EDTA对磁性壳聚糖的改性及对Mn2+的吸附性研究

Preparation of EDTA modified magnetic chitosan and its adsorption on Mn2+

关键词:  EDTA改性  壳聚糖  磁性  吸附  Mn²⁺

Key words:  EDTA modification  chitosan  magnetic  adsorption  Mn²⁺

摘要:

目的 为解决现有水体除Mn²⁺技术条件苛刻、成本高、传统吸附剂回收利用难等问题,通过交联反应和乳化反应分别制备了磁性壳聚糖(CMS)和EDTA改性磁性壳聚糖(EDTA-CMS)两种Mn²⁺吸附剂。方法 采用SEM、FT-IY、XRD等对CMS、EDTA-CMS进行了表征,并考察了CMS、EDTA-CMS在不同实验条件下对Mn²⁺的吸附性能。结果 与CMS相比,在温度为25 ℃、pH值为6、吸附剂用量为1 g/L、吸附时间为720 min时, EDTA-CMS对Mn²⁺ 的吸附率更高；CMS、EDTA-CMS对Mn²⁺的吸附过程符合准二级动力学模型,表明化学吸附主要控制着吸附速率；且吸附过程符合Langmuir等温模型,最大吸附容量分别可达95.638 mg/g、119.363 mg/g；循环吸附5次后, EDTA-CMS对Mn²⁺的吸附率为71.47％,仍高于CMS对Mn²⁺的初次吸附率。结论 EDTA-CMS不仅对Mn²⁺的吸附效果较好且重复利用率高,是处理含Mn²⁺废水的潜在可回收吸附剂。 

Abstract:

Objective In order to solve the existing problems such as harsh technical conditions, high cost, and poor recovery with traditional adsorbents for Mn²⁺ removal from water, magnetic chitosan (CMS) and EDTA-modified magnetic chitosan (EDTA-CMS) were prepared by crosslinking reaction and emulsification reaction, respectively. Methods The characteristic of CMS and EDTA-CMS was analyzed by corresponding methods, while the adsorption and desorption capacity for Mn²⁺ was investigated under different experimental conditions. Results When the temperature was 25 ℃, pH value was 6, the amount of adsorbent was 1 g/L, and the adsorption time was 720 min, the adsorption rates of Mn²⁺ by CMS and EDTA-CMS were 63% and 89%, respectively. The adsorption processes of CMS and EDTA-CMS for Mn²⁺ were in line with the quasi-second-order kinetic model, which indicated that the adsorption rate was mainly controlled by chemisorption. Besides, the adsorption process could be explained by Langmuir isothermal model and the maximum adsorption capacities of CMS and EDTA-CMS were 95.638 mg/g and 119.363 mg/g, respectively. After 5 cycles of adsorption-desorption, the adsorption rate of EDTA-CMS for Mn²⁺ could reach 71.47%, which was still higher than the initial adsorption rate of CMS for Mn²⁺. Conclusion sThis study demonstrated that EDTA-CMS not only has good adsorption effect on Mn²⁺, but also could be regarded as a potential recyclable adsorbent for treating wastewater containing Mn²⁺.