水中除草剂阿特拉津降解的高级氧化技术

近年来水体除草剂污染问题越来越严重,阿特拉津是目前应用广泛的化学除草剂之一,阿特拉津施用后在水中的残留对人类健康产生了极大威胁。综述了电化学Fenton法、γ-辐照法、超声化学法、催化臭氧氧化法、光催化法等各种高级氧化技术降解阿特拉津的效果、影响因素,同时阐述了可能的降解产物和降解机理,提出了今后水中阿特拉津处理方面应该进一步研究的问题。     

阿特拉津的化学降解性研究进展

阿特拉津作为一种高效廉价的三嗪类除草剂被广泛应用于农业生产中。但其结构稳定,不易降解,具有一定的毒性和生物蓄积性,会给环境和人类带来危害。因此,如何高效去除水环境中残留的阿特拉津成为研究热点。由于在自然环境中阿特拉津被生物降解的速度慢,半衰期长,本文将重点对采用化学降解方法降解农药阿特拉津的研究进展进行系统的综述。总体来说,目前有多种方法可以不同程度的降解阿特拉津,各有其优势和不足。其中阿特拉津光催化降解法绿色、环保,极具发展潜力,是未来重点发展的方向。阿特拉津的化学降解性尚需进一步研究。     

TiO2光催化技术在气态污染物降解的应用研究

综述了TiO_2光催化氧化技术在降解气态污染物方面的应用及其提高TiO_2光降解气态污染物性能的方法,并提出了TiO_2光催化剂在未来发展中需要解决的问题。     

TiO_2光催化降解废水中多环芳烃的研究进展

多环芳烃是一类对人身和环境安全有着巨大危害的有机污染物。光催化氧化技术可以在相对温和的反应条件下实现多环芳烃的无害化处理。高效的光催化过程是制约该技术发展的关键。本文主要介绍了TiO_2基光催化剂的催化机理,并根据不同的增强光催化效率的途径,介绍了TiO_2光催化降解水中多环芳烃的研究进展。     

TiO_2光催化剂的制备及应用进展

光催化氧化技术具有高效、节能、适用范围广、氧化能力强可彻底去除污染物、不产生二次污染等优点,是近年来新兴起的一种环保技术。TiO_2光催化剂以其催化活性高、无毒价廉等优势成为半导体光催化剂研究的热点。本文从TiO_2光催化机制、制备方法以及性能改良和应用等方面,对近年来TiO_2光催化技术进行了简单介绍,并提出TiO_2光催化技术在未来的研究进程中亟待解决的问题。     

改性TiO_2光催化剂催化降解双酚A的研究进展

内分泌干扰物双酚A的污染日益严重,对人体健康和水生生物产生很大负面影响。光催化氧化法是废水净化常用的一种高级氧化技术。TiO_2是研究最多、最具潜力的光催化剂之一,但其带隙较宽、电子-空穴复合率较大而无法大规模应用,因此对TiO_2光催化剂进行改性得到广泛关注。介绍了近年来改性TiO_2光催化剂降解双酚A的研究进展,并提出改性TiO_2光催化剂今后的研究方向。     

光催化降解阿特拉津的研究

以浸渍法自制复合型光催化剂铁改性金红石TiO2,以阿特拉津为目标物,在pH=3的条件下,考察铁改性金红石TiO2经可见光催化H2O2对阿特拉津的降解情况.结果表明,此反应15min,阿特拉津的降解率达到95％以上.探讨了催化剂的投量、反应体系H2O2的初始浓度、反应体系初始pH值、阿特拉津初始质量浓度、催化剂含铁量等对...     

纳米二氧化钛光催化及其降解印染废水研究进展

TiO_2光催化氧化技术在污水治理上显示出巨大的优越性,从光催化原理着手,详细阐明了光催化动力学过程包括初级反应过程和次级反应过程,并对当前TiO_2光催化降解印染废水进行综述。基于对印染废水传统处理手段的分析,认为TiO_2光催化氧化技术是一种有前景和工业化应用价值的污水处理方法。最后,对于TiO_2光催化在光催化降解印染废水的未来发展提出四点看法,包括效率优先、兼顾固定、微观机理、宏观应用。     

纳米二氧化钛光催化及其降解印染废水研究进展

TiO_2光催化氧化技术在污水治理上显示出巨大的优越性,从光催化原理着手,详细阐明了光催化动力学过程包括初级反应过程和次级反应过程,并对当前TiO_2光催化降解印染废水进行综述。基于对印染废水传统处理手段的分析,认为TiO_2光催化氧化技术是一种有前景和工业化应用价值的污水处理方法。最后,对于TiO_2光催化在光催化降解印染废水的未来发展提出四点看法,包括效率优先、兼顾固定、微观机理、宏观应用。     

光催化氧化技术在处理甲醛中的研究进展

介绍了甲醛的危害来源、归纳了吸附法、植物净化法、负离子法、微生物降解法等降解甲醛的主要优缺点，分析了光催化氧化技术的工作原理，叙述了光催化氧化技术在甲醛处理中的具体应用。最后针对现阶段室内甲醛净化面临的问题和挑战，进行展望。光催化氧化技术对于室内甲醛的降解提供了一种高效污染物去除的新思路，提出进一步加强对光催化氧化反应的特性研究、新型高效的光催化剂开发以及光催化剂的改性，同时指出实验室基础研究与生活实际要有机结合，最终实现光催氧化技术在提高室内的空气品质方面的应用。     

The effect of platinum and silver deposits in the photocatalytic oxidation of resorcinol

The effects of platinum (Pt) and silver (Ag) metallisation in the photocatalytic oxidation of resorcinol at pH 3 ± 0.5 have been investigated. The photocatalytic degradation of resorcinol was significantly improved by Pt/TiO₂, while the presence of Ag/TiO₂ enhanced the initial photocatalytic degradation rate of resorcinol slightly. Likewise, the photocatalytic mineralisation of resorcinol continued to be enhanced by Pt/TiO₂, but it was retarded when Ag/TiO₂ was used.

The function of Pt and Ag deposits on the surface of TiO₂ has been found to be markedly influenced by the interaction of resorcinol and its degradation products with the metal deposits. The presence of Pt or Ag on the surface of TiO₂ altered the distribution of degradation products of resorcinol as well as the production of photoactive species for the photocatalytic oxidation of resorcinol. The X-ray photoelectron spectroscopy (XPS), zeta potential and transmission electron microscopy (TEM) analyses have indicated that the contrasting effect of Pt and Ag deposits were governed by the oxidation states and the catalytic property of metal deposits. In addition to that, it has been found that the roles of metal deposits are specific and should not be generalised.     

Photocatalytic degradation of organic compounds diluted in water using visible light-responsive metal ion-implanted TiO2 catalysts: Fe ion-implanted TiO2

The application of metal ion-implantation method has been made to improve the electronic properties of the TiO₂ photocatalyst to realize the utilization of visible light. The photocatalytic properties of these unique TiO₂ photocatalysts for the purification of water have been investigated. By the metal ion-implantation method, metal ions (Fe⁺, Mn⁺, V⁺, etc.) are accelerated enough to have the high kinetic energy (150 keV) and can be implanted into the bulk of TiO₂. TiO₂ photocatalysts which can absorb visible light and work as a photocatalyst efficiently under visible light irradiation were successfully prepared using this advanced technique. The UV-Vis absorption spectra of these metal ion-implanted TiO₂ photocatalysts were found to shift toward visible light regions depending on the amount and the kind of metal ions implanted. They were found to exhibit an effective photocatalytic reactivity for the liquid-phase degradation of 2-propanol diluted in water at 295 K under visible light (λ>450 nm) irradiation. The investigation using XAFS analysis suggested that the substitution of Ti ions in TiO₂ lattice with implanted metal ions is important to modify TiO₂ to be able to adsorb visible light.     

Degradation of pesticides in water using solar advanced oxidation processes

Alachlor, atrazine and diuron dissolved in water at 50, 25 and 30 mg/L, respectively were photodegraded by Fe²⁺/H₂O₂, Fe³⁺/H₂O₂, TiO₂ and TiO₂/Na₂S₂O₈ treatments driven by solar energy at pilot-plant scale using a compound parabolic collector (CPC) photoreactor. All the advanced oxidation processes (AOPs) employed mainly compared the TOC mineralisation rate to evaluate treatment effectiveness. Parent compound disappearance, anion release and oxidant consumption are discussed as a function of treatment time. The use of Fe²⁺ or Fe³⁺ showed no influence on the reaction rate under illumination and the reaction using 10 or 55 mg/L of iron was quite similar. TiO₂/Na₂S₂O₈ showed a quicker reaction rate than TiO₂ and a similar rate compared to photo-Fenton. The main difference found was between TiO₂/Na₂S₂O₈ and photo-Fenton, detected during atrazine degradation, where pesticide transformation into cyanuric acid was confirmed only for TiO₂/Na₂S₂O₈.     

Optimisation of degradation conditions of 1,8-diazabicyclo[5.4.0]undec-7-ene in water and reaction kinetics analysis using a cocurrent downflow contactor photocatalytic reactor

The photocatalytic degradation of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, a non-biodegradable nitrogenous organic compound) in water was optimised under UV radiation using titanium dioxide photocatalyst. The reactor used was a pilot scale cocurrent downflow contactor photocatalytic reactor (CDCPR), a system offering very high mass transfer efficiency. The effect of photocatalyst loading, initial substrate concentration, temperature, pH, and different combinations of UV, O₂, H₂O₂ and TiO₂ on the photocatalytic oxidation of DBU was investigated. The TiO₂ photocatalyst used was Degussa VP Aeroperl P25/20, a granulated form of Degussa P-25, recently developed to ameliorate downstream catalyst separation problems. The CDCPR was fitted with an internally and vertically mounted 1.0 kW UV lamp. The reactions were carried out at 40–60 °C and 1 barg, with the reactor being operated in closed loop recycle mode and suspended photocatalyst being re-circulated. Optimisation of reaction conditions using a combination of TiO₂, UV radiation and O₂ gave the most rapid degradation and mineralisation of the DBU in comparison with other processes. Under optimised conditions, 100% degradation of DBU was achieved in 45 min, with a quantum yield of 7.39, using a 1 kW lamp, 0.5 g/dm³ TiO₂, 100 mg/dm³ DBU, 1 barg, 50 °C and pH of 3.17. Investigating the reaction pathway and its modelling showed a first order dependency, incorporating the effect of first intermediates of degradation. The activation energy was found to be 54.68 kJ mol⁻¹ showing a significant influence of temperature on the photocatalytic degradation of DBU.     

Efficient adsorption and photocatalytic degradation of organic pollutants diluted in water using the fluoride-modified hydrophobic titanium oxide photocatalysts: Ti-containing Beta zeolite and TiO2 loaded on HMS mesoporous silica

Using the F⁻ media, the hydrophobic zeolite and mesoporous silica can be synthesized. These hydrophobic porous materials exhibit the high ability for the adsorption of organic compounds diluted in water and become the useful supports of photocatalyst. The hydrophobic Ti-Beta(F) zeolite prepared in the F⁻ media exhibited high efficiency than the hydrophilic Ti-Beta(OH) zeolite prepared in OH⁻ media for the liquid-phase photocatalytic degradation of 2-propanol diluted in water to produce CO₂ and H₂O. The TiO₂ loaded on the hydrophobic mesoporous silica HMS(F) (TiO₂/HMS(F)), which was synthesized using tetraethyl orthosilicate, tetraethylammonium fluoride as the source of the fluoride and dodecylamine as templates, also exhibited the efficient photocatalytic performance for the degradation. The amount of adsorption of 2-propanol and the photocatalytic reactivity for the degradation increased with increasing the content of fluoride ions on these photocatalysts. The efficient photocatalytic degradation of 2-propanol diluted in water on Ti-Beta(F) zeolite and TiO₂/HMS(F) mesoporous silica can be attributed to the larger affinity for the adsorption of propanol molecules on the titanium oxide species depending on the hydrophobic surface properties of these photocatalysts.     

TiO2纳米管阵列的制备改性及应用研究进展

TiO₂纳米管阵列作为一种新型的三维立体纳米材料,因其大的比表面积及特殊的几何结构而受到了广泛的关注与研究。本文回顾了近年来阳极氧化法在Ti基底上原位生成TiO₂纳米管阵列所用电解液的发展趋势,介绍了TiO₂纳米管阵列的特性,如晶型结构、光学和电学特性以及催化活性,阐述了TiO₂纳米管阵列的金属离子掺杂、非金属离子掺杂、金属沉积、导电聚合物复合、半导体复合以及其他等多种改性手段,探讨了TiO₂纳米管阵列在光电催化降解污染物、光解水制氢、染料敏化太阳能电池和传感器以及其他多个领域的应用研究进展。最后,展望了TiO₂纳米管阵列的主要研究方向是对其形貌调控与表面改性等方面作进一步研究,以期为后续研究提供参考依据。     

Photocatalysis by polyoxometallates and TiO2: A comparative study

Polyoxometallates (POMs) as a homogeneous photocatalyst and TiO₂ as a heterogeneous photocatalyst seem to exhibit overall similar photocatalytic behavior. Both systems cause photodecomposition of a variety of organic pollutants via the formation and decay of several similar intermediates formed by OH addition (hydroxylation), dehalogenation, deamination, decarboxylation, etc. The final degradation products, for most organic substrates for both systems are CO₂, H₂O and inorganic anions. The similarity of behavior has been attributed to the formation of the common powerful oxidizing reagent, OH radical, from the reaction of the excited catalyst and water molecules.

On the other hand, lately, various laboratories have pointed out differences in reactivity and degradation mechanism between the two photocatalysts. The results are interesting and to a great extent contradictory.

This study compares the photodegradation of four substrates with diversified structures, namely, atrazine, fenitrothion, 4-chlorophenol (4-ClPh), and 2,4-dichlorophenoxyacetic acid (2,4-D) by both PW₁₂O₄₀³⁻ and TiO₂ and how their photodegradation is affected by the presence of strong OH radical scavengers, i.e., Br⁻ and isopropyl alcohol (i-prOH).

The results provide substantial evidence that the literature data on the apparent photooxidation mechanism of these two categories of photocatalysts is circumstantial, depending on substrate and the mode of investigation. Overall, though, the action of OH radicals relative to h⁺ appears to be more pronounced with PW₁₂O₄₀³⁻ than TiO₂.

With respect to thermal (dark) reaction of photoreduced catalysts, both systems can deliver their electrons to a variety of oxidants including metal ions. The advantages of POM relative to TiO₂ relates to the selective reduction precipitation of metal ions and to their unique ability to form metal nanoparticles in which POM serve both as reducing reagents and stabilizers.     

光催化与微生物燃料电池耦合对Cu-EDTA的降解特性

工业废水中重金属与有机络合剂形成的重金属络合物是常规水处理方法难以有效去除的污染物之一。光催化氧化是降解水体中重金属络合物的有效方法,但纯TiO₂催化光生电子-空穴对的较高复合效率限制了该技术在降解重金属络合物方面的应用。微生物燃料电池(microbial fuel cell, MFC)可以通过对光催化氧化单元施加电势提升光生电子与空穴分离率的同时有效降低复合效率,最终表现为高效的破络合反应。本文将MFC与光催化氧化进行耦合,在提高Cu-EDTA破络合效率的同时去除Cu²⁺。结果表明单MFC、串联MFC与并联MFC三种耦合方式均能提高光催化单元对Cu-EDTA的去除率,去除率分别为52.6%、73.57%和61.54%;对Cu²⁺的去除效果分别为18.09%、36.87%和21.09%。说明串联MFC耦合方式可以更大程度发挥光催化单元的效率。     

Photocatalytic treatment of wastewater from cottonseed processing: Effect of operating conditions, aerobic biodegradability and ecotoxicity

The heterogeneous and homogeneous UV-A photocatalytic treatment of an acidic waste stream originating from cottonseed processing was investigated. Several TiO₂ samples were screened in heterogeneous slurry experiments and a commercially available TiO₂ anatase (Millennium PC 500) was found to be considerably more active than the rest. The effect of key operating conditions such as effluent dilution (COD from 800 to 8000 mg/L), Millennium TiO₂ loading (from 100 to 1500 mg/L), solution pH (from 2.6 to 10) and the water matrix (presence of effluent solids and dissolved oxygen) on treatment efficiency was also studied. In general, degradation decreased with increasing effluent concentration, increasing solution pH from acidic to neutral and alkaline conditions and in the absence of oxygen serving as electron acceptor. Experiments with 500 mg/L TiO₂ for 240 min led to nearly complete mineralization at 800 mg/L initial COD but higher catalyst loadings suppressed degradation. Homogeneous experiments with 100 mg/L Fe²⁺ or Fe³⁺ were also performed leading to about 50% COD reduction; this increased to about 65% when H₂O₂ was added, i.e. simulating a Fenton reaction. The original, un-treated effluent was very toxic to marine bacteria Vibrio fischeri and very slowly biodegradable aerobically as assessed by shake-flask tests. Nonetheless, a 10-fold dilution (i.e. 800 mg/L COD) eliminated completely ecotoxicity and improved substantially biodegradation rates. On the other hand, photocatalytically pre-treated samples were less biodegradable than the un-treated one. Deep photocatalytic oxidation resulted in decreased ecotoxicity to V. fischeri, while moderate photocatalytic oxidation increased toxicity probably due to the formation of toxic intermediates.     

稀土元素Ce掺杂TiO_2光催化剂制备及微波强化光催化活性

在[Bmim]PF6离子液体介质中微波辅助制备稀土元素Ce掺杂改性的TiO_2光催化剂TiO_2-Ce,以甲基橙溶液和苯酚溶液为模拟污染物,在紫外光照和微波辐射-紫外光照降解条件下考察TiO_2-Ce催化剂的光催化活性。利用荧光技术以对苯二甲酸作为荧光探针检测TiO_2-Ce催化剂表面产生的羟基自由基,并对光催化降解反应进行动力学分析,以了解光催化降解反应机理。结果表明,通过优化反应条件制得的TiO_2-Ce催化剂具有较高光催化降解活性和热稳定性,在紫外光照和微波辐射-紫外光照条件下降解60 min后,甲基橙降解率分别为98.6%和99.3%,苯酚降解率分别为96.6%和97.2%。荧光光谱分析表明,TiO_2-Ce在微波辐射-紫外光照条件下产生的羟基自由基比紫外光照多,因而微波辐射-紫外光照具有强化TiO_2-Ce降解模拟污染物作用的效果。反应动力学数据表明,TiO_2-Ce光催化降解甲基橙溶液反应呈一级反应动力学规律,其表观速率常数k最大值为0.056 2 min-1。