隨(sui)著(zhe)我(wo)國(guo)社(she)會(hui)經(jing)濟(ji)的(de)迅(xun)速(su)發(fa)展(zhan),不(bu)可(ke)避(bi)免(mian)地(di)伴(ban)隨(sui)著(zhe)大(da)量(liang)廢(fei)棄(qi)物(wu)排(pai)放(fang),這(zhe)導(dao)致(zhi)了(le)嚴(yan)重(zhong)的(de)環(huan)境(jing)汙(wu)染(ran)和(he)生(sheng)態(tai)破(po)壞(huai)。這(zhe)些(xie)因(yin)素(su)正(zheng)危(wei)及(ji)我(wo)國(guo)居(ju)民(min)生(sheng)存(cun)安(an)全(quan)。另(ling)外(wai),調(tiao)查(zha)表(biao)明(ming)環(huan)境(jing)汙(wu)染(ran)問(wen)題(ti)也(ye)會(hui)影(ying)響(xiang)到(dao)我(wo)國(guo)的(de)可(ke)持(chi)續(xu)性(xing)發(fa)展(zhan)。所(suo)以(yi),保(bao)護(hu)與(yu)治(zhi)理(li)環(huan)境(jing)是(shi)構(gou)建(jian)環(huan)境(jing)友(you)好(hao)、和he諧xie社she會hui和he實shi現xian我wo國guo社she會hui經jing濟ji叮ding持chi續xu發fa展zhan的de重zhong要yao任ren務wu。傳chuan統tong汙wu染ran物wu處chu理li方fang法fa不bu能neng徹che底di消xiao除chu降jiang解jie汙wu染ran物wu,也ye容rong易yi造zao成cheng二er次ci汙wu染ran,使shi用yong範fan圍wei窄zhai。僅jin適shi合he特te定ding的de汙wu染ran物wu,還hai伴ban隨sui著zhe能neng耗hao高gao,不bu適shi合he大da規gui模mo推tui廣guang等deng缺que陷xian。近jin些xie年nian來lai,利li用yong光guang催cui化hua技ji術shu降jiang解jie和he消xiao除chu汙wu染ran物wu得de到dao人ren們men的de廣guang泛fan關guan注zhu。光guang催cui化hua氧yang化hua技ji術shu是shi一yi種zhong集ji高gao效xiao節jie能neng、操作簡便、反應條件溫和、tongshikejianshaoerciwurandengtuchutedianyuyishendeyixiangxindewuranzhilijishu,erqiecongdiqiubuwuzhixunhuandejiaodulaikan,guangcuihuajishukeyijiangdaliangdeyoujiwuranwujiangjieweiCO2和H2O.從而被植物利用.形成了循環,如圖l所示,可以說光催化技術正足人類所急需的一種技術。
光催化技術起源於20世紀70年代.自從日本學者Fujishima和Honda發現了利用TiO2單晶可將水光催化分解之後。範圍內,便開始了光催化氧化技術在汙水處理、空氣淨化、抗(kang)菌(jun)殺(sha)毒(du)等(deng)方(fang)麵(mian)的(de)應(ying)用(yong)研(yan)究(jiu),於(yu)是(shi)光(guang)催(cui)化(hua)技(ji)術(shu)受(shou)到(dao)全(quan)的(de)廣(guang)泛(fan)關(guan)注(zhu)。並(bing)得(de)到(dao)了(le)快(kuai)速(su)發(fa)展(zhan)。如(ru)今(jin)人(ren)們(men)對(dui)於(yu)光(guang)催(cui)化(hua)技(ji)術(shu)的(de)研(yan)究(jiu)主(zhu)要(yao)分(fen)為(wei)對(dui)光(guang)催(cui)化(hua)劑(ji)的(de)研(yan)究(jiu)(如TiO2、ZnO)heduiguangcuihuafanyingtiaojiandeyanjiu,qizhong。duifanyingtiaojiandeyanjiuzhong,renmenweilerangguangcuihuayanghuafanyingnengwendinghegaoxiaodejinxing,huishejichuxiangyingdefanyingqi,yonglaiweifanyingtigonglianghaodepingtai,yigeshejilianghaodefanyingqi,jiangnengdadatigaofanyingtixidefanyingxiaolv,congerdadaogaoxiao、節能、穩定等目的。
1 光催化反應器的設計依據
guangcuihuafanyingqideshejizhuyaomudeshiweilegeiguangcuihuayanghuafanyingtigonggaoxiaohewendingdefanyingkongjianhehuanjing。shixianguangcuihuaguochengduiguangdechongfenliyong,congertigaofanyingxiaolv。youyuguangcuihuafanyingxuyaoyouguangzicanyu,guangcuihuajicainengjiangguangnengzhuanhuachengweihuaxuefanyingsuoxudenengliang,laijinxingcuihuajiangjiezuoyong,yinerzaishejifanyingqideshihou,zui主(zhu)要(yao)的(de)兩(liang)個(ge)理(li)論(lun)依(yi)據(ju)就(jiu)是(shi)光(guang)的(de)傳(chuan)輸(shu)理(li)論(lun)和(he)催(cui)化(hua)反(fan)應(ying)動(dong)力(li)學(xue)理(li)論(lun)。光(guang)的(de)傳(chuan)輸(shu)以(yi)及(ji)在(zai)光(guang)在(zai)反(fan)應(ying)器(qi)中(zhong)的(de)分(fen)布(bu)直(zhi)接(jie)影(ying)響(xiang)到(dao)催(cui)化(hua)劑(ji)對(dui)於(yu)光(guang)的(de)吸(xi)收(shou)效(xiao)率(lv)。充(chong)分(fen)均(jun)勻(yun)的(de)催(cui)化(hua)劑(ji)分(fen)散(san)可(ke)保(bao)證(zheng)光(guang)在(zai)傳(chuan)輸(shu)途(tu)中(zhong)浪(lang)費(fei)少(shao),這(zhe)樣(yang)催(cui)化(hua)劑(ji)對(dui)光(guang)的(de)利(li)用(yong)效(xiao)率(lv)高(gao),反(fan)之(zhi)將(jiang)會(hui)有(you)較(jiao)多(duo)催(cui)化(hua)劑(ji)由(you)於(yu)得(de)不(bu)到(dao)或(huo)者(zhe)隻(zhi)接(jie)受(shou)到(dao)很(hen)少(shao)的(de)光(guang)照(zhao)而(er)不(bu)能(neng)充(chong)分(fen)的(de)進(jin)行(xing)光(guang)催(cui)化(hua)氧(yang)化(hua)反(fan)應(ying)。
2 國內外光催化反應器的發展
早zao期qi的de光guang催cui化hua研yan究jiu大da多duo是shi在zai一yi些xie很hen隨sui意yi的de反fan應ying條tiao件jian下xia進jin行xing的de。比bi如ru在zai液ye相xiang光guang催cui化hua反fan應ying中zhong,催cui化hua劑ji與yu汙wu染ran物wu溶rong液ye混hun合he時shi,一yi般ban的de實shi驗yan過guo程cheng都dou是shi人ren工gong用yong玻bo璃li棒bang進jin行xing攪jiao拌ban。由you於yu人ren為wei誤wu差cha的de因yin素su難nan以yi避bi免mian,會hui對dui結jie果guo的de準zhun確que性xing和he再zai現xian性xing產chan生sheng較jiao大da影ying響xiang。為wei了le滿man足zu對dui光guang催cui化hua反fan應ying器qi準zhun確que、wendinghegaoxiaodeyaoqiu,fanyingqideshejiyezaibuduandebianhua。yigeshejijiaohaodefanyingqi,buyikeyitigaoguangcuihuafanyingdexiaolv,erqiekeyijiangqidaguimohua。kegaoxiaowendingdejinxingguangcuihuazuoye,congershixianchanyehua。daomuqianweizhi,youyixieleixingdefanyingqiyijingyongyuzhuruwushuihekongqichulidegongyehuayingyong。
2.1 流動床光催化反應器
liudongchuangguangcuihuafanyingqishijiangcuihuajiyudaijiangjiewuzhizhijiehunhedeyizhongfanyingqi。yizhiyilai,renmendouzaiweimanzubutongdeguangcuihuafanyingyaoqiu,shejibutongdefanyingqi。yingyongzui多的兒種類型的反應器包括橢圓型、底燈型和柱型,如圖2所suo示shi。這zhe幾ji種zhong反fan應ying器qi的de特te點dian是shi不bu僅jin效xiao率lv較jiao高gao,製zhi作zuo難nan度du低di。而er且qie可ke以yi用yong於yu大da多duo數shu的de反fan應ying類lei型xing,可ke以yi同tong時shi滿man足zu液ye相xiang和he氣qi相xiang兩liang種zhong類lei型xing的de光guang催cui化hua反fan應ying,因yin而er得de到dao了le廣guang泛fan的de應ying用yong。
橢圓型反應器(圖2(a)所示)是將燈管和反應區分別放在橢圓的2個(ge)焦(jiao)點(dian)上(shang),這(zhe)樣(yang)可(ke)以(yi)很(hen)好(hao)的(de)將(jiang)燈(deng)管(guan)所(suo)發(fa)出(chu)的(de)光(guang)集(ji)中(zhong)在(zai)反(fan)應(ying)區(qu)內(nei),減(jian)少(shao)了(le)光(guang)的(de)浪(lang)費(fei),提(ti)高(gao)了(le)整(zheng)體(ti)的(de)效(xiao)率(lv)。雖(sui)然(ran)反(fan)應(ying)器(qi)中(zhong)的(de)反(fan)應(ying)區(qu)在(zai)橢(tuo)圓(yuan)型(xing)焦(jiao)點(dian)上(shang),但(dan)是(shi)這(zhe)不(bu)表(biao)示(shi)燈(deng)管(guan)所(suo)發(fa)出(chu)的(de)光(guang)線(xian)都(dou)能(neng)達(da)到(dao)反(fan)應(ying)器(qi),而(er)且(qie)這(zhe)種(zhong)類(lei)型(xing)的(de)反(fan)應(ying)器(qi).光的傳輸路程較長,這樣就增加了光在傳輸過程中的損失,並且反應區域內光的分布不均勻。底燈型反應器(圖2(b)所示)shiduituoyuanxingfanyingqidegaijin,tadeguangyuanweiyupaowuxiandejiaodianshang,danshiguangyuandeguangxianbingbushijujiaozailingyigejiaodian,ershicongxiawangshangsherenfanyingqu,guangjinrulefanyingquyuhoujiubuhuizaibeifanshehuilai。gengdachengdudeliyongleguangyuan。zhuxingfanyingqishixianzaibijiaochengshudeleixing,yibankefenweizhongdengwaifanyingqu(圖2(c)所示)和中反應區外燈(圖2(d)所示)2種。柱型反應器有著較高的光利用率和良好的對稱性(可使光在反應區內均勻的分布,減少局部差異)。一些發達園家,這兩種反應器已經用來處理汙水,在這2種反應器中.光從光源發出來後,基本上都會通過反應區。特別是中燈外反應區這樣的反應器.光的利用率幾乎可以達到zui大。在光源的光照強度合適的情況下,甚至可以不需要反射壁。都可以達到光的zui大da利li用yong率lv。而er且qie這zhe種zhong柱zhu型xing的de反fan應ying器qi製zhi造zao難nan度du小xiao,成cheng本ben低di。適shi合he大da規gui模mo的de生sheng產chan和he運yun用yong。因yin此ci現xian在zai的de大da多duo數shu針zhen對dui反fan應ying器qi的de研yan究jiu,也ye是shi以yi柱zhu型xing為wei模mo型xing來lai進jin行xing的de。
2.2 固定床光催化反應器
在近年來,人們將催化劑固定在一些載體表麵來進行催化反應.即固定床反應器,這樣避免了光催化劑的分離問題。固定床與傳統的流動床的區別在於,催化劑不隨液體或者氣體一起流動.而er是shi固gu定ding在zai玻bo璃li或huo者zhe其qi它ta介jie質zhi表biao麵mian,汙wu染ran物wu流liu經jing其qi表biao麵mian來lai進jin行xing反fan應ying。這zhe樣yang一yi來lai,人ren們men就jiu可ke能neng更geng的de了le解jie催cui化hua劑ji的de性xing質zhi,並bing易yi於yu控kong製zhi催cui化hua反fan應ying的de進jin行xing,也ye易yi於yu催cui化hua劑ji和he反fan應ying物wu的de分fen離li。基ji於yu這zhe種zhong思si路lu,人ren們men設she計ji了le一yi些xie新xin型xing的de光guang催cui化hua反fan應ying器qi,其qi中zhong效xiao果guo比bi較jiao好hao的de是shi平ping
板型和噴泉型,如圖3所示。
平板型的反應器是將催化劑固定在平板上,在光照的條件下.將jiang汙wu染ran物wu液ye體ti或huo者zhe氣qi體ti緩huan慢man的de通tong過guo催cui化hua劑ji表biao麵mian降jiang解jie,屬shu於yu層ceng流liu型xing反fan應ying器qi。這zhe種zhong反fan應ying器qi的de好hao處chu在zai於yu製zhi造zao簡jian單dan,待dai降jiang解jie物wu經jing過guo催cui化hua劑ji的de時shi候hou光guang照zhao時shi間jian和he光guang照zhao強qiang度du基ji本ben一yi致zhi,並bing很hen容rong易yi控kong製zhi流liu動dong速su度du。當dang流liu速su放fang慢man的de時shi候hou可ke提ti高gao反fan應ying物wu的de降jiang解jie程cheng度du。但dan是shi所suo需xu時shi問wen也ye就jiu相xiang應ying增zeng加jia;當加快流速的時候雖然降解的程度不如流速慢的情況.但dan是shi所suo需xu時shi間jian較jiao少shao。這zhe種zhong平ping板ban反fan應ying器qi可ke以yi根gen據ju不bu同tong的de降jiang解jie需xu求qiu。調tiao整zheng流liu速su,達da到dao相xiang應ying的de效xiao果guo。平ping板ban型xing的de反fan應ying器qi還hai有you另ling一yi個ge其qi他ta反fan應ying器qi不bu具ju備bei優you點dian,由you於yu催cui化hua劑ji是shi固gu定ding在zai平ping板ban上shang的de。不bu會hui隨sui著zhe待dai降jiang解jie物wu的de流liu動dong而er流liu動dong,也ye就jiu省sheng去qu了le後hou續xu催cui化hua劑ji分fen離li的de步bu驟zhou。但dan是shi也ye由you於yu催cui化hua劑ji固gu定ding的de原yuan因yin,在zai降jiang解jie一yi定ding時shi間jian後hou,催cui化hua劑ji的de催cui化hua效xiao率lv會hui降jiang低di,而er更geng換huan催cui化hua劑ji比bi較jiao困kun難nan,並bing且qie光guang的de損sun失shi也ye比bi較jiao嚴yan重zhong。因yin為wei光guang源yuan發fa出chu的de光guangzui多隻有50%被利用.即使加裝了反射壁.也會有大量的光損失掉。鑒於平板型反應器的造價低.易於控製的優點,很多實驗室都運用平板反應器來進行一係列的光催化研究。
噴泉型反應器是近幾年由Puma和Yueu等deng人ren提ti出chu的de,此ci類lei反fan應ying器qi與yu平ping板ban型xing反fan應ying器qi大da致zhi相xiang同tong,將jiang催cui化hua劑ji固gu定ding在zai斜xie麵mian上shang,在zai頂ding部bu固gu定ding光guang源yuan,將jiang待dai降jiang解jie物wu斜xie麵mian中zhong心xin的de噴pen嘴zui噴pen出chu,然ran後hou在zai重zhong力li作zuo用yong下xia流liu經jing催cui化hua劑ji從cong而er得de到dao降jiang解jie。此ci種zhong反fan應ying器qi主zhu要yao是shi用yong於yu研yan究jiu催cui化hua劑ji的de反fan應ying效xiao率lv.由於結構相對比較複雜,所以應用也較少。還有很多種新型的反應器.比如球型反應器.這種反應器在理論上能達到非常高的光利用率,並且無論是光的分布。還是汙染物的分布.還有催化劑的分布都能達到非常高的均勻性和穩定性.反應效率也是非常理想的,但是製作非常的困難.所以現在這種球型的反應器並不常見,是一種理想化的反應器。
3 結語
隨光催化技術的提高,光催化反應器也在被不斷的改進和優化.越來越受到人們的重視.特別是光催化技術實現工業化後,反應器的設計需要進行係統的優化沒計才能使光催化反應效率達到zui優值,一個設計優良的反應器,不僅可以提高反應效率,還能減少對能源和原材料的浪費.提高經濟效益。




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