挥发性有机物光催化降解研究进展

阐述了挥发性有机物（ＶＯＣｓ）光催化降解的基本原理，分析了气相条件下不同ＶＯＣｓ的降解途径以及Ｏ２和Ｈ２Ｏ在光催化反应中的作用、光催化反应过程的传质和动力学规律，提出了反应器设计需要遵循的基本原则，叙述了ＶＯＣｓ光催化降解的催化剂及其换活现象、已研究的ＶＯＣｓ的光催化降解效率、部分物质难光催化降解的原因，讨论了ＶＯＣｓ光催化降解进一步研究的方向和应用前景。     

纳米TiO2光催化氧化酸性嫩黄研究

采用纳米TiO2光催化降解酸性嫩黄.当进水中嫩黄质量浓度为20 mg·L-1时,通过速率常数的比较得出反应的最佳条件为:TiO2的投加质量浓度为600 mg·L-1,pH值为3.56.当向UV/TiO2体系中投加H2O2对,UV/TiO2体系与H2O2具有协同作用.向溶液中充氧也能提高酸性嫩黄的光催化降解速率,但效果不如投加H2O2明显.     

Fabricating Fe3O4-schwertmannite as a Z-scheme photocatalyst with excellent photocatalysis-Fenton reaction and recyclability

Here we reported an effective method to solve the rate-limiting steps, such as the reduction of Fe³⁺ to Fe²⁺ and an invalid decomposition of H₂O₂ in a conventional Fenton-like reaction. A magnetic heterogeneous photocatalyst, Fe₃O₄-schwertmannite (Fe₃O₄-sch) was successfully developed by adding Fe₃O₄ in the formation process of schwertmannite. Fe₃O₄-sch shows excellent electrons transfer ability and high utilization efficiency of H₂O₂ (98.5%). The catalytic activity of Fe₃O₄-sch was studied through the degradation of phenol in the heterogeneous photo-Fenton process. Phenol degradation at a wide pH (3 - 9) was up to 98% within 6 min under visible light illumination with the Fe₃O₄-sch as heterogeneous Fenton catalyst, which was higher than that using pure schwertmannite or Fe₃O₄. The excellent photocatalytic performance of Fe₃O₄-sch is ascribed to the effective recycling between Fe³⁺ and Fe²⁺ by the photo-generated electron, and also profit from the formation of the “Z-Scheme” system. According to the relevant data, photocatalytic mechanism of Fe₃O₄-sch for degrading phenol was proposed. This study not only provides an efficient way of enhancing heterogeneous Fenton reaction, but also gives potential application for iron oxyhydroxysulfate mineral.     

TiO_2太阳能光催化降解有机污染物的研究进展

以太阳能为激发光源的 Ti O2 光催化氧化技术是一项极具运用前景的绿色环保技术。简要介绍了 Ti O2 光催化氧化的原理、催化剂 Ti O2 的制备研究、Ti O2 太阳能反应器的研制以及该项技术在有机污染物降解中的应用     

BiVO4光催化降解废水中高浓度磺胺嘧啶的研究

以五水合硝酸铋与偏钒酸铵为原料,采用水热反应法制备了不同晶体结构的钒酸铋(BiVO 4)光催化剂,分析了该催化剂对废水中高浓度磺胺嘧啶的处理效果。结果显示:BiVO 4光催化剂为单斜白钨矿型和四方锆石型,呈片状结构且颗粒分散性较好;磺胺嘧啶的光催化降解率与BiVO 4投加量、光照强度和反应时间呈正相关性,与磺胺嘧啶的初始浓度呈负相关性,随着BiVO 4合成pH值的增大呈先升高后下降的趋势;采用BiVO 4光催化剂处理磺胺嘧啶的最优条件为磺胺嘧啶初始浓度10 mg/L、合成pH=5,投加量0.25 g/L、10000 lux紫外光照下反应4 h,最优条件下的磺胺嘧啶平均去除率达到90.97%。     

Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline

This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41,which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM), and ultraviolet–visible spectroscopy(UV–Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET(Brunauer–Emmett–Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3–5 nm and a high surface area of 883 m~2/g. FTIR results illustrated the existence of Si–O–Si and Si–O–Ti bonds in Ti-MCM-41. The appearance of Ti2 p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta(ζ)-potential results indicated that the iso-electric point(IEP) of Ti-MCM-41 was at about pH 3.02. In this study, the photocatalytic degradation of oxytetracycline(OTC) at different pH was investigated under Hg lamp irradiation(wavelength 365 nm). The rate constant(K′_(obs)) for OTC degradation was 0.012 min-1at pH 3. Furthermore, TOC(total organic carbon) and high resolution LC–MS(liquid chromatography–mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH 3, 7 and 10, respectively. LC–MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring.     

Review on design and evaluation of environmental photocatalysts

Heterogeneous photocatalysis has long been considered to be one of the most promising approaches to tackling the myriad environmental issues. However, there are still many challenges for designing efficient and cost-effective photocatalysts and photocatalytic degradation systems for application in practical environmental remediation. In this review, we first systematically introduced the fundamental principles on the photocatalytic pollutant degradation. Then, the important considerations in the design of photocatalytic degradation systems are carefully addressed, including charge carrier dynamics, catalytic selectivity, photocatalyst stability, pollutant adsorption and photodegradation kinetics. Especially, the underlying mechanisms are thoroughly reviewed, including investigation of oxygen reduction properties and identification of reactive oxygen species and key intermediates. This review in environmental photocatalysis may inspire exciting new directions and methods for designing, fabricating and evaluating photocatalytic degradation systems for better environmental remediation and possibly other relevant fields, such as photocatalytic disinfection, water oxidation, and selective organic transformations.

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UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide

• UV-LED with shorter wavelength was beneficial for photocatalytic degradation. • SRNOM dramatically inhibit the degradation. • ·OH acts as the active radical in photocatalytic degradation. • Degradation mainly undergoes oxidation, hydrolysis and chain growth reactions. In this work, LED-based photocatalysis using mixed rutile and anatase phase TiO₂ (P25) as the photocatalyst could effectively remove 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and methylisothiazolone (MIT) simultaneously, with removal efficiencies above 80% within 20 min. The photocatalytic degradation of both CMIT and MIT could be modeled using a pseudo-first-order rate equation. The photocatalytic degradation rates of CMIT and MIT under LED280 illumination were higher than under LED310 or LED360 illumination. At concentrations below 100 mg/L, the degradation rate of CMIT and MIT under LED illumination significantly increased with increasing catalyst dosage. Additionally, the effects of the chloride ion concentration, alkalinity and dissolved organic matter on the photocatalytic degradation reaction were also investigated. The ·OH free radicals were determined to play the primary role in the photocatalytic degradation reaction, with a degradation contribution of >95%. The photocatalytic degradation of CMIT and MIT mainly occurred via oxidation, hydrolysis, and chain growth reactions. Finally, the possible photocatalytic degradation pathways of CMIT and MIT over LED/P25 are proposed.     

光催化氧化法降解直链十二烷基苯磺酸钠的研究

本文采用紫外光—双氧水 (UV/H2 O2 )氧化过程并加入亚铁盐作催化剂 ,对直链十二烷基苯磺酸钠 (LAS)的光催化氧化降解进行了研究。从实际应用出发 ,实验得出影响LAS降解的各因素的最佳取值及影响显著性次序。     

Photocatalytic decomposition of crotamiton over aqueous TiO(2) suspensions: determination of intermediates and the reaction pathway

The photocatalytic degradation of crotamiton in aqueous solution using TiO₂ was investigated. To investigate the effect of initial pH, the photodegradation behaviors of three types of pharmaceuticals were compared (crotamiton, clofibric acid, sulfamethoxazole). The degradation rates of crotamiton in the pH range 3-9 were nearly equal, but those of clofibric acid and sulfamethoxazole were affected by pH. At pH > 6.5, TiO₂ particles, clofibric acid and sulfamethoxazole had negative charge, therefore, the repulsive force between TiO₂ particles and anionic pharmaceuticals occurred and a low reaction rate at high pH was observed. The effect of UV intensity and TiO₂ concentration on photodegradation efficiency was also investigated. Linear and logarithmical relationships between UV intensity, TiO₂ concentration and the reaction rate constant were confirmed. Furthermore, the structures of photodegradation intermediates formed concomitantly with the disappearance of crotamiton were estimated. Seven intermediates were characterized by LC/MS/MS analyses, and it was assumed that the photocatalytic degradation of crotamiton was initiated by the attack of electrophilic hydroxyl radicals on aromatic rings and alkyl chains.