夏文君,徐 劼,劉 鋒,2,黃天寅,王忠明,陳家斌*

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秸稈生物炭對雙氯芬酸鈉的吸附性能研究

夏文君1,徐 劼1,劉 鋒1,2,黃天寅1,王忠明3,陳家斌1*

(1.蘇州科技大學(xué)環(huán)境科學(xué)與工程學(xué)院,江蘇 蘇州 215009；2.城市生活污水資源化利用技術(shù)國家地方聯(lián)合工程實驗室,江蘇 蘇州 215009；3.常州市市政工程設(shè)計研究院有限公司,江蘇 常州 213003)

利用廉價的農(nóng)業(yè)廢棄物稻草秸稈,通過磷酸氫二銨((NH4)2HPO4)活化制備得到秸稈生物炭(SBC),通過掃描電子顯微鏡(SEM)、比表面積分析(BET)、紅外光譜(FTIR)等手段對其進行表征.研究了SBC對雙氯芬酸鈉(DCF)的吸附去除,并探討了吸附時間、SBC投加量、pH值、陰離子濃度對吸附過程的影響.結(jié)果表明,當(dāng)SBC投加量為0.3g/L時,DCF濃度為0.05mmol/L,60min后吸附量達到平衡;pH值范圍在5.00~9.00時,SBC對DCF的吸附量去除率隨著pH值的增加而減少;Cl-、SO42-和HCO3-對吸附過程的影響不大.擬合結(jié)果表明,SBC對DCF的吸附過程更符合準二級動力學(xué)模型和Freundlich吸附等溫線.經(jīng)Langmuir等溫線模型計算理論最大吸附量為277.78mg/g(pH=7.00,=20℃).熱力學(xué)參數(shù)表明SBC對DCF的吸附是自發(fā)吸熱過程.同活性炭和碳納米管相比,SBC對DCF的吸附效果更好.

吸附；秸稈生物炭；雙氯芬酸鈉；動力學(xué)；熱力學(xué)

近年來,藥物與個人護理用品(PPCPs)的產(chǎn)量和用量日趨增大,其對生態(tài)環(huán)境的潛在影響包括耐藥性以及對水生生物的毒性等[1-3].雙氯芬酸鈉是一種常用的非甾體抗炎藥,在風(fēng)濕病臨床用藥中占有很重要的地位[4],每年的全球消耗量在1443t左右[5].由于雙氯芬酸鈉的大量使用,導(dǎo)致其在污水處理廠、河水和地表水中被頻繁的檢測出來[6-8],并且已有關(guān)于雙氯芬酸鈉對水體中不同生物體產(chǎn)生了不良影響的報道[9-12].

據(jù)文獻報道,傳統(tǒng)的水處理技術(shù)和生物方法對雙氯芬酸鈉的去除率很低[13-14].目前常用的去除雙氯芬酸鈉的方法主要有高級氧化法(光降解、臭氧氧化和芬頓等)和吸附法[15-17].雖然高級氧化法對雙氯芬酸鈉的去除有良好的效果,但同時它也存在著成本高和產(chǎn)生有毒副產(chǎn)物的問題[18].吸附法則具有簡單可靠,成本低,無副產(chǎn)物生成等優(yōu)勢[14].Nam等[19]用氧化石墨烯吸附雙氯芬酸鈉,去除率可達到75%.但吸附劑的經(jīng)濟環(huán)保性能是影響其廣泛實際應(yīng)用的關(guān)鍵因素.因此利用價廉易得的廢棄生物質(zhì)材料來制備生物炭吸附材料成為近年來研究的熱點.

我國是傳統(tǒng)的農(nóng)業(yè)大國,農(nóng)作物秸稈的年產(chǎn)量可達7億多t.隨著秸稈還田、秸稈造紙、秸稈堆肥等技術(shù)的逐漸應(yīng)用,秸稈得到了一定程度的資源化利用,但仍未使得秸稈被充分消耗,仍然有大量秸稈被堆置,甚至直接焚燒,這不僅造成了大量生物質(zhì)能源浪費,同時也產(chǎn)生了煙霧、灰塵等污染物,導(dǎo)致大氣中二氧化硫、二氧化氮和可吸入顆粒物污染指數(shù)明顯升高,造成大氣污染和農(nóng)田土壤結(jié)構(gòu)破壞.利用農(nóng)業(yè)廢棄物制備生物炭,不僅能使農(nóng)業(yè)廢棄物資源化利用,也解決了秸稈焚燒污染問題.Bashir等[20]利用氫氧化鉀改性稻草秸稈制備的生物炭可吸附99%以上的Cd2+;Tan等[21]把氧化錳負載在稻草秸稈生物炭上吸附Pb2+,最大吸附量為1.4732mmol/g. Feng等[22]分別用堿改性的稻草、木材和竹子制備生物炭,對多環(huán)芳烴的去除有很好的效果.本研究以稻草秸稈為原材料,通過磷酸氫二銨活化制備出秸稈生物炭(SBC),研究了SBC對雙氯芬酸鈉的吸附性能,利用吸附動力學(xué)模型和吸附等溫線模型對實驗數(shù)據(jù)進行擬合,探討吸附機制,并為其在實際應(yīng)用中提供基礎(chǔ)依據(jù).

1 材料與方法

1.1 材料與試劑

秸稈收集于蘇州地區(qū)農(nóng)田;甲醇(CH3OH)、磷酸(H3PO4)、雙氯芬酸鈉(C14H10Cl2NNaO2,DCF)均購于Sigma-Aldrich,DCF化學(xué)結(jié)構(gòu)式如圖1所示;硫酸(H2SO4)、氫氧化鈉(NaOH)、磷酸氫二銨((NH4)2HPO4)均為分析純,實驗用水為超純水.

圖1 雙氯芬酸鈉的化學(xué)結(jié)構(gòu)式 Fig.1 Chemical structure of diclofenac sodium

1.2 制備方法

挑選干燥的優(yōu)質(zhì)秸稈剪切成5cm左右,在濃度為2%(Wt)的NaOH溶液中浸泡48h后用超純水洗至中性并在105℃條件下烘干以備用.稱量20g干燥好的秸稈置于300mL濃度為30%(Wt)的(NH4)2HPO4溶液中浸泡24h,然后在105℃條件下烘干,再置于恒溫鼓風(fēng)烘箱中200℃下預(yù)氧化2h,最后于箱式氣氛爐中700℃條件下活化1h.冷卻至室溫后將其取出并研磨,篩選取100目粒徑,記為SBC.

1.3 實驗方法

室溫下,準確稱取0.03g的SBC加入到100mL初始濃度為0.05mmol/L的雙氯芬酸鈉溶液中,用稀H2SO4和NaOH調(diào)節(jié)pH值,在置于磁力攪拌器攪拌上反應(yīng),并在預(yù)定時間內(nèi)取樣,用0.22μm水相針式濾頭過濾后通過高效液相色譜儀(HPLC)測定DCF濃度.

重復(fù)利用實驗中準確稱取0.03g吸附后的SBC放入到100mL甲醇溶液中解吸24h,之后用超純水清洗并烘干,再次進行吸附實驗,重復(fù)4次測定吸附量.實際水樣來自污水廠出水和地表水,過0.45μm水相濾膜,4℃保存?zhèn)溆?數(shù)據(jù)均取自2組平行實驗數(shù)據(jù)的平均值.

1.4 分析方法

采用WTW inLab pH7110pH計測定pH值;利用Agilent 1260高效液相色譜儀測定DCF濃度,操作條件為:分離柱是C18柱(4.6mm×250mm,5μm),流動相為甲醇和6‰磷酸,配比為83/17,流動相流速1mL/ min,檢測波長280nm.

采用美國FEI Quanta 250掃描電子顯微鏡(SEM)、美國Micromeritics ASAP2020全自動比表面積測定儀(BET)和美國Nicolet 6700型傅里葉變換紅外光譜儀(FTIR)對材料進行表征.

1.5 計算方法

單位吸附劑對雙氯芬酸鈉的吸附量e通過式(1)計算,去除率通過式(2)計算:

式中:0和e分別為溶液中DCF的初始濃度和平衡濃度,mg/L,e為SBC的平衡吸附量,mg/g,為溶液體積,L,為SBC的投加量,g.

準一級動力學(xué)、準二級動力學(xué)模型及顆粒內(nèi)擴散模型表達式分別為(3)~(5).

式中:e和t分別為平衡時和時刻的吸附量,mg/g,1為準一級動力學(xué)方程的吸附速率常數(shù),min-1.2為準二級動力學(xué)的吸附速率常數(shù), g/(mg×min).3為內(nèi)擴散速率常數(shù), mg/(g×min1/2).

Langmuir和Freundlich吸附等溫模型數(shù)學(xué)表達式分別為(6)~(7).

式中:e是DCF吸附達到平衡時的濃度,mg/L,e為平衡吸附量,mg/g,m是最大吸附量, mg/g;L,L/mg和F,mg/g分別為Langmuir和Freundlich吸附速率常數(shù).

標(biāo)準自由能(Δθ)、標(biāo)準焓變量(Δθ)、標(biāo)準熵變量(Δθ)有關(guān)方程式分別為(8)~(9).

式中:d為平衡吸附常數(shù),L/g,T為反應(yīng)溫度,K,R為理想氣體常數(shù),8.314J/(mol×K).

2 結(jié)果與討論

2.1 SBC的表征

2.1.1 SEM分析 圖2(A)、(B)是不同放大倍數(shù)下SBC的掃描電鏡圖.由圖可看出,其表面粗糙凹凸不平,存在較多孔隙,而且孔隙分布比較密集.通過BET分析可以得出SBC孔徑主要以微孔為主,平均孔徑為2.19nm,具體結(jié)構(gòu)參數(shù)如表1所示.

圖2 SBC的SEM Fig.2 SEM images of SBC

表1 SBC結(jié)構(gòu)參數(shù) Table 1 Texrural parameters of SBC

2.1.2 FTIR分析 圖3為吸附前后SBC的FTIR圖譜.可以看出它們的吸收峰位置基本相同,在1095, 1385,1637,2922和3443cm-1處均存在吸收峰.1095, 1385,1637和2922cm-1處可歸于C—O對稱伸縮振動峰、—COOH官能團的對稱與反對稱伸縮特征峰、羧基的C=O特征伸縮振動峰和—CH3或—CH2的對稱與反對稱伸縮特征峰;3443cm-1處對應(yīng)于O—H伸縮振動吸收峰.因此可以得出SBC主要有含氧官能團為—OH、C=O、—COOH等.

圖3 吸附前后SBC的FTIR圖譜 Fig.3 FTIR spectra of of SBC before and after adsorption

2.2 吸附時間對吸附的影響

圖4顯示了吸附時間對吸附性能的影響.可以看出,當(dāng)吸附時間為0~60min時,隨著時間的增加,對DCF的去除率不斷增加,在60min時,去除率達到91.89%,吸附量為49.84mg/g.當(dāng)吸附時間增加到240min時,去除率和吸附量均無變化,說明此時吸附已經(jīng)基本達到平衡.原因可能是,隨著吸附時間的不斷增加,吸附在孔隙內(nèi)的DCF占據(jù)了活性位點,使其不斷減少從而阻礙了吸附的繼續(xù)進行,使得吸附容量趨于平衡.

圖4 吸附時間對去除雙氯芬酸鈉的影響 Fig. 4 Effect of contact time on the removal of DCFc(DCF)=0.05mmol/L, m(SBC)=0.3g/L, pH=7.00, T=20℃

2.3 SBC投加量對吸附的影響

由圖5可見,隨著SBC投加量的增加,對DCF的去除率不斷增加,同時對DCF的單位吸附量卻在逐漸降低.當(dāng)(SBC)=0.4g/L時,平均去除率為98.65%,當(dāng)投加量繼續(xù)增加到(SBC)=0.5g/L時,DCF已經(jīng)被全部去除.在吸附過程中,隨著SBC投加量的增加,可吸附的活性位點增多,使得被吸附的DCF總量增多;但是隨著SBC投加量的增加,溶液中DCF與SBC的質(zhì)量比逐漸降低,導(dǎo)致單位質(zhì)量SBC的利用率降低,從而使SBC的單位吸附容量下降.

圖5 SBC投加量對去除雙氯芬酸鈉的影響 Fig. 5 Effect of adsorbent dosage on the removal of DCFc(DCF)=0.05mmol/L, pH=7.00, T=20℃

2.4 pH值的影響

pH值是吸附過程的重要影響因素.由圖6可以看出,DCF的去除率隨著pH值不斷升高而降低.這可能與SBC的表面零電荷點(pHpzc = 2.40,如圖7所示)有關(guān).當(dāng)溶液pH > pHpzc時,SBC表面帶負電荷.而DCF的pKa = 4.1[23],當(dāng)pH值大于4.1時,DCF帶負電.所以當(dāng)pH = 5.00~9.00時,隨著pH值的升高,靜電排斥力逐漸增強,SBC對DCF的去除率不斷降低.利用碳納米管負載氧化鋁和功能化二氧化硅多孔材料等材料吸附DCF的時候也有同樣的發(fā)現(xiàn)[24-25].

圖6 pH對去除雙氯芬酸鈉的影響 Fig. 6 Effect of pH on the removal of DCFc(DCF)=0.05mmol/L, m(SBC)=0.3g/L, T=20℃

圖7 SBC的pHpzc測定 Fig. 7 pHpzc measured of SBC

2.5 陰離子的影響

在實際應(yīng)用時,天然水體中存在的陰離子(Cl-、SO42-和HCO3-)可能會影響材料的吸附性能.不同陰離子濃度對雙氯芬酸鈉吸附過程的影響見圖8.隨著Cl-濃度的增加,對DCF的去除率逐漸增加.對SO42-和HCO3-來說,當(dāng)濃度小于10mmol/L時,去除率隨著濃度的增加而減少;當(dāng)濃度大于10mmol/L時,去除率隨著濃度的增加而有所增加.但就整體而言,對DCF去除率的變化不超過5%,說明各共存陰離子對吸附過程的影響較小.

圖8 共存陰離子對去除雙氯芬酸鈉的影響 Fig. 8 Effect of coexistence anionic on the removal of DCFc(DCF)=0.05mmol/L, m(SBC)=0.3g/L, pH=7.00, T=20℃

2.6 動力學(xué)分析

為了更好地分析SBC對DCF的吸附行為,采用準一級、準二級動力學(xué)模型和顆粒內(nèi)擴散動力學(xué)方程對吸附過程進行模擬,結(jié)果如圖9所示.由圖9可見,與準一級動力學(xué)模型相比,準二級動力學(xué)模型對實驗數(shù)據(jù)的擬合相關(guān)性系數(shù)較高(2>0.98),而且準二級動力學(xué)方程中的e測定值與計算值更接近.說明準二級動力學(xué)模型能更好地描述SBC對DCF的吸附過程.顆粒內(nèi)擴散模型擬合結(jié)果見圖9(C),可以看出吸附過程分為2個階段:急劇上升階段和平緩階段.急劇上升階段對應(yīng)分子內(nèi)擴散過程,平緩階段對應(yīng)最終的平衡階段.由擬合參數(shù)可知,顆粒內(nèi)擴散模型不通過原點,說明吸附過程受其他吸附階段的共同控制.

表2 SBC對DCF的吸附動力學(xué)擬合參數(shù) Table 2 Kinetics parameters for adsorption of DCF by SBC

2.7 吸附等溫線和熱力學(xué)研究

吸附等溫線可反映被吸附的分子在平衡時液相和固相間的分布情況,是評價吸附劑吸附性能的重要指標(biāo),擬合參數(shù)見表3.從中可看出,雖然Langmuir等溫線方程與實驗數(shù)據(jù)有很好的相關(guān)性(2>0.96),但是Freundlish等溫線方程的相關(guān)性系數(shù)更高(2>0.98),能夠更好地解釋實驗中發(fā)生的現(xiàn)象.Freundlish模型描述了吸附分子在非均勻表面相互作用產(chǎn)生的多層吸附.模型參數(shù)>1[26],說明SBC對DCF的吸附屬于優(yōu)惠吸附.活性炭、碳凝膠等材料對雙氯芬酸鈉的吸附過程也可以更好地通過Freundlish模型來解釋[27-29].

為了更深入地了解吸附過程,通過不同溫度下的吸附實驗,計算吸附過程的標(biāo)準吉布斯自由能變(Δθ)、焓變(Δθ)和熵變(Δθ)等相關(guān)的吸附熱力學(xué)參數(shù),具體結(jié)果見表4.在不同溫度條件下經(jīng)計算得出的Δθ為負值,表明吸附過程是自發(fā)進行的.而且Δθ隨著溫度的升高呈減少趨勢,同時Δθ的值為正,進一步說明該吸附過程屬于吸熱反應(yīng),提高溫度有利于對DCF的吸附.而正的Δθ值則反映出在吸附過程中固液界面上混亂度的增加.

表3 SBC對DCF的吸附等溫線擬合參數(shù) Table 3 Isotherms parameters for adsorption of DCF by SBC

表4 SBC吸附DCF的熱力學(xué)參數(shù) Table 4 Thermodynamic parameters for adsorption of DCF by SBC

2.8 與其他碳質(zhì)材料對比

實驗對比了活性炭(AC)、碳納米管(CNT)與SBC對DCF的吸附性能.與活性炭和碳納米管相比,SBC表現(xiàn)出更好的吸附性能.活性炭和碳納米管對DCF的吸附量分別為18.03和36.05mg/g,而SBC的吸附量則得到顯著提高,為48.78mg/g,對DCF有較好的吸附去除效果,其在環(huán)境微污染水處理領(lǐng)域具有應(yīng)用前景

2.9 重復(fù)利用性

吸附劑的重復(fù)利用性是其經(jīng)濟性的關(guān)鍵因素[30].采用甲醇作為脫附劑,考察SBC的穩(wěn)定性和再生性.如圖10所示,隨著循環(huán)使用次數(shù)的增加,SBC對DCF的吸附量在逐漸下降,與第1次的吸附量相比,使用5次后的吸附量下降了12%左右,但是吸附量仍能達到44mg/g,而且吸附量保持相對穩(wěn)定.因此SBC具備可重復(fù)利用性,有實際應(yīng)用的潛力.

圖10 SBC重復(fù)使用對吸附DCF的影響 Fig.10 Effect of the regeneration of SBC on the removal of DCFc(DCF)=0.02mmol/L, m(SBC)=0.3g/L, pH=7.00, T=20℃

2.10 實際水樣影響

為了進一步檢驗SBC的實際應(yīng)用性,分別選取了污水廠出水和地表水,探究在不同水體中SBC對DCF的吸附性能.超純水體系中SBC對DCF的吸附量最大,為49.31mg/g,而在實際水樣中均體現(xiàn)出抑制作用,吸附量分別為37.65mg/g和44.54mg/g.兩種實際水樣的常規(guī)檢測指標(biāo)結(jié)果見表5.由表5可知,原因可能是實際水樣中存在的天然有機物會與DCF競爭吸附劑上的活性位點,從而抑制對DCF的吸附.

表5 兩種實際水樣的常規(guī)檢測指標(biāo)結(jié)果 Table 5 Indicators for different water matrix samples

3 結(jié)論

3.1 利用磷酸氫二銨活化制備得到秸稈生物炭,對DCF有較好的去除效果,經(jīng)Langmuir等溫線模型計算理論最大吸附量為277.78mg/g;當(dāng)pH=5.00時,去除效果最好;共存陰離子對吸附過程影響較小.

3.2 SBC對DCF的吸附過程更符合準二級動力學(xué)模型和Freundlish等溫吸附線模型.

3.3 與活性炭和碳納米管相比,SBC對DCF的吸附效果更好,而且循環(huán)使用5次后,依然保持了良好的吸附去除效率,具有實際應(yīng)用前景.

[1] Hu J Y, Shi J C, Chang H, et al. Phenotyping and genotyping of antibiotic-resistant Escherichia coli isolated from a natural river basin [J]. Environmental Science & Technology, 2008,42(9):3415-3420.

[2] Pei R, Kim S C, Carlson K H, et al. Effect of river landscape on the sediment concentrations of antibiotics and corresponding antibiotic resistance genes (ARG) [J]. Water Research, 2006,40(12):2427-2435.

[3] Dutta K, Lee M Y, Lai W W, et al. Removal of pharmaceuticals and organic matter from municipal wastewater using two-stage anaerobic fluidized mrmbrane bioreactor [J]. Bioresource Technology, 2014, 165(8):42-49.

[4] Vieno N, Sillanp?? M. Fate of diclofenac in municipal wastewater treatment plant - a review [J]. Environment International, 2014, 69(30):28-39.

[5] Acu?a V, Ginebreda A, Mor J R, et al. Balancing the health benefits and environmental risks of pharmaceuticals: Diclofenac as an example [J]. Environment International, 2015,85(3):327-333.

[6] Bueno M J, Gomez M J, Herrera S, et al. Occurrence and persistence of organic emerging contaminants and priority pollutants in five sewage treatment plants of Spain: two years pilot survey monitoring [J]. Environmental Pollution, 2012,164:267-273.

[7] Ginebreda A, Mu?oz I, Alda M L D, et al. Environmental risk assessment of pharmaceuticals in rivers: Relationships between hazard indexes and aquatic macroinvertebrate diversity indexes in the Llobregat River (NE Spain) [J]. Environment International, 2010, 36(2):153-162.

[8] Caban M, Lis E, Kumirska J, et al. Determination of pharmaceutical residues in drinking water in Poland using a new SPE-GC-MS(SIM) method based on Speedisk extraction disks and DIMETRIS derivatization [J]. Science of the Total Environment, 2015,538:402-411.

[9] Mehinto A C, Hill E M, Tyler C R. Uptake and biological effects of environmentally relevant concentrations of the nonsteroidal anti- inflammatory pharmaceutical diclofenac in rainbow trout (Oncorhynchus mykiss) [J]. Environmental Science & Technology, 2010,44(6):2176-2182.

[10] Taggart M A, Cuthbert R, Das D, et al. Diclofenac disposition in Indian cow and goat with reference to Gyps vulture population declines [J]. Environmental Pollution, 2007,147(1):60-65.

[11] Zhang Y J, Gei?en S U, Gal C. Carbamazepine and diclofenac: removal in wastewater treatment plants and occurrence in water bodies [J]. Chemosphere, 2008,73(8):1151-1161.

[12] Schwaiger J, Ferling H, Mallow U, et al. Toxic effects of the non- steroidal anti-inflammatory drug diclofenac Part I: histopathological alterations and bioaccumulation in rainbow trout [J]. Aquatic Toxicology, 2004,68(2):141-150.

[13] Rosal R, Rodríguez A, Perdigón-Melón J A, et al. Occurrence of emerging pollutants in urban wastewater and their removal through biological treatment followed by ozonation [J]. Water Research, 2010,44(2):578-588.

[14] Sotelo J L, Ovejero G, Rodríguez A, et al. Competitive adsorption studies of caffeine and diclofenac aqueous solutions by activated carbon [J]. Chemical Engineering Journal, 2014,240(6):443-453.

[15] Aziz K H H, Miessner H, Mueller S, et al. Degradation of pharmaceutical diclofenac and ibuprofen in aqueous solution, a direct comparison of ozonation, photocatalysis, and non-thermal plasma [J]. Chemical Engineering Journal, 2017,313:1033-1041.

[16] Moreira N F F, Orge C A, Ribeiro A R, et al. Fast mineralization and detoxification of amoxicillin and diclofenac by photocatalytic ozonation and application to an urban wastewater [J]. Water Research, 2015,87:87-96.

[17] Ravina M, Campanella L, Kiwi J. Accelerated mineralization of the drug Diclofenac via Fenton reactions in a concentric photo-reactor [J]. Water Research, 2002,36(14):3553-3560.

[18] Coelho A D, Sans C, Agüera A, et al. Effects of ozone pre-treatment on diclofenac: intermediates, biodegradability and toxicity assessment [J]. Science of the Total Environment, 2009,407(11):3572-3578.

[19] Nam S W, Jung C, Li H, et al. Adsorption characteristics of diclofenac and sulfamethoxazole to graphene oxide in aqueous solution [J]. Chemosphere, 2015,136:20-26.

[20] Bashir S, Zhu J, Fu Q L, et al. Comparing the adsorption mechanism of Cd by rice straw pristine and KOH-modified biochar [J]. Environmental Science & Pollution Research International, 2018,25: 11875-11883.

[21] Tan G, Wu Y, Liu Y, et al. Removal of Pb(II) ions from aqueous solution by manganese oxide coated rice straw biochar-A low-costand highly effective sorbent [J]. Journal of the Taiwan Institute of Chemical Engineers, 2018,84:85-92.

[22] Feng Z J, Zhu L Z. Sorption of phenanthrene to biochar modified by base [J]. Frontiers of Environmental Science & Engineering, 2018,12(2):1-11.

[23] Dai C M, Geissen S U, Zhang Y L, et al. Selective removal of diclofenac from contaminated water using molecularly imprinted polymer microspheres [J]. Environmental Pollution, 2011,159(6):1660-1666.

[24] Wei H, Deng S B, Huang Q, et al. Regenerable granular carbon nanotubes/alumina hybrid adsorbents for diclofenac sodium and carbamazepine removal from aqueous solution [J]. Water Research, 2013,47(12):4139-4147.

[25] Suriyanon N, Punyapalakul P, Ngamcharussrivichai C. Mechanistic study of diclofenac and carbamazepine adsorption on functionalized silica-based porous materials [J]. Chemical Engineering Journal, 2013,214(1):208-218.

[26] Danmaliki G I, Saleh T A. Influence of conversion parameters of waste tires to activated carbon on adsorption of dibenzothiophene from model fuels [J]. Journal of Cleaner Production, 2016,117:50-55.

[27] Sotelo J L, Rodríguez A, álvarez S, et al. Removal of caffeine and diclofenac on activated carbon in fixed bed column [J]. Chemical Engineering Research & Design, 2012,90(7):967-974.

[28] Jodeh S, Abdelwahab F, Jaradat N, et al. Adsorption of diclofenac from aqueous solution using Cyclamen persicum tubers based activated carbon (CTAC) [J]. Journal of the Association of Arab Universities for Basic & Applied Sciences, 2016,20:32-38.

[29] álvarez S, Ribeiro R S, Gomes H T, et al. Synthesis of carbon xerogels and their application in adsorption studies of caffeine and diclofenac as emerging contaminants [J]. Chemical Engineering Research & Design, 2015,95:229-238.

[30] Liu T, Xie Z H, Zhang Y, et al. Preparation of cationic polymeric nanoparticles as an effective adsorbent for removing diclofenac sodium from water [J]. Rsc Advances, 2017,7(61):38279-38286.

Adsorption of diclofenac on straw-biochar.

XIA Wen-jun1, XU Jie1, LIU Feng1,2, HUANG Tian-yin1, WANG Zhong-mimg3, CHEN Jia-bin1*

(1.School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China；2.National and Local Joint Engineering Laboratory of Municipal Sewage Resource Utilization Technology, Suzhou 215009, China；3.Changzhou Municipal Enginerring Design Research College Co., Ltd, Changzhou 213003, China)., 2019,39(3)：1054~1060

Straw-biochar (SBC) was prepared by rice straw, a cheap agricultural waste, through activation with ammonium hydrogen phosphate ((NH4)2HPO4). SBC was characterized by scanning electron microscopy (SEM), surface area measurements (BET) and Fourier transform infrared spectroscopy (FTIR). The effect of contact time, SBC dosage, initial pH and concentration of anions were investigated. The results indicated that adsorption capacity of SBC reached an equilibrium within 60min with 0.3g/L of SBC and 0.05mmol/L DCF. The removal rate of DCF decreased with pH increasing from 5.00 to 9.00. The addition of Cl-、SO42-and HCO3-had a negligible impact on the adsorption of DCF. The adsorption of diclofenac on SBC could be well fitted by the pseudo-second-order kinetics and Freundlich isotherm model. The maximum adsorption capacity of SBC for DCF was calculated to be 277.78mg/g based on Langmuir isotherm model. Thermodynamic parameters illustrated that the adsorption process was spontaneous and endothermic. Compared with activated carbon (AC) and carbon nanotube (CNT), SAC achieved a better performance on the removal of DCF.

adsorption；straw-biochar；diclofenac；kinetics；thermodynamics

X522

A

1000-6923(2019)03-1054-07

夏文君(1994-),女,江蘇南通人,蘇州科技大學(xué)碩士研究生,主要研究方向為污水處理與回用技術(shù).發(fā)表論文2篇.

2018-08-07

江蘇省研究生實踐創(chuàng)新計劃項目(SJCX17_0676);蘇州市科技計劃項目(SS201722);國家自然科學(xué)基金資助項目(51778391)

* 責(zé)任作者, 副教授, chenjiabincn@163.com