曲宏斌,萬東錦,肖書虎,章麗萍,劉瑞霞
1.中國礦業(yè)大學(xué)(北京)化學(xué)與環(huán)境工程學(xué)院,北京 1000832.中國環(huán)境科學(xué)研究院城市水環(huán)境科技創(chuàng)新基地,北京 1000123.河南化工大學(xué)化工學(xué)院,河南 鄭州 450001
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離子交換樹脂對水中高氯酸根的吸附及其機理研究
曲宏斌1,2,萬東錦3,肖書虎2*,章麗萍1,劉瑞霞2
1.中國礦業(yè)大學(xué)(北京)化學(xué)與環(huán)境工程學(xué)院,北京1000832.中國環(huán)境科學(xué)研究院城市水環(huán)境科技創(chuàng)新基地,北京1000123.河南化工大學(xué)化工學(xué)院,河南 鄭州450001
摘要通過對比幾種常用的離子交換樹脂,篩選出處理的最佳樹脂。研究表明:氯型717陰離子交換樹脂(Cl717)表現(xiàn)出較好的吸附效果,其吸附動力學(xué)符合偽二級動力學(xué)模型,吸附等溫線符合Langmuir吸附等溫式,屬于單層吸附;升高溫度和增加投加量有利于Cl717對的吸附;共存陰離子對Cl717吸附產(chǎn)生抑制作用,干擾能力依次為 關(guān)鍵詞離子交換樹脂;;水處理;吸附動力學(xué);吸附機理 1材料與方法 1.1試驗材料 表1 3種樹脂的技術(shù)參數(shù) 1.2試驗方法 1.2.1吸附動力學(xué)試驗 分別稱取0.05 g的3種樹脂于3個250 mL的錐形瓶中,各加入200 mL濃度為20 mgL的高氯酸鈉溶液。將錐形瓶于恒溫振蕩箱(298 K、180 rmin)中振蕩,分別于15、30、45、60、90、120、180、360、480和600 min時取樣,經(jīng)0.45 μm濾膜過濾,檢測的濃度。 1.2.2吸附平衡試驗 分別稱取0.06 g的3種樹脂于一系列250 mL的錐形瓶中,加入濃度為20~130 mgL的高氯酸鈉溶液200 mL?;旌弦涸诤銣卣袷幭?298 K、180 rmin)中振蕩24 h,用0.45 μm濾膜過濾,檢測的濃度,計算樹脂對的吸附容量。 1.2.3樹脂再生試驗 對吸附效果最好的Cl717進行再生,已知其總體積干交換量為3.5~3.6 mmolg,濕交換量為1.38~1.42 mmolmL,以氫氧化鈉溶液為再生劑。依據(jù)美國ASTM法測定樹脂的再生度[10]:用NaCl取代樹脂上的OH-,用HCl滴定流出液中的OH-,過量的HCl使樹脂充分轉(zhuǎn)變?yōu)镃l型,再用Na2SO4取代樹脂上的Cl-,最后用AgNO3滴定流出液中的Cl-。再生度的計算公式: 再生度=[(V1-V2)×NA×100(V3×NB)]×100% 式中:V1和V2分別為滴定至pH為9.0和3.9時所消耗的HCl量,mL;NA和NB分別為所消耗的HCl和AgNO3的濃度,mgL;V3為操作中所消耗的AgNO3量,mL。 1.3分析方法 2分析與討論 2.1吸附動力學(xué) 注溶液初始濃度為20 mgL,樹脂投加量為0.20 gL,初始pH為7.20±0.10。圖1 298 K時離子交換樹脂吸附的吸附動力學(xué)曲線Fig.1 Adsorption kinetics of perchlorate adsorbedby anion exchange resin at 298 K 一級反應(yīng)動力學(xué): (1) 偽二級反應(yīng)動力學(xué): (2) 粒內(nèi)擴散模型: qt=k3t0.5 (3) 式中:qe為平衡時吸附量,mgg;qt為t時刻吸附量,mgg;k1為一級吸附速率常數(shù),min-1;k2為偽二級吸附速率常數(shù),mg(g·min)[17];k3為粒內(nèi)擴散速率常數(shù),mg(g·min0.5)。 表2 3種反應(yīng)動力學(xué)模型在298 K時的擬合參數(shù) 注:qe exp為平衡時吸附量的試驗值,mgg;qe cal為平衡時吸附量的擬合值,mgg。 2.23種樹脂的吸附等溫線 采用Langmuir 和Freundlich等溫吸附模型對298 K時3種樹脂的吸附能力進行擬合,擬合后的參數(shù)如表3所示。 表3 298 K時等溫吸附參數(shù) 1)qe為平衡時吸附量,mgg;Ce為平衡時溶液中濃度,mgL;Q0為最大吸附量,mgg;K為吸附能量相關(guān)的常數(shù),Lmg。2)KF為Freundlich吸附常數(shù),(mgg)(Lmg)n;n為吸附常數(shù)。 注:吸附劑投加量為0.24 gL,吸附時間24 h,初始pH為7.20 ± 0.10。圖2 298 K時離子交換樹脂吸附的吸附等溫線Fig.2 Adsorption isotherms of perchlorate adsorbedby anion exchange resin at 298 K 2.3影響因素 2.3.1溫度的影響 表4 Cl717不同溫度下的吸附參數(shù) 注:同表3。 標(biāo)準(zhǔn)吉布斯函數(shù)由下述公式確定: ΔGΘ=-RT·lnKL (6) 式中:R為理想氣體常數(shù),8.314 J(mol·K);T為開氏溫度,K;KL為Langmiur常數(shù),Lmol。標(biāo)準(zhǔn)摩爾焓變(ΔHΘ)和標(biāo)準(zhǔn)摩爾熵變(ΔSΘ)可以由范特霍夫回歸方程的斜率和截距確定。方程如下: (7) 注:吸附劑投加量為0.08 gL,吸附時間為24 h,初始pH為7.20 ± 0.10。圖3 不同溫度下Cl717吸附的吸附等溫線Fig.3 Adsorption isotherms of perchlorate adsorbedby Cl717 at different temperature 溫度∕KlnKLΔGΘ∕(kJ∕mol)ΔHΘ∕(kJ∕mol)ΔSΘ∕〔J∕(mol·K)〕28810.27-24.5811.53125.3529810.40-25.8430810.61-27.1731810.71-28.30 2.3.2共存離子的影響 注:溫度為298 K,吸附時間為24 h,初始pH為7.20±0.10,平衡時pH為11.20±0.10。圖4 共存離子存在時對Cl717吸附的影響Fig.4 Effects of perchlorate adsorbed by Cl717when competitive anion exists 2.3.3投加量的影響 圖5 Cl717投加量對去除率和吸附容量的影響Fig.5 Effect of Cl717 resin dosage on removal rate 2.3.4再生試驗 分別用0.54、1.08、1.62、2.16、3.25 molL的NaOH溶液,對失效的Cl717進行再生,結(jié)果見圖6。由圖6可見,隨著NaOH溶液濃度和用量的增加,樹脂再生度逐漸增大。NaOH溶液濃度為3.25 molL,用量為樹脂體積的7倍時,再生度達89%以上,樹脂再生效果基本令人滿意。但由于再生液濃度過高會導(dǎo)致樹脂破碎率增加,故試驗得出最佳再生液濃度為2.16 molL,再生液用量為樹脂體積的5倍。 圖6 再生液濃度、用量與再生度的關(guān)系Fig.6 The relationship between the concentration ofregenerate liquid, the dosage and the degree of regeneration 2.4紅外光譜分析 圖7 Cl717吸附前后紅外光譜Fig.7 Infrared spectrum diagram beforeand after adsorption by Cl717 3結(jié)論 (4)再生試驗表明:堿法再生方法可行,最佳再生液濃度為2.16 molL,再生液用量為樹脂體積的5倍。 參考文獻 [1]邱華.高氯酸鹽污染地下水生物修復(fù)研究[D].長春:吉林大學(xué),2015. 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[23]馬楠楠,趙娟,陳?;?紅外與化學(xué)法聯(lián)用表征環(huán)氧樹脂環(huán)氧值[J].玻璃鋼復(fù)合材料,2013(5):3-6. ○ Study on Adsorption of Perchlorate by Anion Exchange Resins and Its Mechanisms QU Hongbin1,2, WAN Dongjin3, XIAO Shuhu2, ZHANG Liping1, LIU Ruixia2 1.School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China2.Department of Urban Environmental Research, Chinese Research Academy Environmental Sciences, Beijing 100012, China3.School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou 450001, China AbstractSeveral commonly used ion exchange resins were compared and the optimal resins to absorb perchlorate were screened out. It showed that Cl717 anion exchange resin acquired the best adsorption efficiency. The adsorption process attributed to the pseudo second order kinetics model, and the equilibrium isotherm for perchlorate uptake corresponded closely to the Langmuir model, belonging to the adsorption type of single layer. The increase of temperature and dosage was beneficial to the adsorption. Co-existed anions could affect the adsorption process with the interference order of Key wordsexchange resin; perchlorate; water treatment; adsorption kinetics; adsorption mechanism 收稿日期:2016-01-11 基金項目:國家自然科學(xué)基金項目(21277134,21107103);環(huán)境基準(zhǔn)與風(fēng)險評估國家重點實驗室自由探索基金 作者簡介:曲宏斌(1990—),男,碩士研究生,主要從事水污染控制技術(shù)研究,1151337802@qq.com *責(zé)任作者:肖書虎(1979—),男,副研究員,博士,主要從事水質(zhì)凈化技術(shù)與原理研究,xiaoshuhu@126.com 中圖分類號:X703 文章編號:1674-991X(2016)04-0343-07 doi:10.3969?j.issn.1674-991X.2016.04.051 曲宏斌,萬東錦,肖書虎,等.離子交換樹脂對水中高氯酸根的吸附及其機理研究[J].環(huán)境工程技術(shù)學(xué)報,2016,6(4):343-349. QU H B, WAN D J, XIAO S H, et al.Study on adsorption of perchlorate by anion exchange resins and its mechanisms[J].Journal of Environmental Engineering Technology,2016,6(4):343-349.