Li Weixue, Ju Benzhi, Zhang Shufen
State Key Laboratory of Fine Chemicals, Dalian University of Technology Dalian 116024 PR China
RSC Adv. 2019 Mar 1;9(12):6986-6994. doi: 10.1039/c9ra00048h. eCollection 2019 Feb 22.
Using a green biosorbent to remove toxic mercury ions from aqueous solutions is a significant undertaking. In the present study, a novel biosorbent, l-cysteine modified cellulose nanocrystals (Lcys-CNCs), was prepared by functionalizing high surface area cellulose nanocrystals with l-cysteine through periodate oxidation and reductive amination reaction. Lcys-CNCs were characterized by FT-IR, C CP-MAS NMR, elemental analysis, XPS, zeta potential and SEM. As cellulose nanocrystals are the natural nanomaterial, and l-cysteine contains strong mercury chelating groups, Lcys-CNCs show excellent adsorption capacity for mercury ions. The experimental conditions such as pH, contact time, and initial mercury ion concentration are discussed. The pseudo-second order model can describe the removal kinetics of Hg(ii) more accurately than the pseudo-first order model. The adsorption isotherm study of Hg(ii) followed the Langmuir model of monolayer adsorption. The maximum uptake capacity of Lcys-CNCs was determined to be 923 mg g. Lcys-CNCs can remove mercury ions with 93% removal efficiency within 5 min from a 71 mg L solution. For Cd(ii), Pb(ii), Cu(ii) and Zn(ii) ions, Lcsy-CNCs can selectively adsorb Hg(ii) ions and the removal efficiency is 87.4% for Hg(ii). This study suggests Lcsy-CNCs are a green and highly efficient biosorbent for adsorption of mercury ions from aqueous solutions.
使用绿色生物吸附剂从水溶液中去除有毒汞离子是一项重大任务。在本研究中，通过高碘酸盐氧化和还原胺化反应，用L-半胱氨酸对高比表面积纤维素纳米晶体进行功能化，制备了一种新型生物吸附剂L-半胱氨酸修饰纤维素纳米晶体（Lcys-CNCs）。通过傅里叶变换红外光谱（FT-IR）、碳交叉极化魔角旋转核磁共振（C CP-MAS NMR）、元素分析、X射线光电子能谱（XPS）、zeta电位和扫描电子显微镜（SEM）对Lcys-CNCs进行了表征。由于纤维素纳米晶体是天然纳米材料，且L-半胱氨酸含有强大的汞螯合基团，Lcys-CNCs对汞离子表现出优异的吸附能力。讨论了pH值、接触时间和初始汞离子浓度等实验条件。准二级模型比准一级模型能更准确地描述Hg（II）的去除动力学。Hg（II）的吸附等温线研究遵循单层吸附的朗缪尔模型。测定Lcys-CNCs的最大吸附容量为923 mg/g。Lcys-CNCs能在5分钟内从71 mg/L的溶液中以93%的去除效率去除汞离子。对于Cd（II）、Pb（II）、Cu（II）和Zn（II）离子，Lcsy-CNCs能选择性吸附Hg（II）离子，Hg（II）的去除效率为87.4%。本研究表明Lcsy-CNCs是一种从水溶液中吸附汞离子的绿色高效生物吸附剂。
