Enhanced degradation of organic wastewater containing p-nitrophenol by a novel wet electrocatalytic oxidation process: Parameter optimization and degradation mechanism

This paper explored a novel advanced oxidation process (AOP) for wastewater treatment—wet electrocatalytic oxidation (WEO), which introduced a small current into wet air oxidation (WAO) to promote the formation of hydroxyl radical and accelerate the oxidation of organic pollutants. The results showed that this novel process could couple the advantages of both WAO and electrochemical oxidation (EO). The effects of major operational factors of WEO were studied at relatively moderate condition (T = 100–160 °C, C = 1000 mg L⁻¹, P_O2 = 4 TOD, P_N2 = 0.50 MPa, current density = 0–7.08 mA cm⁻² and pH 2.7–10.6) aiming to p-nitrophenol (PNP) degradation, TOC and COD removal. The cost-effective operational parameters were found and the current efficiencies were highly beyond 100% with the maximum value of 386%. The degradation mechanism of WEO was carefully studied based on the formation of free radical. After the detail analysis of Hammett theory and quantitative structure-activity relationships (QSAR), the reaction pathway of hydroxyl radical with PNP was analyzed with the help of Gaussian 03W and the probable degradation pathway of PNP by WEO was deduced.     

Kinetic Studies on Oxirane Cleavage of Epoxidized Soybean Oil by Methanol and Characterization of Polyols

The kinetics of the oxirane cleavage of epoxidized soybean oil (ESO) by methanol (Me) without a catalyst was studied at 50, 60, 65, 70 °C. The rate of oxirane ring opening is given by k[Ep][Me]², where [Ep] and [Me] are the concentrations of oxiranes in ESO and methanol, respectively and k is a rate constant. From the temperature dependence of the kinetics thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), free energy of activation (ΔF) and activation energy (ΔE _a) were found to be 76.08 (±1.06) kJ mol⁻¹, −118.42 (±3.12) J mol⁻¹ k⁻¹, 111.39 (±2.86) kJ mol⁻¹, and 78.56 (±1.63) kJ mol⁻¹, respectively. The methoxylated polyols formed from the oxirane cleavage reaction , were liquid at room temperature and had three low temperature melting peaks. The results of chemical analysis via titration for residual oxiranes in the reaction system showed good agreement with IR spectroscopy especially the disappearance of epoxy groups at 825, 843 cm⁻¹ and the emergence of hydroxy groups at the OH characteristic absorption peak from 3,100 to 3,800 cm⁻¹.     

A comparative investigation on the properties of Cr-SBA-15 and CrOx/SBA-15

High-surface area and well-ordered mesoporous Cr-incorporated SBA-15 (Cr-SBA-15) and SBA-15-supported chromia (CrO_x/SBA-15) with Cr surface density = 0.05–1.11 Cr-atom/nm² have been prepared, respectively, using the one-step synthesis and incipient wetness impregnation method, and characterized by AAS, XRD, BET, ESEM, TEM, XPS, laser Raman, UV-Vis, FT-IR, and H₂-TPR. It is observed that the Cr-SBA-15 and CrO_x/SBA-15 samples showed an evolution of surface morphology from long chain-shaped to short rod-like and further to an irregularly spherical architecture at elevated Cr content, which might arise from the interaction of Cr ions or CrO_x domains with SBA-15. There were co-presence of tetrahedrally coordinated mono- and poly-chromate (Cr⁶⁺) as well as octahedrally coordinated Cr³⁺ species in Cr-SBA-15 and CrO_x/SBA-15, with the Cr⁶⁺ species being dominant at Cr surface density ≤0.22 Cr-atom/nm² in Cr-SBA-15 and Cr ≤0.54 Cr-atom/nm² in CrO_x/SBA-15, whereas the amount of the Cr³⁺ species increased markedly at Cr surface density ≥0.53 Cr-atom/nm² due to the formation of crystal Cr₂O₃ phase. Maximal Cr incorporation into Cr-SBA-15 and one monolayer surface CrO_x coverage on CrO_x/SBA-15 occurred at Cr surface density ≤0.53 Cr-atom/nm² and <1.11 Cr-atom/nm², respectively. The CrO_x/SBA-15 samples exhibited better reducibility than the Cr-SBA-15 samples, with the best reducibility exhibited at Cr surface densities of 0.54 and 0.12 Cr-atom/nm², respectively.     

高相对分子质量聚丙烯弹性体合成催化体系的研究

采用环戊二烯基三叔丁基苯酚基钛［(CptBu3PhO)TiCl2］与硼助剂［Ph3CB(C6F5)4］组成新的催化剂体系进行丙烯的聚合。研究了影响聚合活性及产物相对分子质量的各种因素。结果表明,环戊二烯基钛化合物取代基的不同可使聚合产物的相对分子质量有很大的变化,所得的聚丙烯为无规弹性聚丙烯,具有较高的相对分子质量（Mw＝8×104～40×104）。     

生物处理工艺处理工业废水

针对"油封"造成的膜堵塞问题,采取了一些特殊的技术措施,对冷轧废水处理工艺进行了改进,从而稳定了膜生物反应器的膜通量,提高了生化处理工艺的处理效率,收到了较好的社会效益和经济效益.     

2007年我国热塑性工程塑料进展

根据2007年国内公开发表的文献,综述了我国热塑性工程塑料的研究进展,着重介绍了(丙烯腈/丁二烯/苯乙烯)共聚物、聚酰胺、聚碳酸酯、饱和聚酯、改性聚苯醚等通用热塑性工程塑料的高性能化,聚苯硫醚、聚醚酮类、聚四氟乙烯等特种工程塑料的实用化,以及聚乙烯、聚丙烯、聚氯乙烯、聚苯乙烯等通用塑料的工程化研究进展,展望了今后热塑性工程塑料的发展趋势。     

粉末熔化工艺制备YBCO先驱粉末的相转变

采用粉末熔化工艺(PMP)制备YBa2Cu3O7-x先驱粉末.研究了在加热过程中加热速率和保温时间对其相成分的影响,并对粉末的显微结构进行了分析.通过高温X射线衍射仪原位研究了400°C/h和6000°C/h的加热速率对先驱粉末加热到包晶分解温度过程中的相变化过程.结果表明:加热速率为400°C/h时,先驱粉末会形成YBa2Cu3O7-x相;加熟速率为6000°C/h时,则不会有YBa2Cu3O7-x相生成.通过研究不同保温时间对粉末熔化工艺先驱粉末的影响,得出YBa2Cu3O7-x相的形成区间,其结果有助于控制粉末熔化工艺的参数和理解工艺的本质.     

热处理工艺对中碳合金钢冲击磨料磨损耐磨性的影响

研究淬火加热温度和回火温度对中碳合金钢６０ＳｉＭｎＣｒＭｏＶＲＥ冲击磨料磨损耐磨性的影响。试验结果表明,耐磨性随淬火加热温度升高而提高,９５０℃淬火后可获得最高的耐磨性,超过９５０℃淬火,耐磨性随淬火温度升高而降低。淬火回火后的耐磨性在３５０℃以下随回火温度升高略有降低,３５０℃以上回火耐磨性迅速提高,４００℃回火后耐磨性达到最大值,以后,随回火温度升高,耐磨性连续降低     

铝硅基复合材料中硅相形貌研究

在金相显微镜和扫描电子显微镜上观察和研究了氧化铝／铝硅合金复合材料中的硅相形貌。结果表明氧化铝纤维与硅相之间存在共格界面,可作为硅相非自发形核的衬底;复合材料中的初生硅可在纤维表面形核生长为颗粒状;复合材料中的纤维在铝硅共晶体的共生生长过程中,可触发孪晶,导致纤维附近的共晶硅呈变质形态。     

A model for biomass screw feeding

Successful feeding is critical to biomass utilization processes, but trouble-free delivery is difficult due to particle heterogeneity, physical characteristics and moisture content. A model, extended from previous models in the literature, is proposed to delineate what limits screw feeding in terms of the mechanisms of blockage and to predict torque requirements for biomass materials. Predictions on feeding of wood pellets, sawdust, hog fuel and wood shavings in a screw feeder/lock hopper system are in good agreement with our earlier experimental findings. The choke section and seal plug are shown to play important roles in determining the torque requirements for biomass screw feeding, although they are rarely mentioned in previous research on screw feeding of other materials.