活性污泥吸附重金属离子的研究进展

从处理含重金属离子废水的现状出发,简述了活性污泥吸附重金属离子过程中的表面有机络合、离子交换及其它机理;讨论了温度、时间、pH值、污泥种类、预处理、重金属离子浓度等因素对活性污泥吸附重金属离子的影响,并对解吸方式进行了论述;综述了目前国内外有关活性污泥吸附重金属离子的最新研究成果,指明了进一步加强吸附机理和固定化技术以提高活性污泥应用性的研究是今后的方向。     

Covalently Immobilized Regenerable Immunoaffinity Layer with Orientation-Controlled Antibodies Based on Z-Domain Autodisplay

A regenerable immunoaffinity layer comprising covalently immobilized orientation-controlled antibodies was developed for use in a surface plasmon resonance (SPR) biosensor. For antibody orientation control, antibody-binding Z-domain-autodisplaying Escherichia coli (E. coli) cells and their outer membrane (OM) were utilized, and a disuccinimidyl crosslinker was employed for covalent antibody binding. To fabricate the regenerable immunoaffinity layer, capture antibodies were bound to autodisplayed Z-domains, and then treated with the crosslinker for chemical fixation to the Z-domains. Various crosslinkers, namely disuccinimidyl glutarate (DSG), disuccinimidyl suberate (DSS) and poly (ethylene glycol)-ylated bis (sulfosuccinimidyl)suberate (BS(PEG)₅), were evaluated, and DSS at a concentration of 500 μM was confirmed to be optimal. The E. coli-cell-based regenerable HRP immunoassay was evaluated employing three sequential HRP treatment and regeneration steps. Then, the Oms of E. coli cells were isolated and layered on a microplate and regenerable OM-based HRP immunoassaying was evaluated. Five HRP immunoassays with four regeneration steps were found to be feasible. This regenerable, covalently immobilized, orientation-controlled OM-based immunoaffinity layer was applied to an SPR biosensor, which was capable of quantifying C-reactive protein (CRP). Five regeneration cycles were repeated using the demonstrated immunoaffinity layer with a signal difference of <10%.     

用固定化Oil-56黄杆菌修复地表水菌体形态变化

利用聚乙烯醇-海藻酸钠(PVA-Na.A lg)联合包埋固定化一株黄杆菌O il-56,进行污染地表水修复实验研究,结果表明固定化细菌的修复效果明显好于游离细菌。同时利用扫描电子显微镜观察了固定化颗粒内部细菌形态的变化,解释了由于Na.A lg溶解导致水体CODC r升高的原因,并分析了固定化颗粒传质扩散性能的缺陷,指出PVA-Na.A lg固定化工艺尚需改进。     

海藻酸钠-硅藻土包埋石油脱硫菌Rhodococcus sp.H-412

生物菌固定化研究对生物脱硫技术的推广应用具有重要的意义。本文以实验室筛选的、符合4S脱硫代谢途径的Rhodococcus sp．H．412为研究对象,二苯并噻吩（DBT）为生物催化脱硫模拟化舍物,考察了脱硫菌Rhodococcus sp．H．412的固定化操作条件和使用条件。试验结果表明：在交联温度为4℃,交联剂氯化钙溶液浓度为0．10mmol／L,海藻酸钠质量分数为3．0％,添加剂硅藻土质量分数为1．0％,菌胶比（菌体湿重：胶体体积）为1：20的条件下,用8号医用针头造粒,可以得到具有较高的脱硫活性、较好的机械强度和传质性能的固定化细胞颗粒。固定化细胞相对游离细菌而言,具有较高的温度适应能力和较宽的pH适应范围。     

Immobilization of lipase onto metal–organic frameworks for enantioselective hydrolysis and transesterification

Enzyme immobilization enhances the catalytic activity and stability of the enzyme, and also improves reusability. Metal–organic frameworks (MOFs), which possess diversified structures and porosity, have been used as excellent carriers for enzyme immobilization. Pseudomonas fluorescens lipase (PFL) has been successfully immobilized onto MOFs by covalent cross-linking to obtain a series of immobilized lipase (PFL@MOFs). PFL@MOFs are used for catalytic enantioselective hydrolysis of 2-(4-hydroxyphenyl) propionic acid ethyl ester enantiomers (2-HPPAEE) in aqueous medium and transesterification of 4-methoxymandelic acid enantiomers (4-MMA) in organic medium. The experimental results indicated that PFL@Uio-66(Zr) exhibits excellent enzymatic catalysis performances and high enantioselectives. In addition, to improve catalytic activity and reusability, PFL is modified by the polyethylene glycol (PEG) to prepare PEG-modified lipase (PFL-PEG), then PFL-PEG is immobilized onto Uio-66(Zr) to prepare PFL-PEG@Uio-66(Zr), demonstrating better reusability and catalytic activity compared with PFL@Uio-66(Zr).     

酵母菌的磁性载体固定化及处理精炼大豆油废水

采用发酵性丝孢酵母菌处理精炼大豆油废水,首先利用海藻酸钠和所制备的Fe₃O₄磁性载体分别对酵母菌进行固定化,然后分别用酵母菌、磁性载体、海藻酸钠固定化酵母菌和磁性载体固定化酵母菌来处理精炼大豆油废水。对处理结果进行对比分析,结果显示：4种物质中,磁性载体固定化酵母菌对精炼大豆油废水处理36 h时效果最佳。pH值6.0比较适合磁性载体固定化酵母菌的生长,处理36 h的废水中的酵母菌的OD₆₀₀值为19.78。通过研究不同pH值和不同接种量条件对磁性载体固定化酵母菌处理精炼大豆油废水的情况,得到处理废水的较优条件：废水pH值6.0,酵母菌接种量10%,处理时间36 h,此条件下废水的化学需氧量(COD)值为2 430 mg/L。     

Rapid synthesis of Gd2Zr2O7 ceramics by flash sintering and its aqueous durability

The high radiation resistance and long time stability of Gd₂Zr₂O₇ ceramics make it a promising candidate for high level waste (HLW) immobilization materials. In this study, single phase nanocrystalline Gd₂Zr₂O₇ was successfully synthesized and consolidated at temperatures around 1050 °C for only 1 min by flash sintering for the first time. The phase evolution and microstructural development during flash sintering were systematically studied and compared with the conventionally sintered samples. The flash sintered Gd₂Zr₂O₇ exhibit defect fluorite structure, and a following heat treatment at 1400 °C could transform the Gd₂Zr₂O₇ ceramics from defect fluorite phase into pyrochlore phase. The MCC-1 leaching test shows that the flash sintered Gd₂Zr₂O₇ samples exhibit good aqueous durability.     

醇脱氢酶在聚乙烯膜表面的固定化研究

以聚丙烯酸（PAA）改性的聚乙烯（PE）膜为载体,研究了醇脱氢酶（ADH）的两种固定化路线,并以甲醛为底物考察了固定化酶的催化性能。路线1用聚乙烯亚胺（PEI）进一步改性,使用戊二醛（GA）固定化ADH。最优固定化pH为6.0,温度为5～15℃,酶浓度为1.0 mg/ml,GA浓度为0.01%(质量);固定化酶的最适反应pH为6.5,温度为15～30℃,反应速率最高为9.6 μmol/(L·min);重复利用10次后可保持47.3%的活性。路线2以PAA-PE为载体,用1-(3-二甲氨基丙基)-2-乙基碳二亚胺盐酸盐（EDC）和N-羟基琥珀酰亚胺（NHS）为活化剂,固定化ADH。EDC和NHS最优摩尔比为1∶0.5,固定化时间为24 h;固定化酶的最适反应pH为6.5,温度为20～37℃,反应速率为15.58 μmol/(L·min);重复利用10次后可保持53.8%的活性。     

AlCl3-磺酸树脂催化噻吩类硫化物与异丁烯烷基化硫转移反应

选择以噻吩的甲基取代衍生物(包括2-甲基噻吩、3-甲基噻吩及2,5-二甲基噻吩)与异丁烯的烷基化反应为模型反应,考察了经三氯化铝气相固载法改性的CT175树脂催化剂催化噻吩的甲基取代衍生物与烯烃的烷基化反应性能. 研究结果表明,负载AlCl3的CT175树脂催化剂对催化2-甲基噻吩、3-甲基噻吩及2,5-二甲基噻吩与异丁烯的烷基化硫转移反应均具有很高的活性,在80℃、常压、异丁烯(与氮气按摩尔比1:1配制的混合气)流量5.0 mL/min、液体(含模型硫化物2-甲基噻吩、3-甲基噻吩及2,5-二甲基噻吩的浓度分别为2033, 2045, 1543 mg/g的苯溶液)质量空速为2.5 h-1的条件下,上述5种模型硫化物均接近于完全转化. 对催化剂的活性稳定性进行了为期30 d的连续考察,结果表明,3种模型硫化物的烷基化转化率均高于99%,且催化剂活性未见下降趋势.     

一种新型纤维素基吸附剂的制备及其对漆酶的固定化性能研究

利用NaOH/尿素体系溶解纤维素并加入纳米碳酸钙,而后在盐酸溶液中再生,制得具备多孔结构的纤维素小球;之后采用丙烯酰胺对纤维素小球的羟基进行改性,接枝碳链并引入酰胺基,在碱性条件下酰胺基水解为羧基,得到改性纤维素基吸附剂;其可通过静电吸附和氢键间作用力固定漆酶。对接枝改性和漆酶固定化的最佳条件进行了探索,得到最佳改性条件为：时间6 h、温度50℃、单体配比8∶5、引发剂浓度0.08%;最佳固定化条件为：pH值=5.0、初始酶浓度10 g/L、固定化时间3 h。利用此最佳改性纤维素小球在最佳条件下固定的漆酶具有良好的热稳定性和可重复使用性,酶活提高了52%。结果表明,改性纤维素小球作为一种新型的绿色载体,在漆酶固定化方面具有广阔的应用前景。