TiO2光催化反应机理及动力学研究进展唐玉朝

　　:20014,:20016TiO2光催化反应机理及动力学研究进展唐玉朝　胡　春　王怡中(中国科学院生态环境研究中心环境水化学国家重点实验室　北京100085)　　光催化处理环境污染物是基于催化反应过程中的一些自由基对污染物的氧化或还原作用,反应途径通常是HO·攻击或空穴直接攻击,对可见光敏感的化合物也可能通过激发态来分解。动力学的表述多数符合L-H模式,广泛研究了L-H模式下的吸附与催化活性的关系,对动力学的研究也是了解其反应机理的重要途径。　光催化反应　机理　动力学:O612.4;O643.1;O644.1　:A　:1005-281X(2002)03-0192-08RecentAdvancesinMechanismsandKineticsofTiO2PhotocatalysisTangYuchao　HuChun　WangYizhong(ResearchCenterforEco-EnvironmentalSciences,StateKeyLabofEnvironmentalAquaticChemistry,CAS,Beijing100085,China)Abstract　FundamentalmechanismsofTiO2heterogeneousphotocatalysisfordegradingwastesarebasedonsomeradicalreactions.Underultravioletlightthephotocatalystsproduceholesandelectrons,whichsubsequentlyinitiateoxidationandreductionreactions.Holesandelectronscanreactdirectlywithorganicspeciesadsorbedonthesurfaceofthecatalystsandalsocantransformintohigh-energychemicalspeciessuchashydroxylradicals.Someorganicssuchasdyes,whicharesensitivetovisiblelight,canalsobedegradedviaexcitedstates.Langmuir-Hinshelwoodkineticsmodeldescribesthedegradationrateex-pressionsintermsofthedisappearanceofcompounds.Thekineticsofthephotocatalysisisnotonlyessen-tialtopracticalapplicationsbutalsoiskeyaspectforunderstandingmechanismsofthephotocatalysis.Keywords　photocatalysis;mechanisms;kinetics、　,、。,,。,H2O、CO2,,,。,,,,,,,,,,[1—6]。,,,,。,,。TiO214320025化　学　进　展PROGRESSINCHEMISTRYVol.14No.3　May,2002。、TiO21.TiO2TiO2,,(e-),(h+)。,,,,。1　TiO2。OH-H2OHO·。HO·,,。O2HO2·O2·-,。1(a),[7—9]:TiO2+hν→TiO2(e-,h+)(1)e-+h+→heatorhν(2)h++OH-ads→HO(3)h++H2Oads→HO+H+(4)e-+O2→O2-(5)　　HO·,,e-,h+:HO+D→D++H2O(6)e-+A→A-(7)h++D→D+(8)　　(～10-2)。,:;。,。,TiO210-9s,,10-7—10-8s[2]。,。、、。,,El-morsi[10]10-3MAg+,,Ag+,-。,Joseph[11],ns,fspsms,ns-,,ms。HO·,,HO·[12—14]。ESRHO·[15],Mao[16]HO·C—H。,,。,pH[17]。Assabane[18]1,2,4。[19]。IshibashiFujishima[20]HO·,HO·7×10-5,5.7×10-2,～10-2,。。·193·3　TiO2Langmuir-Hinshelwood,Langmuir,[21]。,L-HHO·,。Turchi[12]HO·,HO·,。Yang[22]50%0%,:,。,,。,(1dye*)(3dye*),TiO2。TiO2O2O-2·,HO2·。,,CO2、H2O。1(b),:dye+hν→1dye*or3dye*(9)1dye*(or3dye*)→dye+(10)dye++O2(O-2,HO)→(11)　　Zhao[23—26]B。Pyrex470nm,470nmTiO2,TiO2。,,,COD,。Vinodgopal[27]AO7。,。Johannes[28]。CCl4Cl,HO·,Cl-,0.2—12M,6,:eTiO2-+CCl4→CCl3+Cl-(12)CCl3+TiO2+OH-→eTiO2-+CCl3OH(13)CCl3+CCl3→C2Cl6(14)　　HO·,(12),HO·,Cl-。2.(1)O2,O2。O2TiO2,,O2·-O2·2-。O2,-,,-,O2,。Schwarz[29]EPR(electronparamagneticresonance)HO·O2,O2-。O2,Wang[30]2-CBTiO2,,2-chlorobiphenylol,0.5kO25h16%2-CBCO2,186kO2,94%。,。(2)H2O2H2O2HO·。H2O2O2·-HO·。,H2O2,H2O2HO·。H2O2+O2-→HO+OH-+O2(15)H2O2+λ→H2O*2(16)H2O*2→2HO(17)　　H2O2HO·,O2HO2·,HO2·,HO·,,H2O2。H2O2+HO→H2O+HO2(18)HO2+HO→H2O+O2(19)　　,H2O2·194·化　学　进　展14,2.2eV,(5)3.0eV。H2O2,H2O2,O2。H2O2,H2O2,H2O2,。Dionysion[31]4-H2O2248mg/l,4-。Ku-mar[32],H2O2,H2O21mM10mM,DNT10%。,。H2O2,,H2O2,TiO2,H2O2TiO2。Wang[30]TiO2/UVH2O2,,H2O2,H2O2TiO2/UV。3.pHpH、。DegussaP25(TiO2),pH6.6,pH6.6,,TiO-,pH6.6,,TiOH+2。,。Hu[33]R15CBXTiO2/SiO2(pH=3)pH,pH。Coleman[34]17-U-(oestradiol)pH,2。pH7,pH,OH-,HO·;7pH10,pH,TiO-,OH-TiO-,。pH10,HO·O·-,O·-phe-noxideion,TiO2,。Okamoto[35]。2　pH17-U-HO·(3),(4),HO·H2O2HO2·,pHHO·pKa(4.88),(3)、(4)HO·H2O2HO2·,pH,HO·,。pH。Chen[36]pH,pH,OH-CO2(),。,,,pH。,pH,。、TiO21.Langmuir-HinshelwoodTiO2Langmuir-Hinshelwood[37—42]。Langmuir,,,L-H:-dC/dt=v=kθ=kK[C]/(1+K[C])(20)　　θ,K,,C。,K[C]1,v=kK[C],;,,K[C]1,v=k,,·195·3　TiO2。,(20):lnC0/C=kKt=K′t(21)　　K′=kK,。,、,,,:v=kθ=kK[C]/(1+K[C]+∑Ki[Ci])(22)　　∑Ki[Ci]i。,,C,,1+K[C]+∑Ki[Ci],。,1+K[C]+∑Ki[Ci],。,,。Xu[43]acetophe-none,lnCt,C0。L-H,[44—48]。,L-H,,。LangmuirK,,。,L-H,Zhang[49]TiO25.4×104L/mol、7.5×105L/mol;Mills[50]4-KK200。,KL-H,。,K(photoadsorption),。Maria[51],,,。3-,K。K,Xu[43]K,K,K。L-H,,L-H。MillsMorris[50]TiO24-,L-H(RCO2),RCO2[O2]4-[CP]:RCO2=VKO2[O2](Ia)θKCP[CP]/{(1+KO2[O2])(1+KCP)[CP]}(23)　　KO2=0.044±0.005,[O2]-1O2Langmuir,V,KCP=(29±3)×103dm3mol-14-CP。Ti(Ⅲ),O2,,Langmuir。Cun-ninghamAl-Sayyed[52]。、4-3--4-,TiO2。40H2O。,。TiO2/HO·,,。TiO2,,L-H(5×10-6—2×10-4)。,[53]。Vorontsov[54],Ti3+,L-H,:R=k1K1Ca/(1+K1Ca)+k2K2Ca/(1+K2Ca)(24)　　k1k2,K1K2。·196·化　学　进　展14,,。2.Yang[22]Cu-EDTA,:Cu-EDTA;Cu-EDTA,。-dC/dt=k1Caq/(1+k2Caq)+kadsCads[S](25)　　k1、k2kads,Caq、CadsCu-EDTA,[S]。k1Caq/(1+k2Caq),kadsCads[S]。,k1Caq/(1+k2Caq)L-H,,,L-H。Cunningham[55]。(2×1018einmin-1、λ=365nm),TiO2(2g/L),4-CP。,(1.7×1016einmin-1),4-CP,,L-H。,,AgNO3,4-CP。Ag+O2TiO2/,,-,。,,。、,4-CPTiO2HO·h+。D'Oliveira[56]TiO2,L-H,Hammette/Kow,kapp(h-1),:Kapp=-10e+5.2logKow-7.5(26)　　。DavisHuang[57],。M:-dM/dt=k0[HO]Ms{(V+KM)2/[(V+KM)2+CmwKV]}(27)　　[HO]Ms。V,w,Cm。,Langmuir:Ms=CmwKM/(V+M)(28)　　,K。,、K、Cm、MspH。Okamoto[35]。Lang-muir,L\|H,methylperfluoroalkylethersTiO2,Henry,[58]:rs0=kK0.5p0.5(29)　　k,K,p。3-,Zeltner[59]L-H/Hougen-Watson:Rate=kKaKbCaCox/[(1+KaCa)(1+KbCox)](30)　　k、Ka、Kb,CaCox3-。。Chen[60],:r=k0exp[-(E/RT)]ITUKO2pO2KSCS/(1+KO2pO2)(1+KsCs0)　(31)　　I,U,KO2、Ks。,Chang[61],。4-,、、。,(O2、、、、、pH)·197·3　TiO2,。,,,。dv;d,vd,d,vd1/2;d,v,d,d。[62]:dC/dt=constCndm(32)　　C,d,const。n→0,m→1;n→1,m→0。dC。、　,,,。,。。,,,。,。L-H,,。,,,,。,。,。,。[1]OllisDF,Al-EkabiH.PhotocatalyticPurificationandTreatmentofWaterandAir.Amsterdam:Elsevier,1993[2]HoffmannMR,MartinST,ChoiW,BahnemannDW.Chem.Rew.,1995,95:69—96[3]ChenJ,RulkensWH,BruningH.Wat.Sci.T