g-C3N4基PVDF蒸馏膜的制备及性能研究

在水处理领域中,膜蒸馏技术是处理工业废水的一种有效方法,而膜污染问题是制约该技术发展的重要因素。采用非溶剂致相分离法(NIPS),制备出了具有光催化自清洁性能的g-C_3N_4基聚偏氟乙烯(PVDF)蒸馏膜,对其的形貌、晶型构成、疏水性等特性进行了表征分析,通过膜蒸馏和光催化实验测试了所制蒸馏膜的相关性能,考察了其在光催化-膜蒸馏反应器中的运行效果。研究成果如下:优化制备的蒸馏膜(M-2)具有良好的渗透通量和疏水性,其对氯化钠溶液和罗丹明B模拟废水的截留率均高于99%;蒸馏膜在受污染后进行光催化实验可基本消除膜面污染,其通量恢复率可达到95. 3%,实现了对膜表面有机污染物的降解,从而为膜蒸馏技术在水处理过程中的高效、稳定运行提供依据。     

半导体光催化氧化

主要介绍半导体光催化氧化降解有机污染物的过程和影响光催化氧化活性的因素，指出了光催化氧化领域的一些新进展。     

P-25纳米TiO2在含酚废水处理方面的应用

采用室内模拟研究,以P-25纳米TiO2作为光催化剂进行了苯酚水溶液的光催化降解性能探讨,初步考察了溶液的pH、P-25纳米TiO2用量对光催化降解苯酚过程的影响,以获得P-25纳米TiO2光降解含酚废水的较好反应条件.实验结果表明,当溶液pH=8时,降解水体中苯酚效果最佳,强酸和强碱条件均不利于苯酚的降解;在pH 8的反应体系中,当光催化剂用量为0.4g/L时,催化水体中苯酚降解的效果最好.     

多氯联苯光化学降解研究的最新进展

综述了近10年以来多氯联苯(PCBs)在有机相、表面活性剂中的直接光化学降解行为,以及PCBs在水相中的光敏化反应和光催化反应等间接光化学降解行为。从光解动力学、光解途径、光解机理以及光解产物等几方面阐述了PCBs的光化学行为,光催化降解有机污染物是一种很有发展前景的有机污染物治理技术。     

超声波、电场和光催化协同降解有机污染物的研究现状

以自由基反应为主的高级氧化工艺是处理有机污染物的新型技术，具有良好的拓展和应用环境。超声氧化、电化学氧化工艺和紫外光催化工艺都属于高级氧化工艺，许多研究者发现单独使用这些工艺降解有机污染物效果不够理想，更有效的方法是联合使用。本文系统地介绍了超声波和光催化、光催化和电场、超声波和电场协同降解有机污染物的机理和研究现状。     

光催化法降解有机废水的显著性研究

本文采用紫外光照射并加入催化剂的方法，对有机废水一阳离子艳红染料(5GN)进行了光催化降解的研究。从实际应用出发，实验得出了影响阳离子艳红染料降解的各因素的最佳取值及影响显著性次序。     

液相光催化降解有机污染物的研究与进展

光催化技术是一种处理液相有毒有机污染物的新型技术。对有机废水的光催化降解进行了研究,综合论述了影响光催化效率的各种因素,如晶粒尺寸、pH值、光照强度、外加氧化剂等。同时,对提高光催化效率的途径以及光催化反应器的设计因素进行了讨论。     

TiO2/ACF与TiO2/Bi2WO6/ACF材料吸附光催化降解VOCs条件优化及性能评价

通过开展TiO2/ACF与TiO2/BiWO6/ACF材料吸附光催化降解VOCs废气的室内模拟实验,探究反应环境（流量、初始浓度、温度、湿度）对吸附光催化降解效率的影响。结果表明：TiO2/ACF材料的最优降解条件为浓度1000 mg/m3,流量1.2 m3/h,湿度30％,温度33℃;TiO2/BiWO6/ACF材料的最优降解条件 为浓度1000 mg/m3,流量1.2 m3/h,湿度33％,温度34℃;两种材料在最优条件下均具有对高浓度污染物响应速度快、反应平衡后污染物转化率高的特点,TiO2/ACF材料三级反应总体转化率达到81.71％,TiO2/BiWO6/ACF材料三级反应总体转化率达到85.96％。因此,将吸附光催化技术与其他处理技术相结合作为一种预处理方法,针对储罐呼吸气排放源,在实现VOCs初步降解的同时还可以稳定平衡VOCs浓度,具有较好的缓冲、减排效果,该技术工艺流程简单,能耗低,具有很好的应用前景。     

Ag/AgX(X=Cl~-,Br~-,I~-)等离子体光催化降解有机物研究进展

自半导体Ti O2在紫外光照射下催化水制氢获得成功以来,人们对光催化剂的研究延伸至多个领域。其中光催化剂在解决能源紧缺和环境治理方面取得了丰硕的研究成果:光催化剂Ag/Ag X复合纳米材料还原CO2生成甲醇等低分子燃料减少了温室效应,利用太阳能光催化制氢,等离子体光催化剂降解有机污染物等。笔者主要介绍了Ag/Ag X(X=Cl-,Br-,I-)等离子体光催化剂的结构、光催化机理以及对各种有机污染物的降解活性,最后提出了这一类新型光催化剂发展的前景和努力的方向。     

聚丙烯酰胺化学降解技术研究进展

聚丙烯酰胺化学降解技术是目前油田含聚污水处理的重要技术之一,包括氧化降解法、光降解法和光催化降解法。文章介绍了此项技术在降解机理和应用方面的研究进展,并通过实验证明了聚丙烯酰胺氧化降解和光降解的可行性,对油田污水中聚丙烯酰胺的化学降解处理具有一定的指导意义。     

Photocatalytic activity of titanium dioxide modified concrete materials – Influence of utilizing recycled glass cullets as aggregates

Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material – Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing.     

Influence of parameters on the heterogeneous photocatalytic degradation of pesticides and phenolic contaminants in wastewater: a short review

In recent years, the application of heterogeneous photocatalytic water purification processes has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible-light spectrum. This paper aims to review and summarize the recent works on the titanium dioxide (TiO(2)) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and wastewater effluents. The effects of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed. Results reported here suggest that the photocatalytic degradation of organic compounds depends on the type and composition of the photocatalyst and, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcination temperature in the water environment. A substantial amount of research has focused on the enhancement of TiO(2) photocatalysis by modification with metal, non-metal and ion doping. Recent developments in TiO(2) photocatalysis for the degradation of various pesticides and phenols are also highlighted in this review. It is evident from the literature survey that photocatalysis has good potential to remove a variety of organic pollutants. However, there is still a need to determine the practical utility of this technique on a commercial scale.     

Photocatalytic degradation of organic wastes by electrochemically assisted TiO2 photocatalytic system

Photocatalytic degradation of organic wastes with nanosized titanium dioxide particles has been studied for a long time in order to offer an appropriate method for wastewater treatment, but its practical application is greatly limited by the slow process. In this work, an electrochemically assisted TiO2 photocatalytic system was set-up by combining a TiO2 photocatalytic cell with a three-electrode potentiostatic unit. The composite system revealed high photocatalytic activity towards organic wastes mineralization. After continuous treatment for 0.5 h, the maximum absorption of rhodamine 6G (R-6G) was reduced by more than 90%; chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) of textile dye wastewater (TDW) were decreased by 93.9 and 88.7%, respectively. The biodegradability of TDW was also improved because the COD/BOD5 ratio decreased from 2.1 to 1.2. All these results indicated that the composite system could be used for effective organic wastes mineralization or as a feasible detoxification and color removal pretreatment stage for biological post treatment.     

Applicability of a continuous-flow system inner-coated with S-doped titania for the photocatalysis of dimethyl sulfide at low concentrations

The present study investigated the photocatalytic activity of an S-doped TiO₂ photocatalyst with regards to dimethyl sulfide degradation under visible-light irradiation, along with its deactivation and reactivation. The dimethyl sulfide conversion was between 85% and 93% for the lowest relative humidity range (10–20%) and close to 100% for the two higher relative humidity ranges (45–55% and 80–90%). The conversion was also close to 100% for the two lowest input concentrations (0.039 and 0.195 ppm), while it was between 91% and 96% at 3.9 ppm and between 85% and 90% at 7.9 ppm. In contrast to the input concentration dependences on conversion, the calculated degradation rates increased as input concentrations increased. The dimethyl sulfide conversion at low concentrations (≤0.39 ppm), which are associated with non-occupational inn occurring. However, catalyst deactivations were observed during the photocatalytic process whdoor air quality issues, was up to nearly 100% for long time periods (at least 603 h), without any significant catalyst deactivatioen higher concentrations (3.9 and 7.8 ppm) were used. The photocatalyst, reactivated by using two types of air (dried and humidified) under visible-light irradiation, did not regain all of its initial activities. Sulfate groups were qualitatively identified as the reaction products on the photocatalyst surface. In addition, gaseous byproducts, quantitatively determined, included dimethyl disulfide, methanol, and SO₂. It is noteworthy that the peak concentration of dimethyl disulfide (0.79 ppm = 790 ppb), generated over the photocatalytic process with the highest dimethyl sulfide input concentration, exceeded the odor threshold value of 0.1–3.6 ppb for dimethyl disulfide.     

Photocatalytic degradation of disperse blue 1 using UV/TiO2/H2O2 process

The photocatalytic degradation of a dye derivative, C.I. disperse blue 1 (1), has been investigated under UV light irradiation in the presence of TiO2 and H2O2 under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic technique as a function of irradiation time. The degradation was studied under different conditions such as different types of TiO2, reaction pH, catalyst and substrate concentration containing hydrogen peroxide (H2O2), besides molecular oxygen in the presence of TiO2. The degradation of dye was also investigated under sunlight and the efficiency of degradation was compared with that of the artificial light source. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient for the degradation of the dye.     

Heterostructure CdS/ZnS nanoparticles as a visible light-driven photocatalyst for hydrogen generation from water

(CdS)_x/(ZnS)_1–x nanoparticles were synthesized as a visible light-driven photocatalyst using the stepped microemulsion technique with a series of the ratio factors (x). The photocatalytic test results showed that (CdS)_x/(ZnS)_1-x with x = 0.8 had the highest photo-reactivity for H₂ production from water under visible light. The composite (CdS)_0.8/(ZnS)_0.2 catalyst had a heterogeneous structure that exhibited a much greater photocatalytic hydrogen production activity than either pure CdS or the homogeneous Cd_0.8Zn_0.2S solid solution. ZnS deposition also was shown to largely improve the stability of CdS in the heterostructured CdS/ZnS catalyst. Thermal treatment of the catalyst, i.e., annealing (CdS)_0.8/(ZnS)_0.2 at 723 K, improved the crystallinity of the catalyst and increased its photocatalytic H₂ production rate by more than 36 times. Deposition of Ru on the surface of the catalyst particles by in situ photo-deposition further increased the photo-H₂ generation rate by 3 times. The photocatalyst of 0.5%Ru/CdS/ZnS achieved the highest H₂ production activity, at a rate of 12650 μmol/g-h and with a light to hydrogen energy conversion efficiency of 6.5%.     

TiO2光催化法处理难降解废水的研究进展

以TiO2为催化剂，催化氧化法处理污水是近年来兴起的一种现代水处理技术，本文介绍了提高TiO2光催化剂催化效率，及对催化剂进行改性的方法，主要的手段主要有以下几个方面：减小催化剂尺寸、沉积贵金属、掺杂金属离子、光催化剂负载化、半导体复合等。介绍了国内外近年来有关多相光催化反应中光催化反应器设计与研究的进展情况。     

Photocatalytic degradation of para-hydroxybenzoic acid: Relationship between substrate adsorption and photocatalytic degradation

Dark adsorption and photocatalytic degradation of para-hydroxybenzoic acid (PHBA) was studied in the presence of Degussa P-25 titanium dioxide photocatalyst under concentrated solar radiation. This work includes the study of the effect of pH, and of the presence of different anions and cations on dark adsorption and photocatalytic degradation (PCD) of PHBA on titanium dioxide. The results obtained clearly indicate that there is a link between the extent of adsorption of PHBA and its PCD. Conditions that favor greater adsorption of PHBA also favor a greater PCD. This points to the possibility that the mechanism of PCD involves a surface reaction between adsorbed PHBA and OH ° radical. Anions were generally found to have a detrimental effect on the photocatalytic degradation of PHBA. Cl^- caused the greatest decrease in the PCD followed by NO₃^-, HCO₃^- and SO₄^2-. Cations Cu²⁺ and Fe²⁺ were not found to assist the degradation of PHBA, possibly due to the anions associated with them.     

Heterogeneous photocatalysed degradation of a herbicide derivative, isoproturon in aqueous suspension of titanium dioxide

Heterogeneous photocatalysed degradation of a herbicide derivative, N-(4-isopropylphenyl)-N',N'-dimethylurea (Isoproturon, 1) was investigated in aqueous suspensions of titanium dioxide by monitoring the change in absorption intensity and depletion in Total Organic Carbon content as a function of irradiation time. The degradation kinetics was studied under different conditions such as pH, catalyst concentration, substrate concentration, different types of TiO(2) and in the presence of electron acceptors such as hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)) and potassium persulphate (K(2)S(2)O(8)) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts. An attempt was made to identify the degradation product through GC-MS analysis technique.     

Photocatalytic degradation of phenol on different phases of TiO(2) particles in aqueous suspensions under UV irradiation

Photocatalytic degradation of phenol on different phases of TiO₂ particles was examined under 400-W UV irradiation. The effects of various operating parameters including TiO₂ dosage, solution pH (4–10), and initial phenol concentration (0.13–1.05 mM) on phenol degradation were investigated. Three forms of TiO₂ photocatalysts such as pure anatase phase, pure rutile phase, and the mixed phase were prepared by sol-gel method and followed annealing at different temperatures. The annealing temperature used were 500 °C, 700 °C and 900 °C for pure anatase phase, the mixed phase, and pure rutile phase, respectively. It was shown that pure anatase TiO₂ exhibited higher photocatalytic activity than the physical mixture of pure anatase and rutile TiO₂. Moreover, the TiO₂ particle with a specific fraction of mixed anatase and rutile phases exhibited better performance than pure anatase TiO₂. Finally, the degradation rate could be satisfactorily fitted by a pseudo-first-order kinetic model.