β-PbO2和BDD電極處理印染反滲透濃水性能

劉梓鋒,鄭睿豪,周青青,王家德,史學(xué)儒

β-PbO2和BDD電極處理印染反滲透濃水性能

劉梓鋒,鄭睿豪,周青青,王家德*,史學(xué)儒

(浙江工業(yè)大學(xué)環(huán)境學(xué)院,浙江 杭州 310014)

系統(tǒng)比較了β-PbO2/Ti-Ti和BDD/Si-Ti兩種電極體系處理實(shí)際印染行業(yè)反滲透濃水(ROC)的性能, 考察了同步去除化學(xué)需氧量(COD)和總氮(TN)的動力學(xué),以及對廢水可生化性的改善情況.結(jié)果表明,BDD/Si-Ti電極體系的析氧電位(2.45V)和析氯電位(1.90V),以及陽極氧化電位和陰極還原電位的絕對值均高于β-PbO2/Ti-Ti電極體系;兩種電極體系對COD以及TN的去除符合擬一級動力學(xué),其中BDD/Si-Ti電極體系對COD去除的表觀速率常數(shù)和能量利用效率均優(yōu)于β-PbO2/Ti-Ti電極體系;而β-PbO2/Ti-Ti電極體系對TN去除的表觀速率常數(shù)和能量利用效率更優(yōu).β-PbO2/Ti-Ti電極體系在5mA/cm2的電流密度下電解15min,可使反滲透濃水BOD/COD從0.18升至0.42 (提高1.33倍),而BDD/Si-Ti電極體系僅提升0.78倍.兩者相比, BDD/Si-Ti電極體系適用于礦化污染物,β-PbO2/Ti-Ti電極體系適用于改善廢水可生化性.

反滲透濃水；電化學(xué)；印染廢水；動力學(xué)

反滲透是工業(yè)水處理領(lǐng)域清潔高效的水處理技術(shù).印染行業(yè),反滲透濃水(ROC)鹽度高、色度高,截留污染物成分復(fù)雜, 可生化性差[1],納管(或直排)前需要作進(jìn)一步處理.針對這類反滲透濃水,單一生物處理效果差,吸附處理存在吸附劑次生污染問題.相比臭氧氧化[2]、光催化[3]、芬頓反應(yīng)[4]等高級氧化,使用電氧化方法處理反滲透濃水,通過電極表面的電子遷移以及活性物種的化學(xué)反應(yīng),實(shí)現(xiàn)污染物轉(zhuǎn)化或完全礦化,反應(yīng)條件溫和,設(shè)備操作簡單,且無額外添加反應(yīng)藥劑,處理過程清潔綠色[5],為這類廢水處理提供了一條新途徑[6-7].目前,電氧化技術(shù)已經(jīng)成功應(yīng)用于農(nóng)藥、紡織以及垃圾滲濾液等行業(yè)廢水的深度處理[8-9].反滲透濃水高含鹽,為電化學(xué)體系提供了支持電解質(zhì),且無需添加額外電解質(zhì),降低了槽電壓,節(jié)約能耗;同時,Cl-和SO42-電氧化生成的活性氯和過硫酸根[10],會與污染物發(fā)生氧化分解反應(yīng)[11],提高了反應(yīng)效率.

廢水電氧化處理常用的陽極材料有二氧化鉛(PbO2)電極和摻硼金剛石(BDD)電極,它們在電解過程中具有高析氧電位和低析氧產(chǎn)率[12],氧化性能強(qiáng).β-PbO2/Ti電極成本低,表面活性層呈開放的多孔結(jié)構(gòu),活性表面積大,電子遷移率高,穩(wěn)定性強(qiáng)[13-15]. BDD/Si電極電化學(xué)和理化性能優(yōu),電化學(xué)勢窗寬、背景電流小[16-17],可實(shí)現(xiàn)高電流效率和有機(jī)物完全礦化[18-19].電極材料會直接影響電氧化體系的性能[20],目前,國內(nèi)外針對兩種電極體系的對比多傾向于特定的物質(zhì)降解[21-24],而非應(yīng)用于特定行業(yè)的實(shí)際廢水,因此,本文通過系統(tǒng)地比較β-PbO2/Ti-Ti和BDD/Si-Ti電極體系處理實(shí)際印染行業(yè)反滲透濃水的性能,考察同步去除化學(xué)需氧量(COD)、總氮(TN)的動力學(xué)、能耗以及對廢水可生化性的改善情況,為廢水的電化學(xué)處理技術(shù)實(shí)際工程應(yīng)用提供支持.

1 材料與方法

1.1 原水水質(zhì)

反滲透濃水取自浙江紹興柯橋?qū)嶋H印染廠反滲透末端外排濃水.經(jīng)分析檢測,水質(zhì)參數(shù)如表1所示.

表1 反滲透濃水的基本水質(zhì)特征

1.2 實(shí)驗(yàn)裝置

本文所使用的β-PbO2/Ti電極以Ti電極為基底、通過熱分解法以錫銻氧化物作為底層、堿性電鍍α-PbO2層和酸性電鍍β-PbO2作為活性層,共4步驟制成;BDD/Si電極的制備方法主要以硅板作為基底采用化學(xué)氣相沉積技術(shù)(CVD)所制成.

電極性能測試主要在常規(guī)的三電極體系中完成(圖1a),電解試驗(yàn)在電解槽中進(jìn)行(圖1b).陽極選用β-PbO2/Ti電極和BDD/Si電極,陰極選用網(wǎng)板鈦(Ti)電極,分別構(gòu)成β-PbO2/Ti-Ti電極體系和BDD/ Si-Ti電極體系.

1.3 分析項目及測試方法

使用電化學(xué)工作站CHI660(中國)進(jìn)行電極循環(huán)伏安測試, 掃描速率100mV/s,工作電極為β- PbO2/Ti電極(1cm2)、BDD/Si電極(1cm2),對電極為Pt片(1cm2),參比電極為飽和甘汞電極,測試在室溫下進(jìn)行,支持電解質(zhì)為0.5mol/LNa2SO4;線性伏安測試掃描速率10mV/s,測試條件同上,電解質(zhì)體系分別為0.5mol/LNa2SO4和0.5mol/L NaCl以及實(shí)驗(yàn)所使用的反滲透濃水,測得電極的析氧、析氯電位,以及在實(shí)際廢水中的陽極氧化電位;電極電化學(xué)阻抗譜(EIS)中交流阻抗測試頻率范圍為104～100Hz,擾動振幅為0.5mV.

化學(xué)需氧量(CODCr)使用重鉻酸鉀法測定(GB 11914-89) ,在預(yù)處理中使用硫酸汞屏蔽廢水中氯離子的干擾;五日生化需氧量(BOD5)使用Hach BOD TRAK Ⅱ(美國)裝置測定;總有機(jī)碳(TOC)使用島津TOC-V(日本)測定;總氮(TN)采用堿性過硫酸鉀消解紫外分光光度法,使用Hach DR6000紫外分光光度計(美國)測定;氨氮選用納氏試劑比色法確定;pH值使用EZDO B6339儀器(中國臺灣)測定,TDS、電導(dǎo)率使用EZDO W6277便攜式測定筆(中國臺灣)測定;Cl-、SO42-、NO3-等陰離子,Na+、Mg2+、NH4+等陽離子濃度使用離子色譜儀器Dionex ICS-2000(美國)測定.

所有實(shí)驗(yàn)數(shù)據(jù)均取自3個獨(dú)立實(shí)驗(yàn)的平均值,并且計算得出的誤差<6%.

2 結(jié)果與討論

2.1 電極的基本特征

在掃速為100mV/s時,在圖2(a)1.2V處有氧化峰,在0.9V處有還原峰,屬于PbO2/PbO的氧化還原對[25-26],是典型的PbO2電極.圖2(b)可看出與β- PbO2/Ti相比BDD/Si電極背景電流小,電化學(xué)勢窗口較大,析氧電位明顯高于β-PbO2/Ti電極.

在電化學(xué)阻抗譜(EIS)中,判斷電子在基體和鍍層之間的難易程度主要是依據(jù)圓弧半徑的相對大小[10].不同電極在0.5mol/L Na2SO4溶液中的電化學(xué)交流阻抗圖如圖2(c)所示, BDD/Si電極的電化學(xué)反應(yīng)界面的電荷轉(zhuǎn)移電阻小,說明相比β-PbO2/Ti電極,BDD/Si電極具有更高的電化學(xué)活性.

圖2 β-PbO2/Ti 和BDD/Si電極的循環(huán)伏安及阻抗圖 (vs. SCE)

如圖3所示,β-PbO2/Ti電極析氧電位為1.78V,析氯電位為1.61V;BDD/Si電極的析氧電位為2.45V,析氯電位為1.90V;設(shè)定電流密度為10mA/cm2時 ,使用實(shí)際廢水作為溶液 BDD/Si電極電位為2.35V, β-PbO2/Ti電極電位為1.69V.兩者相比,BDD/Si電極具有較高的析氧電位、析氯電位及實(shí)際廢水中的陽極氧化電位[18-27],具有更強(qiáng)的電催化性能.兩種電極的陽極氧化電位均介于析氧電位和析氯電位之間,實(shí)際廢水發(fā)生電解反應(yīng)時,析氧副反應(yīng)可以得到有效控制,但析氯反應(yīng)無法避免.

圖3 β-PbO2/Ti 和BDD/Si電極的線性伏安掃描圖(vs. SCE)

2.2 不同電極體系的電位分布

實(shí)際電解體系包括陽極和陰極,體系中電極電位直接影響著污染物分解.實(shí)驗(yàn)設(shè)計鹽橋檢測不同電流密度下的兩種電解體系陰陽兩極電位分布,以此揭示電極反應(yīng)本質(zhì),科學(xué)控制副反應(yīng).

如圖4所示,實(shí)際電解體系伏安特性曲線具有與圖3極化曲線相一致的形狀,以10mA/cm2電流密度下舉例,陽極電位2.77V(BDD/Si電極)、1.60V (β-PbO2/Ti電極),Ti陰極電位-2.30V(BDD/Si-Ti電極體系)、-2.03V(β-PbO2/Ti-Ti電極體系),控制相同電流密度,BDD/Si-Ti電極體系的電壓絕對值大于β-PbO2/Ti-Ti電極體系,這意味著達(dá)到同樣的電極電位,BDD/Si-Ti電極體系輸入的電流密度小于PbO2電極體系.同時,過高的電極電位容易導(dǎo)致反應(yīng)過度(如陰極NO3-,NO2-過度還原成NH3,影響TN和NH3-N的去除).

2.3 動力學(xué)分析

2.3.1 CODCr去除 低污染物濃度廢水電氧化過程符合擬一級動力學(xué)[28].

式中:[COD]0/[COD]是t時間(min)相對于初始時間的濃度相對值;app是擬一級表觀速率常數(shù).

實(shí)際反滲透濃水電解實(shí)驗(yàn)結(jié)果顯示(圖5),不同電流密度下的ln[COD]0/[COD]和app成線性關(guān)系,電流密度越大,app的值越大,如表2所示,通過對表觀速率常數(shù)和電流密度之間的關(guān)系擬合,可以得到描述兩者關(guān)系的數(shù)學(xué)式.

表2 COD去除擬一級表觀速率常數(shù)

β-PbO2/Ti-Ti電極體系:

BDD/Si-Ti電極體系:

式中:為電流密度,mA/cm2.

兩種電極體系均能有效去除污染物,但相同電流密度下(如10mA/cm2),BDD/Si-Ti電極體系對COD去除性能強(qiáng)于β-PbO2/Ti-Ti電極體系.120min所達(dá)到去除率分別為68.7%以及57.7%,前者app是后者的1.84倍.兩種電極體系下陽極對有機(jī)污染物的氧化性能,往往取決于析氧副反應(yīng)[29](式(4)),由于BDD電極比β-PbO2電極具有更高的析氧電位,析氧反應(yīng)較難發(fā)生,減少了析氧副反應(yīng).在實(shí)際電解中,相比具有水合性的β-PbO2電極,BDD電極的惰性表面對其產(chǎn)生羥基自由基(·OH)的吸附性能弱[28-30]·OH更容易參與有機(jī)物氧化反應(yīng)(式(5)),同時,由于體系中Cl-存在,通電過程中發(fā)生析氯反應(yīng)產(chǎn)生大量活性氯(式(6))且在溶液中轉(zhuǎn)換成不同形態(tài)(式(7)、(8)),不同形態(tài)的活性氯參與間接氧化降解有機(jī)物質(zhì)(式9)[31-33],提高了系統(tǒng)對COD的處理能力.

除了上述原因之外,大量研究結(jié)果已經(jīng)證明BDD電極可以產(chǎn)生SO4·-與過硫酸根(式(10)、(11)),SO4·-(2.5～3.1V)具有比·OH(1.8～2.7V)更高的氧化電位,能夠進(jìn)一步提升電極本身的氧化能力[28]. Sun等[30]比較兩種電極氧化蒽醌染料茜素紅S,BDD電極直接礦化有機(jī)物;PbO2電極則先裂解—C=O基團(tuán)附近的C—C鍵,形成鄰苯二甲酸、小羰基等中間體.Lazhar等[34]考察了兩種電極處理甲基橙水溶液,BDD電極處理污染物快速、礦化徹底,而PbO2電極體系傾向于產(chǎn)生中間體再進(jìn)一步礦化. 相比之下,PbO2電極產(chǎn)生SO4·-僅在TiO2納米管結(jié)構(gòu)時被觀測到[35-36],在這之前鮮有報道.實(shí)驗(yàn)所使用的并非TiO2納米管結(jié)構(gòu)電極,因此相比之下,BDD/ Si-Ti電極體系具有更強(qiáng)的礦化能力.

S(·OH)→S+1/2O2+H++e-(4)

R+S(·OH)→S+CO2+H2O+H++e-(5)

2Cl-→Cl2+2e-(6)

R+ Active Chlorine→CO2+H2O+zCl-(9)

SO42-+S(·OH) →S(SO4·-)+OH-(10)

SO42-+S(SO4·-) →S2O82-+e-(11)

2.3.2 TN去除 印染反滲透濃水TN包括NO3--N、NO2--N和NH3-N.電化學(xué)去除TN主要為陽極上NH3-N氧化成N2(式(12)和(13)),NO3--N、NO2--N在陰極還原成N2(式(15)和(16)),并且存在一個適合的電位范圍[37].在溶液HOCl濃度遠(yuǎn)大于NH3的條件下,HOCl與NH3反應(yīng)生成NO3-以及N2[31-38].高電極電位下,陽極上NH3-N易過氧化生成NO3-- N、NO2--N,陰極上NO3--N、NO2--N還原成NH3-N,這些反應(yīng)均會影響NH3-N和TN的去除.

2NH3+6OH-→N2+6H2O+6e-(12)

2NH3+3HOCl→N2+3H2O+3H++3Cl-(13)

NH3+4HOCl→NO3-+H2O+6H++4Cl-(14)

NO3-+H2O+2e-----→NO2-+2OH-(15)

NO2-+4H2O+6e-→N2+8OH-(16)

實(shí)際反滲透濃水TN電解去除如圖6所示,不同電流密度下的ln[0]/[C]和app也成線性關(guān)系,電流密度越大,app值越大,同樣通過對表觀速率常數(shù)和電流密度之間的關(guān)系擬合,可以得到描述兩者關(guān)系的數(shù)學(xué)式.

表3 TN去除擬一級表觀速率常數(shù)

β-PbO2/Ti-Ti電極體系:

app=0.0019e0.0632J(2=0.954)(17)

BDD/Si-Ti電極體系:

app=0.0019e0.0611J(2=0.975)(18)

由上述可知,在相同電流密度下,BDD/Si-Ti電極體系對TN去除性能低于β-PbO2/Ti-Ti電極體系,并且在相同電流密度下,BDD/Si-Ti體系在3h的處理時間內(nèi)難以達(dá)到理想的去除率50%以上(TN< 30mg/L),這與陰極過度還原和陽極過度氧化有關(guān).實(shí)際電解時,低陰極電位易發(fā)生析氫副反應(yīng),大量的·H吸附在電極表面上,促進(jìn)N-H結(jié)合,不利于N-N形成,NO3-還原成NH4+(式(19))[39];高陽極電位使析氯反應(yīng)劇烈,活性氯將NH4+過氧化生成NO3--N、NO2--N[40],從而導(dǎo)致TN去除效果減弱.BDD/Si-Ti電極體系的陰極電位和陽極電位絕對值均高于β-PbO2/Ti-Ti電極體系,陰極析氫反應(yīng)強(qiáng),導(dǎo)致NO3--N、NO2--N過度還原為NH3-N,形成N2的選擇性下降.

NO3-+10H++8e-→NH4++3H2O(19)

NH4++4HOCl→NO3-+H2O+6H++4Cl-(20)

2.4 可生化性實(shí)驗(yàn)

生物法是廢水處理最經(jīng)濟(jì)的方法.污染物通過生物代謝活動分解為CO2、H2O或成為生物自身物質(zhì),整個處理過程經(jīng)濟(jì)安全綠色.相比之下,電化學(xué)徹底分解污染物能耗高,相對經(jīng)濟(jì)的方法是提高廢水可生化性后,再用生物工藝處理.反滲透濃水TDS為12.85～ 13.83g/L,鹽度為1%～1.5%,對照Kokabian[41]、Abou-Elela等[42]研究成果,該濃度下不會對生物處理產(chǎn)生大的影響.

使用BOD/COD(B/C比)比作為生化指標(biāo),試驗(yàn)考察了反滲透濃水電分解后的B/C比變化.圖7為相同電流密度下,兩種電極體系TOC、BOD值以及B/C比隨時間的變化情況.根據(jù)圖7(a)可以看出在電流密度5mA/cm2時,BDD/Si-Ti電極體系在長時間的電解情況下去除TOC效率高于β-PbO2/Ti-Ti電極體系,且β-PbO2/Ti-Ti電極體系在60～150min TOC去除效率有所放緩,而由圖7(b)可知,隨著電解進(jìn)行,兩個體系BOD值與B/C比均經(jīng)歷了先升后降的過程.電流密度5mA/cm2、電解15min,β-PbO2/Ti-Ti電極體系將反滲透濃水的B/C比從0.18提升至0.42(>0.35),高于BDD/Si-Ti電極體系,結(jié)合前面COD、TN去除情況,BDD/Si-Ti電極體系陽極氧化電位高,催化能力強(qiáng),適合污染物礦化;β-PbO2/Ti-Ti電極體系陽極氧化電位低,更適合將污染物轉(zhuǎn)化為可生化性好的物質(zhì),便于后續(xù)生物降解.

2.5 能耗評估

大量研究表明,低污染物濃度廢水電氧化過程符合擬一級動力學(xué)[28-34],COD以及TN的去除符合擬一級動力學(xué),因此本文引入指數(shù)能耗eo[43-44],科學(xué)評估電化學(xué)體系污染物去除的耗能情況以及電化學(xué)系統(tǒng)的能量利用效率,計算公式如(21).

式中:eo是電解降低一個數(shù)量級所需要的能量, kW·h/(m3·order);是平均功率,kW;是反應(yīng)時間,h;是溶液的體積,m3可以根據(jù)擬一級動力學(xué)簡化該表達(dá)式.

式中:0.0383是轉(zhuǎn)換因子(1/60/0.4343);1是擬一級速率常數(shù),min-1.

對于特定的電極體系,電流密度小(接近極限電流密度),去除單位COD能耗低,能量利用效率高,但反應(yīng)速度慢,完成相同反應(yīng)量需要時間長,設(shè)備體積大.實(shí)際電解過程電流密度大小與能耗有一個平衡點(diǎn).表4和表5分別列出了不同電流密度下的指數(shù)能耗(eo),同一電流密度下,BDD/Si-Ti電極體系對COD去除的能量利用效率高于β-PbO2/Ti-Ti電極體系.分析認(rèn)為,實(shí)驗(yàn)所選取電流密度的陽極氧化電位均高于析氯電位,略低于析氧電位,易發(fā)生析氯析氧副反應(yīng);相比之下,BDD/Si-Ti體系陽極具有更低的·OH基團(tuán)的吸附能力[45],有利于COD去除[34-46],能量利用率高.進(jìn)一步地,兩種電極對·OH基團(tuán)的吸附量受電流密度影響不同, β-PbO2/Ti電極較BDD/Si電極敏感,低電流密度提升階段電極表面·OH基團(tuán)吸附量上升迅速,析氧副反應(yīng)劇烈,能耗增加明顯.

表4 不同電流密度下兩種電極體系去除COD的Eeo

TN去除主要取決于陽極和陰極的電位控制[47].由表5可知,同一電流密度下,β-PbO2/Ti-Ti體系TN去除效果更好,能量利用效率更高.分析認(rèn)為,兩種體系實(shí)際陰極還原電位均低于析氫電位,但β-PbO2/ Ti-Ti電極體系具有相對較低的陰極電位,減少NH4+形成,提高NO3-、NO2-還原為N2的選擇性,提高了能量利用效率;而BDD/Si-Ti電極體系過度氧化和過度還原嚴(yán)重,不利于TN的高效去除.

綜上所述, COD和TN去除的eo隨著電流密度增大而增大,且高電流密度下析氧析氯副反應(yīng)也更加劇烈,考慮實(shí)際情況,電化學(xué)處理時間需要控制在2.5h以內(nèi),應(yīng)盡可能選用低電流密度.以《紡織染整工業(yè)水污染物排放標(biāo)準(zhǔn)》(GB4287-2012)現(xiàn)有企業(yè)間接排放標(biāo)準(zhǔn)(COD<200mg/L、TN<30mg/L)作為參考,β-PbO2/Ti-Ti電極體系建議選用15mA/cm2作為主要處理參數(shù),BDD/Si-Ti電極體系在僅考慮COD達(dá)標(biāo)的情況下應(yīng)選用10mA/cm2作為主要處理參數(shù).

表5 不同電流密度下兩種電極體系去除TN的Eeo

圖8為COD和TN達(dá)到上述排放標(biāo)準(zhǔn)時,不同電流密度下所需的電解能耗c.c計算見式(23).

式中:c是處理單位體積廢水的能耗,kW·h/m3.

相比之下,β-PbO2/Ti-Ti電極體系處理單位體積廢水的能耗高于BDD/Si-Ti電極體系.需要說明的是, β-PbO2/Ti-Ti電極體系能實(shí)現(xiàn)COD和TN 兩者達(dá)標(biāo), 而BDD/Si-Ti電極體系僅COD達(dá)標(biāo),對TN最高去除率僅為35%,出水TN濃度大于30mg/L,難以達(dá)到同步去除要求.

圖8 廢水處理至達(dá)標(biāo)排放的能耗對比

按上述的排放標(biāo)準(zhǔn),對比分析單獨(dú)電化學(xué)深度處理和電化學(xué)僅作預(yù)處理(提升B/C)后續(xù)結(jié)合生物處理兩種工藝所需的總能耗,其中電化學(xué)深度處理部分能耗來源于圖8;電化學(xué)作為預(yù)處理提高B/C的生化處理能耗則選取通電處理的時間為15min時不同的電極體系所消耗的能耗(此時β-PbO2/Ti-Ti電極體系預(yù)處理廢水B/C為0.42,BDD/Si-Ti電極體系預(yù)處理廢水B/C為0.30),生化處理部分參考Yan He等研究成果[46].結(jié)果如表6所示,相比之下,β-PbO2/ Ti-Ti電極體系預(yù)處理反滲透濃水,之后采用生物處理至達(dá)標(biāo),能耗僅為1.74kW·h/m3,遠(yuǎn)低于直接電解至達(dá)標(biāo)所消耗的能耗,節(jié)能顯著.

表6 不同處理方式下兩種電極體系的能耗Ec

3 結(jié)論

3.1 BDD/Si陽極的析氧電位(2.45V)和析氯電位(1.90V)高于β-PbO2/Ti陽極,BDD/Si-Ti電極體系的電極電位絕對值大于β-PbO2/Ti-Ti電極體系;控制相同電流密度,BDD/Si-Ti電極體系的槽電壓會高于β-PbO2/Ti-Ti電極體系.

3.2 兩種電極體系對COD和TN去除遵循擬一級動力學(xué)模型,在電流密度為5～20mA/cm2范圍內(nèi),根據(jù)擬合方程及實(shí)驗(yàn)結(jié)果,BDD/Si-Ti電極體系COD去除表觀速率常數(shù)app高于β-PbO2/Ti-Ti電極體系,TN去除表觀速率常數(shù)低; BDD/Si-Ti電極體系COD去除指數(shù)能耗Eeo低,TN去除指數(shù)能耗高.在處理實(shí)際印染行業(yè)反滲透濃水時β-PbO2/Ti-Ti電極體系能實(shí)現(xiàn)COD和TN同步去除,適用于COD和TN超標(biāo)的廢水,而BDD/Si-Ti電極體系更適合用于污染物完全礦化處理.

3.3 β-PbO2/Ti-Ti電極體系在5mA/cm2條件下電解15min可以將B/C從0.18提升至0.42(提升1.33倍)而BDD/Si僅提升0.78倍.相比之下,使用β-PbO2/ Ti-Ti電極體系,在低電流密度下作為預(yù)處理可進(jìn)一步降低處理全過程所需能耗.

[1] Joo S H, Tansel B. Novel technologies for reverse osmosis concentrate treatment: A review [J]. Journal of Environmental Management, 2015, 150:322-335.

[2] Weng J, Jia H, Wu B, et al. Is ozonation environmentally benign for reverse osmosis concentrate treatment? Four-level analysis on toxicity reduction based on organic matter fractionation [J]. Chemosphere, 2018,191:971-978.

[3] Lin X H, Li S F Y. Impact of the spatial distribution of sulfate species on the activities of SO42?/TiO2photocatalysts for the degradation of organic pollutants in reverse osmosis concentrate [J]. Applied Catalysis B: Environmental, 2015,170-171:263-272.

[4] Barreto-Rodrigues M, Silva F T, Paiva T C B. Combined zero-valent iron and fenton processes for the treatment of Brazilian TNT industry wastewater [J]. Journal of Hazardous materials, 2009,165(1):1224-1228.

[5] Chen M, Pan S, Zhang C, et al. Electrochemical oxidation of reverse osmosis concentrates using enhanced TiO2-NTA/SnO2-Sb anodes with/without PbO2layer [J]. Chemical Engineering Journal, 2020, 399:125756.

[6] Radjenovic J, Bagastyo A, Rozendal R A, et al. Electrochemical oxidation of trace organic contaminants in reverse osmosis concentrate using RuO2/IrO2-coated titanium anodes [J]. Water Research, 2011, 45(4):1579-1586.

[7] 李金城,宋永輝,湯潔莉.電化學(xué)氧化法去除蘭炭廢水中COD和NH3-N [J]. 中國環(huán)境科學(xué), 2022,42(2):697-705.

Li J C, Song Y H, Tang J L Removing of COD and NH3-N from blue-coke wastewater by electrochemical oxidation [J]. China Environmental Science, 2022,42(2):697-705.

[8] Onn S W, Bashir M J K, Sethupathi S, et al. Colour and COD removal from mature landfill leachate using electro-persulphate oxidation process [J]. Materials Today: Proceedings, 2020,31:69-74.

[9] Olvera-Vargas H, Gore-Datar N, Garcia-Rodriguez O, et al. Electro-Fenton treatment of real pharmaceutical wastewater paired with a BDD anode: Reaction mechanisms and respective contribution of homogeneous and heterogeneous OH [J]. Chemical Engineering Journal, 2021,404:126524.

[10] Pereira G F, Rocha-Filho R C, Bocchi N, et al. Electrochemical degradation of the herbicide picloram using a filter-press flow reactor with a boron-doped diamond or β-PbO2anode [J]. Electrochimica Acta, 2015,179:588-598.

[11] Garcia-Segura S, Ocon J D, Chong M N. Electrochemical oxidation remediation of real wastewater effluents — A review [J]. Process Safety and Environmental Protection, 2018,113:48-67.

[12] Zhou X, Wang s, Ma C, et al. Effect of Ag Content and β-PbO2Plating on the Properties of Al/Pb-Ag Alloy [J]. Rare Metal Materials and Engineering, 2018,47(7):1999-2004.

[13] Sirés I, Low C T J, Ponce-de-León C, et al. The characterisation of PbO2-coated electrodes prepared from aqueous methanesulfonic acid under controlled deposition conditions [J]. Electrochimica Acta, 2010,55(6):2163-2172.

[14] Abaci S, Yildiz A. Electropolymerization of thiophene and 3- methylthiophene on PbO2electrodes [J]. Journal of Electroanalytical Chemistry, 2004,569(2):161-168.

[15] Zhou X, Zhou Q, Chen H, et al. Influence of dimethylphenol isomers on electrochemical degradation: Kinetics, intermediates, and DFT calculation [J]. Science of The Total Environment, 2021,794:148284.

[16] Pérez G, Saiz J, Iba?ez R, et al. Assessment of the formation of inorganic oxidation by-products during the electrocatalytic treatment of ammonium from landfill leachates [J]. Water Research, 2012,46(8): 2579-2590.

[17] Panizza M, Kapalka A, Comninellis C. Oxidation of organic pollutants on BDD anodes using modulated current electrolysis [J]. Electrochimica Acta, 2008,53(5):2289-2295.

[18] He Y, Huang W, Chen R, et al. Anodic oxidation of aspirin on PbO2, BDD and porous Ti/BDD electrodes: Mechanism, kinetics and utilization rate [J]. Separation and Purification Technology, 2015,156: 124-131.

[19] Panizza M, Cerisola G. Application of diamond electrodes to electrochemical processes [J]. Electrochimica Acta, 2005,51(2):191-199.

[20] Mart??nez-Huitle C A, Ferro S, De Battisti A. Electrochemical incineration of oxalic acid: Role of electrode material [J]. Electrochimica Acta, 2004,49(22):4027-4034.

[21] Li A, Weng J, Yan X, et al. Electrochemical oxidation of acid orange 74using Ru, IrO2, PbO2, and boron doped diamond anodes: Direct and indirect oxidation [J]. Journal of Electroanalytical Chemistry, 2021, 898:115622.

[22] Santos J E L, de Moura D C, Cerro-López M, et al. Electro- and photo-electrooxidation of 2,4,5-trichlorophenoxiacetic acid (2,4,5-T) in aqueous media with PbO2, Sb-doped SnO2, BDD and TiO2-NTs anodes: A comparative study [J]. Journal of Electroanalytical Chemistry, 2020,873:114438.

[23] Xing X, Ni J, Zhu X, et al. Maximization of current efficiency for organic pollutants oxidation at BDD, Ti/SnO2-Sb/PbO2, and Ti/SnO2-Sb anodes [J]. Chemosphere, 2018,205:361-368.

[24] 鄧冬莉,吳明珠,李 應(yīng),等.電催化氧化處理鄰苯二甲酸酯類物質(zhì)陽極材料的研究進(jìn)展 [J]. 化工新型材料, 2021,49(4):267-271.

Deng D L, Wu M Z, LI Y. Advance on anode material for electrocatalytic oxidation of phthalate ester [J]. New Chemical Materials, 2021,49(4):267-271.

[25] Song S, Fan J, He Z, et al. Electrochemical degradation of azo dye C.I. Reactive Red 195by anodic oxidation on Ti/SnO2–Sb/PbO2electrodes [J]. Electrochimica Acta, 2010,55(11):3606-3613.

[26] 葉志平,周丹飛,劉梓鋒,等.對甲基苯磺酸在Ti/PbO2電極上的電氧化反應(yīng)信息. [J]. 化工學(xué)報, 2021,72(5):2810-2816.

Ye Z P, Zhou D F, Liu Z F, et al Electro-oxidation information of p-toluene sulfonic acid on Ti/PbO2electrode [J]. CIESC Journal, 2021,72(5):2810-2816.

[27] Zhang C, Lu X, Lu Y, et al. Titaniumboron doped diamond composite: A new anode material [J]. Diamond and Related Materials, 2019,98:107490.

[28] Santos J E L, Gómez M A, Moura D C d, et al. Removal of herbicide 1-chloro-2,4-dinitrobenzene (DNCB) from aqueous solutions by electrochemical oxidation using boron-doped diamond (BDD) and PbO2electrodes [J]. Journal of Hazardous materials, 2021,402:123850.

[29] Chen X, Gao F, Chen G. Comparison of Ti/BDD and Ti/SnO2–Sb2O5electrodes for pollutant oxidation [J]. Journal of Applied Electrochemistry, 2005,35(2):185-191.

[30] Sun J, Lu H, Du L, et al. Anodic oxidation of anthraquinone dye Alizarin Red S at Ti/BDD electrodes [J]. Applied Surface Science, 2011,257(15):6667-6671.

[31] Deborde M, von Gunten U. Reactions of chlorine with inorganic and organic compounds during water treatment—Kinetics and mechanisms: A critical review [J]. Water Research, 2008,42(1):13-51.

[32] Zhou Q, Zhou X, Zheng R, et al. Application of lead oxide electrodes in wastewater treatment: A review [J]. Science of The Total Environment, 2022,806:150088.

[33] Huang Y K, Li S, Wang C, et al. Simultaneous removal of COD and NH3-N in secondary effluent of high-salinity industrial waste-water by electrochemical oxidation [J]. Journal of Chemical Technology and Biotechnology, 2012,87(1):130-136.

[34] Labiadh L, Barbucci A, Carpanese M P, et al. Comparative depollution of Methyl Orange aqueous solutions by electrochemical incineration using TiRuSnO2, BDD and PbO2as high oxidation power anodes [J]. Journal of Electroanalytical Chemistry, 2016,766:94-99.

[35] Santos J E L, Antonio Quiroz M, Cerro-Lopez M, et al. Evidence for the electrochemical production of persulfate at TiO2nanotubes decorated with PbO2[J]. New Journal of Chemistry, 2018,42(7): 5523-5531.

[36] Zaidi S Z J, Harito C, Walsh F C, et al. Decolourisation of reactive black-5at an RVC substrate decorated with PbO2/TiO2nanosheets prepared by anodic electrodeposition [J]. Journal of Solid State Electronics, 2018:1-12.

[37] Kuang P, Natsui K, Einaga Y, et al. Annealing enhancement in stability and performance of copper modified boron-doped diamond (Cu-BDD) electrode for electrochemical nitrate reduction [J]. Diamond and Related Materials, 2021,114:108310.

[38] Kapa?ka A, Joss L, Anglada á, et al. Direct and mediated electrochemical oxidation of ammonia on boron-doped diamond electrode [J]. Electrochemistry Communications, 2010,12(12):1714-1717.

[39] Yao J, Mei Y, Yuan T, et al. Electrochemical removal of nitrate from wastewater with a Ti cathode and Pt anode for high efficiency and N2selectivity [J]. Journal of Electroanalytical Chemistry, 2021,882: 115019.

[40] Su L, Li K, Zhang H, et al. Electrochemical nitrate reduction by using a novel Co3O4/Ti cathode [J]. Water Research, 2017,120:1-11.

[41] Kokabian B, Bonakdarpour B, Fazel S. The effect of salt on the performance and characteristics of a combined anaerobic–aerobic biological process for the treatment of synthetic wastewaters containing Reactive Black 5 [J]. Chemical Engineering Journal, 2013, 221:363-372.

[42] Abou-Elela S I, Kamel M M, Fawzy M E. Biological treatment of saline wastewater using a salt-tolerant microorganism [J]. Desalination, 2010,250(1):1-5.

[43] Asaithambi P, Sajjadi B, Abdul Aziz A R, et al. Ozone (O3) and sono (US) based advanced oxidation processes for the removal of color, COD and determination of electrical energy from landfill leachate [J]. Separation and Purification Technology, 2017,172:442-449.

[44] Daneshvar N, Aleboyeh A, Khataee A R. The evaluation of electrical energy per order (EEo) for photooxidative decolorization of four textile dye solutions by the kinetic model [J]. Chemosphere, 2005, 59(6):761-767.

[45] Long Y, Li H, Jin H, et al. Interpretation of high perchlorate generated during electrochemical disinfection in presence of chloride at BDD anodes [J]. Chemosphere, 2021,284:131418.

[46] He Y, Zhu Y, Chen J, et al. Assessment of energy consumption of municipal wastewater treatment plants in China [J]. Journal of Cleaner Production, 2019,228:399-404.

[47] Yao J, Pan B, Shen R, et al. Differential control of anode/cathode potentials of paired electrolysis for simultaneous removal of chemical oxygen demand and total nitrogen [J]. Science of The Total Environment, 2019,687:198-205.

致謝：審稿專家提出修改意見和建議,浙江省科學(xué)技術(shù)廳提供的支持,此一并致謝.

Performance comparison of β-PbO2and BDD electrodes for treating reverse osmosis concentrate in printing and dyeing industry.

LIU Zi-feng, ZHENG Rui-hao, ZHOU Qing-qing, WANG Jia-de*, SHI Xue-ru

(College of Environment, Zhejiang University of Technology, Hangzhou 310014, China)., 2022,42(6)：2671～2679

Two electrode systems of β-PbO2/Ti-Ti and BDD/Si-Ti were systematically compared for the performance in treating reverse osmosis concentrate (ROC) from a real printing and dyeing industry. Kinetics of simultaneous remove chemical oxygen demand (COD) and total nitrogen (TN), as well as the improvement of the biochemical properties of the effluent were also investigated. It is shown that the BDD/Si-Ti electrode system has a high anodic oxygen evolution reaction (OER) potential (2.45V) and chlorine evolution reaction (CER) potential (1.90V), and the absolute values of anodic oxidation potential and cathodic reduction potential are higher than those of the β-PbO2/Ti-Ti electrode system; the degradation of COD and TN followed pseudo-first-order kinetics. The BDD/Si-Ti electrode system is more effective in COD removal and current efficiency while the β-PbO2/Ti-Ti electrode system is more effective in TN removal. Electrolysis at a low current density (5mA/cm2) for 15min resulted in a rise in BOD/COD from 0.18 to 0.42 (a 1.33-fold enhancement) for the ROC for the β-PbO2/Ti-Ti electrode system, while the BDD/Si-Ti electrode system only showed a 0.78-fold enhancement. As a result, the BDD/Si-Ti electrode system is suitable for pollutant mineralization, and the β-PbO2/Ti-Ti system is more suitable for the improvement of wastewater biochemical properties.

reverse osmosis concentrate；electrochemistry；printing & dyeing wastewater；kinetics

X703.1

A

1000-6923(2022)06-2671-09

劉梓鋒(1997-),男,浙江湖州人,浙江工業(yè)大學(xué)碩士研究生,主要從事電化學(xué)處理反滲透濃水研究.

2021-11-01

浙江省科技廳重點(diǎn)研發(fā)項目(2019C03094);浙江省“萬人計劃”人才培養(yǎng)項目(2017R52018)

* 責(zé)任作者, 教授, jdwang@zjut.edu.cn