Photocatalytic degradation of methyl orange over ITO/CdS/ZnO interface composite films

ITO/CdS/ZnO interface composite films were successfully prepared by subsequent electrodeposition of CdS and ZnO onto indium tin oxide (ITO) glass substrates. The obtained ITO/CdS/ZnO composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photocatalytic activity of ITO/CdS/ZnO composite films were investigated using methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including initial concentration of MO, pH value of solution, and inorganic anion species over the composite films were examined. A blue shift of absorption threshold was observed for the ITO/CdS/ZnO film in comparison with ITO/ZnO film. ITO/CdS/ZnO composite films prepared under specific conditions showed a higher photocatalytic activity than that of ITO/ZnO films. It was also found that the photocatalytic degradation of MO on the composite filing followed pseudo-first order kinetics.     

加氢站用45 MPa高压储氢瓶式容器火烧试验模拟*

为研究加氢站用高压储氢容器在火灾下的安全性能,采用计算流体力学（CFD）方法对45 MPa高压储氢瓶式容器火烧试验过程进行模拟研究,结合气瓶火烧试验,分析高压储氢容器火灾下的热响应过程,研究不同因素对储氢容器压力泄放装置动作时间的影响。结果表明:613 s以内试验压力与模拟数据的最大相对误差为3.9%,模型误差在可接受范围;不同充装介质对安全泄放装置动作时间影响不大;不同充装压力对容器内介质压升速率影响较大,充装水平较高时压力泄放装置更快动作,较低的充装压力下容器内介质温升较快;不同环境温度对介质温升影响较小。     

反硝化脱硫微生物燃料电池的可行性研究

微生物燃料电池(microbial fuel cell,MFC)可在去除废水中污染物的同时回收电能.以S2-和NO-3-N分别作为阳极电子供体和阴极电子受体,研究了反硝化脱硫MFC的同步阳极除硫与阴极脱氮,分析了阳极进水S2-浓度对MFC产电性能及污染物去除情况的影响,探究了MFC阳极石墨纤维丝上的硫沉积情况及其对内阻的影响.结果表明,反硝化脱硫MFC在32 d内实现稳定的阳极除硫与阴极脱氮.外阻为100Ω时,电压稳定在(176.0±6.9)m V,相应的S2-和NO-3-N去除负荷分别为(0.94±0.04)kg·m-3NC·d-1和(11.1±0.6)g·m-3NC·d-1.MFC的产电能力随着阳极进水S2-浓度的增加逐渐增强,SO_2-4的生成率和NO-3-N去除负荷受S2-浓度影响较小.在试验S2-浓度下S2-的去除较彻底,SO_2-4的生成率均超过65%.NO-3-N去除负荷维持在12 g·m-3NC·d-1左右,出水NO-2-N浓度均低于0.01 mg·L-1.反硝化过程较完全.在运行过程中,MFC阳极的石墨纤维丝上会沉积颗粒硫,降低电极的有效面积,使MFC的内阻升高.     

芦苇酶解对氢气-甲烷联产过程微生物群落演替规律的影响

采用10 mg/g纤维素酶R-10预处理芦苇秸秆,研究了酶解预处理对芦苇厌氧产气潜力的影响,分析了氢气-甲烷联产过程中微生物群落结构演替规律. 结果表明:酶解预处理后,芦苇秸秆在产氢阶段的累积产气量和φ(H₂)分别达到42.5 mL/g和52.1%;在产甲烷阶段,累积产气量稳定上升,最高值可达137.5 mL/g,是对照组产气量的5倍. 由扫描电镜(SEM)观察可知,产氢阶段以短杆状和梭状菌为主,产甲烷阶段以长杆菌为主. PCR-DGGE(聚合酶链式反应-变性梯度凝胶电泳)分析表明,芦苇在酶解预处理后,其厌氧联产过程中微生物群落呈规律性演替,产氢阶段的优势微生物分别为具有降解纤维素产氢气功能的嗜热纤维素菌Clostridium thermocellum(条带B20)、具有高效产氢潜力的兼性厌氧产气肠杆菌Enterobacter aerogenes(条带B28);在产甲烷阶段,其优势微生物为可利用氢营养途径合成甲烷的产甲烷古菌Methanoculleus bourgensis(条带A3)、Methanoculleus horonobensis(条带A13). 经纤维素酶预处理后,芦苇秸秆厌氧联产的累积产气量、φ(H₂) 提高显著,具有纤维素降解功能的细菌和可利用氢营养途径合成甲烷的古菌为主要优势微生物.      

Development of a PEMFC-based heat and power cogeneration system

Hydrogen-fed proton exchange membrane fuel cell (PEMFC) has to overcome high installation and operation cost before being adopted as a distributed power candidate. Cogeneration of power and heat is a good approach to increase hydrogen energy utilization rate. A PEMFC-based power and heat cogeneration system is proposed and established in the current study to investigate system’s technological and economical feasibility. This cogeneration of heat and power (CHP) system composes of a 2.5-kW fuel cell stack, hydrogen supply system, air supply system, water and heat management system, and heat recovery system. The control strategies to automate the system operation are realized by a programmable automation controller (PAC) system. Detailed measurement of the system is also constructed along with a web-based human–machine interface (HMI) platform to facilitate experiments and demonstration. Preliminary testing of the CHP system shows good performance of heat and power outputs. System’s electrical power conversion efficiency and thermal efficiency of the CHP system are measured at 38% and 35%, respectively. System combined efficiency therefore reached about 73%.     

Pd/Al2O3粒子电极电催化还原BrO3-的研究

针对常规方法难以去除水中Br_3~-的问题,采用浸渍煅烧法制备了负载型纳米Pd/Al_2O_3粒子电极,研究了该电极电催化还原Br O-3的效果.催化剂的结构表征表明该反应实现了Pd纳米晶的均匀负载,纳米Pd/Al_2O_3具有较高的电催化活性和较低的能耗,其最佳反应条件为3%Pd负载量,0.9 m A·cm-2电流密度和1 g·L催化剂投量,酸性条件可促进Br O-3的直接或间接还原.ESR检测证实了Pd的负载增强了反应体系活性物种[H]的生成,进而促进了Br O-3的间接电催化还原.     

含硫废水受控氧化及单质硫团聚过程研究

采用过氧化氢在常温常压下对模拟含硫废水进行受控氧化,探讨了受控氧化过程对单质硫收率的影响,并对氧化过程中固相产物的形态特性进行了研究.结果表明,在过氧化氢投加量为9 m L·L-1、初始p H为6、反应时间为10min条件下,将反应体系氧化还原电位(ORP)控制在(30±5)m V时能较好实现含硫废水的受控氧化,此时单质硫收率达76.35%,当体系ORP由(-50±5)m V升高至(50±5)m V时,副产物S2O2-3收率显著下降,由26.54%下降至5.32%.X射线衍射分析表明,氧化过程中的固相产物主要为正交晶系斜方硫;扫描电子显微镜分析表明,液相中的单质硫由多个极小的颗粒聚集而成,其粒径由纳米级逐渐增大至微米级.同时,通过向反应体系中加入分散剂证明了单质硫颗粒增大的主要原因是颗粒间发生了团聚.     

Sulfate reducing bacterial community and in situ activity in mature fine tailings analyzed by real time qPCR and microsensor

Sulfate reducing bacteria(SRB) play significant roles in anaerobic environments in oil sands mature fine tailings(MFTs). Hydrogen sulfide(H2S) is produced during the biological sulfate reduction process. The production of toxic H_2S is one of the concerns because it may hinder the landscape remediation efficiency of oil sands tailing ponds. In present study, the in situ activity and the community structure of SRB in MFT and gypsum amended MFT in two settling columns were investigated. Combined techniques of H_2S microsensor and dissimilatory sulfite reductase β-subunit(dsrB) genes-based real time quantitative polymerase chain reaction(qPCR) were applied to detect the in situ H_2S and the abundance of SRB. A higher diversity of SRB and more H_2S were observed in gypsum amended MFT than that in MFT, indicating a higher sulfate reduction activity in gypsum amended MFT; in addition, the activity of SRB varied as depth in both MFT and gypsum amended MFT: the deeper the more H_2S produced. Long-term plans for tailings management can be assessed more wisely with the information provided in this study.     

翻堆频率对厨余垃圾堆肥过程中H_2S和NH_3排放的影响

为研究厨余垃圾堆肥过程中翻堆频率对H2S和NH3排放的影响,以大类粗分后的厨余垃圾为研究对象,玉米秸秆为调理剂,设置4组翻堆频率不同的处理(每周2次,2周1次,2周1次和不翻堆)进行对比研究。结果表明:翻堆频率的变化对H2S的排放影响不大,对NH3的排放有显著的影响,翻堆频率过高会增加NH3的累积排放量,翻堆频率过低虽然能降低NH3的累积排放量,但会影响到堆肥产物的腐熟。综合厨余垃圾堆肥的无害化指标、H2S和NH3的排放以及最终堆肥产品的毒性检验,在实验条件下,翻堆频率设为每周1次在堆料腐熟的基础上对H2S和NH3减排效果最好。     

氢氧稳定同位素在植物水分来源研究中的应用

植物的生长和分布与水分的可利用程度紧密相关,不同生态系统中的植物如何利用水分,以及这些植物在季节变化中的水分利用模式有何变化,特别是在水资源匮乏的干旱地区,如何合理配置有限的水资源,以使植物有效吸收利用水分,维护生态环境不致恶化,这些问题的回答都离不开植物水分来源的研究.本文介绍了氢氧稳定同位素示踪植物水分来源的原理以...