胶束介质中pH效应对含硫化合物催化降解β-乙二醇苯醚的影响

本文以β-乙二醇苯醚为原料,研究了三种含硫亲核试剂在不同的pH下,5种不同的胶束中及巯基乙醇在两种溶剂中催化降解β-乙二醇苯醚(EGPE)的反应情况。结果发现巯基乙醇在1,4-二氧六环非质子性溶剂中反应速率远远大于在质子性溶剂乙醇。反应速率随着1,4-二氧六环和乙醇的体积的增大而增大,但是当1,4-二氧六环和乙醇的体积增大到14 m L(1,4-二氧六环和乙醇与水的比例为7:3)左右的时候,速率突然有一个突跃,达到最大值,然后随着它们体积的增大,速率减小。同时发现pH值的变化对五种胶束介质中亲核试剂的催化速率均有影响,且随着pH的增大催化EGPE降解的反应速率迅速增加,但是分别在超过它们的p Ka后又急速下降,由此可见,溶剂的极性、介电常数及环境的pH值对亲核试剂的催化活性均有影响。     

钴酞菁/PAN纳米纤维催化PMS降解染料的研究

采用静电纺丝法制备钴酞菁/聚丙烯腈纳米纤维(CoTAPc-PAN-NF),并通过XRD和FTIR对其进行表征。选择偶氮染料酸性红(AR1)为目标污染物,探讨了pH、温度、氧化剂浓度等因素对CoTAPcPAN-NF/PMS体系催化性能的影响,结果表明,随着pH(4~7)的升高、温度的升高以及氧化剂浓度的增加,CoTAPc-PAN-NF/PMS体系的催化活性均能得到一定程度的提高。异丙醇(IPA)的加入明显抑制了CoTAPc-PAN-NF/PMS体系的催化活性,而NaCl的加入较大程度上提高了体系的催化效果,从而推测出CoTAPc-PAN-NF催化PMS降解染料的主要活性种是SO_4~-·和HO·。     

新型Fenton-固定床催化载体的制备及其对造纸废水深度处理的研究

以陶粒填料为载体,采用浸渍-焙烧法制备了新型Fenton-固定床催化载体,考察了FeCl_3溶液浓度和焙烧温度对催化载体催化活性的影响。结果表明,在FeCl_3溶液浓度0.75 moL/L、焙烧温度600℃的条件下,制备得到的催化载体对造纸废水的催化活性最好。将此新型催化载体置于固定床内联合Fenton氧化法进行造纸废水深度处理,在最佳工艺条件(水样初始pH值=5、催化载体添加量10 g/L、0.5 g/L FeSO_4·7H_2O、0.3 mL/L H_2O_2(质量分数30%)、反应时间60 min)下,其对造纸废水COD_(Cr)的去除率为72%。对比3种处理工艺(常规Fenton、填料-Fenton和Fenton-固体床催化载体)可知,达到相同的废水处理效果时,Fenton-固定床催化载体处理工艺所需的药品添加量最少,所需的水样初始pH值最高。     

碳纳米纤维负载钴酞菁催化分解双氧水的研究

通过将四氨基钴酞菁(CoTAPc)以共价键方式负载到碳纳米纤维(CNF)上,制备得到了碳纳米纤维负载钴酞菁催化剂(CoTAPc-CNF)。研究了CoTAPc-CNF对H2O2的催化分解性能,考察了不同底物浓度、pH和温度对CoTAPc-CNF催化分解H2O2的影响。结果表明:随着底物浓度的增加,CoTAPc-CNF催化分解H2O2的速率加快;在碱性条件下,CoTAPc-CNF具有较好的催化分解H2O2性能;温度越高,CoTAPc-CNF催化分解H2O2越快,并求得该催化反应的活化能为17.917kJ/mol。     

改性PAN纤维负载hemin催化降解染料的研究

使用含有偕胺肟基团的改性聚丙烯腈(PAN)纤维作为载体材料,通过轴向配位作用负载氯化血红素(hemin)制备了非均相催化剂hemin-PAN,重点对其在有机染料氧化降解反应中的催化性能进行研究。结果表明,hemin-PAN能够通过活化H2O2催化染料的氧化降解反应,其催化活性与纤维中偕胺肟基团数量密切相关,PAN增重率为14.9%时,hemin-PAN有最高的催化活性;增加催化剂hemin负载量或提高反应温度都有利于染料的氧化降解反应,hemin-PAN(增重率为14.9%,hemin负载量为0.026 mmol/g)催化罗丹明B染料氧化降解反应的活化能为63.83 k J/mol。     

锦纶纤维负载钴酞菁催化氧化酸性红G的研究

将可反应的水溶性钴酞菁(Co-TDTAPc)负载到锦纶纤维上制备了催化功能纤维(F-CoTDTAPc)。利用紫外/可见分光光度法对F-CoTDTAPc/H2O2体系催化氧化酸性红G进行研究,考察了氧化剂质量浓度、pH值、反应温度等对F-CoTDTAPc/H2O2体系氧化降解酸性红G的影响。结果表明,F-CoTDTAPc在H2O2存在下能快速催化氧化酸性红G,并具有较好的原位再生能力。气质联用分析结果表明,酸性红G分子已被氧化降解为可生物降解的脂肪酸类化合物,酸性红G在反应过程中发生了深度氧化降解。     

亚麻催化氧化与碱煮一浴脱胶工艺及其性能

使用棉纺系统进行亚麻纺纱前需经过脱胶处理,为解决传统碱脱胶工艺得到的亚麻纤维白度低和氧化脱胶时纤维易氧化受损、木质素残留造成纤维断裂伸长率低的问题,采用N-羟基-3,4,5,6-四苯基邻苯二甲酰亚胺(NHTPPI)催化氧化与碱煮一浴的方法对亚麻落麻进行脱胶,研究了pH值,反应温度以及催化剂NHTPPI、助催化剂9,10-蒽醌、双氧水、氢氧化钠质量浓度等因素对脱胶后亚麻纤维断裂强度以及白度的影响,得到了NHTPPI催化氧化与碱煮一浴亚麻脱胶的最佳工艺：pH值为10.5,反应温度为83.6℃,NHTPPI、 9,10-蒽醌、双氧水、氢氧化钠质量浓度分别为0.6、 0.5、10.35、5.67 g/L,此优化条件下得到的亚麻纤维断裂强度为4.39 cN/dtex,白度为70.53%。将催化氧化与碱煮一浴脱胶、高碘酸钠氧化脱胶以及传统碱脱胶与双氧水漂白3种工艺进行对比,发现3种工艺得到的纤维主体长度在28 mm左右,白度均在70%以上,但催化氧化与碱煮一浴脱胶得到的亚麻纤维断裂强度最高,处理时间最短。     

快速黏度分析仪表征籼米陈化过程中蛋白质与淀粉相互作用的研究

以新收获籼米为原料,在温度37℃、相对湿度85%条件下储藏20周,采用快速黏度分析仪研究,以不同浓度氯化钠、十二烷基硫酸钠(SDS)、β–巯基乙醇和抗坏血酸为测试溶剂对储藏过程中籼米峰值黏度和回生值的影响。结果发现,随着储藏时间的增加,籼米峰值黏度先上升后下降,回生值则持续上升;随着四种测试溶剂浓度的增加,峰值黏度增加,其中以β–巯基乙醇和SDS为测试溶剂峰值黏度增加最为显著;回生值随氯化钠、β–巯基乙醇和抗坏血酸浓度的增加而下降,随SDS浓度的增加而增加,其中以β–巯基乙醇为测试溶剂回生值下降最为显著。表明陈化导致大米蛋白形成二硫键以及疏水相互作用,通过抑制大米淀粉颗粒的糊化性质从而降低稻米的蒸煮食用品质。     

PAN纤维增强hemin/TiO_2可见光催化性能研究

使用偕胺肟改性聚丙烯腈(PAN)纤维作为载体,通过配位作用同时负载氯化血红素(hemin)和二氧化钛(TiO_2)制备了复合光敏催化材料,在对其表面形貌和光吸收特性进行表征的基础上,考察其在有机染料降解反应中的可见光催化性能。结果表明,hemin/TiO_2能够有效负载于改性PAN纤维表面,而且所制备的催化剂在可见光区显示出较强的吸收性能。通过对染料光催化降解试验发现,纤维载体能够大幅提升hemin/TiO_2的光催化活性,而且其活性与催化剂中hemin含量相关;该复合光敏催化材料具有较宽的pH适用范围,而且增加可见光强度能够提升其光催化活性。     

类芬顿铁基双金属催化过硫酸盐降解苯胺

为了考察类芬顿铁基双金属催化剂催化过硫酸盐降解污染物的效能,以苯胺作为目标污染物,研究了催化剂质量浓度、过硫酸钠质量浓度、pH值和反应时间等因素对苯胺降解的影响规律,并利用紫外光谱检测苯胺降解中特征峰的变化,初步探讨苯胺降解机理。试验结果表明,苯胺去除率随着氧化剂和催化剂质量浓度的增加而提高;随着反应时间的延长而提高;随着pH值增加先增大后减小,并在pH=6时去除率最佳。对比苯胺降解前后的紫外光谱图可知,降解之后的苯胺在波长为545 nm处的特征吸收峰几乎消失,说明苯胺基本降解完全,最终转化为小分子物质CO_2和H_2O。当催化剂质量浓度为0.1 g/L,氧化剂质量浓度为0.1 g/L,pH=6,反应时间达到20 min时,5 mg/L的苯胺废水经过催化氧化后质量浓度低于0.03 mg/L,达到国家标准规定的苯胺排放值以下。     

Characteristics of CuO-MoO3-P2O5 catalyst and its catalytic wet oxidation (CWO) of dye wastewater under extremely mild conditions

In order to develop a catalyst with high activity for catalytic wet oxidation (CWO) processing at lower temperatures (35 degrees C) and atmospheric pressure, a new CuO-MoO3-P2O5 catalystwas synthesized by a solid-state reaction method and was characterized by X-ray diffraction (XRD), Fourier transformation infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), selected area electronic diffraction (SAED), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS) for elemental mapping. Methylene blue (MB) was adopted to investigate the catalytic activity of CuO-MoO3-P2O5 in CWO processing. The results show that this new catalyst has a high catalytic activity to decolorize MB under mild condition. The color removal of MB (the initial concentration was 0.3 g L(-1) and initial pH was 5) can reach to 99.26% within 10 min at 35 degrees C and atmospheric pressure. Catalyst lifespan and selectivity were also tested, and the results show that after the catalyst was used three times, catalyst activity still remains. Selectivity testing shows that CuO-MoO3-P2O5 has high catalytic activity on degradation of MB, whereas this catalyst has less impact on methyl orange (the color removal was 99.65% for MB and 55% for methyl orange under the same conditions). According to the experimental results, a possible mechanism of catalytic degradation of MB was proposed.     

Highly efficient decomposition of organic dyes by aqueous-fiber phase transfer and in situ catalytic oxidation using fiber-supported cobalt phthalocyanine

A novel metallophthalocyanine derivative, cobalt tetra (2,4-dichloro-1,3,5-triazine) aminophthalocyanine (Co-TDTAPc), was prepared and immobilized on cellulosic fiber by covalent bond to obtain a supported oxidation catalyst (Co-TDTAPc-F). Co-TDTAPc-F/H202 system based on phase-transfer catalytic oxidation for decomposing dyes, including acid, reactive, and direct dyes, has been investigated thoroughly. Compared to traditional adsorption technologies and advanced oxidation processes (AOPs) for dye treatment, Co-TDTAPc-F/H202 combines the advantages of both and is more efficient and more effective. Azo dyes such as C. I. Acid Red 1 (AR1) can be quickly adsorbed onto/into the fiber from aqueous solution and decomposed in situ simultaneously in the presence of Co-TDTAPc-F and H2O2. It has been found that the reaction process is not affected by the visible light. Furthermore, it turns the negative effect of NaCl normally observed in homogeneous catalysis into positive one. The catalytic reaction can proceed at a wide pH range from acidic to alkaline. In 60 min, more than 98% of AR1 was eliminated at initial pH 2. In 90 min, about 40% of the carbon was found mineralized as determined by the analysis of the residual total organic carbon. The high-performance liquid chromatography result indicated that a substantial amount of the starting AR1 was converted to other organic products, while gas chromatography/mass spectrometry analysis showed the rest of the carbon existed mainly as small molecular biodegradable aliphatic carboxylic compounds such as oxalic acid, malonic acid, and maleic acid, etc. Co-TDTAPc-F is stable, causes no secondary pollution, and remains efficient in repetitive test cycles with no obvious degradation of catalytic activity.     

Mechanism and kinetics of the catalytic oxidation of aqueous ammonia to molecular nitrogen

Aqueous phase catalytic oxidation of ammonia has been studied over Ru/TiO2 catalyst in a batch reactor by changing the solution pH, concentration of catalyst in the solution, temperature, and reaction time. The oxidation reaction of ammonia over Ru/TiO2 catalyst has been found to take place exclusively for the aqueous NH3 with a preferred mode in strong alkaline pH region. An oxidation reaction pathway has been proposed as follows: Oxidation of ammonia is initiated by the reaction of aqueous ammonia with catalytically activated oxygen. After undergoing further successive oxidation reactions with activated oxygen, ammonia is finally oxidized to a molecule of nitrous acid. Nitrous acid dissociates into a nitrite ion and a proton. The solution pH is decreased with the protons from the dissociation of HNO2 so that the solution concentration of NH4+ is increased. Molecular nitrogen as a final product is produced from the homogeneous aqueous phase reaction between nitrous ion and ammonium ion. Further reaction of nitrous ion with the activated oxygen leads to the formation of nitrate ion. The reaction pathway proposed has been validated with the changes of solution pH along with the ammonia conversions, and the formation of N2 from the solution containing NO2- and NH4+ ions in equimolar amounts of nitrogen has been confirmed in a separate experiment. The kinetics of aqueous ammonia oxidation reaction has been well represented as a first-order reaction with respect to the concentration of aqueous ammonia, and an apparent rate constant has been obtained as a function of catalyst concentration in solution, oxygen pressure, and reaction temperature.     

Heterogenous and homogenous catalytic oxidation by supported gamma-FeOOH in a fluidized-bed reactor: kinetic approach

Oxidation of benzoic acid (BA) by H2O2 was performed with a novel supported gamma-FeOOH catalyst in a circulating fluidized-bed reactor (CFBR). This study focused mainly on determining the proportions of homogeneous catalysis and heterogeneous catalysis in this CFBR. Also studied herein was how pH, H2O2 concentration, and BA concentration affect the oxidation of BA. Experimental results indicate that the decomposition rate of H2O2 was proportional to its concentration and that the oxidation rate of BA depended on both H2O2 and BA concentrations. The change in the rate constant of heterogeneous catalysis by pH was described in terms of ionization fractions of surface hydroxyl group. From the mathematical deduction, we can infer thatthe reaction rate associated with ...Fe(III)OH2+ is markedly higher than that with ...Fe(III)OH. Conclusively, although heterogeneous catalysis contributes primarily to the oxidation of BA at pH 4.4-7.0, the homogeneous catalysis is of increasing importance below pH 4.4 because of the reductive dissolution of gamma-FeOOH.     

催化氧化皂洗在涤纶/棉织物一浴染色中的应用

为提高涤纶/棉织物一浴染色的色牢度和节能减排的水平,开发了一种金属配合物/H₂O₂催化氧化技术用于涤纶/棉针织物一浴法染色后的皂洗工艺。利用理论计算和皂洗实验研究了柠檬酸亚铁和柠檬酸锰2个配合物的催化活性,采用单因素和正交试验探讨了配合物催化氧化皂洗工艺对脱色率和织物表观色深度K/S值的影响,对比研究了催化氧化皂洗与免还原清洗工艺的综合性能。得到最佳的皂洗工艺:1.0%柠檬酸亚铁 1.0 g/L,30%H₂O₂ 3.3 g/L,皂洗温度 85 ℃,皂洗时间 25 min,浴比1:20。结果表明:柠檬酸亚铁具有更高的催化活性和更高的脱色率;催化氧化皂洗的织物各项色牢度(大于4级)优于免还原清洗工艺,残液毒性低,节水节能效果显著,对发展涤纶/棉织物染色的清洁生产具有重要意义。     

Degradation of cationic red GTL by catalytic wet air oxidation over Mo-Zn-Al-O catalyst under room temperature and atmospheric pressure

To overcome the drawback of catalytic wet air oxidation (CWAO) with high temperature and high pressure, the catalytic activity of Mo-Zn-Al-O catalyst for degradation of cationic red GTL under room temperature and atmospheric pressure was investigated. Mo-Zn-Al-O catalyst was prepared by coprecipitation and impregnation. XRD, TG-DTG, and XPS were used to characterize the resulting sample. Central composition design using response surface methodology was employed to optimize correlation of factors on the decolorization of cationic red GTL. The results show that the optimal conditions of pH value, initial concentration of dye and catalyst dosage were found to be 4.0, 85 mg/L and 2.72 g/L, respectively, for maximum decolorization of 80.1% and TOC removal of 50.9%. Furthermore, the reaction on the Mo-Zn-Al-O catalyst and degradation mechanism of cationic red GTL was studied by Electron spin resonance (ESR) and GC-MS technique. The possible reaction mechanism was that the Mo-Zn-Al-O catalyst can efficiently react with adsorbed oxygen/H(2)O to produce ·OH and (1)O(2) and finally induce the degradation of cationic red GTL. GC-MS analysis of the degradation products indicates that cationic red GTL was initiated by the cleavage of -N ═ N- and the intermediates were further oxidized by ·OH or (1)O(2).     

Mechanism of influence of initial pH on the degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation

The influences of initial pH on the degradation efficiency of nitrobenzene in aqueous solution were investigated with a semicontinuous batch reactor in the processes of ozone alone, ozone/ceramic honeycomb, and adsorption of ceramic honeycomb. The results indicated that initial pH significantly affected the concentrations of offgas, residual ozone, and the utilization efficiency of ozone. The experiments also detected the generation of hydroxyl radicals (*OH), the removal of TOC, and the formation and evolution of byproduct at different initial pHs in the ceramic honeycomb catalytic ozonation process. It was found that the systems of different initial pHs exhibited the different extent of the conversion of pH, the leaching of effective components, and the establishment of pH at the point of zero charge (pH(PZC)) in the catalytic oxidation process. The experimental findings presented a good correlation between initial pH and terminal pH and the establishment of pHpzc with terminal pH, and indicated the relationship between the absolute value of the difference between terminal pH and terminal pH(PZC) (A) and the density of surface hydroxyl groups. Based on the correlation between the density of surface hydroxyl groups in the neutral state and A, possible mechanism of influence of initial pH on the degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation was proposed, suggesting that the conversion of initial pH determines the establishment of pHpzc, and the synergistic effect of pH terminal and pHpzc terminal affects the density of surface hydroxyl groups in the neutral state, which controls the concentration of *OH, determining the degradation of nitrobenzene and the formation of byproduct.     

Autoxidation of Methyl Linoleate in Freeze-Dried Model Systems. 4. Effects of Metals and of Histidine in the Absence of Water

SUMMARY: Autoxidation of methyl linoleate dispersed on filter paper was studied in the dry state in the presence and absence of additives. Oxidation was followed volumetrically and by measuring the increase in conjugated dienes. Evaluation of the rate data indicates that added histidine is antioxidant in the very early stages of the oxidation and becomes prooxidant in the later stages. Increasing the concentration of histidine promoted an earlier appearance of its prooxidant effect. Cobalt chloride and manganese sulfate had a pronounced catalytic effect on the oxidation reaction in the model systems buffered to a high (8.0 and 9.0) but not to a low (4.0) pH. Histidine increased the catalytic activity of manganese but eliminated that of cobalt. Thin-layer chromatography showed that conditions under which histidine increased the prooxidant effect of manganese also resulted in the appearance of some decomposition products of histidine. These decomposition products may have catalytic activity.     

静电纺MnO2/PAN纳米纤维膜的制备及其催化氧化甲醛性能

通过液相沉积法制备MnO2,以PAN/MnO2/N,N-二甲基甲酰胺溶液作为纺丝液进行静电纺丝制备出MnO2/PAN纳米纤维膜。利用扫描电镜、透射电镜、傅里叶红外光谱、热重分析对纤维膜的结构和性能进行分析;并在甲醛废水体系中测试纤维膜催化氧化甲醛性能。结果表明：制备的纳米纤维其平均直径为196.46nm;随MnO2质量分数的增大和纺丝电压的增加,纤维平均直径均下降;pH值为2,温度60℃时,具有最佳甲醛催化氧化性能;纤维吸收12h后,对甲醛去除率达到44.0%;MnO2/PAN纤维膜比MnO2粉末具有更好的催化氧化甲醛性能。     

云芝(Coriolus versicolor)木质素过氧化物酶(LiP)酶学性质分析

研究云芝(Coriolus versicolor)产木质素过氧化物酶(Lip)酶活力随时间的变化情况,以及温度、pH 值、金属离子及化合物对云芝LiP 酶活力和稳定性的影响,对该酶底物浓度效应和Km 值进行测定。结果表明：云芝培养12d,其酶活力最高,为72U/mL。该酶的最适温度为40℃,在30～40℃范围内稳定;最适pH 值为2.5,pH 值在2.0～3.5 较稳定;Zn2+ 对LiP 有激活作用,Na+ 对酶活力没有影响,Ca2+、K+、Mg2+、Mn2+、Cu2+ 及EDTA、SDS、β- 巯基乙醇都表现出抑制作用;Km 值为2.05 × 10-4mol/L。