Kinetics of photoelectrocatalytic degradation of humic acid using B2O3·TiO2/Ti photoelectrode

An innovative photoelectrode, B₂O₃·TiO₂/Ti electrode, was prepared by galvanostaticanodisation. The morphology and crystalline texture of the B₂O₃·TiO₂ film on electrode were examined by acomic force microscopy (AFM) and X-ray diffraction respectively. The examination results indicated that the anatase was the dominant component. The kinetics of photoelectrocatalytic(PEC) degradation of humic acid(HA) was investigated; the results demonstrated that effects from strongness to weakness on the photoelectrocatalytic degraded rate of humic acid: power of UV-lamp, area of TiO₂ film, bias, original concentration of humic acid solution. The optimum conditions were power of UV-lamp 125 W, area of TiO2 film 42.0 cm² , bias 1.4 V, original concentration of humic acid solution 5 mg/L in this PEC reaction system.     

Preparation of TiO_2/Ti mesh photoelectrode and properties

ＩｎｔｒｏｄｕｃｔｉｏｎＭｕｃｈｉｎｖｅｓｔｉｇａｔｉｏｎｓｓｈｏｗｅｄｔｈａｔｐｈｏｔｏｃａｔａｌｙｔｉｃｏｘｉｄａｔｉｏｎｏｆＴｉＯ2 ｐｒｏｖｉｄｅｓａｎｅｆｆｅｃｔｉｖｅｔｅｃｈｎｏｌｏｇｉｃａｌｍｅｔｈｏｄｆｏｒｔｈｅｄｅｇｒａｄａｔｉｏｎｏｆｔｈｅｏｒｇａｎｉｃｃｏｎｔａｍｉｎａｎｔｓｉｎｗａｔｅｒ(Ａｎｄｊｅｌｋａ ,2 0 0 0 ;Ｆｕｊｉｓｈｉｍａ ,1972 ;Ｈｉｄａｋａ ,1992 ;Ｋｅｓｓｅｌｍａｎ ,1997) .Ｉｎｏｒｄｅｒｔｏｏｖｅｒｃｏｍｅｔｈｅｓｈｏｒｔｃｏｍｉｎｇｓｔｈａｔｔｈｅｒｅｃｏｖ…     

Effects of methyl-CD and humic acid on hydrolytic degradation of the herbicide

IntroductionDiclofopmethylhasbeenintroducedbyFarbwerkeHoechstAGforthecontrolofabroadspectrumofwildoatsandotherannualgrassweedsinavarietyofcrops.Theherbicidehaslowsolubility,strongadsorptionandlowvaporpressure,indicatingthatitwouldbeimmobileunderfieldconditions(Smith,1986).Laboratoryandfieldstudieshaveshownitunderwentarapidhydrolysistodiclofopinplantandsoil,thecorrespondingpropionicacidthatislessherbicidalthantheparentcompounddiclofopmethyl(Smith,1977;1986;Martens,1978).Cyclodextrinsarecycli…     

Photocatalytic degradation of dichlorvos using TiO_2 supported on hollow glass microbeads

ＰｈｏｔｏｃａｔａｌｙｔｉｃｄｅｇｒａｄａｔｉｏｎｏｆｄｉｃｈｌｏｒｖｏｓｕｓｉｎｇＴｉＯ２ｓｕｐｐｏｒｔｅｄｏｎｈｏｌｏｗｇｌａｓｍｉｃｒｏｂｅａｄｓＲｅｃｅｎｔａｄｄｒｅｓ：ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＨｕａｉｂｅｉＣｏａｌＴｅ...     

附载型复合光催化剂TiO_2·Al_2O_3/beads降解有机磷农药

研究以四异丙醇钛 [Ti(iso OC3H7) 4]、异丙醇铝为原料 ,以空心玻璃微球为载体 ,用溶胶 -凝胶法制备可漂浮附载型复合光催化剂TiO2·Al2 O3/beads的过程。用该光催化剂降解有机磷农药 ,并与光催化剂DegussaP 2 5TiO2 光活性进行比较。结果表明 ,附载型复合光催化剂活性显著提高 ,最高光活性为同样降解条件下 ,同样含量DegussaP 2 5TiO2 光活性的 1.4倍 ,且TiO2 ·Al2 O3 组分摩尔比存在最佳值。同时还研究了TiO2 ·Al2 O3/beads对有机磷农药的吸附性 ,并用XRD和TEM对附载型复合光催化剂进行表征。     

Determination of hydroxyl radicals in TiO2/Ti photoelectrocatalytic oxidation system using Fe(phen)3 2+ spectrophotometry

A new method of determining the cumulate concentration of hydroxyl radicals in the TiO₂/Ti photoelectrocatalytic(PEC)oxidation system was established by o-phenanthroline-Fe(Ⅱ)(Fe(phen)₃²⁺) spectrophotometry and using anion     

Photocatalytic degradation of carbofuran in TiO2 aqueous solution：Kinetics using design of experiments and mechanism by HPLC/MS/MS

The photocatalytic degradation kinetics of carbofuran was optimized by central composite design based on response surface methodology for the first time. Three variables, TiO2 concentration, initial pH value and the concentration of carbofuran, were selected to determine the dependence of degradation efficiencies on independent variables. Response surface methodology modeling results indicated that the degradation efficiency of carbofuran was highly affected by the initial pH value and the concentration of carbofuran. Then nine degradation intermediates were detected by HPLC/MS/MS. The Frontier Electron Densities of carbofuran were calculated to predict the active sites on carbofuran attacked by hydroxyl radicals and photoholes. Point charges were used to elucidate the chemisorption pattern on TiO2 catalysts during the photocatalytic process. By combining the experimental results and calculation data, the photocatalytic degradation pathways of carbofuran were proposed, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain.     

VUV/TiO_2/O_3去除水中微量硝基苯的研究

采用负载在钛片上的二氧化钛(TiO2)薄膜光催化剂,以能发射185 nm真空紫外线(VUV)的紫外灯为光源,研究臭氧强化的真空紫外光催化方法(VUV/TiO2/O3)对水中微量硝基苯的去除效果.结果表明,VUV/TiO2/O3是一种有效地去除水中微量硝基苯的方法,VUV/TiO2/O3的表观一级反应速率常数比UV/TiO2/O3和VUV/O3分别高102.8%和30.8%,去离子水中50 μg/L的硝基苯反应60 s后就降低到检测限以下.VUV/TiO2/O3对硝基苯的降解速率随臭氧投加量的增加而显著增大,臭氧投加量1.52 mg/L时的反应速率比不加臭氧时提高了134.4%;虽然表观一级反应速率常数随初始浓度增加而稍有下降,但初始浓度170 μg/L的硝基苯反应2 min后也无法检出.水中常见的重碳酸盐和腐殖酸对硝基苯降解有显著的抑制作用,两者浓度分别为2 mmol/L和3.2 mg/L时,VUV/TiO2/O3对硝基苯的表观反应速率常数分别下降82.9%和71.6%,反应速率常数的倒数与重碳酸氢根浓度线性相关.VUV/TiO2/O3能快速有效地去除地表水(含碳酸盐和天然有机物)中的微量硝基苯,4 min内初始浓度为90 μg/L的硝基苯去除率达到96%,UV254降低了80%.     

TiO_2/beads as a photocatalyst for the degradation of X_(3B) azo dye

ＩｎｔｒｏｄｕｃｔｉｏｎＥｎｖｉｒｏｎｍｅｎｔａｌｐｒｏｔｅｃｔｉｏｎｅｘｐｅｒｔｓｉｎｍａｎｙｃｏｕｎｔｒｉｅｓｐａｙｈｉｇｈａｔｔｅｎｔｉｏｎｔｏｔｈｅｄｉｓｐｏｓａｌｏｆｔｈｅｗａｓｔｅｗａｔｅｒｗｉｔｈｄｙｅｏｒｗｉｔｈｄｅｅｐｃｈｒｏｍａ.Ｔｈｏｕｇｈａｔｐｒｅｓｅｎｔｂｉｏｄｅｇｒａｄａｔｉｏｎｉｓｕｓｅｄｉｎｔｈｅｄｉｓｐｏｓａｌｏｆｔｈｅｗａｓｔｅｗａｔｅｒ,ｔｈｅｃｏｎｃｅｎｔｒａｔｉｏｎａｎｄｃｈｒｏｍａｉｎｔｈｅｄｉｓｐｏｓｅｄｗａｔｅｒａｒｅｓｔｉｌｌｖｅｒｙｈｉｇｈａｎｄ…     

NiO-Cr_2O_3/TiO_2系列催化剂的结构和脱硝性能

NOx是主要的大气污染物之一,如何有效地消除NOx污染,一直是全球研究的热点。CO催化还原NO是NOx污染控制中的一个重要反应。TiO2具有较好的抗水,抗SO2性能,除用NH3作为还原剂的V-W-Ti催化体系外,有关TiO2作为脱硝催化剂载体的研究或应用报道不多。因此,开展对TiO2基催化剂用于脱销具有十分重要的理论和实际意义。本研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。以计算量的Ni(NO3)2和Cr(NO3)3混合溶液,浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃、0.08 Mpa下至水分蒸干为止,在550℃下、空气气氛中焙烧4 h既得所需催化剂。用以上方法分别制备2%NiO-10%Cr2O3/TiO2、4%NiO-8%Cr2O3/TiO2、6%NiO-6%Cr2O3/TiO2、8%NiO-4%Cr2O3/TiO2与10%NiO-2%Cr2O3/TiO2等5种催化剂样品。     

V-W/TiO_2/γ-Al_2O_3催化剂催化还原NO的研究

掺杂15%TiO2对γ-Al2O3改性制备了TiO2/γ-Al2O3复合氧化物载体,以此复合氧化物及TiO2、γ-Al2O3为载体用浸渍法负载钒钨制备了一系列催化剂,采用比表面积和孔结构分析、X射线衍射(XRD)、高分辨电镜(HRTEM)、原位红外(in situ FT-IR)等技术对载体和催化剂进行宏观-微观表征,同时在模拟氨气选择性催化还原NO(NH3-SCR)的反应条件下对催化剂的脱硝反应活性进行考察,比较研究TiO2掺杂对V2O5-WO3/TiO2和V2O5-WO3/γ-Al2O3催化剂的改性作用。结果发现,少量TiO2掺杂制得的TiO2/γ-Al2O3复合载体中,TiO2和γ-Al2O3之间的协同作用使得V2O5-WO3/TiO2/γ-Al2O3催化剂的选择性催化还原脱硝效率及活性窗口明显优于单一载体制备的催化剂,并表现出了良好的热稳定性;各种表征结果表明,TiO2/γ-Al2O3复合载体中TiO2高度分散在γ-Al2O3上,复合载体具有较大的比表面积,载体表面存在大量的Br?nsted酸位和较多的活性中间产物,这些可能是TiO2/γ-Al2O3复合载体催化剂具有较好SCR活性的原因。     

Photocatalytic degradation of perfluorooctanoic acid with β-Ga2O3 in anoxic aqueous solution

Perfluorooctanoic acid (PFOA) is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical (HO·) due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with β-Ga₂O₃ in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron (e_cb^-) coming from the β-Ga₂O₃ conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids (PFCAs, C_nF_2n+1COOH, 1 ≤ n ≤ 6) were the dominant products. Furthermore, the concentration of F^- was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N₂. The degradation reaction followed first-order kinetics (k = 0.0239 min^-1, t_1/2 = 0.48 hr). PFCAs (C_nF_2n+1COOH, 1 ≤ n ≤ 7) were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves e_cb^- attacking the carboxyl of C_nF_2n+1COOH, resulting in decarboxylation and the generation of C_nF_2n+1·. The produced C_nF_2n+1· reacted with H2O, forming C_nF_2n+1OH, then C_nF_2n+1OH underwent HF loss and hydrolysis to form C_nF_2n+1COOH.     

WO_3对V_2O_5/TiO_2-ZrO_2催化剂NH_3-SCR脱硝的影响

采用共沉淀法制备TiO_2-ZrO_2固溶体浸渍法负载WO_3和V_2O_5得到一系列V_2O_5-(x%)WO_3/TiO_2-ZrO_2催化剂。利用比表面积测定(BET)、X射线衍射(XRD)、原位漫反射傅里叶变换红外光谱(In situ DRIFTS)、程序升温脱附(NH_3-TPD)、高分辨率透射电子显微镜(HRTEM)等表征技术,结合脱硝性能测试,研究催化剂的表面特性、微观结构及脱硝活性;同时针对优选出的脱硝性能较好的催化剂,研究SO_2和H_2O对其活性的影响。结果表明:WO_3的负载增强了催化剂孔隙结构的稳定性和Lewis酸的强度。当WO_3含量为9%时,催化剂的孔隙结构最稳定,表面-NH_2活性物种最多,NH_3的吸附量最大脱硝活性最高,在300~400℃的温度窗口平均保持在92%以上。而当烟气中同时含有SO_2和H_2O时,催化剂活性会显著下降,且中毒不可逆。     

Photocatalytic degradation of dichlorvos using TiO2 supported on hollow glass microbeads

In this paper, a method for TiO₂ supported on hollow glass microbeads was described and the feasibility of photocatalytic degradation of dichlorvos using supported TiO₂(TiO₂/beads) was studied. The results showed that 1.0×10^-4 mol.dm^-3 of dichlovos could be completely photocatalytically degraded into PO₄^3- after 120 min illumination with a 375 W medium pressure mercury lamp. The effects of the amount of TiO₂/beads and concentration of Cu²⁺ on the photocatalytic degradation were also investigated. Some intemediate products of photocatalytic degradation of dichlorvos were detected.     

Photocatalytic degradation of organochlorine compounds using TiO2 supported on fiberglass cloth

The feasibility of photocatalytic degradation of organochlorine compounds using TiO₂ supported on fiberglass cloth as a photocatalyst was studied. The results showed that 2.0×10^-4 mol/dm³ of dichloroethylene, trichloroethylene and tetrachloroethylene can be completely photocatalytically degraded within a short time under illumination with a 375W medium pressure mercury lamp. The effects of parameters such as illumination time, initial concentration of organochlorine compounds, amount of air flow and concentration of H₂O₂ on the photocatalytic degradation were investigated. The TiO₂ supported on the fiberglass was not easily detached and after 500h illumination there was no significant loss of photocatalytic activity of TiO₂. The passible mechanisms of photocatalytic degradation were discussed.     

核壳结构TiO_2/SiO_2/Fe_3O_4颗粒的制备及性能研究

针对纳米Ti O2光催化剂回收困难、成本较高等问题,采用溶胶-凝胶法在表面包覆了Si O2的磁基体Fe3O4上负载Ti O2,制备出一种具有光催化作用的核壳结构Ti O2/Si O2/Fe3O4功能纳米颗粒。通过TEM、XRD等对其包覆效果及结构进行表征,结果表明,Si O2、Ti O2包覆的醇∶酯∶水的比例分别为4.6∶12.3∶1和30.3∶12.5∶1时可以得到包覆均匀的Ti O2/Si O2/Fe3O4功能颗粒。在可见光和紫外光的照射下,Ti O2/Si O2/Fe3O4光催化剂降解亚甲基蓝溶液的脱色率分别为85.16%和78.86%,使用5次后颗粒的回收率仍能保持在75%以上,具有优异的光催化降解性能,并且可重复利用率高。     

Photocatalytic degradation of organochlorine compounds using TiO2 supported on fiberglass cloth

１ＩｎｔｒｏｄｕｃｔｉｏｎＯｒｇａｎｏｃｈｌｏｒｉｎｅｃｏｍｐｏｕｎｄｓａｒｅｗｉｄｅｌｙｕｓｅｄｉｎｖａｒｉｏｕｓｉｎｄｕｓｔｒｉｅｓ，ａｎｄｈａｖｅｂｅｎｒｅｐｏｒｔｅｄｔｏｃｏｎｔａｍｉｎａｔｅｒｕｎｎｉｎｇｗａｔｅｒ，ｒｉｖｅｒｓ，ｌａｋｅｓ...     

O_3和O_3/H_2O_2法氧化处理制药废水的研究

采用O3和O3/H2O2氧化法对某制药厂的制药废水进行氧化处理,主要考察废水的pH值、O3流量、反应时间对COD去除率的影响。结果表明,O3氧化法的最佳条件为:废水的pH值为9.00,O3流量为5 g/h,反应时间为90 min。在此条件下,废水的COD和TOC的去除率分别达到64.16%和75.34%。O3/H2O2氧化法更能有效的提高废水COD和TOC的去除率,但需要合适的H2O2投加量。处理后两者去除率分别达87.45%和91.49%,且处理后的COD值(351 mg/L)符合该厂排入市政管网的要求(500 mg/L),同时废水的可生化性提高,B/C由0.12提高至0.32。对O3/H2O2处理制药废水的反应机制研究表明,COD的去除率随自由基抑制剂浓度的增加而降低,COD的去除主要是体系中.OH的贡献。另外,采用COD和TOC结合起来作为评价指标更能准确的反映出制药废水中有机物的去除规律。     

掺杂ZrO_2、TiO_2、γ－Al_2O_3对Pt、Pd／Al_2O_3燃烧

运用ＸＲＤ、ＢＥＴ、ＤＴＡ等测试技求，研究并考察了掺杂ＺｒＯ＿２、ＴｉＯ＿２、ｒ－Ａｌ＿２Ｏ＿３对Ｐｔ－Ｐｄ／Ａｌ＿２Ｏ＿３燃烧催化剂性能的影响，结果表明，ＺｒＯ＿２对Ａｌ＿２Ｏ＿３晶相的γ型转为α型有明显的抑制作用，而ＴｉＯ＿２的添入则起促进作用；高温引起催化剂活性下降的主要原因是作为第一载体的Ａｌ＿２Ｏ＿３的比表面积和孔容减少以及Ａｌ＿２Ｏ＿３晶态从γ型转为α型所造成的。     

H_2O_2/TiO_2氧化法处理氨基丁酸工业废水的研究

用H2O2／TiO2氧化法处理氨基丁酸工业废水。实验结果表明：当H2O2／CODcr＝2．0（g／g），每L废水中加入2gTiO2，在95℃下反应0．5h，废水CODcr和氨基值去除率分别达85．4％和69．8％，且TiO2经高温活化后可重复利用。