两性纤维素基吸附剂的制备及其吸附性能研究

Preparation and Adsorption Properties of Amphoteric Cellulose-based Adsorbent

关键词:  纤维素  重金属离子  吸附  氨基  羧基

Key Words:cellulose  heavy metal ion  adsorption  amino groups  carboxyl groups

摘要:本研究以蔗渣制备的微晶纤维素为基体，以含氨基和羧基的两性小分子为功能试剂，以环氧氯丙烷为交联剂，采用交联法制备了一种具有高羧基含量（5.11 mmol/g）和氨基含量（7.43 mmol/g）的两性纤维素基吸附剂，并解析了重金属离子在其表面的竞争吸附行为和吸附动力学。结果表明，该吸附剂可在120 min内将1.0 mg/L的Cr(Ⅵ)、Pb(Ⅱ)、Cd(Ⅱ)和2.0 mg/L的Cu(Ⅱ)同步去除至0.0030 mg/L以下，使溶液中重金属离子残余浓度符合国家安全饮用水标准GB 5749—2022，实现了低浓度多种重金属离子的同步高效去除；吸附剂对重金属离子的吸附吻合Langmuir吸附等温线模型，以单层化学吸附为主，对Cr(Ⅵ)、Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)的理论最大吸附容量分别为373.1、128.4、134.4和113.3 mg/g。

Abstract:In this study， the amphoteric cellulose-based adsorbent with high carboxyl content of 5.11 mmol/g and amino content of 7.43 mmol/g was prepared via cross-linking method using microcrystalline cellulose prepared from bagasse as the substrate， amphoteric small molecules containing amino and carboxyl groups as functional reagents， epichlorohydrin as the cross-linking agent， and the competitive adsorption behaviors and adsorption kinetics of heavy metal ions on the surface were resolved. The results showed that the adsorbent could remove 1.0 mg/L of Cr（Ⅵ）， Pb（Ⅱ）， Cd（Ⅱ）， and 2.0 mg/L of Cu（Ⅱ） to below 0.0030 mg/L within 120 min， so that residual concentration of heavy metal ions in the solution complied with the national safe drinking water standard GB 5749—2022， which achieved simultaneous and efficient removal of multiple heavy metal ions with low concentration. The adsorbent fitted the Langmuir adsorption isotherm model for heavy metal ions and was dominated by monolayer chemisorption. The maximum theoretical adsorption capacities were 373.1， 128.4， 134.4， and 113.3 mg/g for Cr（Ⅵ）， Cu（Ⅱ）， Pb（Ⅱ）， and Cd（Ⅱ）， respectively.