用于水处理过程的铜催化剂制备及性能研究

高效催化臭氧化催化剂的研制是金属催化臭氧化技术发展的重点.采用浸渍法,以Al2O3为载体,制备了铜的负载型金属催化臭氧化催化剂.以松花江水的UV254去除率作为催化剂活性指标,通过正交试验,确定催化剂的最佳制备工艺.使用扫描电镜和比表面测定仪对催化剂结构进行了表征.实验结果表明:当浸渍液浓度为1 mol/L,浸渍时间为6 h,焙烧温度为300 ℃时,所制得的铜催化剂具有很高的催化活性.     

制备生物柴油负载型固体催化剂的研究进展

非均相催化剂的研制一直是生物柴油领域的研究热点,而其中的负载型催化剂以其制备材料广、活性高、重复利用性好等优点成为生物柴油制备的首选催化剂。本研究综述了以金属氧化物及复合物、活性炭和分子筛为主要载体的负载型固体酸碱催化剂最新研究进展,包括催化剂的制备、催化性能和存在的问题。最后,展望了负载型固体催化剂在生物柴油产业的应用前景。     

负载型催化剂催化二氧化碳和环氧化合物共聚的研究进展

为了实现二氧化碳与环氧化合物共聚制备脂肪族聚碳酸酯过程中催化剂的循环利用,提高产物的热力学和力学性能,对其均相催化剂进行载化,即将活性组分/中心负载在无机或高分子载体上是一条有效的途径。文中综述了二氧化碳和环氧化合物共聚中负载型催化剂的研究进展,重点对羧酸锌催化体系、SalenMX催化体系、稀土三元催化体系等不同负载型催化剂的制备方法、催化效率、产物性能及优缺点进行了系统阐述,为负载型催化剂的进一步研究提供了参考。     

聚苯乙烯非均相催化加氢研究进展

随着国民经济发展和人民生活水平的不断提高,聚苯乙烯(PS)产品的多样化、专业化成为了市场竞争和用户需求的发展趋势。聚合物催化加氢工艺作为提高PS专用料性能的重要改性手段,近几年来已成为不饱和聚合物化学改性领域的研究热点。文中主要综述了国内外PS非均相催化加氢制备聚环己烷基乙烯(PCHE)体系中加氢工艺的改进、加氢催化剂的设计优化及反应机理研究的新进展。阐述了催化剂的结构设计、物化性能以及反应过程中传质扩散阻力等对PS加氢活性的影响,探讨了PS非均相催化加氢体系中的"Blocky"加氢机理,提出未来PS非均相加氢催化剂研究重点应该放在催化剂的结构设计上,既要保证聚合物分子与活性中心高接近性,又要实现在加氢体系中的传质扩散与催化剂载体上活性位点高分散的最佳平衡。同时,为进一步提高加氢催化剂的综合性能,需要加强对聚合物加氢反应机理和催化剂合成改性技术的基础性研究。     

NiO-MnO2/Al2O3催化臭氧化催化剂的制备及性能

采用浸渍法,以Al2O3为载体,制备了氧化镍和氧化锰复合的双组分负载型金属催化臭氧化催化剂.以松花江江水中UV254的去除率作为催化剂活性指标,通过正交试验,寻找催化剂的最佳制备工艺.实验结果表明:催化剂的最佳制备工艺为浸渍3h,活性组元体积比1:1,90℃干燥2h,400℃焙烧4h.通过扫描电镜对催化剂结构进行了表征;通过TG-DTA测试,分析了催化剂的热分解过程中反应速率、热效应和物质变化过程;运用XPS分析了催化剂表面元素的组成情况,催化剂的主要活性成分为MnO2.     

生物炭负载金属催化剂的制备及其应用的研究进展

金属具有高活性、选择性等优点被广泛应用于催化领域。近年来,金属催化剂的易失活、中毒等问题严重影响催化技术的发展。由此,研究人员正在探寻比表面积高、孔隙率高、热稳定性良好以及机械稳定性优异的惰性物质作为载体。其中生物炭因其表面官能团丰富,将其作为载体负载金属催化剂可缓解金属的团聚,可有效促进各类催化反应的进行。本文综述了负载金属的生物炭催化剂的研究进展,简述了金属-生物炭催化剂不同炭化方式的优劣,分析了不同改性处理对催化性能的影响。回顾了其在生物柴油、生物油提质、氢化、焦油裂解以及电化学等催化领域方向上的产业应用。分析了在各催化反应中的可能作用机理,为推动国内负载金属生物炭催化剂研究和产业落地发展提供参考。     

载钯高分子载体材料的最新研究进展

高分子催化剂钯作为一种非均相催化剂,它能在合适的反应条件下、高选择性、高效率地催化某些化学反应,并且不会对环境造成污染。本文就高分子催化剂钯的特点和目前适用于负载钯的高分子载体材料的优缺点、研究进展进行了系统的分析和综述,对这些载体材料的发展前景进行了预测。     

用于CO催化氧化的负载型纳米金催化剂的研究进展

CO作为许多工业环境和室内、室外环境的主要有毒气体污染物之一,其消除问题得到了研究者的广泛关注.利用负载型纳米金催化剂在温和条件下催化氧化CO一直是催化领域的研究热点.从载体种类、结构、制备方法和条件的角度阐述了近年来CO催化氧化负载型纳米金催化剂的研究进展,对现阶段研究存在的问题进行了总结,并展望了未来发展前景.     

氧化钴/高炉渣催化剂的丙烷氧化脱氢性能

以攀钢高炉渣为载体,采用固体研磨法负载氧化钴,制备了氧化钴/高炉渣负载型催化剂,并以XRD、 H2-TPR技术对催化剂进行表征,研究了其对丙烷氧化脱氢制丙烯反应的催化性能.实验结果表明氧化钴负载在高炉渣上提高了丙烯选择性,氧化钴的负载量为20%时催化剂表现较好的催化性能,在550℃时丙烷转化率为28.80%,丙烯选择性为35.51%.本实验为资源综合利用及减少环境污染提供了新方法.     

负载型催化剂对风化煤制备腐植酸的影响

以自制碳纳米管(CNTs)为载体,制备了负载型催化剂CeO2/CNTs、TiO2/CNTs和Ce-Ti-Ox/CNTs,并进行了TEM及XRD表征。以所得样品为催化剂用于东都风化煤降解制备腐植酸的研究,探讨了催化剂用量、反应温度及不同负载型催化剂对风化煤降解制备腐植酸的产率、分子结构及吸光度的影响。结果表明,所用负载型催化剂催化性能明显高于未负载的催化剂,能显著提高腐植酸的产率,而且所得腐植酸分子量较小,吸光度较高,其中Ce-Ti-Ox/CNTs催化效果最为显著,可使腐植酸的产率提高到65.43%,表明铈钛活性组分表现出了协同催化效应。     

Heterogeneous catalytic degradation of phenolic substrates: catalysts activity

This review article explored the catalytic degradation of phenol and some phenols derivates by means of advanced oxidation processes (AOPs). Among them, only the heterogeneous catalyzed processes based on catalytic wet peroxide oxidation, catalytic ozonation and catalytic wet oxidation were reviewed. Also selected recent examples about heterogeneous photocatalytic AOPs will be presented. In details, the present review contains: (i) data concerning catalytic wet peroxide oxidation of phenolic compounds over metal-exchanged zeolites, hydrotalcites, metal-exchanged clays and resins. (ii) Use of cobalt-based catalysts, hydrotalcite-like compounds, active carbons in the catalytic ozonation process. (iii) Activity of transition metal oxides, active carbons and supported noble metals catalysts in the catalytic wet oxidation of phenol and acetic acid. The most relevant results in terms of catalytic activity for each class of catalysts were reported.     

Rate constants for the reactions of ozone with chlorophenols in aqueous solutions

The oxidation by ozone of several chlorophenols (CPs): 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4, 6-tetrachlorophenol, tetracholorocatechol (3,4,5, 6-tetrachloro-2-hydroxy phenol) and 4-chloroguaiacol (4-chloro-2-methoxy phenol), is studied in order to provide values of the overall rate constant for the reaction between ozone and these chlorophenols. Single ozonation experiments of 4-chlorophenol were conducted in an homogeneous system, and ozonation reactions of CP mixtures were performed in a heterogeneous system, leading to the evaluation of the overall ozonation rate constants in acidic aqueous solutions. These second order rate constants increase several order of magnitude with the pH as does the degree of deprotonation of the dissolved compounds (i.e. from 10(3) to 10(9)l/(mols) for different CPs). The specific rate constants for the ozonation of the non-dissociated and dissociated forms of the studied CPs are also determined and reported. The values obtained allow calculation of the overall rate constants and prediction of the reactivities of the several CPs at different operating conditions in the whole range of pH.     

Efficient mineralization of dimethyl phthalate by catalytic ozonation using TiO2/Al2O3 catalyst

The removal of dimethyl phthalate (DMP), which is a pollutant of concern in water environments, was carried out by catalytic ozonation with TiO₂/Al₂O₃ catalysts. The heterogeneous catalytic ozonation was an ozonation process combined with the catalytic and adsorptive properties of the TiO₂/Al₂O₃ catalysts to significantly accelerate the mineralization efficiency. Semi-batch ozonation was performed under various experimental conditions including the fed ozone concentration, catalyst type, catalyst dosage, and ultraviolet radiation on the degradation of DMP. The complete removal of DMP was efficiently achieved by both sole and catalytic ozonation; meanwhile, the presence of the catalysts slightly accelerated the elimination rate of DMP. On the other hand, the mineralization efficiency, in terms of total organic carbon (TOC) removal, was substantially enhanced by employing the TiO₂/Al₂O₃ catalyst. The mineralization efficiency using the TiO₂/Al₂O₃ catalyst was the highest, followed in decreasing order by the Al₂O₃ catalyst, the TiO₂ catalyst, and sole ozonation. In addition, the use of the TiO₂/Al₂O₃ catalyst would increase the utilization efficiency of the fed ozone, especially in the late ozonation period. Furthermore, the decrease in the catalytic activity of the TiO₂/Al₂O₃ catalyst after multi-run experiments can be mostly recovered by an incineration process at a high temperature.     

Ozonation of acid yellow 17 dye in a semi-batch bubble column

A semi-batch bubble column was used to evaluate the effect of ozonation on the removal of acid yellow 17 dye from water. Results indicate that ozonation is very effective at removing acid yellow 17 dye from synthetic textile wastewater. The ozone consumed to apparent dye removal ratio ranged from 2 to 15,000 mg ozone per mg of dye decolorized and was dependent on both ozonation time and apparent dye concentration. The biodegradability of the dye wastewater was evaluated by monitoring changes in 5-day biochemical oxygen demand (BOD5) with respect to chemical oxygen demand (COD). Results indicate that the wastewater biodegradability increased with an increase in ozonation time. Film theory was used to kinetically model the gas-liquid reactions occurring in the reactor. Modeling results indicated that during the first 10-15 min of ozonation, the system could be characterized by a fast, pseudo-first-order regime. With continued ozonation, system kinetics transitioned through a moderate then to a slow regime. Successful modeling of this period required use of a kinetic equation corresponding to a more inclusive condition. Model results are presented.     

Color removal of distillery wastewater by ozonation in the absence and presence of immobilized iron oxide catalyst

Ozone is a strong oxidant, which can oxidize both biodegradable and non-biodegradable organics. The main objective of this study was to use iron oxide as a heterogeneous catalyst to enhance the ozone oxidation process. The wastewater used in this study was distillery wastewater, which was diluted 20 times before use. The diluted distillery wastewater was fed continuously in a downflow direction in an ozonation column. The iron oxide catalyst was coated on 10.3mm diameter alumina balls (5.5 m2/g specific surface area) by using Fe(NO3)3 as a precursor. The prepared catalyst was in the form of ferric oxide, and its loading was 0.07%. From the experimental results of both with and without the iron oxide catalyst, an increase in hydraulic retention time resulted in an increase in the treatment efficiencies of both chemical oxygen demand (COD) and color reduction, since the residence time of ozone increased. When the ozone mass flow rate increased, both COD and color reduction increased, resulting from an increase in the hydroxyl radical available in the system. The ozonation system with the iron oxide catalyst gave the highest efficiency in both COD and color removals because the hydroxyl free radical generated from the catalyst is more reactive than the ozone molecule itself.     

Review of strategies for minimizing bromate formation resulting from drinking water ozonation

Ozonation is a more attractive disinfection method than chlorine in that it can meet the current USEPA regulations. Indeed, ozone and its primary reactive products, the hydroxyl free radical (OH^·) especially, are strong oxidizing agents, capable of substantial oxidation. However, ozonation can also lead to the formation of potentially harmful by-products, which can be dealt with either by removing the disinfection by-products themselves or by inhibiting their formation via precursor removal methods and process optimization techniques. This paper provides a review of ozonation and by-product formation chemistry, effective approaches toward the control of bromate formation, and bromate precursor removal technologies.     

Catalytic ozonation of p-chlorobenzoic acid by activated carbon and nickel supported activated carbon prepared from petroleum coke

The aim of this research was to investigate catalytic activity of petroleum coke, activated carbon (AC) prepared from this material, Ni supported catalyst on activated carbon (Ni/AC) in the ozonation of aqueous phase p-chlorobenzoic acid (p-CBA). Activated carbon and Ni/AC catalyst were characterized by XRD and SEM. The presence of petroleum coke did not improve the degradation of p-CBA compared to ozonation alone, but it was advantageous for p-CBA mineralization (total organic carbon, TOC, reduction), indicating the generation of highly oxidant species (*OH) in the medium. The presence of either activated carbon or Ni/AC considerably improves TOC removal during p-CBA ozonation. Ni/AC catalyst shows the better catalytic activity and stability based on five repeated tests during p-CBA ozonation. During the ozonation (50 mg/h ozone flow rate) of a 10 mg/L p-CBA (pH 4.31), it can be more mineralized in the presence of Ni/AC catalyst (5.0 g/L), TOC removal rate is over 60% in 60 min, 43% using activated carbon as catalyst, only 30% with ozonation alone.     

Treatability of a simulated disperse dye-bath by ferrous iron coagulation, ozonation, and ferrous iron-catalyzed ozonation

Dyeing and finishing of textile yarns and fabrics are extremely important processes in terms of both quality and environmental concerns. Among the commercial textile dyes, particularly disperse dyestuffs are of environmental interest because of their widespread use, their potential for formation of toxic aromatic amines and their low removal rate during aerobic waste treatment as well as advanced chemical oxidation. Thus, in the present paper ferrous iron coagulation, ozonation and ferrous iron-catalyzed ozonation were employed at varying pH (3-13) and Fe(II)-ion doses (0.09-18mM) for the treatment of a simulated disperse dye-bath (average initial apparent color as absorbance at 566nm=815.4m(-1); COD(0)=3784mgl(-1); TOC(0)=670mgl(-1); BOD(5,0)=58mgl(-1)) that more closely resembled an actual dyehouse effluent than an aqueous disperse dye solution. Coagulation with 5000mgl(-1) FeSO4-7H2O (18mM Fe(2+)) at pH 11 removed up to 97% color and 54% COD, whereas oxidation via ozonation alone (applied ozone dose=2300mgl(-1)) was only effective at pH 3, resulting in 77% color and 11% COD removal. Fe(II)-ion-catalyzed ozonation (3.6mM Fe(2+) at pH 3; Fe(2+):O3 molar ratio 1:14) eliminated 95% color and 48% COD and appeared to be the most attractive option among the investigated chemical treatment methods as for its applicability at the natural acidic pH of the disperse dye-bath effluent and at relatively low Fe(2+)-ion doses as compared to ferrous sulfate coagulation. However, no TOC reduction was observable for ozonation and catalytic ozonation at the investigated reaction conditions (14gl(-1) O3 at pH 3). An average six-fold enhancement in the biodegradability parameter of the synthetic dye wastewater expressed in terms of the BOD(5)/COD ratio could be achieved by the investigated chemical treatment methods.     

Sulfamethoxazole abatement by means of ozonation

Sulfamethoxazole (SMX) is a bacteriostatic antibiotic largely used for diverse types of illness. Its widely use in humans and even in animals releases unmetabolized and active metabolites that have a strong potential in terms of effect in organisms. In this work, 200 mg L⁻¹ solution of sulfamethoxazole was treated by ozonation at different pH. Results showed that ozonation was proved to be an efficient method to degrade sulfamethoxazole. After 15 min of ozonation (corresponding dose = 0.4 g of ozone L⁻¹), the complete antibiotic abatement was almost achieved with just 10% of mineralization. The biodegradability and toxicity of the ozonation intermediates were also studied. A biodegradability enhancement (increment of BOD₅/COD ratio) from 0 to 0.28 was observed after 60 min of ozonation. The acute toxicity of the intermediates was followed by the Microtox^® test and the toxicity profile showed a slight acute toxicity increment in the first stage of ozonation. The pH variation had an important role in the TOC and COD removal, promoting their growth with the increment of alkalinity. The second order kinetic constants for the ozonation of the SMX in an order of magnitude of 10⁵ L mol⁻¹ s⁻¹ were also determined for pH 5 and 7.     

Application of electrochemically generated ozone to the discoloration and degradation of solutions containing the dye Reactive Orange 122

Aqueous solutions containing the commercial azo dye Reactive Orange 122 (RO122) were ozonated in acid and alkaline conditions. Ozone was electrochemically generated using a laboratory-made electrochemical reactor and applied using semi-batch conditions and a column bubble reactor. A constant ozone application rate of 0.25gh(-1) was used throughout. Color removal and degradation efficiency were evaluated as function of ozonation time, pH and initial dye concentration by means of discoloration kinetics and COD-TOC removal. Experimental findings revealed that pH affects both discoloration kinetics and COD-TOC removal. A single pseudo-first-order kinetic rate constant, k(obs), for discoloration was found for ozonation carried out in alkaline solutions, contrary to acidic solutions where k(obs) depends on ozonation time. COD-TOC removal supports degradation of RO122 is more pronounced for alkaline conditions. Evaluation of the oxidation feasibility by means of the COD/TOC ratio indicates that the ozonation process in both acid and alkaline conditions leads to a reduction in recalcitrance of the soluble organic matter.