Photochemically enhanced degradation of phenol using heterogeneous Fenton-type catalysts

The degradation of phenol was carried out using heterogeneous Fenton-type catalysts in the presence of H_2O_2 and UV. Catalysts were prepared by exchanging and immobilizing Fe 2+ in zeolite 13X, silica gel or Al_2O_3. The concentration of phenol solution was 100 mg/L. The amount of H_2O_2 added was the stoichiometric amount of H_2O_2 required for the total oxidation of phenol. Under the irradiation of medium pressure light (300 W) phenol was mineralized within 1 h in the presence of Fe 2+/zeolite 13X. The COD removal rate was enhanced in the presence of Fe 2+/zeolite 13X compared to that of Fe 2+/silica gel or Fe 2+/Al_2O_3. Analogous homogenous photo-Fenton reaction with equivalent Fe 2+ was also carried out to evaluate the catalysis efficiency of Fe 2+/zeolite 13X. Results showed that the COD removal rate was near to that of homogeneous Fenton, while heterogeneous Fe 2+/zeolite 13X catalyst could be recycled.

EFFECTS OF ORGANIC COLORANTS ON PHOTO-INITIATED CROSSLINKING AND PHOTO-OXIDATION DEGRADATION OF POLYETHYLENE AND RELATED MECHANISM

The effects of three organic colorants on photo-initiated crosslinking and photo-oxidation degradation of polyethylene (PE) samples irradiated by microwave excited (MWE) UV lamp in the melt and the related mechanism have been studied by gel content and thermal extension rate determinations,X-ray photoelectron spectroscopy (XPS),mechanical property tests,UV spectroscopy,and light microscope.The data from the gel content and thermal extension rate determinations of photo-crosslinked polyethylene (XLPE) sample...

Degradation of Residual Formaldehyde in Fabric by Photo-catalysis

The residual formaldehyde （HCHO） in fabric was degraded using photo-catalysis assisted by the compound catalyst of nano-TiO2 and nano-ZnO. The effects of several factors on the degradation, such as the composing of catalyst, irradiation time, pH value and the H2CHO concentration of the immersed solution were investigated. Results showed that H2CHO of the immersed solution had degraded 93% after 5 h irradiation, and the degradation ratio of formaldehyde could be improved and the aging of the fabric can be avoided with the addition of ZnO nanoparticles and pH value of the immersed-fibric solution. The fabric with residual formaldehyde about 1 800 μg/g can be efficiently treated to satisfy the China National Standard （GB/2912.1-1998） with the photo-catalytic degradation.

WO3 nanofibers on ACF by electrospun for photo-degradation of phenol solution

Electrospun WO_3 nanofibers were fabricated by coaxial electrospinning and directly annealing WCl_6/polyvinylpyrrolidone(PVP) nanofibers on activated carbon fibres(ACF), and characterized by scanning electron microscopy(SEM) and X-ray diffractometry(XRD). The most suitable condition for electrospinning is the mass ratio of WCl_6 to PVP 0.6, appropriate amount DMF and ethanol, a voltage of 28 kV, the reception distance of 15 cm, the humidity range within 10% and 20% and the moving rate of the pump 0.001 mm/s. The photocatalytic activities of WO_3 nanofibers were evaluated by the photo-degradation of phenol solution under the irradiation of 500 W xenon lamp. The results showed that, the sizes of the fibers are about 100 nm, and after being photodegraded for 210 min, the concentration of phenol decreased from 20.05 mg/L to 8.60 mg/L. Thus, the photo-degradation rate of WO_3 nanofibers for phenol solution is 2.87 mg/(L·h).

Investigations on the Degradation of Triazine Herbicides in Water by Photo-Fenton Process

In this work, the degradation of 2-chloro-4,6-diamino-1,3,5-triazine in aqueous solutions by photo-Fenton process has been investigated. The preliminary results have shown that the degradation of 2-chloro-4,6-diamino-1,3,5-triazine by photo-Fenton process is more rapid and more effective than Fenton and UV/H2O2 processes. The effects of certain experimental parameters on kinetics and efficiency of the degradation of 2-chloro-4,6,-diamino-1,3,5-triazine by photo-Fenton process, have been evaluated. Under optimal conditions, photo-Fenton process achieved more than 90% of chloride release and about 30% of nitrate formation. The results of total organic carbon (TOC) and total Kjeldahl nitrogen (TKN) analyses have shown that no carbon dioxide and ammonia are formed during photo-Fenton treatment of aqueous solutions containing 40 mg/L triazine. These results indicate that only substituent groups of triazine ring are released;however, nitrogen atoms of triazine ring remain unaffected. A simple mechanism of degradation of 2-chloro-4,6-diamino-1,3,5-triazine has been proposed. The degradation starts by a rapid release of chlorine atoms as chloride ions to form 2-hydroxy-4,6-diamino-1,3,5-triazine. The amino groups of 2-hydroxy-4,6-diamino-1,3,5-triazine undergo are oxidized into nitro groups by hydroxyl radicals to form 2-hydroxy-4,6-dinitro-1,3,5-triazine which undergoes a slow release of nitro groups and their substitution with hydroxyl groups to form cyanuric acid and nitrate ions. The degradation of cyanuric acid by photo-Fenton process has also been investigated. The results of TOC and TKN analyzes show that no carbon dioxide is formed during the treatment.

Studies on Photocatalytic Degradation of Acridine Orange and Chloroform Sensing Using As-Grown Antimony oxide Microstructures

Flower shaped antimony oxide (Sb2O3) microstructures were synthesized in a large quantity via simple solution method using aqueous mixtures of antimony chloride and hexamethylene diamine (HMDA). The morphological characterizations were done by field emission scanning electron microscopy (FESEM), which revealed that the synthesized products possess flower-shaped microstructures. The detailed structural characterizations performed by X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FT-IR) and Raman spectrophotometer confirmed that the synthesized microstructures are well-crystalline antimony oxide. The Energy dispersive spectroscopy (EDS) shows that the grown products are composed of Sb and O. Optical properties of the synthesized products were characterized by UV-Visible spectrophotometer which exhibits a well defined peak at ~ 291.0 nm. The photo-catalytic activity of the Sb2O3 microstructures was evaluated by degradation of acridine orange (AO), which mineralized almost 63.0% in 150 min. The chemical sensing properties of Sb2O3 microstructures was also studied by I-V technique using chloroform as a detecting solvent. The fabricated chloroform sensor demonstrates good sensitivity of 0.1154 μA cm–2 mM–1, lower-detection limit (~0.1 mM), large-linear dynamic range (LDR, 0.122 mM to 1.22 M) with linearity (R = 0.7898) in short response time (10.0 sec).

Facile Preparation of PVA-AA/TiO2 Composite Gel Particles and Their Tunable Photo-catalytic Property for the Degradation of Methyl Orange

In the presence of titanium dioxide powder, cross-linking reaction between commercial polyvinyl alcohol(PVA)-based macromonomer and acrylic acid(AA) was initiated with potassium persulfate in an emulsifying system. As a result, PVA-AA/TiO2 composite gel particles were obtained. The morphology and composition of the particles were analyzed with scanning electron microscopy(SEM), energy scattering x-ray spectroscopy(EDS), Fourier infrared spectroscopy(FTIR), and thermogravimetric analysis(TGA). The analysis results confirmed that the particles were the expected ones. TiO2 was dispersed homogeneously within the spheroidal particles. Compared to the control gel, the composite gel particles not only contained Ti element but also showed higher thermal stability. In addition, the photo-catalytic behavior of the particles for the degradation of methyl orange contained in aqueous solution was examined. The particles exhibited photocatalytic characteristic for the degradation of the model dye, which could be modulated by simply varying the amount of cross-linking agent or TiO2. The photo-catalytic degradation percentage of methyl orange maintained at 91%-96% after using the particles three times, which indicated that TiO2 could played its role repeatedly via being fixated within polyvinyl alcohol-based gel.

玻纤负载α-Fe_(2)O_(3)/CuFe_(2)O_(4)异质结薄膜的制备 及其催化性能

为了克服传统芬顿催化剂的降解速率慢、pH适用范围窄、难回收等缺点,采用浸涂溶胶-凝胶法制备了玻璃纤维负载的α-Fe_(2)O_(3)/CuFe_(2)O_(4)异质结薄膜(FCGF),对其结构、形态和化学组成进行表征,并将其用于亚甲基蓝的光芬顿催化降解,考察其催化活性、pH值适用性和重复使用稳定性。结果表明:CuFe2O4颗粒生长在α-Fe_(2)O_(3)颗粒表面,形成α-Fe_(2)O_(3)/CuFe_(2)O_(4)异质结;在模拟太阳光辐射条件下,加入2 g FCGF和20 mmol/L的H_(2)O_(2),50 mL质量浓度为30 mg/L的MB溶液在40 min后降解率达到97%,而在相同条件下加入α-Fe_(2)O_(3)与CuFe_(2)O_(4)降解率分别为20%和30%,其催化活性的增强可归因于异质结光催化剂产生的光诱导电位差驱动的光生载流子的有效分离;同时,FCGF在宽pH范围显示出较高活性,pH=10时,MB溶液40 min后降解效率仍达到63%;FCGF具有良好的稳定性,5次循环后其催化性能没有衰减,反应40 min后MB降解率仍可达97%。

TiO_(2)光阳极材料光-电催化降解恩诺沙星影响因素研究

制备二氧化钛(TiO_(2))光阳极材料,通过表征手段考察其形貌、晶相与元素组成特征。TiO_(2)纳米棒形成纳米管阵列,在XRD图谱27.5°、36.1°、37.8°和62.7°处有明显特征峰,无明显杂峰,Ti元素以Ti^(4+)的形式存在。选取一种喹诺酮类抗生素恩诺沙星(ENR)作为目标污染物,探究光-电催化体系下TiO_(2)光阳极材料对ENR降解的影响因素。实验结果表明,ENR初始浓度为10mg/L,电解质NaCl浓度为0.10mol/L,外加偏压为1.2V,初始pH值为7时,TiO_(2)光阳极材料对ENR的光-电催化降解率可达90.74%,经四次循环实验材料保持了良好的稳定性,在抗生素降解方面具有较大的应用潜力。

Degradation of Microcystin-RR by Combination of UV/H_2O_2 Technique

The experiments were performed to investigate the degradation of microcystins in order to assess the effectiveness and feasibility of UV/H2O2 system for the disinfection of water polluted by microcystins. The influence factors such as H2O2, pH and UV light intensities were investigated respectively. Degradation of microcystin-RR （MC-RR） could be fitted by either the pseudo-first-order or second-order rate equations. This homogenous system could significantly enhance the degradation rate due to the synergetic effect between UV and H2O2. The degradation mainly followed the mechanism of direct photolysis and .OH oxidation reactions. Experimental results showed that 94.83% of MC-RR was removed under optimal experimental conditions and the UV/H2O2 system provided an alternative to promote the removal of microcystins in drinking water supplies.

Photo Degradation of Dyes from Their Aqueous Solutions of Their Binary Mixture, Using TiO2 as the Oxidant with Different Sources of Energy

The photodegradation has been widely used in water and waste water treatment of all the methods like froth flotation coagulation etc., photodegradation appears to offer the best prospects for overall treatment of dyestuff effulent. Photodegradation of aniline blue and crystal violet dyes from aqueous solutions of their binary mixture was carried out using TiO2 as photocatalyst. By carrying out photodegradation, varying the experimental parameters, the optimum conditions required for maximum degradation was found out. The photodegradation of dye was carried out using different sources of energy like solar radiation and microwave radiation. The degradation studies were carried out at temperatures 25 ℃, 35 ℃ and 45 ℃ so as to calculate the rate constant and activation parameters. Both energy sources are equivalent in causing degradation in all respects except time and dose of photo catalyst. Time required is less for microwave than solar radiation, but dose of photo catalyst needed was high for microwave radiation. These results will be helpful in designing effluent treatment plants in industries.

Effects of Cu(Ⅱ) or Zn(Ⅱ) on photodegradation of some toxic organic compounds in wastewater by using TiO_2 as catalyst

The effects of Cu (Ⅱ) or Zn (Ⅱ) on the photo-catalytic degradation of some organic chemicals in water, such as acetone, phenol, dyes, and tea saponin were studied. Dyes in wastewater from a textile factory can be effectively degraded by photo-catalysis with TiO 2 and ultraviolet light or sunshine, but the reaction rate could be slowed down if copper or zinc salt exists in the solution.

Fenton及Photo-Fenton非均相体系降解有机污染物的研究进展

Fenton及photo-Fenton氧化法是一种有效的应用于环境污染物处理领域的高新氧化技术之一,对Fenton试剂的固定化可以减少铁离子的二次污染,提高催化能力和光利用率,及扩展pH等优势。本文综述了近年来Fenton及photo-Fenton非均相体系氧化降解有机污染物的研究状况。引用文献57篇。

Fenton及Photo-Fenton氧化处理垃圾渗滤液的研究

通过Fenton高级氧化方法对宜昌市黄家湾垃圾处理厂的垃圾渗滤液进行了氧化降解处理,考察了Fe2+、H2O2的用量和pH等因素对垃圾渗滤液COD去除率的影响,研究了引入可见光的情况下加入C2O4-2与Fe2+的比对降解效果的影响,在pH=3.0,H2O2的量为2.0×10-2mol/L,Fe2+的量为2.3×10-3mol/L的条件下,可使垃圾渗透液的COD去除率达70.0%,在加入一定量的草酸根离子(C2O4-2/Fe2+为0.67)的可见光协助下和引入紫外光都能够极大地提高Fenton试剂对垃圾渗滤液的氧化降解的效果,并比较了在不同条件及光源下Photo-Fenton对此垃圾渗滤液的氧化降解.

Photo-Fenton技术处理难降解有机废水的研究进展

Photo-Fenton氧化法是将紫外或可见光引入到Fenton体系中形成的一种高级氧化技术.介绍了Photo-Fen-ton技术处理难降解有机废水的作用机理,探讨了不同外界影响因素对处理效果的影响,阐述了该技术在水处理中研究和应用的最新进展,并提出了Photo-Fenton试剂的发展方向和前景.

Iron–doped bismuth oxybromides as visible-light-responsive Fenton catalysts for the degradation of atrazine in aqueous phases

Pesticides and its degradation products,being well–known residues in soil,have recently been detected in many water bodies as pollutants of emerging concerns,and thus there is a contemporary demand to develop viable and cost–effective techniques for the removal of related organic pollutants in aqueous phases.Herein,a visible-light-responsive Fenton system was constructed with iron–doped bismuth oxybromides(Fe–BiOBr)as the catalysts.Taking the advantage of sustainable Fe(Ⅲ)/Fe(Ⅱ)conversion and optimized H_(2)O_(2)utilization,the optimal Fe–BiOBr–2 catalyst showed an excellent atrazine removal efficiency of 97.61%in 120 min,which is superior than the traditional homogeneous Fenton and the majority of heterogeneous processes documented in the literature.In this photo–Fenton system,hydroxyl(·OH)and superoxide(·O_(2)^(-))radicals were dominant active species contributed to the oxidative degradation of atrazine.Due to the production of various active radicals,five degradation pathways were proposed based on the identification of intermediates and degradation products.Overall,this work not only demonstrates a fundamental insight into creating highly efficient and atom economic photo-Fenton systems,but also provides a complementary strategy for the treatment of organic pollutants in water.

Preparation and Characterization of Fe^(3+)-doped Nanometer TiO_2 Photocatalysts

Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.

photo-Fenton试剂法降解硝基苯废水

应用photo-Fenton过氧化过程研究对硝基苯水溶液的降解。测定反应物质量质量浓度、温度和pH对硝基苯降解的影响。使photo-Fenton法更加有效的降解水溶液中的硝基苯。在pH等于3、初始质量质量浓度H2O2为200 mg/L、Fe2+为30 mg/L条件下仅在30min内应用photo-Fenton法可将硝基苯降解50%左右(硝基苯初始质量浓度为200 mg/L)完全降解。

立方体形α-Fe_(2)O_(3)光催化剂的合成及其可见光芬顿降解抗生素

抗生素的滥用和生产废水的无序排放造成了水体中抗生素污染问题日益严重。通过溶剂热法合成了立方体形貌的α-Fe_(2)O_(3)光芬顿催化剂,采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)等方法对其微观结构、物相等进行了表征。以盐酸四环素(TC)为模型抗生素污染物,研究了新型催化剂对TC的吸附和光芬顿降解性能,并探究了催化剂浓度、H_(2)O_(2)加入量、LED光源波长和pH等因素对TC降解效果的影响规律。结果表明,该工作成功合成出了粒径分布均一且具有立方体形貌的α-Fe_(2)O_(3),其对TC的吸附在30 min内即可达到平衡,吸附量可达7.06 mg/g。当TC的初始质量浓度为20 mg/L、α-Fe_(2)O_(3)催化剂的质量浓度为0.5 g/L时,采用可见光LED光源光芬顿降解30 min,TC的去除率可达80%以上。

具有孪晶结构的红细胞状硫化铜的制备及其光-芬顿催化性能

采用简单的溶剂热法制备出具有孪晶结构的红细胞状硫化铜材料。研究不同前驱体比例和反应时间对硫化铜产物微观形貌的影响,并对孪晶结构红细胞状硫化铜可能的形成机理进行分析。在可见光照射下孪晶结构红细胞状硫化铜与H_(2)O_(2)组成的类芬顿系统表现出优异的降解性能,光照50 min后,亚甲蓝降解率可达95%。对比孪晶结构红细胞状硫化铜与合成的花球状硫化铜的催化性能,结果表明含有孪晶结构的红细胞状硫化铜对亚甲蓝的降解性能更好,说明孪晶的存在有利于加速光生电子-空穴的分离。