高铁酸盐在环境治理方面的应用

考察了高铁酸盐在环境治理领域中的应用研究进展：污水处理和消毒;合成有机污染物的降解;饮用水治理中的消毒能力。高铁酸盐作为氧化剂/消毒剂在环境治理方面的优越性能已经显示在各种最新的研究里,但由于高铁酸盐溶液的不稳定性和固体高铁酸盐的高昂成本,要实现高铁酸盐技术在环境治理方面尤其是水处理中的全面应用还存在很多问题。     

Use of coaxial photocatalytic reactor (CAPHORE) in the TiO2 photo-assisted treatment of mixed E. coli and Bacillus sp. and bacterial community present in wastewater

This paper reports the photocatalytic disinfection of water contaminated by a mixture of Escherichia coli and Bacillus sp. as well as that of wastewater containing a larger microbial community. The photocatalytic reactions were carried out in a coaxial photocatalytic reactor called CAPHORE, using TiO₂ P-25 of Degussa. E. coli is more sensitive than Bacillus sp. to photocatalytic treatment. Bacterial inactivation was dependent on organic matter and dissolved oxygen (DO) concentration.

Of the bacterial community present in partially treated wastewater, E. coli appears to be more sensitive to the treatment than Enterococcus sp., coliforms (other than E. coli), and Gram-negative (other than coliforms). After photocatalytic treatment, no bacterial recovery of previous groups was observed for 24 h in the dark. However a very low bacterial inactivation rate was observed for the whole bacterial population present in wastewater and detected by non-selective media. The effective disinfection time (EDT), the time necessary for total inactivation of bacteria without re-growth in a subsequent dark period referenced at 24 h (or 48 h), was reached only for Enterococcus sp., and coliform groups. EDT₂₄ was not reached for the whole population.     

Photocatalytic inactivation of Escherischia coli: Effect of concentration of TiO2 and microorganism, nature, and intensity of UV irradiation

The efficiency of photocatalytic disinfection, used to inactivate Escherischia coli K12 under different physico-chemical parameters, was examined. The photocatalyst chosen was the semiconductor TiO₂ degussa P25 and the irradiation was produced by an HPK 125 lamp. The effect of titania concentration was investigated using two E. coli concentrations. The photocatalyst concentration ranged from 0.1 to 2.5 g/L. The evolution of E. coli inactivation as function of time was discussed depending on the E. coli and TiO₂ concentrations. The optimal concentration of the photocatalyst, 0.25 g/L, is lower than that necessary to absorb all photons and to degrade the organic compounds. Some hypotheses are presented to explain this behaviour. The effect of the different domains of UV light (UVA, UVB, and UVC) was also studied and modification of the light irradiation intensity is discussed. No bacteria photolysis was obtained with UVA but the use UVC had, on the contrary, a detrimental effect on bacteria survival. The addition of titania at a low concentration, 0.25 g/L, improved the inactivation of E. coli in the presence of UVA and UVB, but a detrimental effect was observed under UVC. The disinfection efficiency increases as a function of light intensity, whatever the photocatalytic conditions (different TiO₂ concentrations and different UV domains). No bacterial growth was observed after disinfection, whether the system contained titania or not.     

高铁酸钾的制备工艺研究与表征

高铁酸钾是一种新型绿色高效的水处理剂,为了探索经济、高效的制备高铁酸钾的工艺,以次氯酸钙为主要原料通过氧化反应制备高铁酸钾,考察反应时间、反应温度、次氯酸钙用量、重结晶温度和碱度等因素对产率的影响,并采用红外光谱对产物高铁酸钾进行表征。实验结果如下：当反应温度为25 ℃,次氯酸钙的用量为理论值的1.2倍,反应时间为40 min,在冰水浴中重结晶时,反应产率可达75%以上;红外光谱（FT-IR） 对产物的结构表征证明合成产物为高铁酸钾。结果表明以次氯酸钙代替次氯酸钠制备高铁酸钾的工艺是可行的。     

EVALUATION OF UV DOSE IN FLOW-THROUGH REACTORS FOR FRESH APPLE JUICE AND CIDER

High absorptivity and turbidity interfere with the UV disinfection of apple cider. Three different configurations of flow-through UV reactors were evaluated to overcome this interference. Two approaches were employed: use of an extremely thin film UV reactor and increasing the turbulence within a UV reactor. Multiple-lamp UV reactors including the thin-film laminar flow “CiderSure” (8 lamps) and turbulent flow “Aquionics” (12 lamps) and annular single-lamp “UltraDynamics” reactor were studied. UV disinfection performance in laminar and turbulent flow reactors was compared by evaluation of UV dose delivery. UV fluence rate (irradiance) distribution was calculated using the multiple point source summation method. E. coli K12 was used as a target bacterium in a bioassay, and the log reduction per one pass was determined for each UV reactor. Finally, the UV decimal reduction dose (D₁₀) was calculated by dividing the average UV fluence by log bacterial reduction per pass. Variations of the UV decimal dose were observed with various designs of UV systems. The least inactivation of E. coli K12 but the highest UV decimal reduction dose, ranging from 90 to 150 mJ/cm², was observed in the Aquionics UV reactor in apple cider with apparent absorption coefficient (a) of 5.7 mm^-1. The lower value of UV decimal reduction dose of 7.3-7.8 mJ/cm² was required for inactivation of E. coli K12 in malate buffer and apple juice in the annular single-lamp UltraDynamics reactor. However, the decimal reduction dose for E. coli K12 in apple cider was significantly higher, about 20.4 mJ/cm². Similar UV decimal reduction doses from 25.1 to 18.8 mJ/cm² for inactivation of E. coli K12 were observed in the thin-film 'CiderSure' UV reactor in apple cider with identical absorption coefficient. Mathematical modeling of UV irradiance can improve the evaluation of UV dose delivery and distribution within the reactors.     

Decolorization of azo dye Orange II by ferrate(VI)-hypochlorite liquid mixture, potassium ferrate(VI) and potassium permanganate

Ferrate(VI)-hypochlorite liquid mixture was prepared using hypochlorite, an industrial by-product, via wet oxidation method. Its oxidizing ability was investigated by decolorizing azo dye Orange II in batch experiments, and compared with potassium ferrate(VI) and potassium permanganate. Effects of the oxidant concentration, dye concentration, initial pH of dye solutions and UV 254 nm irradiation were examined. The color removal by potassium permanganate, potassium ferrate(VI) and the ferrate(VI)-hypochlorite liquid mixture at 30 min reached 17.7%, 62.0% and 95.2%, respectively. The ferrate(VI)-hypochlorite liquid mixture maintained a high decolorization efficiency over a wide pH range from 3.0 to 11.0, indicating that the initial solution pH had little impact on its oxidizing power. However, the decolorization efficiency by potassium permanganate was proved to be highly pH dependent and the lowest efficiency was observed at neutral pH. UV 254 nm irradiation did not enhance the decolorization efficiencies significantly for both the ferrate(VI)-hypochlorite liquid mixture and potassium permanganate over a wide pH range.     

高铁酸盐由氢氧化铁残渣再制备及其用于水体脱色的研究

将制备高铁酸盐后所留的氢氧化铁残渣制成六氟合铁酸钾再与次氯酸钠的高碱度溶液反应，第二次生成高铁酸盐溶液。随后用制得的含氟的高铁酸盐溶液处理甲基橙有色配水，其最佳pH在7．0左右，质量浓度为20mg／L的甲基橙的水样500mL，耗用17mg的高铁酸钾，脱色率可达95％以上，处理后的水体中氟离子残留量低于国家排放标准。制得的含氟的高铁酸盐溶液作为脱色的水处理剂不会引起二次污染，工艺可行，效果良好。     

高铁酸钠合成及对污水处理的研究

采用次氯酸钠和硫酸铁为原料，在强碱性条件下制备高铁酸钠溶液。实验结果表明，以次氯酸钠40mL计，高铁酸钠制备溶液制备的优化条件为：硫酸铁2．8g，氢氧化钠17．5g，反应时间60min，反应温度40～45℃。污水处理曝气池出口水样经实验条件下合成的高铁酸钠溶液处理后，其COD和SS值分别降低了48．5％和91．7％，效果显著。     

卤醇脱卤酶催化合成(R)-1-氯-3-苯氧基-2-丙醇的工艺优化

以卤醇脱卤酶重组湿菌体E. coli BL21（pET28a-HHDH）为催化剂,催化外消旋的1-氯-3-苯氧基-2-丙醇的动力学拆分可以获得光学纯的(R)-1-氯-3-苯氧基-2-丙醇。本文系统地研究了卤醇脱卤酶催化合成光学纯(R)-1-氯-3-苯氧基-2-丙醇的影响因素,对反应pH、反应温度、菌体浓度、亲核试剂 {\mathrm{N}}_{\mathrm{3}}^{-} 浓度和底物浓度进行了探究。结果表明,卤醇脱卤酶催化合成(R)-1-氯-3-苯氧基-2-丙醇的最佳工艺条件为：pH为7.0,反应温度为28℃,菌体浓度为22.5g/L,亲核试剂NaN₃的浓度为50mmol/L,底物外消旋1-氯-3-苯氧基-2-丙醇的浓度为10mmol/L。在此工艺条件下,(R)-1-氯-3-苯氧基-2-丙醇的ee值和收率分别为100%和16.97%。     

高铁酸钾的制备及其对低温低浊水的处理

为了研制高效和安全的混凝剂,采用次氯酸盐氧化法制备高铁酸钾,对高铁酸钾处理低温低浊水源水进行研究。试验表明:采用次氯酸盐法制取的高铁酸钾稳定性高,产率和纯度较高;高铁酸钾具有混凝作用,对源水浊度去除效果好于聚合氯化铝,在源水浊度为20NTU,pH值为7.7,水温为6℃的条件下,投加高铁酸钾30mg/L,滤后水浊度为0.2NTU,高铁酸钾具有消毒作用,经其处理的源水细菌总数降为10个/mL,大肠菌群数降为0个/L,其浊度和细菌学指标均能满足国家生活饮用水一级标准。     

微孔聚丙烯膜表面壳聚糖季铵盐的共价修饰及其抗菌性能

为了赋予微孔聚丙烯膜（MPPM）抗菌能力,增强其抗污染性能,本文通过丙烯酸的光引发接枝聚合、壳聚糖与聚丙烯酸的酰胺化反应、壳聚糖胺基与2,3-环氧丙基三甲基氯化铵的开环加成,成功地在MPPM膜表面通过共价修饰技术构建了壳聚糖季铵盐修饰层。构建过程通过FTIR、XPS和荧光素二钠盐染色分析得到了证实。静态水接触角和吸水量实验结果表明,制得的修饰膜具有优异的表面润湿性和吸水性,吸水量可达11.23mg/cm²,为未修饰MPPM的1123倍。以大肠杆菌和金黄色葡萄球菌为代表,采用平板活菌计数法考察了修饰膜的抗菌性能和抗菌稳定性。研究结果表明,修饰膜具有良好的抗菌活性,对大肠杆菌的抗菌率可达98%,对金黄色葡萄球菌的抗菌率可达100%,且抗菌效果稳定,在水处理领域具有潜在的应用前景。     

高铁酸钾的合成及其处理低温低浊水源水

采用次氯酸盐氧化法制备高铁酸钾作为混凝剂处理低温低浊水源水。试验表明：高铁酸钾对浊度去除效果好于聚合氯化铝，其剩余浊度为0．2NTU；高铁酸钾具有消毒作用，经其处理的原水细菌总数降为10 CFU／mL，大肠菌群数降为0个/L;在本试验条件下经高铁酸钾处理后的水源水，其浊度和细菌学指标均能满足国家生活饮用水标准。     

现场电解制次氯酸钠在污水处理厂出水消毒的应用研究

随着污水厂出水排放标准日益提高,对排水中粪大肠菌群的控制也越来越严格。现场电解制次氯酸钠发生系统是一种较为理想的环境友好型氯消毒技术,能够有效杀灭城镇污水处理厂出水中的粪大肠杆菌。因原水水质不同,次氯酸钠的杀菌效果会有差异。次氯酸钠对原水中的氨氮有一定的去除作用,但是有可能氧化原水中残留的有机氮,从而使得氨氮含量重新升高。现场连续投加试验中,反应池次氯酸钠浓度为1．2mg／L,出水中的粪大肠菌群始终稳定达到GB18918-2002一级A标准的要求,且其他水质指标（如氨氮、COD等）良好。     

利用E.coli评价铁碳微电解处理印染废水的生物毒性变化

印染废水的成分复杂、色度高、毒性强，通过分析E.coli（大肠杆菌）的形态、抗氧化酶和生物标志物，研究铁碳微电解工艺处理前后印染废水生物毒性的变化。结果表明：E.coli在进水中呈破碎状态，而在铁碳微电解工艺出水中的E.coli大部分为正常形态；与进水的抗氧化酶系统相比，出水组中的丙二醛（MDA）、谷胱甘肽（GSH）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和总抗氧化能力（T-AOC）分别降低了80.85%、53.73%、67.74%、44.90%和43.38%，铁碳微电解工艺处理后的印染废水E.coli的抗氧化能力接近正常水平。进水和出水的葡萄糖消耗量抑制率分别为85%和47%；与进水的生物标志物相比，出水中热值升高21.95%，内源荧光蛋白升高112.96%，核酸含量降低44.04%。铁碳微电解工艺具有降低实际印染废水生物毒性的作用。     

Antimony Remediation Using Ferrate(VI)

This research investigates a remediation technique for antimony involving the adsorption and co-precipitation of aqueous antimony by in-situ formed ferric hydroxide. Flocculation is initiated by the oxidation of iron(II) with potassium ferrate(VI), K₂FeO₄, along with oxidation of the more toxic Sb(III) to Sb(V). A 3/1 mole ratio of Fe(II)/Fe(VI) and a total Fe/Sb mole ratio of 300/1 was needed to achieve total antimony concentrations below the maximum contaminant levels for drinking water (6 μg/l).     

Effect of pH, inorganic ions, organic matter and H2O2 on E. coli K12 photocatalytic inactivation by TiO2: Implications in solar water disinfection

The effect of different chemical parameters on photocatalytic inactivation of E. coli K12 is discussed. Illumination was produced by a solar lamp and suspended TiO₂ P-25 Degussa was used as catalyst. Modifications of initial pH between 4.0 and 9.0 do not affect the inactivation rate in the absence or presence of the catalyst. Addition of H₂O₂ affects positively the E. coli inactivation rate of both photolytic (only light) and photocatalytic (light plus TiO₂) disinfection processes. Addition of some inorganic ions (0.2 mmol/l) like HCO₃⁻, HPO₄²⁻, Cl⁻, NO₃⁻ and SO₄²⁻ to the suspension affects the sensitivity of bacteria to sunlight in the presence and in absence of TiO₂. Addition of HCO₃⁻ and HPO₄²⁻ resulted in a meaningful decrease in photocatalytic bactericidal effect while it was noted a weak influence of Cl⁻, SO₄²⁻ and NO₃⁻. The effect of counter ion (Na⁺ and K⁺) is not negligible and can modify the photocatalytic process as the anions. Bacteria inactivation was affected even at low concentrations (0.2 mmol/l) of SO₄²⁻ and HCO₃⁻, but the same concentration does not affect the resorcinol photodegradation, suggesting that disinfection is more sensitive to the presence of natural anions than photocatalytic degradation of organic compounds. The presence of organic substances naturally present in water like dihydroxybenzenes isomers shows a negative effect on photocatalytic disinfection. The effect of a mixture of chemical substances on photocatalytic disinfection was also studied by adding to the bacterial suspension nutrient broth, phosphate buffer and tap water.     

液氯和次氯酸钠对饮用水消毒效果的生产性试验研究

以次氯酸钠代替液氯消毒是未来饮用水消毒的重要发展方向,但对于次氯酸钠消毒对供水水质的影响一直缺乏生产性试验研究.以上海2个净水厂实际生产工艺考察了液氯和次氯酸钠2种消毒剂的消毒效果,对于其在微生物消毒效果、消毒副产物生成和对氮磷及有机物去除方面进行了比较分析.研究发现,2种消毒方式对微生物的杀菌效率基本相同,但是次氯酸...     

盖子环替换及定点突变提高菜豆环氧化物水解酶对邻甲基苯基缩水甘油醚的催化性能

菜豆环氧化物水解酶1和2（PvEH1、PvEH2）能够动力学拆分外消旋邻甲基苯基缩水甘油醚（rac-oMGE），从而保留(R)-oMGE。基于对PvEH1和PvEH2结构的同源模拟和分析，发现二者分子中的盖子环差异较大，故本文选择盖子环作为研究目标。经融合聚合酶链式反应（FPCR），获得了PvEH2的盖子环区域被PvEH1对应区域替换的杂合酶Pv2Pv1。用全细胞酶E. coli/pv2pv1催化rac-oMGE，当(S)-oMGE刚好水解完全时，产物(S)-3-邻甲苯基-1,2-丙二醇（(S)-oTPD）的ee_p由PvEH2的58.3%提高至75.5%。为进一步提高酶的性质，在Pv2Pv1中选取11个氨基酸位点进行丙氨酸(A)突变，获得最优突变子E. coli/pv2pv1^K176A，活性为E. coli/pv2pv1（4.2U/g）的2.1倍，且当S构型的底物刚好完全水解时，(S)-oTPD的ee_p进一步提高为80.3%。分子对接分析发现，盖子环替换和K176位点突变为A，均使(R)-oMGE环氧环中的C_α更易受到酶中D101位点的攻击。利用E. coli/pv2pv1^K176A催化150mmol/L rac-oMGE水解制备(R)-oMGE（ee_s＞99%）和(S)-oTPD（ee_p=80.4%），二者的产率Y_S和Y_P分别为32.7%和60.1%，时空产率STY_S和STY_P为1.6g/(L·h)和3.3g/(L·h)。本实验为改善EH的催化性质提供了一种有效策略。     

高铁酸钠溶液的制备及其对染料的脱色作用

采用次氯酸盐氧化法,以次氯酸钠与硫酸铁为原料,现场制备高铁酸钠溶液,确定了铁盐投加量、氢氧化钠投加量、反应温度、反应时间等最佳制备条件,并应用于染料废水。实验结果表明,高铁酸钠溶液最佳制备条件为:10g氢氧化钠,2.80g硫酸铁,反应温度33℃～36℃,反应时间60min。所制备的高铁酸钠摩尔浓度为0.03mol/L。应用于染料废水色度的去除时,其最佳降解工艺参数为:投加的高铁酸钠的体积百分比为1.2%,溶液pH值为中性6～8,反应温度选择室温,反应时间为0～15min时最佳。     

Characterization of four diol dehydrogenases for enantioselective synthesis of chiral vicinal diols

Enantiopure vicinal diols are important building blocks used in the synthesis of fine chemicals and pharmaceutical compounds. Diol dehydrogenase (DDH) mediated stereoselective oxidation of racemic vicinal is an efficient way to prepare enantiopure vicinal diols. In this study, four new bacterial DDHs (AnDDH from Anoxybacillus sp. P3H1B, HcDDH from Hazenella coriacea, GzDDH from Geobacillus zalihae and LwDDH from Leptotrichia wadei) were mined from the GenBank database and expressed in E. coli T7. The four DDHs were purified and biochemically characterized for oxidation activity toward (R)-1-phenyl-1,2-ethanediol, with the optimal reaction condition of pH9.0 (AnDDH), 10.0 (HcDDH) and 11.0 (GzDDH and LwDDH) and the temperatures at 40℃ (AnDDH), 50℃ (HcDDH) and 60℃ (GzDDH and LwDDH), respectively. The four enzymes were stable at the pH from 7.0 to 9.0 and below 40℃. Kinetic parameters of four DDHs showed that the HcDDH from Hazenella coriacea had high activity toward a broad range of vicinal diols. A series of racemic vicinal diols were successfully resolved by recombinant E. coli (HcDDH-NOX) resting cells co-expression of an NADH oxidase (NOX), affording (S)-diols and (1S, 2S)-trans-diols in ≥ 99% ee. The synthetic potential of HcDDH was proved by E. coli (HcDDH-NOX) via kinetic resolution of racemic trans-1,2-indandiol on a 100 ml scale reaction, (S, S)-trans-1,2-indandiol was prepared in 46.7% yield and >99% ee. In addition, asymmetric reduction of four α-hydroxy ketones (10-300 mmol·L^-1) by E. coli (HcDDH-GDH) resting cells resulted in >99% ee and 69-98% yields of (R)-vicinal diols. The current research expands the toolbox of DDHs to synthesize chiral vicinal diols and demonstrated that the mined HcDDH is a potential enzyme in the synthesis of a broad range of chiral vicinal diols.