醚化改性麦糟吸附材料的制备及其对亚甲基蓝的吸附

Preparation and performance investigation of etherification modified spent grain as sorbent materials for dyes

摘要:

麦糟表面结构粗糙且有大量的官能团，被视为一种天然吸附材料，为实现麦糟的资源化利用，本文以麦糟（raw spent grain, RSG）为基材，以氯乙酸为醚化剂、NaOH为催化剂，制备了醚化改性麦糟吸附材料（etherified modified spent grain, MSG）, 用于对亚甲基蓝（methylene blue, MB）的吸附。考察了改性条件对吸附效果的影响，得到在mol(NaOH):mol(ClCH2COOH)=2.5:2.0、醚化温度为75℃、醚化时间为2.5 h的条件下得到的MSG吸附效果最好。通过SEM、N2吸脱附、FT-IR、XPS和pHPZC等手段对改性前后麦糟的外观形貌、比表面积和孔径分布、表面性质等进行了分析。另外，MSG吸附MB的过程可很好地用Langmuir方程和拟二级动力学方程描述，表明了化学吸附为其主要吸附方式。

Abstract:

Spent grain is regarded as a natural adsorption material because of it is rough surface structure and functional groups. In order to realize the recyclization of the spent grain, etherified modified spent grain (MSG) for adsorbing methylene blue (MB) was prepared from raw spent grain (RSG) with NaOH as alkaline catalyst and chloroacetic acid as the etherifying agent. The effect of the modification parameters on the adsorption effect was investigated. The results showed that the adsorption of MSG reached maximum value with 201.20 mg/g, when the ratio of NaOH to ClCH2COOH was 2.5:2.0, etherification temperature was 75 ℃ and etherification time was 2.5 h. The morphology, specific surface area, pore size distribution and surface properties of RSG and MSG were analyzed by means of SEM, N2 desorption, FTIR, XPS and pHpzc. The absorption mechanism of MSG to MB dye can be well described by Langmuir equation and pseudo-second-order kinetic equation, indicating that chemical adsorption is the main adsorption method.