肖谷清,龍立平,王姣亮,徐滿(mǎn)才 (.湖南城市學(xué)院化學(xué)與環(huán)境工程系,湖南 益陽(yáng) 43000；.湖南師范大學(xué)化學(xué)化工學(xué)院,湖南 長(zhǎng)沙 4008)

對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂對(duì)雙酚A的吸附性能

肖谷清1,2*,龍立平1,王姣亮1,徐滿(mǎn)才2(1.湖南城市學(xué)院化學(xué)與環(huán)境工程系,湖南 益陽(yáng) 413000；2.湖南師范大學(xué)化學(xué)化工學(xué)院,湖南 長(zhǎng)沙 410081)

用二氯乙烷為溶劑,用FeCl3為催化劑,使氯球和對(duì)乙酰氨基酚發(fā)生Friedel-Crafts反應(yīng)制得了對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂,對(duì)其結(jié)構(gòu)進(jìn)行了表征,研究乙酰氨基和酚羥基二類(lèi)氫鍵作用位點(diǎn)修飾的后交聯(lián)樹(shù)脂對(duì)雙酚A的吸附性能.結(jié)果表明,紅外光譜顯示對(duì)乙酰氨基酚已被成功地修飾在后交聯(lián)樹(shù)脂上.對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂與氯球相比,BET比表面積、孔容明顯增大,孔徑明顯變小.對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂對(duì)雙酚A的吸附量明顯高于75%活性炭的聚砜微球?qū)﹄p酚A的吸附量.對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂對(duì)雙酚A的吸附為放熱、自發(fā)的過(guò)程;樹(shù)脂可以用100%酒精解吸,解吸率為99.92%;吸附動(dòng)力學(xué)數(shù)據(jù)符合一級(jí)吸附速率方程,顆粒內(nèi)擴(kuò)散是吸附速率的主要控制步驟,吸附速率同時(shí)還受液膜擴(kuò)散的影響.

對(duì)乙酰氨基酚；后交聯(lián)樹(shù)脂；雙酚A；吸附熱力學(xué)；吸附動(dòng)力學(xué)

雙酚A [2,2-雙(4,4′-二羥基苯基)丙烷]在工業(yè)中應(yīng)用廣泛[1-3],具有雌性激素作用,被列為環(huán)境內(nèi)分泌干擾物[4-6].由于其難于生物降解及化學(xué)氧化,常規(guī)水處理工藝很難將其從環(huán)境中去除,因此雙酚A在城市污水和飲用水中的檢出率很高[7-8],常以極高的濃度存在于環(huán)境水體中[9],威脅著人與生物體的健康.

樹(shù)脂吸附法處理廢水具有分離效率高、溶劑消耗少、操作安全、能循環(huán)使用等優(yōu)點(diǎn)[10],其中后交聯(lián)樹(shù)脂因具有優(yōu)良的吸附性能,應(yīng)用廣闊.后交聯(lián)樹(shù)脂的制備過(guò)程中普遍使用劇毒致癌物硝基苯作溶劑,易引起二次污染[11-14].用對(duì)乙酰氨基酚為后交聯(lián)劑尚無(wú)相關(guān)文獻(xiàn)報(bào)道.用對(duì)乙酰氨基酚為后交聯(lián)劑,在乙?；膶?duì)位引入酚羥基,一方面可增加苯環(huán)的活性,有利于Friedel-Crafts反應(yīng)的進(jìn)行,從而制得比表面積高的后交聯(lián)樹(shù)脂,提高樹(shù)脂的吸附性能;另一方面可帶有乙?；头恿u基2類(lèi)氫鍵作用位點(diǎn),提高吸附容量和吸附的選擇性.為此,本研究用毒性較低、易揮發(fā)的二氯乙烷為溶劑,用 FeCl3為催化劑,用對(duì)乙酰氨基酚為后交聯(lián)劑,制得了對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂,探討這類(lèi)同時(shí)含乙酰氨基和酚羥基二類(lèi)氫鍵作用位點(diǎn)的后交聯(lián)樹(shù)脂對(duì)雙酚A的吸附性能.

1 材料與方法

1.1 材料與儀器

交聯(lián)度為 6℅的氯甲基聚苯乙烯(簡(jiǎn)稱(chēng)氯球,南開(kāi)大學(xué)化工廠);雙酚A、對(duì)乙酰氨基酚、二氯乙烷、無(wú)水三氯化鐵、乙醇、鹽酸等試劑均為分析純.

UV3010紫外-可見(jiàn)分光光度計(jì)(日本島津公司);Tristar3000全自動(dòng)比表面積及孔隙率分析儀(美國(guó)micromeritics公司);370FT-IR紅外光譜儀(美國(guó)熱電尼高力公司);SHA-B水浴恒溫振蕩器(江蘇省金壇市醫(yī)療儀器廠);W-O型恒溫油水浴鍋(鞏義市予華儀器有限責(zé)任公司).

1.2 樹(shù)脂的制備

稱(chēng)取一定量的氯球,用二氯乙烷溶脹 12h.在機(jī)械攪拌下加入后交聯(lián)劑對(duì)乙酰氨基酚和催化劑FeCl3,加熱回流12h,然后冷卻到室溫,過(guò)濾,再用乙醇、1mol/LHCl、水和乙醇洗滌樹(shù)脂,以含有1℅ HCl的乙醇為溶劑用索氏提取器抽提12h,晾干后,333K真空干燥.

1.3 樹(shù)脂的結(jié)構(gòu)表征

1.3.1 樹(shù)脂的紅外光譜 樹(shù)脂經(jīng)干燥、研細(xì),用KBr壓片法在傅立葉變換紅外光譜儀上測(cè)定其紅外光譜.

1.3.2 樹(shù)脂孔結(jié)構(gòu)的測(cè)定 樹(shù)脂孔結(jié)構(gòu)用Tristar3000全自動(dòng)比表面積及孔隙率分析儀測(cè)定.

1.3.3 樹(shù)脂氯含量和持水量的測(cè)定 樹(shù)脂的氯含量用 Volhard法測(cè)定,樹(shù)脂的持水量按國(guó)家標(biāo)準(zhǔn)[10]測(cè)定.

1.4 樹(shù)脂對(duì)雙酚A的吸附性能

1.4.1 樹(shù)脂對(duì)雙酚A的吸附等溫線(xiàn) 稱(chēng)取一定量的濕態(tài)樹(shù)脂(約干樹(shù)脂 0.1g)于具塞錐形瓶中,加入50.00mL不同濃度雙酚A水溶液,置于恒溫振蕩器中恒溫振蕩 24h,使吸附達(dá)到平衡,用紫外可見(jiàn)分光光度計(jì)在雙酚 A最大吸收波長(zhǎng)279.2nm處測(cè)定吸附殘液中雙酚A的濃度,根據(jù)式(1)計(jì)算其吸附量:

式中:q為吸附量, mg/g;C0、Ce分別為吸附前和吸附后水溶液中雙酚A的濃度,mg/L;V為吸附液的體積,L;W 為濕態(tài)樹(shù)脂的質(zhì)量,g;X為樹(shù)脂的持水量.

1.4.2 樹(shù)脂上雙酚A的靜態(tài)解吸 稱(chēng)取0.200g濕態(tài)樹(shù)脂6份于6個(gè)具塞錐形瓶中,每份中準(zhǔn)確加入50.00mL已知濃度的雙酚A溶液50.00mL,在298 K條件下于水浴恒溫振蕩器中恒溫振蕩,使吸附達(dá)到平衡,用紫外分光光度計(jì)在 279.2nm處測(cè)定各殘液中雙酚A的濃度.

將錐形瓶中的樹(shù)脂過(guò)濾,加入適量蒸餾水洗滌,往錐形瓶中分別加入 50.00mL蒸餾水,含20%,40%,60%,80%,100%的酒精水溶液.在 298K條件下于水浴恒溫振蕩器中恒溫振蕩,使脫附達(dá)到平衡.用紫外分光光度計(jì)在279.2nm處測(cè)各溶液中雙酚A的濃度.按式(2)計(jì)算其解吸率(%):

1.4.3 樹(shù)脂對(duì)雙酚 A 的吸附動(dòng)力學(xué) 稱(chēng)取2.000g濕態(tài)樹(shù)脂置于 1000mL濃度為 500mg/L的雙酚A溶液中,在298K條件下于水浴恒溫振蕩器中以200r/min左右的轉(zhuǎn)速振蕩,并定時(shí)取樣分析雙酚A溶液的濃度.

2 結(jié)果與討論

2.1 樹(shù)脂的結(jié)構(gòu)表征

2.1.1 樹(shù)脂的紅外光譜 圖 1為氯球和對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂的紅外光譜圖.由圖 1可知,對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂1260, 670cm-1附近的氯甲基的2個(gè)特征峰已基本消失,在 1700cm-1處出現(xiàn)了羰基的特征吸收峰,說(shuō)明對(duì)乙酰氨基酚已被成功地修飾在后交聯(lián)樹(shù)脂上.與氯球相比較,后交聯(lián)的樹(shù)脂在3100～3500cm-1附近處出現(xiàn)寬峰,是后交聯(lián)樹(shù)脂中N-H鍵和O-H鍵的伸縮振動(dòng)吸收峰,進(jìn)一步說(shuō)明對(duì)乙酰氨基酚已被成功修飾在后交聯(lián)樹(shù)脂上.

圖1 樹(shù)脂的紅外光譜Fig.1 IR spectra of resin

2.1.2 樹(shù)脂的孔結(jié)構(gòu) 由表1可見(jiàn),對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂與氯球相比,BET比表面積、孔容明顯增大,孔徑明顯變小.這主要是對(duì)乙酰氨基酚中羥基和乙酰氨基均活化苯環(huán),使得以乙酰氨基酚為“交聯(lián)橋”的后交聯(lián)反應(yīng)容易發(fā)生.在二氯乙烷溶脹的氯球中形成以乙酰氨基酚為“交聯(lián)橋”,使得樹(shù)脂的溶脹態(tài)被“交聯(lián)橋”固定下來(lái),使反應(yīng)后的樹(shù)脂BET比表面積和孔容增大,孔徑減小.

表1 樹(shù)脂的比表面積、孔容和孔徑Table 1 The values of BET surface, pore volume and pore diameter

2.1.3 樹(shù)脂的氯含量和持水量 由表2可見(jiàn),和氯球比較,后交聯(lián)樹(shù)脂中氯含量明顯下降,這是因?yàn)槁燃谆c苯環(huán)發(fā)生了Friedel-Crafts反應(yīng)[12];和氯球比較,后交聯(lián)樹(shù)脂中持水量明顯增大,這是因?yàn)槁燃谆c苯環(huán)發(fā)生了Friedel-Crafts反應(yīng)生成了以乙酰氨基酚為“交聯(lián)橋”,后交聯(lián)樹(shù)脂的“交聯(lián)橋”中羥基和乙酰氨基均可與水形成氫鍵,所以后交聯(lián)樹(shù)脂的持水量要比氯球高很多.

表2 樹(shù)脂的氯含量和持水量Table 2 The chlorine content and water retention capacity of the resins

2.2 樹(shù)脂對(duì)雙酚A的吸附性能

2.2.1 樹(shù)脂對(duì)雙酚A的吸附等溫線(xiàn) 圖2是對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂對(duì)雙酚A的吸附等溫線(xiàn).由圖2可見(jiàn),對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂吸附雙酚A,當(dāng)溫度為30℃,雙酚A平衡濃度為100mg/L時(shí),樹(shù)脂的吸附量為178mg/g,而75%活性炭的聚砜微球?qū)﹄p酚 A的飽和吸附量?jī)H為69mg/g[15].吸附等溫線(xiàn)都是 I型吸附等溫線(xiàn),且隨著溫度的升高,吸附量降低,說(shuō)明吸附過(guò)程是放熱的過(guò)程.

圖2 樹(shù)脂吸附雙酚A的等溫線(xiàn)Fig.2 Adsorption isotherms of bisphenol A onto the hypercrosslinked resin

根據(jù)圖2作吸附等溫線(xiàn),計(jì)算出各個(gè)吸附量下的△H[10].以lnq對(duì)lnCe作圖,用線(xiàn)性回歸法求出參數(shù)n,再由方程△G = -nRT 求出吸附△G[10].由方程△S=(△H-△G)/T求出△S.各熱力學(xué)參數(shù) 如表3所示.

表3 樹(shù)脂吸附雙酚A的熱力學(xué)參數(shù)Table 3 Thermodynamics functions of bisphenol A onto the hypercrosslinked resin

由表 3可見(jiàn) ΔH＜0,表明吸附過(guò)程是放熱的.ΔG＜0,說(shuō)明對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂吸附雙酚 A可以自發(fā)進(jìn)行.ΔS＜0,說(shuō)明樹(shù)脂吸附雙酚A后,雙酚A分子被限制在樹(shù)脂吸附位點(diǎn)上,質(zhì)點(diǎn)數(shù)減少,整個(gè)體系變得更為有序.

2.2.2 樹(shù)脂上雙酚A的靜態(tài)解吸 由表4可見(jiàn),當(dāng)水為解吸劑時(shí),雙酚A解吸率很低,僅為1.99%,這反過(guò)來(lái)也可以說(shuō)明樹(shù)脂在水溶液中可以吸附雙酚A;當(dāng)解吸液中酒精濃度從20%增加到100%,解吸率增加,當(dāng)酒精濃度為100%時(shí),雙酚A解吸率為99.92%,幾乎可以全部解吸出來(lái).

表4 樹(shù)脂上雙酚A的靜態(tài)解吸(%)Table 4 The static elution ratio of bisphenol A onto the hypercrosslinked resin(%)

2.2.3 樹(shù)脂對(duì)雙酚A的吸附動(dòng)力學(xué) 將對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂吸附雙酚A的動(dòng)力學(xué)數(shù)據(jù)按照一級(jí)吸附速率公式進(jìn)行擬合,可求得雙酚A在后交聯(lián)樹(shù)脂上的吸附速率常數(shù)[16].一級(jí)吸附動(dòng)力學(xué)方程公式如下:

式中: k1為一級(jí)吸附動(dòng)力學(xué)方程速率常數(shù);Ct為t時(shí)刻(min)時(shí)溶液中雙酚 A的濃度, mg/L; Ce為平衡時(shí)溶液中雙酚 A的濃度, mg/L; t為時(shí)間,min.

由圖3可見(jiàn),擬合得到的吸附速率常數(shù)k1為1.817× 10-3/min,擬合相關(guān)系數(shù)為0.995.

圖3 樹(shù)脂吸附雙酚A的動(dòng)力學(xué)Fig.3 Adsorption kinetics of bisphenol A onto the hypercrosslinked resin

圖4 樹(shù)脂吸附雙A的擴(kuò)散速率Fig.4 The rate of intrapartical diffusion of the bisphenol A onto the hypercrosslinked resin

將對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂吸附雙酚 A的動(dòng)力學(xué)數(shù)據(jù)按照顆粒內(nèi)擴(kuò)散速率公式進(jìn)行擬合,可求得雙酚A在后交聯(lián)樹(shù)脂顆粒內(nèi)的擴(kuò)散速率常數(shù).顆粒內(nèi)擴(kuò)散速率公式如下:

式中: qt為即時(shí)吸附量, mg/g; ki為顆粒內(nèi)擴(kuò)散速率常數(shù), mg/(g·min0.5).

由圖4可見(jiàn), qt對(duì)t0.5呈良好線(xiàn)性關(guān)系(R為0.996),ki為 11.91mg/(g·min0.5).qt對(duì) t0.5呈良好線(xiàn)性關(guān)系,表明顆粒內(nèi)擴(kuò)散過(guò)程為后交聯(lián)樹(shù)脂對(duì)雙酚A吸附速率的主要控制步驟[16];由于qt對(duì)t0.5的直線(xiàn)未通過(guò)原點(diǎn),說(shuō)明雖然顆粒內(nèi)擴(kuò)散是其主要控制步驟,但吸附速率同時(shí)還受液膜(顆粒外)擴(kuò)散的影響.

3 結(jié)論

3.1 用二氯乙烷為溶劑,用FeCl3為催化劑,用對(duì)乙酰氨基酚為后交聯(lián)劑,制得了比表面積高、吸附性能好的對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂.

3.2 對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂對(duì)雙酚 A的吸附符合 Freundlich等溫吸附方程,吸附為放熱、自發(fā)的過(guò)程.

3.3 對(duì)乙酰氨基酚修飾的后交聯(lián)樹(shù)脂吸附雙酚A時(shí),吸附動(dòng)力學(xué)數(shù)據(jù)符合一級(jí)吸附速率方程,顆粒擴(kuò)散是吸附速率的主要控制步驟,吸附速率同時(shí)還受液膜(顆粒外)擴(kuò)散的影響.

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Adsorption performances for bisphenol A onto the hypercrosslinked resin modified by acetaminophen.

XIAO Gu-qing1,2*, LONG Li-ping1, WANG Jiao-liang1, XU Man-cai2(1.College of Chemistry and Environmental Engineering, Hunan City University, Yiyang 413000, China；2.College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China). China Environmental Science, 2010,30(6)：775～779

The adsorption performances for bisphenol A onto the hypercrosslinked resin with two kinds of the hydrogen bond site of acetamino group and hydroxyl group was studied. The hypercrosslinked resin modified with acetaminophen was synthesized with chloromethylated polystyrene and acetaminophen by Friedel-Crafts reaction. Dichloroethane was used as solvent and ferric chloride was used as catalyst. The structures of the hypercrosslinked resin were characterized. The acetaminophen was successfully modified into the hypercrosslinked resin that revealed by the Infrared spectra. Comparison with the chloromethylated polystyrene, the BET surface area and pore volume of the hypercrosslinked resin modified with acetaminophen was increased significantly, the pore size was much smaller. The adsorption capacity of bisphenol A onto the hypercrosslinked resin was obviously superior to polysulphone micro-ball embedded with 75% activated carbon. Heat was discharged during the adsorption and the adsorption occurred automatically. The resin could be desorbed with 100% ethanol. The desorption rate of 100% ethanol was up to 99.92%. The adsorption kinetic date of bisphenol A was fitted to the first order rate equation. The intrapartical diffusion of bisphenol A was the main rate-controlling step. Adsorption rate was also affected by the impact of film diffusion.

acetaminophen；hypercrosslinked resin；bisphenol A；adsorption thermodynamics；adsorption kinetic

2009-11-10

國(guó)家自然科學(xué)基金資助項(xiàng)目(20474015);湖南省教育廳科研基金資助項(xiàng)目(09C198)

* 責(zé)任作者, 副教授, xiaoguqing@yahoo.com.cn

X703

A

1000-6923(2010)06-0775-05

肖谷清(1970-),男,湖南益陽(yáng)人,副教授,博士,主要從事吸附分離材料研究.發(fā)表論文20余篇.