TiO_2膜光催化降解4,4’-二溴联苯的研究

研究了负载于玻璃上的同定化催化剂TiO2膜光催化降解水中4,4'-二溴联苯(4,4'-DBB)的效果,考察了溶液pH值和4,4'-DBB初始浓度等对TiO2膜光催化降解4,4'-DBB的影响,探讨了降解机理.结果表明.TiO2膜光催化降解水中4,4'-DBB的效果良好,紫外光照射8 b,初始浓度为4 mg/L的4,4'-DBB的降解率高达94%,降解速率随着4,4'-DBB初始浓度的增大而下降.在溶液pH=1时,4,4'-DBB的降解效率最高.超声的加入使降解反应的速率加快.经拟合发现4,4'-DBB的降解符合拟一级反应规律,并推导出动力学方程.     

薄膜负载型TiO_2光催化降解乙酸

利用TiCl_4水解法在玻璃表面制备纳米TiO_2光催化膜,考察了TiO_2光催化膜对乙酸光催化降解过程的影响因素.实验结果表明:使用活化温度为460℃、镀膜4次、表面积168 cm~2的TiO_2光催化膜处理500 mL0.667 mmoL/L的乙酸350 min时,乙酸降解率为80.0%,与等量TiO_2粉末相比光催化膜活性显著增加;当乙酸初始浓度c_0小于0.667 mmoL/L时,光催化降解过程可用Langmuir-Hinshelwood动力学方程来描述;TiO_2膜连续使用5次(30 h)时的光催化活性基本不变;用质量分数为5%的HCl溶液浸泡失去活性的光催化膜1 h,TiO_2光催化膜的活性可完全恢复.     

Formation of recycled plastics from depolymerized monomers derived from waste fiber-reinforced plastics

To develop a new method for the chemical recycling of plastics, we examined the formation of recycled polymers from the recovered monomeric materials of solubilized waste fiber-reinforced plastics (FRP) under supercritical alcoholic conditions. Treatment of waste FRP with supercritical MeOH resulted in the formation of monomeric organic compounds that mainly contained dimethyl phthalate (DMP) and propylene glycol. The presence of these materials was confirmed by gas chromatography and nuclear magnetic resonance analyses and they were mixed with new DMP and glycols in various ratios to form unsaturated polyesters. The polymerization progressed successfully for all mixing ratios of the recovered and new DMP. Hardness tests on these recycled polymers indicated that the polymer made from a 1:1 mixture of recovered and new dimethyl phthalate had almost the same level of hardness as the polymers made from new materials. We also examined the formation of recycled FRP by using glass fibers and monomeric materials recovered through the present depolymerization method. Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6     

Wood Modification Effects on Weathering of HDPE-Based Wood Plastic Composites

The effects of weathering on the constituents of wood and polymer matrix behavior in wood plastic composites (WPCs) were investigated. WPCs were produced from pine, extractives-free pine, and pine holocellulose fibers (60%) together with HDPE (40%). These composites were subjected to xenon-arc accelerated and outside weathering for a total of 1200 h and 120 days, respectively. The color and chemical changes that occurred on the surface of the WPCs were analyzed using a set of analytical techniques. For pine and extractive-free pine filled composites, the results showed that the total color change, lightness, and oxidation increased, while the lignin content decreased. In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of extracted HDPE decreased with an increase in exposure time of the composites. However, HDPE crystallinity increased with longer exposure time. Lightness of holocellulose-based WPC changed the least while the change in its HDPE crystallinity was not significant compared to the other composite types. Therefore, holocellulose-based WPC may be preferred for applications where color stability is of high priority.     

A stochastic weather generation model for Alaska

A specific problem encountered in ecosystem-level simulation of Arctic ecosystems is the depth and extent of the driving variable record. Often, climate records are of short duration, gathered at locations different from the area to be simulated, or do not contain all the variables required by a given model. This paper addresses this problem for ecosystem simulation in Alaska with the development of a weather generator. The generator, called WGENAL, is based on the WGEN climate generator developed and validated in the 48 conterminous states. Because of the extreme variability of weather in Alaska that is not accommodated by the statistical metrics in the earlier model, a new climate generator was developed. WGENAL generates daily values of precipitation, maximum temperature, minimum temperature, solar radiation, and wind run. Precipitation is generated using a Markov chain-gamma model. A two-parameter gamma distribution is used to generate wind run. Temperatures and solar radiation are generated using procedures developed in the earlier study. Validation of the generator shows it provides adequate diurnal and seasonal weather records for Fairbanks. Other comparisons of synthetic weather with observed weather for sites north of the Brooks Range in Alaska are also within the error of the original data.     

碳纤维在钢筋混凝土梁抗弯加固设计中的应用

近年来,在钢筋混凝土结构改造加固工程中,碳纤维材料在加固设计中应用发展迅速.通过工程实例,介绍了碳纤维材料加固技术中提高钢筋混凝土梁抗弯承载力的计算方法和施工工艺.     

溶胶凝胶法制备磷钨酸掺杂TiO2薄膜及其光催化性能

以钛酸四丁酯为前驱物,采用溶胶凝胶法制备了磷钨酸掺杂的二氧化钛薄膜。通过XRD、FT-TR对该薄膜进行了表征,研究了薄膜在对氯苯酚光降解中的催化活性。结果表明,当磷钨酸与二氧化钛摩尔比为0.01∶1、薄膜烧结温度600℃、对氯苯酚溶液浓度30 mg/L（pH＝5）、光催化8 h的条件下,对氯苯酚的降解率超过90%,且薄膜可以重复使用。磷钨酸对二氧化钛的光催化活性具有明显的促进作用。     

高陡岩质边坡抗震稳定性的三维有限元分析

岩质边坡在地震作用下稳定性的计算一般采用拟静力法和有限单元法,拟静力法因应用简便而得到大量应用,至今广泛应用于边坡的抗震计算。建立了某溢洪道引渠左侧整体边坡三维有限元模型,选用ADINA软件并采用拟静力法对三维模型进行了抗震稳定性计算和分析,结合有限元分析的结果,提出溢洪道引渠左侧整体边坡抗震措施和建议。