,研究了不同土壤性质、水分含量、通气条件、外加营养元素比例与外源微生物等条件下,苯并[a]芘(BaP)和二苯并[a,h]蒽(DBA)在土壤中的降解特性.结果表明,当土壤中BaP和DBA的添加水平分别为2.5 mg·kg-1时,至125 d时,BaP在pH较低的江西红壤中降解最快,降解率达87.3%;而DBA在有机质含量较高的中性太湖水稻土中降解较快,降解率为52.0%.土著微生物对BaP和DBA在土壤中的降解起重要作用;合适的土壤C/N比值能明显加快降解速率;好气条件有利于BaP和DBA的降解.     

用醌式染料的合成反应光度法测定水中NO_2~-

报道了以N、N－二甲基苯氨、对氨基苯乙酮为偶联、重氮试剂,利用醌式染料的合成反应测定NO2-的新方法。本法灵敏度高（ε=5．33×104）,选择性好,无试剂空白。NO2-在0～800μg／L内服从比耳定律。醌式染料及试剂均稳定,已用于环境水中NO2-的测定。     

Holographic quantitative structure-activity relationship for prediction acute toxicity of benzene derivatives to the guppy (Poecilia reticulata)

Holographic quantitative structure-activity relationship(HQSAR) is an emerging QSAR technique with the combined application of molecular hologram, which encoded the frequency of occurrence of various molecular fragment types, and the subsequent partial least squares(PLS) regression analysis. In this paper, the acute toxicity data to the guppy( poecilia reticulata) for a series of 56 substituted benzenes, phenols, aromatic amines and nitro-aromatics were subjected and this resulted in a model with a high predictive ability. The influence of fragment size and fragment distinction parameters on the quality of HQSAR model was investigated. The robustness and predictive ability of the model were also validated by leave-one-out (LOO) cross-validation procedure and external testing data set.     

ORC-GAC-Fe0 system for the remediation of trichloroethylene and monochlorobenzene contaminated aquifer: 1. Adsorption and degradation

Activities at a former Chemistry Triangle in Bitterfeld, Germany, resulted in contamination of groundwater with a mixture of tdchloroethylene(TCE) and monochlorobenzene(MCB). The objective of this study was to develop a barrier system,which includes an ORC(oxygen release compounds) and GAC(granular activated carbon) layer for adsorption of MCB and bioregeneration of GAC, a Fe^0 layer for chemical reductive dechlorination of TCE and other chlorinated hydrocarbon in situ. A laboratory-scale column experiment was conducted to evaluate the feasibility of this proposed system. This experiment was performed using a series of continuous flow Teflon columns including an ORC column, a GAC column, and a Fe^0 column. Simulated MCB and TCE contaminated groundwater was pumped upflow into this system at a flow rate of 1.1 ml/min. Results showed that 17%-50% of TCE and 28%-50% of MCB were dissipated in ORC column. Chloride ion, however, was not released, which suggest the dechlorination do not happen in ORC column. In GAC column, the adsorption of contaminants on activated carbon and their induced degradation by adapted microorganisms attached to the carbon surface were observed. Due to competitive exchange processes, TCE can be desorbed by MCB in GAC column and further degraded in iron column. The completely dechlorination rate of TCE was 0.16-0.18 cm^-1, 1-4 magnitudes more than the formation rate of three dichloroethene isomers. Cis-DCE is the main chlorinated product, which can be cumulated in the system, not only depending on the formation rate and its decaying rate, but also the initial concentration of TCE.     

Effect of linear alkyl benzene sulfonates (LAS) on the fate of phenanthrene in a model ecosystem (water-lava-plant-air)

Advanced closed chamber system was used to study the fate of phenanthrene (3-rings PAHs) in the presence of linear alkylbenzene sulphonates (LAS). The results showed mineralization and metabolism of phenanthrene are fast in the “culture solution-lava-plant-air“ model ecological system. The distribution proportions of applied ^14C-activity in this simulative ecological system were 41%-45%, 14% to 10% and 1% in plant, lava and culture solution respectively, and 18% to 29%, 11% to 8% recovered in the forms of VOCs and CO2. Main parts of the applied ^14C-activity exist in two forms, one is polar metabolites(25%) which mainly distribute in the root(23%),the other is unextractable part (23%) which have been constructed into plant root (8.98%), shoot (0.53%) or bonded to lava(13.2%). The main metabolites of phenanthrene were polar compounels (25% of applied ^14C-activity), and small portion of ^14C-activity was identified as non-polar metabolites(6% of applied ^14C-activity) and apparent phenanthrene(1.91% of applied ^14C-activity). Phenanthrene and its metabolites can be taken up through plant roots and translocated to plant shoots. The presence of LAS significantly increased the the concentration of ^14C-activity in the plant and production of VOCs, at the same time it decreased the phenanthrene level in the plant and the production of CO2 at the concentration of 200 mg/L.