过氧化钙缓释氧剂对微生物降解苯系物的强化效能和机理研究

采用聚羟基脂肪酸酯(PHA)包埋过氧化钙制备缓释氧颗粒(OSRG),通过释氧曲线证实该缓释氧颗粒的缓慢释氧可以达到4 d以上。采用序批式比较实验,证实了OSRG可以有效强化微生物对苯和甲苯的降解效率,苯和甲苯的总去除率分别可以达到87.3%和80.4%。除了供氧功能外,OSRG的强化机理还包括表面吸附作用和产生的活性氧氧化作用,在苯和甲苯去除过程中的贡献分别占9.3%,9.4%,8.1%,8.3%。单因素实验表明,投加OSRG与污染物质量比(苯和甲苯总质量)为2∶1时可以获得最佳去除效果,较低的投加量(1∶4)会造成供氧不足问题,流式细胞仪的活菌分析结果表明,较高的投加量(8∶1)时会造成部分细胞膜的氧化损伤。     

过氧化钙缓释氧颗粒的制备及缓释氧过程调控

基于过氧化钙(CP)的缓释氧颗粒(OSRG)的制备和应用是当前土壤和地下水有机污染物修复研究的热点之一。提出以聚羟基脂肪酸酯(PHA)作为包埋剂,以二氯甲烷作为溶解介质,实现无水条件下PHA与CP完全混合获得OSRG。扫描电镜显示,二氯甲烷挥发后导致OSRG表面均匀分布多微孔并且结构紧凑,元素C、O、Ca在OSRG表面分布均匀。当PHA与CP的质量比为1:1时,可以缓慢持续释氧6 000 min以上,DO浓度稳定维持在2.5 mg/L。采用聚乳酸(PLA)作为包埋剂时,效果略优于PHA,但PHA的可生化性更好并且可以为微生物修复过程提供优质的共代谢碳源。制备过程中加入15 wt%的KH_2PO_4可以有效将CP释氧过程中的pH值从12.44降至8.43,为后续微生物修复过程持续供给氧气的同时提供了稳定适宜的pH环境。本研究可为土壤和地下水修复过程中的缺氧问题提供有效的解决途径。     

苯氧羧酸类除草剂的微生物降解研究进展

综述了苯氧羧酸类除草剂的应用概况、微生物降解机理及影响因素,提出了其微生物降解的发展方向,旨在为开展土壤微生物降解苯氧乙酸类除草剂提供参考。     

民用建筑工程室内空气中苯系物的测定

使用2,6-对苯基二苯醚多孔聚合物-石墨化炭黑-X复合吸附管采样,采用气相色谱仪和热解析仪,外标法定量测定民用建筑工程室内环境空气中的苯系物.在本方法条件下,苯系物(苯、甲苯、二甲苯)标准曲线线性良好,相关系数(r)均在0.9991～0.9998之间.该方法在民用建筑工程室内空气中苯系物的检测中操作简单,准确度高,重复...     

新法合成对甲苯氧乙基甲醚和苯氧乙基甲醚

酚与氯乙醇反应，再用硫酸二甲酯甲基化合成了对甲苯氧乙基甲醚和苯氧乙基甲醚。考察了原料配比、反应温度和反应时间对产物收率的影响，找到了最佳反应条件。并对ＺＰＢＢＣ催化乙二醇单酚醚甲基化反应进行了讨论。     

单晶纳米线TiO2光催化反应降解油田采出水中苯系物的研究

以单晶纳米线TiO2为催化剂,采用光催化氧化方法,对油田采出水进行处理,并对处理过程中苯系物的降解规律进行了研究.结果表明,经处理后废水中的苯、甲苯、对二甲苯、间二甲苯、邻二甲苯分别由1 276.0、432.3、183.1、1 319.4、324.3 μg/L降至70.6、14.6、7.7、24.5、6.3 μg/L,出水满足<国家污水综合排放标准>(GB 8978-1996)一级标准.     

芳氧苯氧丙酸酯类新化合物除草活性的研究

JSW002、JSW021是以芳氧苯氧丙酸类和氰基丙烯酸酯类拼接而成的具有除草活性的化合物。针对这两种化合物进行了室内除草活性筛选和作物安全性评价试验,表明JSW002、JSW021对禾本科杂草有较好的防除效果,对大豆、油菜等作物安全,在低剂量情况下对禾本科杂草的防治效果略逊于同剂量下对照药剂精喹禾灵。     

高效液相色谱法同时测定水中的苯系物

建立了高效液相色谱法同时测定水中苯、甲苯、乙苯的方法.方法使用甲醇-水(65:35)为流动相、C18柱和VWD检测器,检测波长为260nm,流速为1.0 mL/min.该方法无需使用有机溶剂对水中苯系物进行提取和浓缩,只需加入少许氯化钠溶解,离心过滤后就可以直接测定.在所采用的色谱条件下苯系物各组分的分离度较好,线性方...     

改性生物质炭/缓释氧剂复合材料的制备及其性能研究

将生物质炭、过氧化钙和有机生物絮凝剂联合改性、吸附结合研制出改性生物质炭/缓释氧剂复合材料,对其进行表征分析,并结合pH、氧化还原电位指标确定去除水体、底泥中重金属镉、砷效果最佳配比的复合材料。结果表明,不同比例制备的复合材料对水体中5 mg/L镉、10 mg/L砷去除率均接近100%,符合地表水水质标准,pH由9.5降至7.0,Eh维持在中度还原状态。此外,当改性生物质炭(BC_(Fe))∶缓释氧剂(BF_(CP))为15∶1质量比时,对于水体镉、砷的去除效果较佳;而当BC_(Fe)∶BF_(CP)为15∶5和15∶1时制备的复合材料稳定化底泥中镉、砷效果较佳,pH处于中性,Eh低于200 mV。     

苯系化合物降解的微生物筛选及其特性初探

为选育高效降解苯系物的菌株,该研究选用污水处理厂处理废水的活性污泥作为菌源,分别以甲苯、乙苯、二甲苯作为底物,在好氧条件下,驯化、筛选和分离出了能以上述化合物作为生长的唯一碳源和能源的微生物菌株,并对其进行了初步的鉴定,分别是假单细胞菌属(Pseudomonas sp.)、芽孢杆菌属(Bacillus sp.)、红球菌属(Rhodococcus sp.)等。结果表明,对甲苯的降解率可以达到95%～98%,对乙苯的降解率为80%～88%,对二甲苯的降解率维持在70%～80%之间。进一步研究表明混合菌的最佳生长条件为培养温度30℃,培养时间48 h,接种量10%,摇床转速180 r/min,降解甲苯、乙苯时的pH为7～9,降解二甲苯时的pH为4或10。     

亚甲基蓝光度法研究基于CaO2的Fenton反应条件

CaO₂作为原位Fenton 氧化修复中H₂O₂持续供源的作用逐渐受到关注。利用亚甲基蓝分光光度法评价了基于CaO₂的Fenton反应中催化剂种类、初始pH值、CaO₂用量、催化剂和CaO₂比例、磷酸缓冲溶液浓度对羟基自由基（HO·）产率的影响。结果表明,采用Fe²⁺作为催化剂,在pH值为4、CaO₂相似文献   

Effect of non-lattice oxygen on ZrO2-based resistive switching memory

ABSTRACT: ZrO2-based resistive switching memory has attracted much attention according to its possible application in the next-generation nonvolatile memory. The Al/ZrO2/Pt resistive switching memory with bipolar resistive switching behavior is revealed in this work. The thickness of the ZrO2 film is only 20 nm. The device yield improved by the non-lattice oxygen existing in the ZrO2 film deposited at room temperature is firstly proposed. The stable resistive switching behavior and the long retention time with a large current ratio are also observed. Furthermore, it is demonstrated that the resistive switching mechanism agrees with the formation and rupture of a conductive filament in the ZrO2 film. In addition, the Al/ZrO2/Pt resistive switching memory is also possible for application in flexible electronic equipment because it can be fully fabricated at room temperature.     

Detection mechanism of TiO2-based ceramic H2 sensors

This work reports an H₂-sensing mechanism of TiO₂ thick-films, deposited on alumina substrates by screen-printing. The role of the catalytic activity of the electrode material on the sensor response was tested with platinum and gold electrodes. An impedance analyser (20 Hz–1 MHz) was used to monitor the film impedance before and after exposure to H₂. Continuous monitoring of the film resistance was performed with a simple dc measurement. The film resistance was measured as a function of temperature (500–650°C), time, and gas phase composition (air and 0–10% H₂ in a N₂-based gas stream). The equilibrium gas phase Po₂ (monitored with a zirconia-based oxygen sensor) was also used to identify the hydrogen detection mechanism of the films.     

Preparation and toughening mechanism of Mo2NiB2-based cermets with SiC whiskers

Mo₂NiB₂ is a kind of cermet with excellent mechanical properties, stable chemical properties, and excellent corrosion resistance and is often used in wear-resistant application fields, such as injection molding machine parts, can making tools and hot copper extruding dies. The brittleness of Mo₂NiB₂-based cermets limits their wide application. Mo₂NiB₂-based cermets were prepared by the vacuum sintering method, the effect of SiC whiskers (SiCw) on the microstructure and mechanical properties of cermets was investigated, and the toughening mechanism of SiCw on cermets was further discussed. The results indicate that with increasing SiCw content, the indentation fracture toughness (K_IC), transverse fracture strength (TRS), and Vickers hardness (HV) of the cermets first increase and then decrease. The HV, TRS, and indentation fracture toughness of Mo₂NiB₂-based cermets with 0.5 wt% SiCw are 1 113 HV, 1 620 MPa, and 27.97 MPa·m^1/2, respectively, which are 16.8%, 22.7%, and 25% higher than those without SiCw. In the sliding friction tests, Mo₂NiB₂-based cermets with 0.5 wt% SiCw have the smallest friction coefficient, low wear rate, and high wear resistance. SEM observation and analysis of the crack path and fracture surface showed that the toughening mechanism is whisker bridging, crack deflection, microcrack toughening, and whisker pull-out. The results indicate that the addition of 0.5 wt% SiCw can effectively improve the mechanical properties of Mo₂NiB₂-based cermets and further expand the application space of Mo₂NiB₂-based cermets.     

Plastic shaping of NiFe2O4-based cermets using granular feedstock: microstructure and mechanical properties

Carbon-free aluminum electrolysis is crucial for achieving the low-carbon development and carbon neutrality in the future aluminum industry. NiFe₂O₄-based cermet is the potential candidate of inert anode, benefiting from the satisfactory corrosion resistance and high-temperature conductivity. Herein, complex-shaped 25(Cu–20Ni)/(NiFe₂O₄–10NiO) cermets were fabricated via a plastic shaping method using the polyformaldehyde (POM)-based granular feedstock. The feedstock showed uniform microstructure with evenly dispersed powders wrapped in polymers, which exhibited shear-thinning behavior during molding. Roles of the feedstock with different powder loadings in the morphology and bending strength of the cermets were investigated. High-precision gear parts exhibited no deformation, a high relative density over 98%. Investigation of different powder loadings revealed that parts prepared with a 56 vol% loading demonstrate the excellent performance, and possessed an impressive flexural strength of 178.4 MPa. This achievement provided a foundation for the future utilization of complex-shaped inert anode material components in industrial applications.     

SMP形成与降解机制分析及其对MBR膜过滤的影响

以膜生物反应器(membrane bioreactor,MBR)中活性污泥为研究对象,考察了溶解性微生物代谢产物(soluble microbial product,SMP)的形成及降解机制,并探讨了SMP对膜过滤的影响。实验结果表明,在基质存在时反应器内的SMP主要以基质利用相关型产物(utilization associated products,UAP)为主;当基质耗尽后,生物生长相关型产物(biomass associated product,BAP)浓度增加;内源呼吸过程中BAP的产出主要来源于松散胞外聚合物(loosely bound EPS,LB)的水解;通过傅里叶变换红外光谱(FTIR)检测表明,UAP主要由多聚糖和蛋白质组成,而BAP主要是多聚糖和腐殖酸;与UAP相比,膜对BAP截留效果较好,最佳的水力停留时间(hydraulic retention time,HRT)时MBR出水同时包含UAP及BAP,BAP浓度与膜过滤阻力呈显著正相关。     

Synthesis and microbial degradation of poly(2-methyl phenylene oxide)

The synthesis and biodegradation of poly(2-methyl phenylene oxide) was studied as an example of a synthetic polymer containing a biodegradable aromatic backbone. Polymer prepared with cuprous 2,2-isopropoxy ethyl pyridine catalyst demonstrated good blending properties with polystyrene. In soil experiments, the homopolymer degraded readily with over 50% reduction in 40 days. No. oligomeric intermediates were observed by gel permeation chromatography, suggesting degradation by cell-associated enzymes. © 1993 John Wiley & Sons, Inc.     

Improvement of energy storage properties of NaNbO3-based ceramics through the cooperation of relaxation and oxygen vacancy defects

The development of materials with high energy storage plays a crucial role in solving energy consumption. Traditional dielectric ceramics have the disadvantages of low energy storage and low efficiency. The most effective solution is to reduce the dielectric loss and increase the breakdown strength. In this paper, (Na_0.73Bi_0.08Sm_0.01)(Nb_0.91Ta_0.09)O₃ relaxor ferroelectric ceramics were prepared, which achieved a high energy storage density of 1.66 J cm^?3, high efficiency (83.6%) at 214 kV/cm at room temperature. The addition of Bi₂O₃ makes the A site cations disordered, thereby generating random fields, breaking the long-range order, and forming polar nanodomains. That allows the ceramic to acquire relaxation properties, reducing the dielectric loss. The impedance analysis proves that the breakdown strength is related to the addition of Sm₂O₃. The addition of Sm reduces the oxygen vacancy defect concentration and inhibits the migration of carriers, thereby improving its breakdown strength. Through proper doping of Bi and Sm, the relaxation properties and breakdown field strength of the ceramics are enhanced to obtain excellent energy storage performance. This provides a new idea in terms of relaxation and oxygen vacancy defects for NaNbO₃-based energy storage ceramics.     

微生物降解石油烃研究进展

石油烃对环境产生的污染是目前全球普遍关注的焦点问题,生物修复是治理石油烃污染的最为有效的途径之一。探讨了石油烃降解菌的分类、细菌对烃的黏附性以及基因工程菌的开发,讨论了微生物降解石油烃的影响因素和新的技术方法,并进行了展望。     

生物除磷颗粒污泥去除Pb2+的效能机制

以好氧颗粒污泥的吸附作用和磷酸盐对重金属的螯合作用为基础,采用富含磷酸盐的生物除磷颗粒污泥作为吸附剂来处理含铅废水,考察了不同吸附条件（pH、Pb²⁺的初始浓度、吸附反应时间）下,颗粒污泥对Pb²⁺的去除效果。结果表明,除磷颗粒污泥在pH为4,初始Pb²⁺浓度为150 mg·L^-1时,对铅的去除率最高（为99.9%）;在吸附反应20 min时即可达到吸附平衡。生物除磷颗粒污泥对Pb²⁺的吸附可以用Langmuir模型拟合（R²=0.993）,最大吸附量为49.5 mg·g^-1。其中离子交换和磷酸盐与Pb²⁺的螯合作用对除磷颗粒污泥去除Pb²⁺起到重要作用;傅里叶变换红外光谱（FTIR）测定表明-COOH、-OH、磷酰基等多种官能团也参与了除磷颗粒污泥除Pb²⁺过程。