新农药吩胺霉素的光化学降解

[目的]研究不同因素对吩胺霉素的光化学降解的影响。[方法]将不同溶液配制的吩胺霉素标准溶液,置于氙灯光解恒温试验箱进行光照试验,固定时间取样,反应液使用HPLC检测。[结果]初始质量分数、pH值、有机溶剂、光源对吩胺霉素的光化学降解均有重要影响。超纯水中,吩胺霉素光解速率随初始质量分数增大而降低。pH值缓冲溶剂中,光解速率随pH值升高而降低。有机溶剂中的紫外光解速率为甲醇正己烷丙酮乙腈。甲醇、正己烷、超纯水、乙腈、丙酮中吩胺霉素的紫外与氙灯光解速率不同,其中丙酮紫外照射下起淬灭作用,氙灯照射下起光敏作用。[结论]随着环境改变吩胺霉素的光解规律发生变化,试验方法简单科学,为吩胺霉素在环境中的迁移转化规律提供可靠依据。     

典型阴离子表面活性剂光降解影响条件研究

[目的]选用典型阴离子表面活性剂十二烷基苯磺酸钠,探讨其在不同条件下的降解行为.[结果]十二烷基苯磺酸钠的光降解速率随着光照强度的增加而增加;在蒸馏水中的效果较人工海水中的好;随着初始质量浓度的增加而降低.[结论]十二烷基苯磺酸钠的光降解速率与光照条件、介质、初始质量浓度都有关系,并且不同的表面活性剂光降解影响因素不同.     

不同水环境条件下马拉硫磷的降解规律

[目的]研究马拉硫磷在不同水环境条件下的降解规律。[方法]在不同pH值、不同温度及不同水样条件下,采用高效液相色谱法检测水环境中马拉硫磷剩余浓度随时间的变化情况。[结果]马拉硫磷降解活化能EA为73.10 kJ/mol,降解速率随pH值增大而加快,随温度升高而加快,湿地原水中降解最快、灭菌湿地原水次之、灭菌超纯水中最慢,准一级反应动力学方程可以描述其在水环境中的降解规律。[结论]马拉硫磷的降解速率受pH值、温度和水样条件的影响,自然水体中马拉硫磷降解速率较快。     

碱度对UV-Fenton法降解对硝基苯酚的影响

考察了溶液初始pH值和碱度对UV-Fenton法降解对硝基苯酚(p-NP)效果的影响。结果表明,酸性条件(pH值3～5)有利于p-NP的降解,而在偏碱性条件下其降解速率明显减缓;碳酸盐能掩蔽.OH自由基反应:p-NP降解速率随着HCO3-浓度的增加而变慢。通过比较不同pH值下HCO3-对p-NP降解效果的影响发现,由于pH值的变化会影响HCO3-在溶液中的存在形态,从而改变其对p-NP降解的抑制作用,通过控制溶液pH值可以降低或消除碳酸盐的影响。     

唑螨酯的水中光解特性

[目的]研究唑螨酯在水中光解特性,为该药的环境风险提供数据支持。[方法]采用室内模拟法研究唑螨酯在不同因素条件下的光解,评价唑螨酯在水环境中的风险性。[结果]唑螨酯在水中光解符合一级动力学方程,光照强度为8000lx时10mg/L唑螨酯的半衰期为49.5min;光照强度为4000lx时,初始质量浓度为5、10、20mg/L唑螨酯的半衰期分别为99、115.5、115.5 min;SDBS添加质量浓度为5、10、30 mg/L时10 mg/L唑螨酯的半衰期分别为138.6、138.6、115.5min;在pH值为4、7、9时10mg/L唑螨酯的半衰期为13.6h及115.5、99min。[结论]光照强度越大,降解越快,初始质量浓度越高,降解时间越长;偏酸时对唑螨酯的水中光解有抑制作用,偏碱时有一定的促进作用;当水溶液中添加SDBS后,随着SDBS质量浓度的增大对唑螨酯水中光解的影响效果减小。     

不同UV光氧化工艺的阿特拉津降解动力学研究

UV光照条件下,研究了反应条件对农药阿特拉津(ATZ)光氧化降解的影响规律与作用机理。结果表明,ATZ在不同UV光氧化工艺中的降解反应均符合准1级反应动力学,溶液pH对降解速率均存在较大影响。单独UV工艺中,ATZ在不同溶液pH下的降解速率、产物生成及形态差异,导致ATZ水溶液的紫外-可见(UV-Vis)吸收光谱存在一定差别。UV/H_2O_2工艺中,ATZ的降解速率随H_2O_2加入量的增加呈现先增大后降低的变化趋势,ATZ溶液在pH分别为7.0和10.0时的UV-Vis吸收光谱的变化趋势与幅度相似,但与pH为4.0时的差别较大。UV/Ti O_2工艺中,ATZ的降解速率随Ti O_2加入量的增加而降低;H_2O_2和Ti O_2同时加入到反应体系时,ATZ降解速率均低于二者单独加入时的降解速率。     

悬浮态TiO2光催化降解萘的方法研究

采用悬浮态TiO2为催化剂,在250 W高压汞灯为光源,研究了溶液中萘的光催化降解方法.探讨了不同催化剂用量、不同pH值、不同初始浓度和光照时间对光催化降解效果的影响.结果表明TiO2对水中的萘有较高的光催化活性,在催化剂用量为2%,溶液的pH值为2,萘的初始质量浓度为500mg/L,光照6 h后萘的降解率达80%以上.     

乙酰甲胺磷残留光降解的动力学研究

对水中的乙酰甲胺磷残留在不同光强和pH条件下的降解及动力学情况进行了研究.结果表明,乙酰甲胺磷在水中的降解与光强和水的pH关系密切,太阳光条件下比水中的降解明显加快;碱性水中乙酰甲胺磷降解较快,酸性水中降解相对较慢;室温下,在pH为4.0、7.0、9.0水中乙酰甲胺磷避光条件下降解速率常数分别为5.4×10-3、 2.24×10-2、 6.49×10-2d-1,半衰期分别为128.36d、 30.94d、 10.68d;太阳光下在pH为4.0、7.0、9.0水中降解速率常数分别为3.92×10-2, 4.0910-2, 6.14×10-2h-1,半衰期分别为17.68h、 16.95h、 11.29h.     

纳米ZnO/Ni电极的制备及光电催化性能研究

采用阴极电沉积法制备泡沫镍负载纳米氧化锌电极,并用扫描SEM和XRD分析其晶粒形貌和物相结构。以刚果红染料为模拟污染物,ZnO/Ni为工作电极,铂丝电极为对电极,对刚果红染料废水进行了光电结合催化降解的试验研究。考察了外加偏压、氯离子浓度和溶液初始pH对刚果红染料废水光电催化降解效率的影响,同时在最优条件下比较了光催化降解、电解与光电结合催化降解对刚果红染料废水的降解效果的差异。结果表明,在相同条件下,光电结合催化降解刚果红染料废水的速率比单纯的光催化降解速率和单纯的电解速率快。在外加偏压为1.2 V,支持电解液浓度为0.20 mol.L-1,溶液pH为6时对40 mg.L-1的刚果红光电催化降解120 min时的降解率、色度和COD去除率分别达到82.57%、94.00%和68.72%。     

Cu_2O光催化降解水中环境内分泌干扰物己烯雌酚性能的研究

采用水解法制备Cu2O,以Cu2O为催化剂,对光催化降解环境内分泌干扰物己烯雌酚(DES)的性能和影响因素进行了研究,利用高效液相色谱法(HPLC)测定降解后水中DES的含量.探讨了溶液的初始浓度、催化剂投加量、pH值以及光照时间对降解效率的影响.当DES初始浓度为51μg/mL,催化剂投加量为0.8g/L,pH值=4.0,光照120min的条件下降解效果达95.02%.     

Surface-enhanced Raman study of electrochemical and photocatalytic degradation of the azo dye Janus Green B

The photocatalytic degradation of Janus Green B azo dye over silver modified titanium dioxide films was investigated by surface-enhanced Raman spectroscopy (SERS). An optimized SERS-active substrate was employed to study the photodegradation reaction of Janus Green B. Considering that photocatalytic degradation processes of organic molecules adsorbed on TiO₂ might involve either their oxidation or reduction reaction, the vibrational spectroelectrochemical study of the dye was also performed, in order to clarify the transformations involved in initial steps of its photochemical decomposition. In order to understand the changes in Raman spectra of Janus Green B after photodegradation and/or electrochemical processes, a vibrational assignment of the main Raman active modes of the dye was carried out, based on a detailed resonance Raman profile. Products formed by electrochemical and photochemical degradation processes were compared. The obtained results revealed that the first steps of the degradation process of Janus Green B involve a reductive mechanism.     

Studies on Aminoanthraquinone Compounds

A study has been made of the action of near-ultraviolet and visible radiation on anaerobic solutions of 1- and 2-piperidinoanthraquin-ones in different organic solvents, and on polymer films dyed with these dyes. In the absence of oxygen, 1-piperidinoanthraquinone is reduced to the anthrahydroquinone on irradiation in solution and on nylon films. Under similar conditions, 2-piperidinoanthra-quinone is reduced to the anthrone in organic solvents, but the photochemical changes are more complex on polymer films. 1-Piperidinoanthraquinone doss not sensitise the photochemical degradation of nylon or cellulose acetate yarn. The results suggest that there is no definite relation between the ease of photoreduction of a dye and its ability to sensitise the photochemical degradation of textile fibres.     

The Photochemistry of Dyes. IV—The Role of Singlet Oxygen and Hydrogen Peroxide in Photosensitised Degradation of Polymers

The effect of sensitising dyes on the photochemical degradation of textile fibres is discussed. The degradation is dependent upon the presence of oxygen, and is accelerated by water vapour and rise in temperature. The study of simple model photochemical systems intended to simulate the dyed fibre system indicates that there are significant differences between the two systems. The sensitising effect of dyes in the textile systems seems to be due to the formation of excited singlet oxygen and hydrogen peroxide. The latter is not formed in the absence of water vapour.     

纳米ZnO/SnO2复合光催化剂的制备研究

研究ZnO/SnO2复合催化剂的合成,考察ZnO/SnO2前驱体在不同Zn/Sn反应剂量的摩尔比、不同沉淀剂Na2CO3与总金属离子溶液的体积,以及不同反应时间条件下制备的复合催化剂对甲基橙光催化降解效果的影响。研究表明,当Zn/Sn反应剂量的摩尔比为9∶1,沉淀剂Na2CO3与总金属离子溶液的体积比为2∶1,反应时间为10min时制取的复合催化剂前驱体对甲基橙的光催化降解效果最好,降解30min甲基橙溶液的脱色率可达96.00%以上。     

Photochemical behaviour of activated carbons under UV irradiation

A series of activated carbons were used to investigate the photochemical behaviour of carbons under UV light as catalysts in the photo-oxidation of phenol in the absence of semiconductor additives. Conventional photocatalytic tests showed an improved photo-oxidation in the presence of activated carbons, beyond the so-called synergistic effect reported in the literature for carbon/titania composites. A novel approach based on UV irradiation of carbons pre-loaded with phenol was used to demonstrate the anomalous photochemical response of carbon materials towards phenol degradation. Analysis of the catalytic reaction from a different standpoint (inside the carbonaceous matrix) demonstrated the catalytic activity of certain carbon materials for phenol photodegradation, without considering photolytic breakdown and adsorption kinetics. The pseudo photochemical quantum yield of several activated carbons was higher than that of photolysis under the same conditions; the nature of the degradation intermediates was also modified in the presence of the carbon materials. Moreover, the degradation of the adsorbed fraction retained inside the pore structure of the carbons has been demonstrated. Our results suggest the occurrence of carbon–photon interactions which could be propagated through the graphene sheets of the materials, and could reach the adsorbed molecules inside the pores.     

The effect of perspiration on photo-induced chemical reaction of azo dyes and the determination of aromatic amine products

In order to investigate the impact of perspiration on photo-induced chemical reaction of azo dyes and the carcinogenic aromatic amine products produced from the reaction, we have carried out experimental studies on the photochemical reaction of C.I. Reactive Red 2 mixed with American Association of Textile Chemists and Colorists（AATCC）standard artificial perspiration. UV-vis spectroscopic technique was employed to monitor the reaction processes, and the reaction products were analyzed by hollow fiber protected liquid-liquid-liquid phase micro-extraction with capillary electrophoresis（HF-LLLME-CE). The results showed that perspiration had remarkable influence on the photochemical reaction of azo dyes. Aromtic amines formed during the photochemical process as a result of reduction of azo dyes by organic components in perspiration. The HF-LLLME-CE methodology was validated in analyzing aromatic amines produced from the photochemical degradation of azo dye C.I. Reactive Red 2 and C.I. Acid Red 35 mixed with artificial perspiration.     

Photo-degradation of methylene blue in the presence of 2-anthraquinone sulfonate and cyclohexanol

Hydroxyl radical is a highly reactive oxygen species and can be used to oxidize many pollutants and toxic organic compounds. 2-Anthraquinone sulfonate (2-AQS) was found capable of producing hydroxyl radicals under UVA exposure. In this study, the photo-induced oxidative degradation of methylene blue (MB) by 2-anthraquinone sulfonate was investigated. Results indicated that 2-anthraquinone sulfonate was able to photo-degrade methylene blue. Addition of some chemical such as cyclohexanol could significantly increase the photo-degradation of methylene blue by 2-anthraquinone sulfonate. The degradation process was investigated by using LC-MS. Potential photochemical reaction mechanism of 2-anthraquinone sulfonate was proposed in this paper. Influence of solution pH value and different ratios of 2-AQS, cyclohexanol and MB mixture on the degradation of methylene blue were also studied.     

Photochemical Decomposition of Some Triazine Reactive Dyes

The photochemical degradation of some selected monoand di– chlorotriazine dyes – C. I. Reactive Orange 13, C. I. Reactive Orange 4, C. I. Reactive Yellow 2, C. I. Reactive Blue 4, C. I. Reactive Blue 5 – and starting compounds used for various applications to cotton are examined. The simple, exponential relationship between relative number of decomposed molecules and absorbed energy is verified. It is found that the structure of the base (chromophore)influences the tendency of a dye to exhibit photodegradation. The bases improve in fastness to light in the following order: base of CI. Reactive Orange 4 and Orange 13 > base of CI. Reactive Yellow 2 > base of C. I. Reactive Blue 4 and Blue 5. By linking the base to the reactive part of the molecule, an increase in resistance to photochemical degradation is brought about, in dependent of the number of reactive chlorine atoms. A covalent bond between the dye and the fibre may, in some cases (C. I. Reactive Yellow 2), cause a decrease in photodegradation.     

光化学降解汽车尾气中多环芳烃污染物的研究

研究了不同条件(如温度、水蒸气含量、光源种类、光照强度和照射时间)下,汽车尾气中的多环芳烃(PAHs)的光化学降解。结果表明,采用模拟日光中紫外部分的荧光灯照射,PAHs光解率随光照强度、照射时间、温度和水蒸气含量的增加而增大。由此推断,在夏季高温、潮湿和高日照条件下,PAHs一般在数小时内即全部降解。而在冬季低温、干燥和低日照的气候条件下,PAHs降解速率很小,可在大气中停留较长时间,扩散到较远距离。还提出了由水蒸气产生的气态OH自由基与激发态PAHs碰撞导致发生PAHs光化学降解的反应机理。     

HPA/SiO2光催化降解甲基橙的研究

用溶胶-凝胶法制备了负载型杂多酸催化剂HPA/SiO2。在光化学反应仪中,以紫外灯为光源,以HPA/SiO2为光催化剂,研究了其对模拟染料废水甲基橙溶液的光催化脱色降解的影响。讨论了影响催化降解效果的重要因素:不同正硅酸乙酯与磷钨酸的配比,溶液初始酸度,催化剂投加量等。在300 W的紫外灯光照下,讨论了HPA/SiO2光催化剂的重复使用性。最后,研究了该条件下10 mg/L的甲基橙溶液的动力学。