淀粉聚乙烯膜在受控条件下的好氧生物降解

采用土埋、真菌生长和 CO₂ 释放试验分别测定了几种淀粉聚乙烯膜的生物降解性 .试验结果表明 ,膜的生物降解性与膜中的淀粉含量正相关 ,并受膜比面积大小的影响 .在受控条件下 ,含淀粉 6%～ 30 %的膜经 28d降解后 ,降解质量变化率在0.6%～ 12.4%范围内 ,其 CO₂ 释放量为 0.02～ 0.15mg/mg膜 .膜中的聚乙烯组分不仅本身难被生物降解 ,而且还抑制微生物对其淀粉组分的降解 .CO₂ 是淀粉聚乙烯膜好氧生物降解的终产物 ,可以作为评估膜生物降解性的一个可靠指标 .     

Removal of phenol by activated alumina bed in pulsed high-voltage electric field

A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe^2＋. The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/L Fe^2＋ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation.     

Role of Hydrophilic and Hydrophobic Interactions in Structure Development of Zein Films

Zein has been studied for its potential as a biobased polymeric material. Due to the fact that films made exclusively from zein are brittle, composites of zein and oleic acid were prepared in our lab and formed into flexible films. Film properties were believed related to their structure. X-ray scattering measurements on zein films suggested the formation of layers along the plane of the film. Oleic acid seemed to play an important role in layer formation. However, X-ray measurements could not yield information on the nature of the interface between oleic acid and zein. Surface plasmon resonance (SPR) was used to further investigate interaction between zein and oleic acid. Dynamic adsorption of zein from alcoholic solutions onto hydrophilic and hydrophobic surfaces generated by self-assembled monolayers of 11-mercaptoundecanoic acid or 1-octanethiol was monitored by SPR. It was observed that zein had a greater affinity for hydrophilic than for hydrophobic surfaces under the prevalent experimental conditions. A mechanism for structure development of zein-oleate films was proposed based on these results and previous X-ray measurements. It is suggested that the structure development involves hydrophilic adsorption of fatty acids onto the zein surface followed by hydrophobic associations leading to a layered film structure organization.     

A spectrophotometric method for detection of enzymatic degradation of thin polymer films

An assay method has been developed for monitoring the enzymatic degradation of thin films of translucent polymers. The method was based on the observation that when a solution-cast film of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was exposed to a solution of a depolymerase fromPseudomonas lemoignei, the surface of the film roughened and the film became visibly turbid. This increase in turbidity could be measured spectrophotometrically and was reproducible during the initial stage of degradation. Turbidity correlated very closely with film weight loss early in the degradation but reached a maximum value before extensive degradation had taken place. For a given set of films, this correlation was independent of the concentration of the enzyme used, although it did vary with the mode of enzyme exposure. The turbidity was associated with the exposure of crystalline domains due to the removal of amorphous material from the film surface. The increase in crystallinity at the surface was verified by attenuated total reflectance infrared spectroscopy (ATRIR). In conjunction with SEM, weight loss, and ATRIR, the film turbidity assay provided much semiquantitative insight into the mechanism of the enzymatic degradation reaction. This assay was used to study the enzymatic degradation of films of PHBV solution blended with cellulose acetate esters (CAE). The presence of only 25% of CAE of degree of substitution 2.9 severely hampered the enzymatic degradability of PHBV, a result which is consistent with the environmental degradation of these same samples exposed to activated sludge.     

黑臭河流沉积物磷、铁、硫的DGT同步分析研究

沉积物中磷(P)、铁(Fe)、硫(S)之间存在密切的耦合关系,但大部分研究并未提供直接的原位证据,需要借助高分辨的获取技术才能表征.为了探索三者之间的耦合关系,本文利用Zr O-Ag I DGT和Chelex DGT对东莞市黑臭河流沉积物中有效态P、Fe、S进行了高分辨分析.结果表明:应用DGT技术能够获得黑臭河流沉积物中有效态P、Fe、S的高分辨率浓度分布,并且实验结果可靠,有效地避免了主动采样方法和沉积物空间异质性对P、Fe、S同步分析的影响.各采样点沉积物中有效态P、S在垂向上的空间分布趋势基本相似,部分采样点出现有效态P、Fe、S同步变化的现象,同步获得的微界面浓度分布较好地反映了三者的耦合关系.对P、Fe、S在水-沉积物界面附近的含量分布进行相关性分析,结果表明三者之间具有显著正相关(p0.05),进一步证实了黑臭河流沉积物中也存在P、Fe、S同步释放的现象.大部分样点沉积物-水界面有效态P、Fe、S的扩散通量为正值,表现为由沉积物向上覆水释放P、Fe、S.沉积物中P、Fe、S的耦合释放表明其对黑臭的形成和内源磷释放至关重要.     

Distribution, risk and bioavailability of metals in sediments of Lake Yamdrok Basin on the Tibetan Plateau, China

Total contents of metals in soil and sediments on the Tibetan Plateau of China have been widely analyzed, but existing information is insufficient to effectively evaluate metal ecological risk because of a lack of metal bioavailability data. In this study, distribution, potential risk, mobility and bioavailability of metals in sediments of Lake Yamdrok Basin in Tibet of China were explored by combined use of total digestion, sequential extraction and the diffusive gradient in thin-films (DGT). Average concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb in surface sediments were 31.25, 30.31, 22.00, 45.04, 31.32, 0.13 and 13.39 mg/kg, respectively. Higher levels of metals were found near the inflowing rivers. Residual form was dominant in Cr, Ni, Zn, Cd and Pb, and reducible form was dominant in As and Cd. Metals in surface sediments showed a low enrichment degree overall, but Cd and As had higher ecological risk levels than the other metals. Furthermore, there was a larger average proportion of exchangeable form of As (20.4%) and Cd (9.0%) than the other metals (1.7%-3.3%), implying their higher mobility and release risk. Average DGT-labile concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb were 0.5, 4.5, 0.7, 25.1, 60.0, 0.22 and 1.0 µg/L, respectively. The DGT-labile As was significantly correlated with extractable As forms (p< 0.01), suggesting that extractable As in sediments acts as a “mobile pool” for bioavailable As. These results suggest potential risks of As and Cd, especially As, deserve further attention in Lake Yamdrok Basin.     

光催化氧化法降解有机磷农药的研究

本研究采用负载型TiO2膜作为催化剂降解有机磷农药敌敌畏，探讨了光催化反应时间、溶液的初始浓度对敌敌畏降解率的影响。试验表明，不同初始浓度的敌敌畏在经过90minUV／TiO2处理后，降解率都能达到90％以上，而且降解率随光照时间的增长而增加，随初始浓度的增加而降低。本研究采用毛细管柱气相色谱检测敌敌畏的剩余浓度，检出效果较好，并通过色谱图探讨敌敌畏的降解过程。     

炼油污水的深度处理

论述了炼油污水深度处理的常用技术--过滤、膜分离及化学氧化技术,对炼油污水深度处理进行了中试试验,并结合试验结果对动态砂滤系统、PAN膜处理系统和高级氧化系统处理炼油厂二级排放水的适用性进行了论证。结果表明,二级排放水经动态砂滤系统和NF纳滤系统处理后,COD、氨氮、SS、硫化物、酚、浊度、总铁等指标均达到循环水补水水质要求,可以回用于循环水场;经PAN膜制成的UF超滤和RO反渗透系统处理后,各种污染物指标和盐类指标都降至微量,且脱盐效果明显。     

水膜除尘装置的技术改造

针对水膜除尘器在实际应用中存在的除尘效率低，风机带水，系统阻力大等问题，在分析原因的基础上，对文丘里洗涤器、除尘器等进行了技术改造。实践证明，改造后除尘器的除尘效率达到95％，烟尘质量浓度为72－93mg/m^3，低于国家排放标准。     

旋流板捕捉麻石水膜烟气除尘脱硫装置的研制与运行

针对常规麻石水膜除尘器分离性能差,烟气净化达不到排放标准且带水严重、引起引风机振动等问题,研制了旋流板捕捉麻石水膜烟气除尘脱硫装置.该装置在常规麻石水膜除尘器的基础上,在主塔内增设2～3层旋流板以强化气流的旋转运动,提高除尘和脱硫效率.本文介绍了该装置的试验研究情况,研究了除尘效率与进口速度、含尘浓度、粉尘粒径的关系;脱硫效率与进口流速、循环水pH值的关系和装置的阻力与进口速度、进口含尘浓度的关系,并通过其实际运行结果证明,该装置除尘效率为98.23%～98.50%,脱硫效率达70%以上.