纳米TiO2掺杂改性与光催化性能研究

从TiO2的光催化降解机理入手,详细论述了纳米TiO2光催化性能,对近年来提高纳米TiO2光催化活性的多种方法进行了介绍。列举了纳米TiO2光催化降解处理染料废水、农药废水等应用,提出了环保领域中的应用研究现状、存在问题及其解决途径。     

TiO2光催化降解聚乙烯薄膜

TiO2光催化降解聚乙烯薄膜;纳米TiO2;固相光催化;聚乙烯塑料;降解     

纳米TiO2光催化降解聚乙二醇反应

纳米TiO2光催化降解聚乙二醇反应;纳米二氧化钛; 光催化; 聚乙二醇     

有机颜料的光催化降解及添加表面活性剂的影响

研究了纳米TiO2浓度、颜料用量、pH值和紫外光强度对有机颜料纳米TiO2光催化降解速率的影响．添加表面活性剂十二烷基苯硝酸钠时，颜料溶解度增加，但降解速率减慢．     

纳米TiO2 的制备及其光催化降解性能

采用低温水解沉淀法以TiCl4为原料制备了纳米TiO2,其结构经TEM和XRD表征。研究了太阳光激发下纳米TiO2对甲基橙的光催化降解性能,结果显示：纳米TiO2的分散性越好,粒径越小,光催化降解能力越强;以锐钛矿为主的复合纳米TiO2晶体比纯锐钛矿晶相具有更优异的光催化活性。     

掺铁纳米TiO2的制备及其光催化性能

掺铁纳米TiO2的制备及其光催化性能;掺铁纳米TiO2;微波合成;光催化降解;维生素B12     

纳米级TiO2光催化氧化聚丙烯酰胺

采用纳米级TiO2微粒为催化剂,研究了液固相悬浮体系中聚丙烯酰胺(PAM)的光催化降解和降粘性质.探讨了不同催化剂用量、PAM浓度和光照时间对光催化降解率的影响.结果表明,纳米级TiO2微粒具有较高的光催化活性,其光催化氧化PAM降解率在90 min时达90%以上,水中残留的PAM浓度为0.001%～0.003%;光催化降粘性能非常显著,光照5～10 min,含PAM的油田污水的粘度下降至蒸馏水的粘度.     

海绵状纳米结构TiO2膜的制备及其光催化活性

采用电化学阳极氧化法在钛表面构筑了海绵状纳米结构TiO2膜. 应用扫描电子显微镜(SEM)和X射线衍射(XRD)对膜层的形貌和晶型进行了分析和表征, 考察了阳极氧化时间对膜层厚度的影响, 并通过海绵状纳米结构TiO2膜对甲基橙的光催化降解研究了膜层厚度与光催化活性的关系. 结果表明, 海绵状纳米结构TiO2膜对甲基橙具有光催化降解作用, 而且随着膜层厚度的增加, 光催化降解速率显著增大, 厚度为2.2 μm的海绵状纳米结构TiO2膜对甲基橙的光催化降解速率是厚度为480 nm的6.4倍.     

负载型纳米TiO2光催化降解活性艳红X-3B染料

光催化氧化;负载型纳米光催化剂;负载型纳米TiO2光催化降解活性艳红X-3B染料     

掺铁TiO2气相光催化降解正己烷的研究

利用钛酸丁酯水解浸渍、共沉淀、水热等方法制备了掺铁TiO2纳米复合粉体材料并通过XRD、BET、TEM等手段作了表征，研究了掺铁TiO2对气相光催化降解正己烷反应的活性并和商品TiO2 Degussa P-25作了比较，考察了制法、掺铁量、焙烧温度等的影响。结果表明，和大多数液相反应不同，铁的掺入抑制了TiO2对正己烷的气相光催化降解。水热处理能较大程度地改善掺铁和未掺铁TiO2的光催化性能。P-25对正己烷的气相光催化活性则明显小于未掺铁TiO2样品，也小于某些掺铁样品。     

硝基酚类化合物在海水中的光化学氧化研究

酚类化合物尤其是硝基苯酚属于国家严格控制排放的有毒物质 .由于工业排污等原因 ,在近岸水体中能检测到许多酚类化合物 .我国胶州湾和杭州湾表层海水中酚的含量分别高达 3和 9mg/L[1] .酚的毒性会影响海水生物的生长和繁殖 ,危及人类健康 .由于硝基苯酚难于生化降解 ,因此研究其在水体中的光降解十分重要 [2～ 6 ] .文献中关于有机污染物的光化学研究大多侧重于废水处理 ,且降解方法也多采用 Ti O2 催化降解 [7,8] .对于硝基苯酚在天然水体中的光降解则知之甚少 .本文通过模拟海水条件下硝基苯酚的光化学反应及其影响因素 ,更加深入地了…     

Separation and Detection of Nitrophenols at Capillary Electrophoresis Microchips with Amperometric Detection

A miniaturized analytical system for the separation and amperometric detection of toxic nitrophenols, based on the coupling of a micromachined capillary electrophoresis (CE) chip with a glassy carbon detector is described. This microsystem enables a rapid (120 s/sample) simultaneous determination of five priority nitrophenolic pollutants (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol, and 2‐methyl‐4,6‐dinitrophenol). These compounds can be detected down to the 1×10^?5 M level using a 15 mM phosphate buffer pH 7.2 (containing 1.3 mM α‐cyclodextrin) as running solution on 77 mm long microchannel by applying a separation voltage of 3000 V and a negative potential of ?0.7 V (vs. Ag /AgCl wire). Applicability to ground water samples was demonstrated.     

以工业粉煤灰为原料制备 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂及其催化性能

2-仲丁基-4,6-二硝基苯酚(DNBP)作为杀虫剂、除草剂和烯烃基芳香族化合物阻聚剂而被广泛地应用于工农业生产中.在 DNBP生产和使用过程中,会产生大量难以降解的有机废水,从而对人类和生态环境造成极大危害.因此,开展含 DNBP废水的处理技术和方法研究具有重要的现实意义. TiO2半导体材料由于具有良好的光化学特性和电化学行为,近几十年来一直是光催化领域的研究热点.在能量等于或大于 TiO2的带隙能级的辐照光照射下, TiO2可以产生光生电子/空穴对(e-/h+).光生电子和空穴分别与 TiO2表面被吸附的 H2O和 O2分子反应,生成具有强氧化性的活性羟基自由基(?OH),对硝基酚类有机污染物具有较强的降解能力. TiO2光催化反应属于非均相反应,反应在催化剂的表面进行,催化剂对污染物的吸附是影响其催化降解性能的重要因素.但是,传统 TiO2光催化剂存在比表面积小,对有机污染物吸附能力差,光生电子与空穴易于复合等缺陷,限制了 TiO2光催化技术的进一步发展和在水处理领域中的大规模应用.我们基于气凝胶具有多孔性、大比表面积和高孔隙率的特点,以富含硅、铝的工业废弃物粉煤灰为反应原料,首先利用碱熔法和常压干燥技术制备出 SiO2-Al2O3气凝胶.在此基础上,以钛酸四丁酯(TBOT)为反应前体, SiO2-Al2O3气凝胶为载体,利用酸催化溶胶-凝胶法(sol-gel)制备出 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂.利用 X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)、透射电子显微镜(TEM)、N2吸附-脱附(BET)、紫外-可见吸收光谱(UV-vis)等分析测试技术对所制备的 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂结构进行了表征.结果显示,在 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂中,粒径尺寸为10~30 nm的锐钛矿型 TiO2纳米颗粒均匀分散在 SiO2-Al2O3气凝胶载体上. TiO2/SiO2-Al2O3气凝胶三元复合光催化剂呈现典型介孔材料的 IV型等温线. SiO2-Al2O3气凝胶的加入极大提高了 TiO2光催化剂的比表面积和对有机污染物的吸附性能,但是对 TiO2光波吸收范围影响不大.在制备出 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂基础上,进一步对其在可见光条件下的光催化性能进行了研究.以500 W的 Xe灯光源模拟自然太阳光, DNBP为探针污染物分子,系统考察了可见光照射条件下溶液 pH值、光催化剂用量、光反应时间、DNBP溶液初始浓度不同因素对 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂催化活性的影响.结果表明, TiO2/SiO2-Al2O3气凝胶三元复合光催化剂对 DNBP有机污染物的吸附率和光降解率明显高于纯 TiO2样品.在 DNBP溶液初始浓度为0.167 mmol/L, pH =4.86,催化剂用量6 g/L,光照时间5 h的条件下, TiO2/SiO2-Al2O3气凝胶三元复合光催化剂对 DNBP的降解率几乎高达100%.根据 Langmuir-Hinshelwood方程,在低浓度下光催化降解反应符合一级反应动力学.所制备的 TiO2/SiO2-Al2O3气凝胶三元复合光催化剂具有良好的稳定性和重复利用性能.重复利用5次后, TiO2/SiO2-Al2O3气凝胶三元复合光催化剂对 DNBP的降解率仍高达90%以上.利用紫外-可见分光光度计、气相-质谱联用仪对 DNBP降解中间产物进行了分析,探讨了 DNBP的光催化降解机理.     

Screen‐Printed Disposable Sensors Modified with Bismuth Precursors for Rapid Voltammetric Determination of 3 Ecotoxic Nitrophenols

This work reports the application of screen‐printed electrodes bulk‐modified with bismuth precursors to the voltammetric determination of 2‐nitrophenol (2‐NP), 4‐nitrophenol (4‐NP) and 2,4‐dinitrophenol (2,4‐DNP) in water samples. A bismuth film was formed at the electrode surface via in situ reduction of the precursor compound contained in the electrode matrix by cathodic polarization at ?1.20 V. The formation of bismuth layer at the precursor‐modified electrodes was assessed by cyclic voltammetric (CV) at different pH values and by optical techniques. The target nitrophenols were voltammetrically determined by recording their reduction peaks in the differential pulse (DP) mode. The composition and content of the precursor compounds in the printed ink and the effect of the pH of the supporting electrolyte on the DP reduction currents of the 3 target nitrophenols were studied. The limits of quantification (LOQs) in three water matrices (distilled water, tap water and surface water) were in the range 1.1–2.2 µmol L^?1_. Using a simple solid‐phase extraction (SPE) procedure with Lichrolut EN cartridges and elution with methanol, a preconcentration factor of 100 was achieved; the LOQs were 0.021, 0.027 and 0.025 µmol L^?1 for 2‐NP, 4‐NP and 2,4‐DNP, respectively. The recoveries of samples spiked with the 3 target nitrophenols at two concentration levels (0.04 and 0.1 µmol L^?1) were always >87 %.     

V2O5-TiO2催化剂光催化降解2,4-二氯苯酚：催化剂载体和表面活性剂的影响

采用固态分散法成功制备了表面活性剂修饰的不同V2O5含量的二元氧化物催化剂,运用X射线衍射、漫反射光谱、红外光谱、扫描电镜和N2吸附-脱附法对该纳米复合物进行了表征,并在紫外光照射下考察了其光催化降解2,4-二氯苯酚的性能.结果表明,50 wt%, V2O5-TiO2(记为50V2O5-TiO2)表现出比单纯V2O5, TiO2和P25更高的光催化活性, V2O5和TiO2之间的相互作用会影响二元氧化物催化剂的光催化效率. CTAB和HTAB的修饰显著增加了50V2O5-TiO2样品的催化效率,其中(50V2O5-TiO2)-CTAB催化剂在反应30 min后表现出最高的2,4-二氯苯酚降解率(100%)和反应速率(2.22 mg/(L·min)).表面活性剂的加入能修饰二元氧化物中V2O5和TiO2的光学和电子性质,从而显著提高其光催化活性.     

An N,N''-dialkyl-4,4''-bipyridinium-modified titanium-dioxide photocatalyst for water remediation - observation and application of supramolecular effects in photocatalytic degradation of p-donor organic compounds

The photocatalytic activity of TiO2 (Degussa P-25) modified with a 4,4'-bipyridinium monolayer (V2+-TiO2) has been compared with that of conventional TiO2-P-25 by investigating the efficiency of degradation of a series of four organic model compounds with increasing pi-donor capacity (2,4-xylidine, 2,4-dimethylphenol, hydroquinone, and dimethylhydroquinone). As far as the mechanism of the first oxidation reaction is concerned, evidence for the formation of supramolecular donor-acceptor complexes with the bipyridinium units at the semiconductor surface was obtained by comparison of the Langmuir-adsorption characteristics and the efficiencies of photodegradation of the different substrates. Furthermore, the main intermediates of the photocatalytic degradation of 2,4-xylidine were identified, and the presence of 2,4-dimethylphenol indicates that the main pathway of substrate oxidation proceeds via electron transfer from the adsorbed organic substrate to the "holes" within the valence band of the photoexcited semiconductors V2+-TiO2 and TiO2. The efficiencies of photocatalytic degradation by both V2+-TiO2 and TiO2 were limited by the trapping efficiency of the conduction band electrons by molecular oxygen.     

Determination of partition coefficient and analysis of nitrophenols by three‐phase liquid‐phase microextraction coupled with capillary electrophoresis

A three‐phase hollow fiber liquid‐phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1‐octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 μL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H₃PO₄, pH 3.0; organic solvent, 1‐octanol; acceptor solution, 40 μL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05–0.30 mg/L with r²>0.9900 and LODs were in the range of 0.01–0.04 mg/L with RSDs of 1.25–2.32%. Excellent enrichment factors of up to 398‐folds were obtained. It was found that the partition coefficient (K_a/d) values were high for 2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol and 2,6‐dinitrophenol and that the individual partition coefficients (K_org/d and K_a/org) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.     

Cathodic Electrochemical Detection of Nitrophenols at a Bismuth Film Electrode for Use in Flow Analysis

The bismuth film electrode (BiFE) is presented for use in both batch voltammetric and flow injection (FI) amperometric detection of some nitrophenols (2‐nitrophenol, 2‐NP; 4‐nitrophenol, 4‐NP; 2,4‐dinitrophenol, 2,4‐DNP). The bismuth film was deposited ex situ (batch measurements) and in‐line (FI) onto a glassy carbon substrate electrode. Batch analysis of the nitrophenols was carried out in 0.04 M Britton Robinson (BR) buffer pH 4, while for FI measurements, a carrier/electrolyte solution composed of 0.1 M BR buffer pH 4 mixed with methanol (20+80, v/v%) was employed to resemble media used in preconcentration/clean‐up and flow separation sample pretreatment procedures. Under batch conditions, the voltammetric behavior of the nitrophenols was examined for dependence on medium pH in the range of 2 to 10. Employing the square‐wave voltammetry mode, the limits of detection were 0.4 μg L^?1, 1.4 μg L^?1, and 3.3 μg L^?1 for 2‐NP, 4‐NP, and 2,4‐DNP, respectively. Under flow conditions, a simple in‐line electrochemical bismuth film renewal procedure was tested and shown to provide very good inter‐ and intra‐electrode reproducibility of the current signals at low μg L^?1 analyte concentrations. The limits of detection for 2‐NP, 4‐NP and 2,4‐DNP obtained using FI and amperometric detection at ?1.0 V (vs. Ag/AgCl) were 0.3 μg L^?1, 0.6 μg L^?1 and 0.7 μg L^?1, respectively, with linear ranges extending up to 20 μg L^?1. The attractive performance of the BiFE under flow analysis conditions offers great promise with respect to its detection capability and to its use for a prolonged period of time with no need for inconvenient removal of the electrode from the system for mechanical surface treatment.     

Comparative modelling of mono- and dinitrophenols sorption on yellow bentonite from aqueous solutions

Equilibrium removal of three substituted nitrophenols, namely 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP), by adsorption on yellow bentonite was tested. The batch kinetic data are described by the pseudo-first order, pseudo-second order, and intraparticle diffusion models. Results show that chemisorption processes could be rate limiting in the sorption step. The adsorption equilibrium was modelled by the Langmuir and Freundlich equations. The Langmuir model better represents the equilibrium isotherm data for 2-NP, 4-NP, and 2,4-DNP uptake on yellow bentonite. 4-NP is adsorbed in larger amounts than the disubstituted nitrophenol. Uptake of nitrophenols increases in the order 2-NP < 2,4-DNP < 4-NP.     

金红石相二氧化钛纳米晶的光催化活性

以苯酚光催化氧化和铬酸根光催化还原反庆为模型反应,研究不同粒径的金红石相二氧化钛纳米晶的光催化性活性。用XRD,TEM和BET等表明超细金红石相二氧化钛的粒径为7～8nm,UV-vis谱表明其吸收带边界蓝移11nm。在上述反应中,具有量子尺寸效应的金红石相二氧化钛(7nm)均表现出很高的催化活性,催化活性随粒径增大而迅速下降。7.2nm金红石相二氧化钛的光催化活性与6.8nm的锐钛矿相二氧化钛相当。