单宁/羧甲基纤维素水凝胶的制备及吸附性能

Preparation and adsorption properties of tannin/carboxymethyl cellulose (TA/CMC) hydrogel

以单宁、羧甲基纤维素为单体,环氧氯丙烷为交联剂,制备单宁/羧甲基纤维素复合水凝胶。通过单体质量比、交联剂用量、交联时间3个因素,优化单宁/羧甲基纤维素复合水凝胶的制备工艺。以阳离子染料亚甲基蓝为有机吸附质,考察了染料初始质量浓度、pH、温度等因素对水凝胶吸附性能的影响。正交实验表明,制备单宁/羧甲基复合水凝胶的最佳条件为:单宁/羧甲基纤维素质量比1.2∶1.0,环氧氯丙烷用量0.8%,交联时间36 h。吸附实验表明,当亚甲基蓝初始质量浓度大于1500 mg/L时,水凝胶中的空隙被填充,吸附位点趋于饱和,吸附量达到最大530.43 mg/g;pH在中性条件下有利于增加水凝胶与亚甲基蓝之间的静电吸附与络合作用,吸附率为80.2%;热力学数据表明,水凝胶对亚甲基蓝的吸附为自发放热物理吸附过程,在常温条件下更利于吸附的进行。

The tannin/carboxymethyl cellulose(TA/CMC)hydrogel was prepared by using tannin and car⁃boxymethyl cellulose as monomer,epichlorohydrin as acrosslinker.The preparation process of tannin/carboxy⁃methyl cellulose composite hydrogel was optimized by 3 factors,such as monomer mass ratio,crosslinking agent dosage and crosslinking time.The effects of dye initial mass concentration,pH and temperature on the adsorption performance of the TA/CMC hydrogel were studied by methylene blue(MB)as the organic adsor⁃bent.The orthogonal results showed that the optimal reaction conditions for preparing TA/CMC hydrogel were as follows:tannin/carboxymethyl cellulose mass ratio 1.2∶1.0,epichlorohydrin dosage 0.8%,and the crosslink⁃ing time 36 h.The adsorption experiments showed that when the initial mass concentration of methylene blue was greater than 1500 mg/L,the gap in the gel was filled,the adsorption sites were saturated,and the ad⁃sorption capacity reached the maximum of 530.43 mg/g.Under the neutral pH condition,the electrostatic ad⁃sorption and complexation between hydrogel and methylene blue were improved,and the adsorption rate was 80.2%.The thermodynamic data showed that the adsorption of methylene blue on hydrogel was self releasing thermophysical adsorption process,which was more conducive to adsorption at normal temperature.