固定化EM菌处理炼油废水的研究

探讨了两种固定EM菌的方法及两种固定化微生物小球的物理性质,通过正交实验,研究炼油废水的pH、投菌量、处理时间3个因素对石油类物质,氨氮去除率的影响。结果表明:①白球在pH为5、小球投加量(投菌量)为40个、处理时间为2 d时,固定化EM菌对炼油废水的石油类物质和氨氮的去除率分别为40.17%和49.51%;②黑球在pH为6、小球投加量为40个、处理时间为3 d的条件下,固定化EM菌对炼油废水的石油类物质和氨氮的去除率分别为52.26%和46.97%。     

GAC-UF一体化净水柱去除水中硝酸盐氮的研究

在硝酸盐氮浓度5～25 mg/L,pH值在5. 5～8. 5,进水流量75～150 mL/min,颗粒活性炭厚度在100～150 mm的变化条件下,考察了GAC-UF一体化净水柱对水中硝酸盐氮去除的效果,以及活性炭和超滤的协同去除效果。结果表明,随着活性炭厚度、硝酸盐氮浓度的增大,硝酸盐氮的去除率增加;在流量75 mL/min时,pH值为5. 5和8时,硝酸盐氮去除率分别可达25. 21%,23. 01%。协同实验表明,超滤对硝酸盐氮的去除率仅为3. 97%,而活性炭的去除率为14. 55%,但一体化净水柱的去除率达到23. 01%,表明颗粒活性炭和超滤具有协同作用。该装置对硝酸盐氮浓度不超过饮用水标准1. 25倍的原水,经处理后,可达到饮用水标准。     

固定化细胞技术在SBR处理造纸废水中的应用

采用海藻酸钠包埋法固定杂色云芝细胞,将固定化细胞投入SBR处理造纸废水。结果表明:SBR中加入固定化细胞后,当进水COD为1265.87 mg/L,固定化细胞组COD去除率为72.14%,对照组COD去除率为65.73%,COD去除率提高了9.75%。提高进水负荷至1641.31 mg/L,固定化细胞组COD去除率为60.52%,对照组COD去除率为47.94%,COD去除率提高了26.24%,说明反应器接入固定化细胞后抗进水负荷冲击能力提高。当进水p H改变时,固定化细胞组反应器仍具有较高的COD去除率。说明反应器接入固定化细胞后抗进水p H冲击能力提高。     

GAC-UF一体化净水柱去除水中硝酸盐氮的研究

在硝酸盐氮浓度5～25 mg/L,pH值在5. 5～8. 5,进水流量75～150 mL/min,颗粒活性炭厚度在100～150 mm的变化条件下,考察了GAC-UF一体化净水柱对水中硝酸盐氮去除的效果,以及活性炭和超滤的协同去除效果。结果表明,随着活性炭厚度、硝酸盐氮浓度的增大,硝酸盐氮的去除率增加;在流量75 mL/min时,pH值为5. 5和8时,硝酸盐氮去除率分别可达25. 21%,23. 01%。协同实验表明,超滤对硝酸盐氮的去除率仅为3. 97%,而活性炭的去除率为14. 55%,但一体化净水柱的去除率达到23. 01%,表明颗粒活性炭和超滤具有协同作用。该装置对硝酸盐氮浓度不超过饮用水标准1. 25倍的原水,经处理后,可达到饮用水标准。     

适度氧化的三维铜电极高效电催化反硝化的研究

利用电化学氧化技术在泡沫铜基底上生长出纳米线,再进行退火氧化处理,使其具备高催化还原硝酸盐的性能。实验结果表明,该三维铜电极的比表面积高、传质效果好;用适度氧化后的电极以15 m A/cm~2的电流密度,在120 min内基本上可将pH=7的水体中存在的30 mg N/L硝酸盐去除(去除率为99%);为了将生成的氨氮副产物去除,加入Na Cl还原120 min,硝酸盐的去除率达91%,氮气选择性高于95%。5次循环实验后硝酸盐的去除率保持在91%～95%,氮气选择性为93%～95%。该材料与工艺的结合解决了水体中硝酸盐的污染问题,为实际水体污染提供了新的解决方案。     

不同有机碳源对SBR工艺同步硝化反硝化影响

采用序批式生物反应器(SBR)处理模拟废水,在pH值7.0～8.0、温度30～32℃、DO浓度0.5～1mg/L、MLSS(4000±300)mg/L、NH4+-N35～45mg/L条件下,考察乙酸钠、淀粉和葡萄糖作为碳源对SBR工艺同步硝化反硝化效果的影响。结果表明:投加葡萄糖时,COD去除率达到93.95%,出水硝酸盐浓度为7mg/L;投加淀粉时,COD去除率仅70%,出水硝酸盐浓度为12mg/L;采用乙酸钠作为碳源时,COD去除率为88.34%,出水硝酸盐浓度为4mg/L。COD/NH4+-N为12,分次投加乙酸钠时,氨氮去除率高于95%,总氮去除率高于90%,实现了同步硝化反硝化。在同步硝化反硝化SBR系统中,乙酸钠比淀粉和葡萄糖更适合作为碳源。     

竹炭对饮用水中硝酸盐的吸附特性及影响因素研究

研究了竹炭对水溶液中硝酸盐(以硝酸钠为例)的吸附特性及影响因素。结果表明,竹炭对硝酸盐的吸附效果与竹炭粒径、吸附温度、竹炭用量等因素有关,其中吸附温度是最主要的影响因素。最佳吸附参数为:竹炭粒径0.06～0.15mm,投加量0.30g/mL,吸附温度30℃,pH值6,硝酸盐的去除率可达到59.1%。饮用水校正试验显示,竹炭对饮用水中的硝酸盐具有较好的去除率,达到了57.4%。本研究为今后饮用水中硝酸盐的去除开辟了一条新的途径。     

多巴胺包埋磁性SiO2固定化漆酶催化去除4-氯酚

以磁性纳米颗粒为载体,通过多巴胺(dopamine,DA)聚合原位包埋制备了磁性SiO₂固定化漆酶(Fe₃O₄@SiO₂-PDA-Lac)。结果显示纳米颗粒尺寸均匀,并且保持较高的饱和磁性。通过最优条件制备出的固定化漆酶在50℃放置6 h后,活性保持在63%,而游离酶仅保留18%。将固定化酶用于催化降解4-氯酚(4-CP),探究了溶液pH、漆酶浓度和ABTS[2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸铵)]对4-CP去除率的影响。固定化漆酶在反应最适pH时,4-CP去除率为84.3%,而游离酶仅为65.7%。当漆酶浓度为1.2 U·ml^-1时,反应8 h后,4-CP去除率可达95%,而游离酶的4-CP去除率仅82%。ABTS可促进固定化漆酶降解4-CP,当体系中加入50 μmol·L^-1 的ABTS,反应10 min后,固定化酶对4-CP去除率可达99%。固定化漆酶在重复使用10次后,4-CP去除率仍可达67%。     

木屑固定化白腐真菌降解焦化废水中酚类化合物的研究

以木屑为载体固定化白腐真菌对焦化废水进行处理,其酚类化合物的去除率明显高于白腐真菌菌丝和木屑的混合物.研究表明,白腐真菌对含酚250 mg·L-1以下的焦化废水处理效果较好,酚类化合物的去除率可达76.87%.固定化的白腐真菌降解高浓度酚类化合物的适宜pH值为5.5～7.0,最佳pH值为6.5;适宜温度为25～35℃,最佳温度为30℃.     

铁碳微电解去除水中硝酸盐影响因素的研究

利用混合海绵铁与活性炭形成微电解,用于去除人工模拟废水中硝酸盐氮并探究其影响因素。通过海绵铁-活性炭混合、海绵铁及活性炭对硝酸盐吸附还原过程探讨其微电解作用机理,考察铁碳比、进水浓度、初始pH、预处理对硝酸盐去除率的影响。结果表明,铁碳混合后形成微电解能有效提高硝酸盐去除率,反应4 h去除率可达80%;对海绵铁进行表面酸预处理能使硝酸盐去除效果提高43%;正常的pH(6～8)对工艺的影响不大;硝酸盐浓度越高反应速率越慢,反应符合准一级动力学方程。     

Immobilization of alcohol dehydrogenase on the surface of polyethylene membrane

Using polyacrylic acid (PAA) modified polyethylene (PE) membrane as a carrier, two immobilization routes of alcohol dehydrogenase (ADH) were studied, and the catalytic performance of immobilized enzyme was investigated using formaldehyde as a substrate. In the first route, PAA-PE membrane was further modified by polyethyleneimine (PEI) and then ADH was covalently linked by glutaraldehyde (GA) to the surface of PEI/PAA-PE. The results show that the optimal immobilization pH was 6.0, immobilization temperature was 5—15℃, ADH and GA concentrations were 1.0mg/ml and 0.01%(mass). For immobilized enzyme, the optimal reaction pH was 6.5, temperature was 15—30℃, and the highest reaction rate was 9.6 μmol/(L·min), the remaining activity was 47.3% after 10 use cycles. In the second route, ADH was immobilized on PAA-PE membrane with 1-(3-dimethylaminopropyl)-2-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as activators. The results show that the optimal molar ratio of EDC and NHS was 1∶0.5, and the immobilization time was 24 h. For immobilized enzyme, the optimal reaction pH was 6.5, temperature was 20—37℃, and the highest reaction rate was 15.58 μmol/(L·min), 53.8% activity was remained after 10 cycles.     

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。     

MTG酶催化羊毛固定化溶菌酶的酶学性质及抗菌性能

利用新型的生物催化剂微生物谷氨酰胺转胺酶（MTG）催化溶菌酶在羊毛织物上的固定化。采用SDS-PAGE法探讨了溶菌酶作为MTG催化底物的可行性以及固定化溶菌酶的酶学性质及抗菌性能。研究结果表明,羊毛织物经过高锰酸钾预处理后可以实现溶菌酶的固定化。固定化酶的pH值稳定性和温度稳定性优于游离酶;与物理吸附法相比,MTG催化法可赋予固定化溶菌酶的羊毛织物更好的耐水洗性和操作稳定性;此外,固定化酶的低温（4 ℃）干储藏稳定性良好,30天内酶活仍维持在80%以上。抗菌测试结果表明,MTG催化法固定化溶菌酶的羊毛织物对金黄色葡萄球菌的抑菌率达73.23%,抗菌效果良好。     

Electromagnetic wave absorbing performance of multiphase (SiC/HfC/C)/SiO2 nanocomposites with an unique microstructure

Dielectric properties and electromagnetic (EM) wave absorbing performance of monolithic (SiC/HfC/C)/SiO₂ nanocomposites (denoted as SHCOs) have been investigated in the X-band (8.2–12.4 GHz). The multiphase SHCOs are composed of insulating SiO₂ and SiC/HfC/C nanocomposite fillers (SHC), which fillers composed of semiconducting β-SiC, conductive HfC-Carbon core-shell nanoparticles, and interconnected carbon nanoribbons. Dielectric response indicates that the increased SHC content results in an enhanced imaginary part of the permittivity and dielectric loss, leading to an improved EM absorbing performance. The unique microstructure with an EM wave-transparent SiO₂ matrix is favorable for impedance matching and effective EM wave propagation. The enhanced interface polarization and conduction loss are considered as the key mechanisms for EM wave attenuation. The minimum reflection loss of the SHCOs achieves – 60.7 dB containing 20 vol% of SHC (at 9.98 GHz) with the sample thickness of 3.33 mm, and the effective absorbing bandwidth (EAB) covers ca. 72 % of the X-band. The monolithic (SiC/HfC/C)/SiO₂ nanocomposites with outstanding EM wave absorbing performance are promising candidates for EM application at high temperatures.     

碱化膨润土-海藻酸钙固定化颗粒作为微生物载体对微污染废水的处理性能

近年来,微污染景观水体表现出氨氮、化学需氧量(COD)超标的水质恶化趋势。使用吸附材料是解决该现状的有效途径之一,但是这类材料往往不具备原位长期稳定的处理性能。针对这一问题,本工作选用生物相容性良好的海藻酸钙作为固定剂,制备得到碱化膨润土-海藻酸钙固定化颗粒,探究固定化颗粒作为微生物载体对模拟微污染水体中NH3-N和COD的去除效果。通过溶胶凝胶法采用海藻酸钙固定不同浓度NaOH溶液碱化的膨润土合成系列碱化膨润土-海藻酸钙固定化颗粒。通过扫描电子显微镜(SEM)、傅里叶红外光谱(FTIR)、Zeta测试、BET比表面积测试对制备得到的系列碱化膨润土及固定化颗粒进行表征,并分析固定化颗粒作为微生物载体对微污染废水的处理性能。研究结果表明,0.5 mol/L NaOH溶液处理的膨润土具有最低的Zeta电位(-27.4 mV),其表面电负性增强,且表面片层状结构增加。制备的0.5B-CA固定化颗粒比表面积最大,为12.1 m2/g,比膨润土原土合成的固定化颗粒(0B-CA)比表面积增加了28%,有利于微生物附着生存。0.5B-CA固定化颗粒作为微生物载体显示出最佳的NH3-N和COD去除性能。在10周期处理中,所有处理后废水的NH3-N浓度和COD浓度均分别降至1和20 mg/L以下,达到了国家地表水环境III类水标准。本工作制备的碱化膨润土-海藻酸钙固定化颗粒作为微生物载体,在污水处理中同时发挥膨润土的吸附作用与微生物的去除作用,对NH3-N和COD有着优异的去除性能及长期稳定的去除能力,为其在实际场景的应用提供了可能。     

Surface-modified Improvement in Catalytic Performance of Cr(salen) Complexes Immobilized on MCM-41 in Solvent-Free Selective Oxidation of Benzyl Alcohol

A series of typical methyl regulators were used to finely modify the Cr(salen) complex immobilized on MCM-41. Such immobilized complexes were effective catalysts for solvent-free selective oxidation of benzyl alcohol (BzOH) with 30% hydrogen peroxide (H₂O₂), and they all exhibited much higher catalytic performance than their homogeneous analogue. Simultaneously, the introduction of methyl regulators was found to significantly improve the catalytic performance of immobilized complexes by modifying their surface properties. The optimal BzOH conversion reached 65.0% with 100% selectivity to benzaldehyde (BzH).     

Immobilization of organophosphorus hydrolase enzyme by covalent attachment on modified cellulose microfibers using different chemical activation strategies: Characterization and stability studies

The plant cellulose powder was activated by two different methods using 1,4-butanediol diglycidyl ether(BTDE)and 1,1′-Carbonyldiimidazole(CDI) as the chemical coupling agents.Organophosphorus hydrolase(OPH) from Flavobacterium ATCC 27551 was immobilized on any of activated support through covalent bonding.The optimal conditions of affecting parameters on enzyme immobilization in both methods were found, and it was demonstrated that the highest activity yields of immobilized OPH onto epoxy and CDI treated cellulose were 68.32%and 73.51%, respectively.The surface treatment of cellulose via covalent coupling with BTDE and CDI agents was proved by FTIR analysis.The kinetic constants of the free and immobilized enzymes were determined, and it was showed that both immobilization techniques moderately increased the Kmvalue of the free OPH.The improvements in storage and thermal stability were investigated and depicted that the half-life of immobilized OPH over the surface of epoxy modified cellulose had a better growth compared to the free and immobilized enzymes onto CDI treated support.Also, the pH stability of the immobilized preparations was enhanced relative to the free counterpart and revealed that all enzyme samples would have the same optimum pH value for stability at 9.0.Additionally, the immobilized OPH onto epoxy and CDI activated cellulose retained about 59% and 68% of their initial activity after ten turns of batch operation, respectively.The results demonstrated the high performance of OPH enzyme in immobilized state onto an inexpensive support with the potential of industrial applications.     

Dielectric response and electromagnetic wave absorption of novel macroporous short carbon fibers/mullite composites

For wider-band and stronger electromagnetic (EM) wave absorption, macroporous short carbon fibers/mullite matrix (C_f/Mu) composites were prepared via introducing short carbon fibers (0, 0.7, and 1.3 vol%) with length of 2-3 mm into macroporous mullite ceramic by gel-casting. The density of as-prepared C_f/Mu composites decreases from 2.93 g/cm³ to 2.74 g/cm³, while the porosity increases from 3.32% to 10.76% with the rise in carbon fibers content. The diameter of macropores in C_f/Mu composites is ranging from several microns to tens of microns. Complex permittivity and dielectric loss of the prepared composites in X-band (8.2-12.4 GHz) are significantly enhanced with increased carbon fibers content. The best EM wave absorption performance is obtained in the macroporous C_f/Mu composites containing only 0.7 vol% carbon fibers (C_f/Mu-0.7). The maximum absorption loss of C_f/Mu-0.7 is −38.3 dB at 12.08 GHz at the thickness of 2.1 mm, and effective absorption bandwidth below −10 dB (over 90% of EM wave absorption) covers the whole X band with the thickness of 2.35 mm. The results suggest that the C_f/Mu composites can be promising high-performance EM wave absorbing materials.     

Rutile TiO2 nanorod with anomalous resonance for charge storage and frequency selective absorption

TiO₂ is not among the traditional electromagnetic (EM) absorbing material candidates owing to its poor response in the EM wave region. Although the EM wave absorption performance can be improved by hybrid and/or hydrogenated TiO₂, the difficulty and risk of the experimental process are increased. Herein, rutile TiO₂ nanorod was successfully prepared by two-step method. The analysis of dielectric properties exhibits that rutile TiO₂ nanorod has excellent charge storage capacity. The results of EM wave absorbing performance show that impedance matching caused by anomalous resonance leads to frequency selective absorption. Such anomalous resonance is due to the resonant polarization of ionic clusters formed by oxygen ions and titanium ions. Moreover, metastructure design shows that the EM absorption frequency and the EM wave absorption bandwidth can be tuned through the design of metamaterial. Our founding will broaden the field of vision for the design of EM wave absorbing materials in the future.