餐廚垃圾水熱炭對(duì)全(多)氟烷基化合物的吸附性能

陳 帆,陳江亮,劉雪梅,智 悅,2,李 偉,2,王小銘,2*

餐廚垃圾水熱炭對(duì)全(多)氟烷基化合物的吸附性能

陳 帆1,陳江亮1,劉雪梅1,智 悅1,2,李 偉1,2,王小銘1,2*

(1.重慶大學(xué)三峽庫(kù)區(qū)生態(tài)環(huán)境教育部重點(diǎn)實(shí)驗(yàn)室,重慶 400044；2.重慶大學(xué)環(huán)境與生態(tài)學(xué)院,重慶 400044)

以高濕餐廚垃圾為對(duì)象,通過(guò)水熱碳化結(jié)合高溫活化制備水熱炭(AC).采用多種表征手段對(duì)水熱炭的理化性質(zhì)進(jìn)行刻畫,并對(duì)一類全球關(guān)注的新污染物——全(多)氟烷基化合物(PFAS)進(jìn)行吸附實(shí)驗(yàn)及動(dòng)力學(xué)分析,以期為“以廢治污”提供新思路.結(jié)果顯示,經(jīng)過(guò)活化處理的水熱炭具有較高的比表面積(206.97m2/g)和疏水表面特性,有利于與PFAS的吸附結(jié)合.在環(huán)境相關(guān)濃度下(～40μg/L),PFAS在AC上的吸附分配系數(shù)(logd)在2.38～6.49L/kg范圍內(nèi),高于其他生物炭的報(bào)道結(jié)果,說(shuō)明AC對(duì)目標(biāo)PFAS具有良好的吸附性能.吸附過(guò)程較符合Langmuir等溫吸附模型及Elovich動(dòng)力學(xué)模型,證明PFAS在AC上的吸附從機(jī)理上近似單分子層化學(xué)吸附過(guò)程.此外,對(duì)于PFCA和PFSA,logd值與全氟烷基鏈長(zhǎng)呈正相關(guān),表明疏水作用在AC與PFAS的吸附過(guò)程中發(fā)揮重要作用.

餐廚垃圾；水熱炭；全(多)氟烷基化合物；吸附

全(多)氟烷基化合物(PFAS)是一類具有強(qiáng)化學(xué)穩(wěn)定性、疏水疏油性的人造化學(xué)品[1].由于其在環(huán)境介質(zhì)中的廣泛分布以及對(duì)動(dòng)物和人類的潛在毒性,近年來(lái)PFAS的污染已經(jīng)引起了全球關(guān)注[2-3].吸附已被證實(shí)是一種經(jīng)濟(jì)、有效的新污染物阻控技術(shù)之一[4],其在去除環(huán)境中的PFAS方面也表現(xiàn)出較高的效率[5-6].已有文獻(xiàn)報(bào)道了PFAS在各種吸附劑上的吸附行為,包括離子交換樹脂[2]、顆?；钚蕴縖4]等.然而,這些傳統(tǒng)吸附劑的生產(chǎn)及使用成本較高[7-8],導(dǎo)致其應(yīng)用在一定程度上受到限制,這促使研究與實(shí)踐人員在不斷尋找低成本的吸附劑[8].利用廢棄生物質(zhì)(如農(nóng)林廢棄物、污水污泥、餐廚垃圾(FW)等)制備生物炭用作吸附劑是一個(gè)重要的發(fā)展方向[7].餐廚垃圾是城市生活垃圾的重要組成部分[9-10],其可以通過(guò)熱解或水熱碳化轉(zhuǎn)化為生物炭.相比之下,水熱碳化過(guò)程無(wú)需干燥預(yù)處理,更適宜具有高含水率餐廚垃圾的碳化處理[11].水熱碳化的固相產(chǎn)物水熱炭是一種多孔碳質(zhì)材料,其表面含有豐富的官能團(tuán)[12].大量研究發(fā)現(xiàn)餐廚垃圾水熱炭對(duì)多種有機(jī)污染物具有很高的吸附能力,如阿特拉津[13]、染料[14]以及疏水性的雙酚A[15]等,然而鮮有研究探究了餐廚垃圾水熱炭對(duì)PFAS的吸附行為,PFAS與餐廚垃圾水熱炭的相互作用機(jī)制尚未見報(bào)道.

因此,本文以餐廚垃圾為原料,采用水熱碳化技術(shù)制備水熱炭,并通過(guò)高溫活化對(duì)其進(jìn)行改性.選擇兼顧官能團(tuán)和碳鏈長(zhǎng)度的PFAS作為吸附質(zhì),探究餐廚垃圾水熱炭對(duì)PFAS的吸附性能及其作用機(jī)制, 為阻控PFAS污染提供吸附相關(guān)的理論支撐,同時(shí)為實(shí)現(xiàn)餐廚垃圾的資源化利用提供新的路徑參考.

1 材料與方法

1.1 實(shí)驗(yàn)試劑

選擇8種具有不同官能團(tuán)及碳鏈長(zhǎng)度的PFAS進(jìn)行吸附實(shí)驗(yàn),包括5種全氟烷基羧酸(PFCA;C4～ C8)和3種全氟烷基磺酸(PFSA;C4,C6,C8).目標(biāo)PFAS標(biāo)準(zhǔn)品及對(duì)應(yīng)的同位素標(biāo)記物均購(gòu)自加拿大Wellington Laboratories(純度>98%,相關(guān)信息詳見表1).HPLC級(jí)的甲醇、乙酸、氨水(25%)和乙酸銨購(gòu)自美國(guó)Sigma Aldrich公司.實(shí)驗(yàn)室用水為屈臣氏蒸餾水.

1.2 餐廚垃圾水熱炭制備與活化

本研究所用餐廚垃圾取自重慶大學(xué)學(xué)生食堂.樣品采集后經(jīng)人工分揀并均質(zhì)化為1～2mm的漿狀物.水熱碳化實(shí)驗(yàn)在配備有自動(dòng)攪拌裝置的500mL不銹鋼(316L)水熱反應(yīng)釜(歐士特,中國(guó)西安)中進(jìn)行.餐廚垃圾投加量為200g,控制水熱反應(yīng)溫度為260°C,停留時(shí)間為4h,加熱速率3～4°C/min,機(jī)械攪拌速率150r/min.反應(yīng)結(jié)束后待水熱釜冷卻至室溫,通過(guò)真空過(guò)濾分離水熱產(chǎn)物,干燥后即制得餐廚垃圾水熱炭(HC).取10g HC加入50mL的200g/L氯化鋅溶液中,常溫下振蕩(150r/min)24h后過(guò)濾并烘干,隨后將樣品轉(zhuǎn)移至可編程式管式爐(LTKCA-5-12,中國(guó)杭州),在500°C下反應(yīng)90min,升溫速率為4°C/min,氮?dú)饬魉贋?L/min.使用0.1mol/L鹽酸溶液、乙醇溶液及去離子水沖洗直至其pH值為中性,烘干后得到餐廚垃圾活化水熱炭(AC).

表1 本研究目標(biāo)PFAS及內(nèi)標(biāo)物相關(guān)信息

注: a.LOD(limits of detection,檢測(cè)限)定義為目標(biāo)PFAS的信號(hào)水平至少是基線信號(hào)噪聲3倍的濃度;b.LOQ(limits of quantification,定量限)定義為目標(biāo)PFAS的信號(hào)水平至少是基線信號(hào)噪聲10倍的濃度;c.平均值±標(biāo)準(zhǔn)偏差.

1.3 餐廚垃圾水熱炭表征

水熱炭的灰分參照《煤的工業(yè)分析方法》(GB/T212-2008)[16]進(jìn)行測(cè)定;使用元素分析儀(Unicube型,德國(guó)元素分析系統(tǒng)公司)在CHNS模式下測(cè)定樣品的C、H、N含量,通過(guò)差減法計(jì)算O含量;利用掃描電鏡(Quattro型,賽默飛)觀察樣品的顆粒結(jié)構(gòu)和表面形貌:實(shí)驗(yàn)前對(duì)樣品進(jìn)行30s噴金處理,電子加速電壓為0.5～30.0kV;利用氮?dú)馕?脫附法測(cè)定樣品的比表面積和孔隙分布,測(cè)定前將樣品在真空下干燥12h;利用傅里葉變化紅外光譜儀(Nicolet型,賽默飛)在4000～400cm-1波長(zhǎng)、4.0cm-1分辨率下進(jìn)行水熱炭的官能團(tuán)分析.

1.4 實(shí)驗(yàn)與分析方法

1.4.1 靜態(tài)吸附實(shí)驗(yàn) 吸附實(shí)驗(yàn)在50mL聚丙烯(PP)離心管中進(jìn)行,離心管內(nèi)裝有預(yù)先確定濃度的PFAS標(biāo)準(zhǔn)工作溶液(～40μg/L,參照真實(shí)環(huán)境PFAS濃度水平設(shè)定[17-18]),同時(shí)該溶液還含有50mmol/L的CaCl2(背景電解質(zhì)溶液)及200mg/L的NaN3(微生物抑制劑).AC投加量經(jīng)預(yù)實(shí)驗(yàn)確定為90mg.設(shè)置未添加吸附劑以及吸附劑添加至蒸餾水的空白對(duì)照組,實(shí)驗(yàn)組與對(duì)照組均設(shè)置3組平行.混合物經(jīng)恒溫振蕩(～22℃,240r/min)后在不同時(shí)間點(diǎn)(1,2,4,6,12, 24,48,72,96h)取樣.AC上PFAS吸附量t(μg/g)利用下式計(jì)算:

式中:0和c分別為PFAS初始濃度以及經(jīng)時(shí)間吸附后溶液中PFAS濃度,μg/L;為溶液體積,L;是AC的投加量,g.

利用平衡時(shí)固相-液相分配系數(shù)(d,L/kg)比較AC對(duì)不同PFAS的吸附效率,即

式中:e和e分別為吸附平衡時(shí)PFAS的固相濃度(μg/g)和液相濃度(μg/L).

1.4.2 樣品分析 使用Xiao等[19]描述的方法對(duì)樣品進(jìn)行預(yù)處理,即取1mL樣品轉(zhuǎn)移至2mL離心管,在16000RCF下離心15min,離心后上清液使用0.22μm有機(jī)相尼龍針式濾器過(guò)濾,之后取0.2mL濾液轉(zhuǎn)移到2mL液相小瓶;加入0.03mL 0.01%氨水和0.05mL同位素標(biāo)記物(=100μg/L),最后用甲醇復(fù)溶至1mL;取樣轉(zhuǎn)入PP進(jìn)樣瓶待測(cè).如有必要,在樣品轉(zhuǎn)移至進(jìn)樣瓶時(shí),可用屈臣氏蒸餾水稀釋.

利用島津HPLC-MS/MS 8060三重四極桿液相色譜質(zhì)譜聯(lián)用儀進(jìn)行PFAS分析.將1μL預(yù)處理后樣品在30℃下注射到Kinetex C18 100A柱(2.1mm′100mm,2.6μm)進(jìn)行色譜分離.流動(dòng)相(流速為0.4mL/ min)為5mmol/L乙酸銨(A相)和甲醇(B相):初始條件為30%甲醇保持4min;然后將B相升至90%保持5min,并于0.1min后恢復(fù)30%;整個(gè)分離過(guò)程為16min.分離后,采用負(fù)離子電噴霧離子化源(-ESI)模式,以多反應(yīng)監(jiān)測(cè)(MRM)方式掃描檢測(cè)目標(biāo)PFAS濃度.

1.4.3 質(zhì)量控制與保證 為避免外界PFAS污染及高背景值影響,實(shí)驗(yàn)過(guò)程中所有材料均采用甲醇和蒸餾水沖洗,并避免使用聚四氟乙烯和玻璃材質(zhì)的器皿.預(yù)實(shí)驗(yàn)結(jié)果表明PP瓶及尼龍過(guò)濾器對(duì)PFAS無(wú)明顯吸附作用.本實(shí)驗(yàn)采用同位素內(nèi)標(biāo)法進(jìn)行定量分析.利用PFAS標(biāo)準(zhǔn)品制備PFAS系列標(biāo)準(zhǔn)溶液(0.1,0.5,1,2,5,10,20,50μg/L),對(duì)應(yīng)內(nèi)標(biāo)濃度均為5μg/L.以標(biāo)準(zhǔn)溶液濃度為橫坐標(biāo),目標(biāo)物峰面積與對(duì)應(yīng)內(nèi)標(biāo)物峰面積比值為縱坐標(biāo),繪制標(biāo)準(zhǔn)曲線.各目標(biāo)化合物在0.1～50μg/L范圍內(nèi)線性關(guān)系良好,相關(guān)系數(shù)均>0.96.同時(shí)本研究還對(duì)8種PFAS進(jìn)行加標(biāo)回收實(shí)驗(yàn),表1總結(jié)了目標(biāo)PFAS的方法檢測(cè)限(LOD)、定量限(LOQ)及加標(biāo)回收率.在實(shí)驗(yàn)過(guò)程中,每10個(gè)樣品設(shè)置一個(gè)雙空白(不含PFAS和內(nèi)標(biāo)物)、空白(不含PFAS)和質(zhì)量控制樣品(含有PFAS和內(nèi)標(biāo)物),以驗(yàn)證分析方法的準(zhǔn)確性和精密性,同時(shí)在分析過(guò)程中每10個(gè)樣品設(shè)置流程空白(甲醇)以監(jiān)測(cè)背景污染.

1.5 數(shù)據(jù)分析方法

1.5.1 等溫吸附模型 采用Langmuir[20]和Freundlich[21]等溫吸附模型進(jìn)行吸附等溫線擬合分析.Langmuir模型:

式中:m和L分別是吸附容量(μg/g)和吸附速率的朗繆爾常數(shù)(L/μg).

Freundlich模型:

式中:F是Freundlich等溫模型常數(shù),(μg/g)×(μg/L)-n;表示等溫線的線性.

1.5.2 吸附動(dòng)力學(xué)模型 準(zhǔn)一級(jí)動(dòng)力學(xué)模型[22]:

式中:1為準(zhǔn)一級(jí)模型吸附速率常數(shù),min-1.

準(zhǔn)二級(jí)動(dòng)力學(xué)模型[23]:

式中:2為準(zhǔn)二級(jí)模型吸附速率常數(shù),g/(μg×min).

Elovich動(dòng)力學(xué)模型0:

式中:和分別為Elovich模型中吸附、解吸速率常數(shù),μg/(g×min-2).

動(dòng)力學(xué)模型的有效性通過(guò)標(biāo)準(zhǔn)偏差(S.D.)[24]進(jìn)行驗(yàn)證:

式中:q,cal和q,exp分別為計(jì)算和實(shí)驗(yàn)的q值,μg/g;為實(shí)驗(yàn)點(diǎn)數(shù)量.

2 結(jié)果與討論

2.1 水熱炭理化性質(zhì)

在水熱炭制備階段得到兩種產(chǎn)物:餐廚垃圾水熱炭(HC)和活化水熱炭(AC).由表2可知,相較于HC,AC表現(xiàn)出較低的產(chǎn)率和較高的灰分含量,這可能是水熱炭中有機(jī)物在高溫活化時(shí)發(fā)生分解所致.由元素分析結(jié)果可知,餐廚垃圾經(jīng)水熱碳化及ZnCl2高溫活化,其C元素含量逐漸升高,O元素和H元素逐漸降低,表明水熱碳化和高溫活化是富集碳元素、去除含氧官能團(tuán)的過(guò)程[25].

碳質(zhì)材料的芳香性和極性可以通過(guò)H/C、O/C和(O+N)/C物質(zhì)的量比描述.由表2可知,較低的H/C和O/C值反映AC表面具有較高的碳化程度及強(qiáng)疏水性[26].此外,極性較高的吸附劑對(duì)有機(jī)化合物的吸附率較低,AC具有最低的(N+O)/C值說(shuō)明其表面極性較低,有利于其對(duì)疏水性PFAS的吸附[27].

表2 餐廚垃圾及水熱炭主要理化特性

注: a.灰分含量基于干基計(jì)算;b.測(cè)定精度￡0.3%;c.氧元素采用扣除灰分的方法計(jì)算所得,即O%=(100-C-N-H-灰分)%.d.FW為餐廚垃圾.

HC和AC的表面形貌如圖1所示.HC表面粗糙、有許多微小的凸起結(jié)構(gòu)且存在少量初級(jí)孔;經(jīng)活化后AC表面球狀結(jié)構(gòu)破裂形成蜂窩狀結(jié)構(gòu),具有不均勻的孔隙分布,這可能歸因于高溫活化過(guò)程中水熱炭孔隙結(jié)構(gòu)的迅速發(fā)展.由表3可知,HC的比表面積為5.54m2/g,AC的比表面積為206.97m2/g,相較于HC顯著增加了近38倍.同時(shí)AC的孔容隨活化而增多,介孔孔徑也得到快速發(fā)展,孔隙分布以微孔為主.

通過(guò)傅里葉變化紅外光譜(FTIR)可觀察餐廚垃圾與水熱炭的表面官能團(tuán).如圖2所示,HC和AC的O-H振動(dòng)吸收峰(3420cm-1)低于餐廚垃圾,表明在水熱碳化及活化過(guò)程中發(fā)生了脫水脫羧反應(yīng)[28],這與上述H/C、O/C變化規(guī)律一致;餐廚垃圾中飽和、不飽和脂肪酸和碳水化合物的分解導(dǎo)致譜帶2中脂肪族C-H的不對(duì)稱(2926cm-1)和對(duì)稱(2854cm-1)吸收峰減弱[29];在1746和1652cm-1觀察到的兩處吸收峰分別對(duì)應(yīng)于脂質(zhì)中甘油三酯的C=O和酮類或酰胺類的C=O伸縮振動(dòng),這些峰值減弱說(shuō)明在處理過(guò)程中存在甘油三酯、酮和酰胺類物質(zhì)的分解[30].

表3 HC和AC的比表面積及孔徑分布

圖2 餐廚垃圾和水熱炭的FTIR譜圖

總而言之,AC的峰振動(dòng)強(qiáng)度相比HC大幅度降低,說(shuō)明AC具有高度碳質(zhì)、官能團(tuán)稀少的表面.高比表面積和高度碳化的結(jié)合使得AC表面具有高疏水性,有利于其與PFAS的吸附作用[31],特別是由疏水性全氟尾端組成的長(zhǎng)鏈PFAS.

2.2 吸附平衡時(shí)間

根據(jù)上述實(shí)驗(yàn)結(jié)果,選擇AC進(jìn)行后續(xù)PFAS吸附實(shí)驗(yàn).由圖3可知,AC對(duì)PFAS的吸附在前6h內(nèi)迅速進(jìn)行,隨后吸附速率逐漸減緩并最終達(dá)到平衡.與72h吸附量相比,96h吸附量增加了-2.02%～6.34%,說(shuō)明AC對(duì)PFAS的吸附基本上可在96h內(nèi)達(dá)到平衡.在8種目標(biāo)PFAS中,PFOS表現(xiàn)出較快的吸附動(dòng)力學(xué)特性(6h即達(dá)到吸附平衡),而其他PFAS動(dòng)力學(xué)曲線較為類似,這可能是因?yàn)閷?duì)碳質(zhì)吸附劑而言PFOS具有相對(duì)優(yōu)越的吸附親和力[19].

圖3 PFCA和PFSA在AC上的吸附動(dòng)力學(xué)

圖4展示了具有不同碳鏈長(zhǎng)度及官能團(tuán)結(jié)構(gòu)的PFAS在AC上的平衡吸附分配系數(shù)(logd).由圖4可知,PFOS具有最高的logd值,而其他短鏈PFAS的logd值相對(duì)較低,這與Xiao等[19]生物炭吸附 PFAS的logd變化類似.值得注意的是,PFOS (6.49L/kg)和PFOA(3.88L/kg)在AC上的平衡logd值分別高于其在不同生物炭上的logd值(PFOS為3.46L/kg,PFOA為2.83L/kg)[26,32].此外,鏈長(zhǎng)相對(duì)較短的PFAS(如PFBA、PFPeA、PFBS和PFHxS)的logd值也高于先前在熱解碳上所報(bào)道的結(jié)果[33-34],這表明本研究制備的AC在環(huán)境真實(shí)濃度下對(duì)PFAS具有良好的吸附性能.

對(duì)于帶有簡(jiǎn)單頭部基團(tuán)的PFCA和PFSA,分析發(fā)現(xiàn)其logd值與全氟烷基鏈長(zhǎng)呈正相關(guān)性,這表明疏水作用在PFAS與AC的吸附過(guò)程中起到重要作用[35],因?yàn)镻FAS的疏水性隨著烷基碳鏈中氟化碳數(shù)量的增加而增加.

PFAS

2.3 等溫吸附特性分析

表4 等溫吸附模型擬合參數(shù)

表4展示了PFAS在AC上的等溫吸附擬合參數(shù).由表4可知,除PFOA外,其余7種PFAS的Langmuir等溫吸附擬合系數(shù)2(0.91～0.99)均高于Freundlich模型(0.85～0.94),表明PFAS在AC上的吸附近似單分子層吸附過(guò)程.m可反映PFAS在AC上的飽和吸附量,根據(jù)表4的擬合結(jié)果,除PFHpA外,PFCA和PFSA的飽和吸附量均隨著全氟烷基鏈長(zhǎng)的增加而增加;L值可反映AC對(duì)PFAS的吸附親和力,PFOS具有最高的L值,說(shuō)明其在AC上具有最大的吸附速率,這與后續(xù)動(dòng)力學(xué)模型觀測(cè)到的現(xiàn)象一致.

2.4 吸附動(dòng)力學(xué)分析

使用準(zhǔn)一級(jí)、準(zhǔn)二級(jí)及Elovich吸附模型對(duì)獲得的動(dòng)力學(xué)數(shù)據(jù)進(jìn)行擬合,并通過(guò)相關(guān)系數(shù)(2)和標(biāo)準(zhǔn)差(S.D.)驗(yàn)證模型的適用性.如表5所示,Elovich模型擬合的2范圍為0.71～0.98,高于其他兩個(gè)模型的擬合結(jié)果,且其具有最小的值,因此Elovich動(dòng)力學(xué)模型能夠更好地反映這8種PFAS在AC上的吸附過(guò)程,即PFAS在AC上的吸附是化學(xué)吸附過(guò)程[24].由于低氧含量的碳質(zhì)吸附劑表面的無(wú)氧堿性位點(diǎn)可能會(huì)吸引質(zhì)子而帶正電[36-37],而目標(biāo)PFAS在水溶液中以陰離子形式存在[4],因此可以推測(cè)吸附過(guò)程的化學(xué)作用是吸附劑和吸附質(zhì)之間的靜電相互作用.此外,是Elovich模型中的吸附速率常數(shù).根據(jù)表5的擬合結(jié)果,除PFPeA外,PFCA和PFSA的值均隨著全氟烷基鏈長(zhǎng)的增加而增加,這表明PFAS在AC上的吸附速率也與全氟烷基鏈長(zhǎng)呈正相關(guān).

表5 PFAS吸附的準(zhǔn)一級(jí)、準(zhǔn)二級(jí)和Elovich動(dòng)力學(xué)擬合參數(shù)

3 結(jié)論

3.1 本研究以餐廚垃圾為原料通過(guò)水熱碳化及高溫活化制備水熱炭,并探究活化水熱炭(AC)對(duì)不同鏈長(zhǎng)和官能團(tuán)PFAS的吸附性能.研究結(jié)果顯示,經(jīng)高溫活化的水熱炭與餐廚垃圾水熱炭相比,比表面積顯著增加38倍,微孔結(jié)構(gòu)增多,比表面積和微孔體積分別高達(dá)206.97m2/g和0.12cm3/g.此外,AC表面具有高碳質(zhì)和疏水性,有助于與PFAS的吸附作用.

3.2 較高的logd值(2.38～6.49L/kg)表明AC在環(huán)境濃度下對(duì)目標(biāo)PFAS具有良好的吸附性能.研究采用的Langmuir等溫吸附模型和Elovich動(dòng)力學(xué)模型可以有效描述PFAS在AC上的吸附過(guò)程.

3.3 研究還發(fā)現(xiàn),針對(duì)PFCA和PFSA兩類代表性PFAS,其平衡吸附量與吸附速率均隨著全氟烷基鏈長(zhǎng)的增加而增加,表明疏水作用在PFAS與AC的吸附過(guò)程中發(fā)揮重要作用.

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Adsorption performance of per- and polyfluoroalkyl substances (PFAS) on hydrochar derived from food waste.

CHEN Fan1, CHEN Jiang-liang1, LIU Xue-mei1, ZHI Yue1,2, LI Wei1,2, WANG Xiao-ming1,2*

(1.Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400044, China；2.College of Environment and Ecology, Chongqing University, Chongqing 400044, China)., 2023,43(10)：5303～5309

This study focused on the preparation of activated hydrochar (AC) from high water content food waste through hydrothermal carbonization combined with high temperature activation. Multiple methods were used to characterize the physicochemical properties of the AC. Adsorption experiments and kinetic analysis were conducted to investigate the adsorption behavior of per- and polyfluoroalkyl substances (PFAS), a class of emerging pollutants of global concern, with the aim of providing insights for waste treatment and pollution control. The results showed that the AC possessed a high specific surface area (206.97m2/g) and hydrophobic surface properties, which facilitated the adsorption of PFAS. At environmentally relevant concentrations (～40μg/L), the adsorption distribution coefficients (logd) of PFAS on AC ranged from 2.38 to 6.49L/kg, higher than those reported for other biochars. This highlighted the favorable adsorption performance of AC towards the studied PFAS. The Langmuir isotherm adsorption model and the Elovich kinetic model effectively described the adsorption process, suggesting that PFAS adsorption on AC occurred similarly to monolayer chemisorption. Additionally, for PFCA and PFSA, the logdvalues exhibited a positive correlation with the perfluoroalkyl chain length, indicating the significance of hydrophobic interactions in the adsorption of PFAS on AC.

food waste；hydrochar；PFAS；adsorption

X705

A

1000-6923(2023)10-5303-07

2023-03-27

國(guó)家自然科學(xué)基金資助項(xiàng)目(52170123)

* 責(zé)任作者, 副教授, wangxiaoming@cqu.edu.cn

陳 帆(2000-),女,湖北孝感人,重慶大學(xué)碩士研究生,主要從事新污染物遷移轉(zhuǎn)化與環(huán)境影響研究.發(fā)表論文1篇. 1823555735@qq.com.

陳 帆,陳江亮,劉雪梅,等.餐廚垃圾水熱炭對(duì)全(多)氟烷基化合物的吸附性能 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(10):5303-5309.

Chen F, Chen J L, Liu X M, et al. Adsorption performance of per- and polyfluoroalkyl substances (PFAS) on hydrochar derived from food waste [J]. China Environmental Science, 2023,43(10):5303-5309.