Ce-La雙金屬氧化物同步去除酸性廢水中磷酸鹽和氟的性能與機(jī)理

李 含,趙 雨,陳嘉超,許海民,朱雅嫻,陳志輝,申萌萌,楊文瀾,*

Ce-La雙金屬氧化物同步去除酸性廢水中磷酸鹽和氟的性能與機(jī)理

李 含1,趙 雨1,陳嘉超1,許海民2,朱雅嫻1,陳志輝1,申萌萌1,楊文瀾1,2*

(1.揚(yáng)州大學(xué)環(huán)境科學(xué)與工程學(xué)院,揚(yáng)州 225127；2.江蘇啟創(chuàng)環(huán)境科技股份有限公司,宜興 214264)

采用共沉淀法制備出能同步吸附磷酸鹽和氟的Ce-La雙金屬氧化物納米吸附劑(CLBOs).結(jié)果表明,CLBOs主要以粒徑20～50nm的納米顆?；蚣{米團(tuán)簇的形式存在,比表面積為117.9m2/g.CLBOs在pH為4～12的范圍內(nèi)具有良好的穩(wěn)定性,且酸性條件有利于CLBOs的除磷除氟;在pH = 4.0、磷酸鹽和氟初始濃度為30、10mg/L的條件下,CLBOs最大磷、氟吸附量分別可達(dá)59.14,19.25mg/g.得益于靜電吸引、配體交換和內(nèi)配位絡(luò)合的綜合作用,CLBOs表現(xiàn)出優(yōu)異的同步除磷除氟性能,且在高濃度競(jìng)爭(zhēng)離子體系中能實(shí)現(xiàn)磷酸鹽和氟的選擇性吸附.CLBOs除磷除氟過(guò)程符合準(zhǔn)二級(jí)動(dòng)力學(xué),且對(duì)氟的吸附速率顯著快于磷酸鹽,其中磷酸鹽的吸附平衡時(shí)間約為240min,氟達(dá)到吸附平衡僅需100min.吸附飽和的CLBOs具有較好的再生性能,可長(zhǎng)期重復(fù)使用,在含磷、氟酸性廢水的深度處理領(lǐng)域具備良好的應(yīng)用潛力.

Ce-La雙金屬氧化物；酸性廢水；磷酸鹽；氟；同步去除

水體中超負(fù)荷的磷和氟化物會(huì)導(dǎo)致生態(tài)系統(tǒng)惡化、危害人類健康.其中磷是引發(fā)水體富營(yíng)養(yǎng)化的限制性污染因子[1-2],氟攝入過(guò)量會(huì)導(dǎo)致人體骨骼脆化甚至神經(jīng)損傷[3-4].更為嚴(yán)重的是,水體中共存的磷和氟化物能夠產(chǎn)生協(xié)同作用,對(duì)生態(tài)環(huán)境和人群健康造成更為嚴(yán)重的危害[5].

工業(yè)生產(chǎn)是水體磷、氟污染的重要來(lái)源,其中半導(dǎo)體、磷肥和礦冶等行業(yè)會(huì)產(chǎn)生大量含磷酸鹽和氟化物的生產(chǎn)廢水[6-7].此類廢水具有水質(zhì)復(fù)雜、毒性強(qiáng),酸度高等特點(diǎn)[8-9],常規(guī)污水處理技術(shù)無(wú)法滿足其穩(wěn)定達(dá)標(biāo)排放的需求,迫切需要開(kāi)發(fā)穩(wěn)定高效的污水磷、氟同步去除新技術(shù).

當(dāng)前磷、氟廢水常用的處理技術(shù)包括混凝沉淀、離子交換、膜分離、吸附法等,其中吸附法因操作簡(jiǎn)單、效果穩(wěn)定、投資運(yùn)行費(fèi)用低等優(yōu)點(diǎn),被廣泛應(yīng)用于污水中陰離子污染物的深度去除[10-11],但常見(jiàn)的商品化吸附劑在處理酸性含磷、氟廢水過(guò)程中存在吸附選擇性差、吸附容量低、易溶解流失等問(wèn)題.近年來(lái),鋁、鐵、鋯、稀土等金屬氧化物因其較高的比表面積和良好的目標(biāo)污染物吸附選擇性,在磷、氟廢水深度處理領(lǐng)域受到研究人員的廣泛關(guān)注[12-13].其中,稀土金屬氧化物具有較強(qiáng)的堿度和較低的離子電位,在水中能夠?qū)⒈砻媪u基(-OH)解離為氫氧根(OH-),易與陰離子污染物發(fā)生配體交換實(shí)現(xiàn)其選擇性吸附[14].鈰(Ce),鑭(La)是地殼中豐度較高的兩類稀土金屬,其氧化物化學(xué)性質(zhì)穩(wěn)定、表面羥基豐富,具有良好的抗酸堿溶出性能和較高的磷、氟吸附容量[15-16].近期研究表明,通過(guò)金屬摻雜制備雙金屬氧化物,能夠顯著提高材料的表面羥基含量進(jìn)而提升材料的吸附性能[17].例如,Zhang等[18]通過(guò)共沉淀法制備的Ce-Fe雙金屬氧化物(CFBOs)羥基含量達(dá)到30.8 %,遠(yuǎn)高于單金屬氧化物CeO2的12.6 %和Fe3O4的19.6 %,使得CFBOs的除砷性能得到顯著提高;Guo等[19]將Al-La雙金屬氧化物載入纖維素/石墨烯載體內(nèi),制備的復(fù)合納米材料Al-La@CG表現(xiàn)出優(yōu)異的磷酸鹽、氟吸附性能.基于此,本研究擬采用共沉淀法制備Ce-La雙金屬氧化物(Ce-La bimetal oxides, CLBOs)納米吸附劑,考察其對(duì)酸性廢水中磷酸鹽和氟的同步吸附性能,探究其理化性質(zhì)及同步除磷除氟機(jī)制,以期為含磷、氟酸性廢水的深度處理提供理論基礎(chǔ)和技術(shù)支撐.

1 材料與方法

1.1 試劑

實(shí)驗(yàn)使用化學(xué)試劑均為分析純,購(gòu)于國(guó)藥集團(tuán)化學(xué)試劑有限公司或南京化學(xué)試劑有限公司,實(shí)驗(yàn)用水為超純水.分別采用KH2PO4和NaF配制1000mg/L的磷酸鹽、氟化物儲(chǔ)備液;使用Na2SO4和NaCl配置SO42-、Cl-競(jìng)爭(zhēng)離子溶液.

1.2 材料制備

稱取11.13g LaCl3·7H2O和12.12g Ce(SO4)2·4H2O置于燒杯中(物質(zhì)的量比為1:1),加入100mL純水充分?jǐn)嚢柚镣耆芙夂?將1mol/L的NaOH溶液緩慢滴入上述混合液中至pH值為8左右,勻速攪拌1h后離心得到沉淀物.用純水多次洗滌沉淀物至出水為中性,置于70 ℃烘箱內(nèi)干燥12h,研磨得到CLBOs納米吸附劑.用同樣方法制得水合氧化鈰(HCO)和水合氧化鑭(HLO)用于對(duì)比研究.

1.3 實(shí)驗(yàn)方法

如無(wú)特別說(shuō)明,實(shí)驗(yàn)中吸附劑用量均為0.50g/L,反應(yīng)在含有100mL溶液的錐形瓶中進(jìn)行,磷酸鹽和氟初始濃度分別為30mg/L和10mg/L,pH值為4.0 ± 0.1,溫度為298K,吸附時(shí)間為12h,使用1mol/L的HCl或NaOH調(diào)節(jié)溶液pH值;吸附后用0.22 μm醋酸纖維膜過(guò)濾分離CLBOs,并測(cè)定濾液中磷酸鹽和氟濃度.穩(wěn)定性實(shí)驗(yàn)中,將0.05g CLBOs分別置于pH值為2～12的100mL溶液中,298K下恒溫振蕩168h后測(cè)定溶液中Ce、La濃度.吸附劑性能對(duì)比實(shí)驗(yàn)中,分別稱取0.05g CLBOs、0.025g HCO+0.025g HLO、0.05g HLO和0.05g HCO于100mL混合溶液中,測(cè)定各吸附劑平衡吸附量.投加量實(shí)驗(yàn)中,分別稱取0.01～0.06g的CLBOs加入到100mL混合溶液中,測(cè)定不同投加量下CLBOs的吸附量和磷酸鹽、氟去除率.pH值影響實(shí)驗(yàn)中,分別調(diào)節(jié)不同錐形瓶中溶液的pH值至2.0～12.0,考察pH值對(duì)CLBOs除磷除氟性能的影響.加入不同濃度的共存離子(SO42?、Cl?),考察CLBOs的選擇性吸附性能.吸附動(dòng)力學(xué)實(shí)驗(yàn)中,將0.5g CLBOs放入含1000mL混合溶液的三口燒瓶中,每隔一段時(shí)間取樣測(cè)定磷酸鹽和氟濃度.采用1.0mol/L NaOH溶液對(duì)吸附后的CLBOs進(jìn)行脫附再生,考察CLBOs的重復(fù)利用性能.

1.4 實(shí)驗(yàn)儀器及分析方法

磷酸鹽濃度采用《水質(zhì)總磷的測(cè)定鉬酸銨分光光度法》(GB 11893-89)的方法通過(guò)紫外/可見(jiàn)分光光度計(jì)(UV-1100B,上海美普達(dá))測(cè)定;氟離子濃度采用《水質(zhì)氟化物的測(cè)定離子選擇電極法》(GB 7484-87)的方法通過(guò)氟離子選擇電極(PXS-270, INESA,上海儀電)測(cè)定;溶液中Ce、La含量通過(guò)ICP-AES(ICP-Optima 7300DV, PerkinElmer, USA)測(cè)定.CLBOs的比表面積采用Nova-3000氮?dú)馕絻x(Quantachrome, USA)測(cè)定,使用掃描電子顯微鏡SEM(S-4800II, 17Hitachi, Japan)考察材料的表面形貌,使用透射電子顯微鏡TEM(Tecnai 12, Philips, Netherlands)和高分辨TEM(HRTEM)觀測(cè)CLBOs的微觀結(jié)構(gòu),使用X射線衍射儀XRD(D8Advance, Bruker-AXS, Germany)分析CLBOs的晶型.材料的表面化學(xué)鍵采用FTIR紅外光譜儀測(cè)定(Cary 5000, Varia, USA),CLBOs與氟、磷的相互作用通過(guò)光電子能譜(XPS)(ESCALAB250Xi, ThermoFisher, USA)進(jìn)行表征分析.

2 結(jié)果與討論

2.1 CLBOs的理化性質(zhì)

圖1 CLBOs的SEM圖(a), TEM圖(b), HRTEM圖(c), XRD圖(d)

圖2 不同pH值下CLBOs的Ce、La溶出率

CLBOs的比表面積為117.9m2/g,SEM圖(圖1a)表明CLBOs納米顆粒具有不規(guī)則的表面形貌;由TEM圖(圖1b)可知,CLBOs主要以粒徑為20～50nm的納米顆?；蚣{米團(tuán)簇的形式存在;HRTEM圖(圖1c)中清晰的晶格衍射條紋表明CLBOs具有微晶特性[20].CLBOs的XRD衍射圖(圖1d)沒(méi)有出現(xiàn)明顯的衍射峰,說(shuō)明CLBOs納米顆粒主要為無(wú)定形形態(tài)[19].

為進(jìn)一步考察CLBOs在酸堿廢水中長(zhǎng)期使用的穩(wěn)定性,實(shí)驗(yàn)測(cè)定了CLBOs在不同溶液pH值條件下Ce、La的溶出率.由圖2可知,在pH值為3.0的條件下,La的溶出率為4.63%,Ce的溶出率僅為0.55%;當(dāng)pH34.0時(shí),CLBOs均未檢測(cè)到Ce、La的溶出,表明CLBOs在pH值4～12的范圍內(nèi)具有良好的穩(wěn)定性,可用于酸性廢水的除磷除氟.

2.2 吸附性能實(shí)驗(yàn)

為評(píng)估CLBOs的同步除磷除氟性能,選用CLBOs、HLO、HCO以及HCO+HLO混合材料(質(zhì)量比為1:1)在相同條件下進(jìn)行了對(duì)比實(shí)驗(yàn).如圖3所示,吸附劑對(duì)磷酸鹽和氟的吸附性能表現(xiàn)為CLBOs > HLO > HCO+HLO > HCO,表明HLO對(duì)磷酸鹽和氟的親和力優(yōu)于HCO.總體而言,CLBOs對(duì)磷酸鹽和氟的吸附性能優(yōu)于單金屬氧化物及其混合材料,這是由于通過(guò)金屬摻雜制備的雙金屬氧化物相比其單金屬氧化物具有更高的表面羥基含量,從而獲得更多的活性位點(diǎn)用于磷酸鹽和氟的吸附[17-19].

CLBOs投加量對(duì)磷酸鹽和氟同步去除性能的影響如圖4所示.當(dāng)吸附劑用量從0.1g/L增加到0.5g/L時(shí),磷酸鹽和氟的去除率分別從24.06%、40.5%提高到98.6%、95.8%,當(dāng)CLBOs用量進(jìn)一步增加到0.6g/L時(shí),其對(duì)磷酸鹽和氟的去除率沒(méi)有明顯提升,綜合考慮處理效果和經(jīng)濟(jì)性,后續(xù)實(shí)驗(yàn)均將CLBOs投加量設(shè)定為0.5g/L.

2.3 pH值影響實(shí)驗(yàn)

溶液pH值是影響吸附性能的主要因素.由圖5可知,酸性條件下CLBOs的吸附性能顯著優(yōu)于中性和堿性條件,當(dāng)pH值為4.0時(shí),CLBOs對(duì)磷酸鹽和氟的吸附量最大,分別達(dá)到59.14mg/g和19.25mg/g.這是因?yàn)樗嵝詶l件下,CLBOs表面質(zhì)子化帶正電荷,有利于CLBOs通過(guò)靜電吸引作用吸附磷酸鹽和氟離子;同時(shí),溶液中的H+也能夠促進(jìn)CLBOs與磷酸鹽和氟的配體交換反應(yīng).當(dāng)pH值降低至2時(shí),溶液中磷酸鹽主要以H3PO4分子存在,靜電吸引和配體交換作用受到抑制,導(dǎo)致磷酸鹽吸附量顯著下降;當(dāng)pH值介于2.12～7.21之間時(shí),磷酸鹽主要以H2PO4-的形式存在;而當(dāng)pH值在7.21～12.31時(shí),HPO42-占主導(dǎo)地位[21],研究表明H2PO4-相比HPO42-具有更低的吸附能,在配體交換方面更具優(yōu)勢(shì)[22].當(dāng)pH值小于3.18時(shí),氟主要以HF存在,此時(shí)氟的吸附主要依賴于CLBOs與HF的內(nèi)配位絡(luò)合作用;而當(dāng)pH值大于3.18時(shí),氟主要以F-存在,CLBOs主要通過(guò)靜電吸引和配體交換作用吸附F-[23].隨著pH值升高至堿性環(huán)境,CLBOs表面去質(zhì)子化呈負(fù)電性,與HPO42-和F-之間產(chǎn)生靜電排斥效應(yīng);同時(shí)溶液中高濃度的OH-會(huì)與HPO42-和F-競(jìng)爭(zhēng)CLBOs的吸附位點(diǎn),導(dǎo)致CLBOs的吸附性能顯著下降.

2.4 共存離子實(shí)驗(yàn)

廢水中常見(jiàn)的共存陰離子(如:SO42?、Cl?、NO3?等)對(duì)磷酸鹽和氟的吸附存在顯著的抑制作用,且SO42-對(duì)吸附性能的影響遠(yuǎn)高于其它一價(jià)陰離子[24-25].本研究中選擇SO42-和Cl-為代表性共存離子,考察其對(duì)CLBOs除磷除氟的影響,并選用HLO和HCO進(jìn)行對(duì)比研究.如圖6所示,SO42-對(duì)CLBOs吸附磷酸鹽和氟化物的抑制作用均大于Cl-.隨著共存離子濃度從0增加到100mg/L,吸附劑對(duì)磷酸鹽和氟的吸附性能都有所下降,進(jìn)一步提高共存離子濃度至500mg/L, CLBOs的吸附性能能夠保持相對(duì)穩(wěn)定.此外,無(wú)論是否存在競(jìng)爭(zhēng)離子,CLBOs均表現(xiàn)出比HLO和HCO更優(yōu)的吸附性能,這是由于Ce-La雙金屬氧化物相比單金屬氧化物具有更多的表面羥基,有利于CLBOs通過(guò)配體交換或內(nèi)配位絡(luò)合作用實(shí)現(xiàn)對(duì)磷酸鹽和氟的選擇性吸附[18-19].

2.5 吸附動(dòng)力實(shí)驗(yàn)

吸附動(dòng)力學(xué)是評(píng)價(jià)吸附速率的重要指標(biāo).由圖7可知,CLBOs對(duì)磷酸鹽和氟的吸附速率均較快,相比較而言CLBOs對(duì)氟的吸附速率顯著快于磷酸鹽,其中氟達(dá)到吸附平衡僅需100min,而磷酸鹽的吸附平衡時(shí)間約為240min.這是由于F-(0.133nm)與OH-(0.133nm)具有相同的離子半徑,而磷酸根的離子半徑較大(0.200nm)[26],使得CLBOs在羥基配體交換過(guò)程中對(duì)氟的親和力更強(qiáng),吸附速率更快,在磷酸鹽和氟共存條件下表現(xiàn)出對(duì)氟的優(yōu)先吸附[8].

為更好的解析整個(gè)吸附過(guò)程,本研究采用準(zhǔn)一級(jí)和準(zhǔn)二級(jí)動(dòng)力學(xué)模型對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行了擬合[27].由表1可知,準(zhǔn)二級(jí)動(dòng)力學(xué)模型能較好的擬合CLBOs對(duì)磷酸鹽和氟的吸附過(guò)程,擬合所得平衡吸附量與實(shí)驗(yàn)結(jié)果較為接近.

表1 CLBOs對(duì)磷酸鹽和氟的吸附動(dòng)力學(xué)參數(shù)

2.6 “吸附-再生”循環(huán)實(shí)驗(yàn)

吸附劑的再生性能是評(píng)價(jià)其實(shí)際應(yīng)用潛力的重要指標(biāo),本研究通過(guò)連續(xù)5批次的“吸附-再生”循環(huán)實(shí)驗(yàn)考察了CLBOs的脫附和重復(fù)利用性能.由圖8可知,整個(gè)循環(huán)實(shí)驗(yàn)中CLBOs對(duì)氟的吸附量能保持基本穩(wěn)定,而對(duì)磷酸鹽的吸附量在第2批次和第3批次較第1批次分別下降了23.79 %和37.97 %,但從第3批次吸附循環(huán)開(kāi)始吸附量能保持穩(wěn)定.整個(gè)“吸附-再生”循環(huán)實(shí)驗(yàn)中CLBOs對(duì)磷酸鹽的吸附量下降約43.57 %,對(duì)氟的吸附量沒(méi)有明顯變化,這可能是因?yàn)槌跏嘉脚沃蠧LBOs的部分吸附位點(diǎn)被磷和氟永久占據(jù),而F-與OH-有相似的離子半徑[26],后續(xù)吸附過(guò)程中CLBOs對(duì)氟表現(xiàn)出優(yōu)先吸附從而導(dǎo)致磷酸鹽吸附量的降低[8].綜上,CLBOs在吸附磷酸鹽和氟后能夠?qū)崿F(xiàn)高效再生,多批次循環(huán)吸附性能保持相對(duì)穩(wěn)定,是一種具有良好再生性能的除磷除氟吸附劑.

圖8 CLBOs同步除磷除氟的“吸附?再生”循環(huán)實(shí)驗(yàn)

2.7 吸附機(jī)理

圖9 CLBOs吸附磷酸鹽和氟前后的FTIR光譜

為了進(jìn)一步探究CLBOs潛在的除磷除氟機(jī)理,本研究通過(guò)FTIR紅外光譜和XPS能譜對(duì)吸附磷酸鹽和氟前后的CLBOs進(jìn)行了表征.如圖9所示, 3470cm-1處的寬峰代表結(jié)合水的彎曲振動(dòng)[28], 600cm-1處的吸收峰代表M—O或O—M—O(M= Ce或La)的伸縮振動(dòng)[29-30],吸附后該處峰強(qiáng)度明顯下降并偏移至590cm-1,同時(shí)在651cm-1處出現(xiàn)一個(gè)新峰,可能是由于CLBOs吸附磷酸鹽和氟后形成了M-O-P和M-F配位鍵[31-34].1370和1510cm-1處的吸收峰代表金屬氧化物表面羥基(M-OH)的彎曲振動(dòng),吸附后M-OH峰強(qiáng)度明顯減弱,這是由于CLBOs的表面羥基與磷酸鹽和氟發(fā)生了配體交換所致[24-25].

由圖10a可知,吸附后在結(jié)合能684.45eV(F 1s)和133.0eV(P 2p)處出現(xiàn)兩個(gè)新的譜峰,表明磷酸鹽和氟化物已被CLBOs成功吸附.F 1s峰的結(jié)合能與NaF標(biāo)準(zhǔn)F 1s峰(684.9eV)相比向低結(jié)合能方向偏移了0.45eV(圖10b),表明CLBOs與氟之間產(chǎn)生了較強(qiáng)的結(jié)合作用[35-36].P 2p高分辨掃描圖譜可分解為L(zhǎng)a-P(133.75eV)和Ce-P(132.95eV)兩個(gè)特征峰(圖10c)[37],峰面積占比分別為59.58 %和40.42 %,表明La對(duì)磷酸鹽的親和力略強(qiáng)于Ce.CLBOs吸附前的O 1s高分辨掃描圖譜可分解為532.20eV、531.35eV和529.25eV三個(gè)特征峰(圖10d),分別代表結(jié)合水(H2O)、金屬羥基(M-OH)和金屬氧化物(M-O)[37-38];吸附后(圖10e)M-O峰的位置向高結(jié)合能方向發(fā)生偏移,這與CLBOs吸附磷酸鹽后形成M-O-P配合物有關(guān)[39];M-OH的峰面積占比從吸附前的46.43%降至吸附后的29.02%,表明CLBOs的表面羥基通過(guò)配體交換被磷酸鹽和氟取代[40-41],這與FTIR紅外光譜的分析結(jié)果一致.

綜上所述,CLBOs同步吸附磷酸鹽和氟的機(jī)制包括:質(zhì)子化CLBOs納米顆粒對(duì)磷酸鹽和氟的靜電吸引作用(非選擇性),CLBOs與磷酸鹽和氟的羥基配體交換和內(nèi)配位絡(luò)合作用(選擇性).

3 結(jié)論

3.1 采用共沉淀法制備了Ce-La雙金屬氧化物納米吸附劑(CLBOs),其比表面積為117.9m2/g,并以粒徑20～50nm的納米顆?；蚣{米團(tuán)簇的形式存在;與HCO、HLO及其混合材料相比,CLBOs具有最佳的同步除磷除氟性能.

3.2 CLBOs具有良好的抗酸堿溶出性能;溶液pH值對(duì)CLBOs同步除磷除氟的性能有較大影響,在pH = 4.0、磷酸鹽和氟初始濃度為30mg/L、10mg/L的條件下,CLBOs最大磷、氟吸附量分別可達(dá)59.14mg/ g、19.25mg/g.

3.3 pH值影響實(shí)驗(yàn)以及FTIR和XPS表征分析表明,CLBOs同步吸附磷酸鹽和氟的機(jī)制主要包括靜電吸引作用、配體交換作用和內(nèi)配位絡(luò)合作用;其中內(nèi)配位絡(luò)合作用有助于CLBOs在高濃度競(jìng)爭(zhēng)離子環(huán)境中實(shí)現(xiàn)磷酸鹽和氟的選擇性吸附.

3.4 吸附飽和的CLBOs能通過(guò)堿液高效再生,再生后其除磷除氟性能保持相對(duì)穩(wěn)定,可長(zhǎng)期穩(wěn)定的用于酸性廢水中磷酸鹽和氟的同步去除.

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Simultaneous removal of phosphate and fluoride from acid wastewater by Ce-La bimetal oxides: Performance and mechanism.

LI Han1, ZHAO Yu1, CHEN Jia-chao1, XU Hai-min2, ZHU Ya-xian1, CHEN Zhi-hui1, SHEN Meng-meng1, YANG Wen-lan1,2*

(1.School of the Environmental Science and Engineering, Yangzhou University, Yangzhou 225127；2.Jiangsu Qichuang Environmental Science and Technology Co., LTD., Yixing 214264)., 2023,43(10)：5148～5156

A novel Ce-La bimetal oxides nano-adsorbent (CLBOs) capable of simultaneous phosphate and fluoride removal from water was successfully synthesized by coprecipitation method. The CLBOs existed primarily as nanoparticles or nanoclusters, with a particle size range of 20～50nm and a specific surface area of 117.9m2/g. Notably, the CLBOs displayed excellent chemical stability across a wide pH range (4～12), with acidic conditions proving beneficial for the adsorption of phosphate and fluoride. Under experimental condition of pH 4.0and initial concentrations of 30mg/L for phosphate and 10mg/L for fluoride, the CLBOs exhibited a remarkable maximum adsorption capacity of 59.14mg/g for phosphate and 19.25mg/g for fluoride. This outstanding adsorption performance was attributed to the combined effects of electrostatic attraction, ligand exchange, and inner-sphere complexation. Furthermore, the presence of competing anions had minimal impact on the removal efficiency of CLBOs. The adsorption process of phosphate and fluoride onto CLBOs followed a pseudo-second-order kinetic model, with fluoride being adsorbed significantly faster than phosphate. Equilibrium was achieved in approximately 100 minutes for fluoride and 240 minutes for phosphate. Importantly, the exhausted CLBOs could be efficiently regenerated through a simple alkaline treatment, enabling their cyclic utilization while maintaining consistent adsorption performance. In conclusion, the results demonstrate that CLBOs is a highly efficient adsorbent with significant potential for practical applications in the simultaneous removal of phosphate and fluoride from wastewater.

Ce-La bimetal oxides；acid wastewater；phosphate；fluoride；simultaneous removal

X703

A

1000-6923(2023)10-5148-09

2023-03-05

國(guó)家自然科學(xué)基金資助項(xiàng)目(52070160);江蘇省重點(diǎn)研發(fā)計(jì)劃(社會(huì)發(fā)展)項(xiàng)目;揚(yáng)州大學(xué)高端人才支持計(jì)劃;宜興市“陶都英才”創(chuàng)新創(chuàng)業(yè)人才項(xiàng)目(CX202011C);宜興市科技創(chuàng)新專項(xiàng)資金重點(diǎn)研發(fā)項(xiàng)目(Y2022002);江蘇省大學(xué)生創(chuàng)新創(chuàng)業(yè)訓(xùn)練計(jì)劃項(xiàng)目(X20220563)

* 責(zé)任作者, 教授,wlyang@yzu.edu.cn

李 含(1998-),女,河南南陽(yáng)人,揚(yáng)州大學(xué)碩士研究生,主要從事環(huán)境功能材料及其在污水深度處理中的應(yīng)用方面研究. 2731278155@qq.com.

李 含,趙 雨,陳嘉超,等.Ce-La雙金屬氧化物同步去除酸性廢水中磷酸鹽和氟的性能與機(jī)理 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(10):5148-5156.

Li H, Zhao Y, Chen J C, et al. Simultaneous Removal of Phosphate and Fluoride from Acid Wastewater by Ce-La Bimetal oxides: Performance and mechanism [J]. China Environmental Science, 2023,43(10):5148-5156.