School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, PR China.
School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China.
Chemosphere. 2019 Jun;224:509-518. doi: 10.1016/j.chemosphere.2019.02.138. Epub 2019 Feb 26.
Heavy metal contamination directly threatened human life and health. In this work, a novel carboxyl, amide, carbonyl sulfide and secondary amino group grafted cellulose derivative adsorbent (modified-cellulose) was prepared in an attempt to remove heavy metal Cd. The XRD, FTIR, C NMR and XPS results showed that the carboxyl, amide, carbonyl sulfide and secondary amino group were grafted onto the cellulose backbone successfully. Effects of various factors on the adsorption performance were investigated as well as the adsorption mechanism. The Cd adsorption capacity of modified-cellulose was pretty good, up to 401.1 mg/g and with 3 times enhancement. The adsorption process was spontaneous, well described by the Freundlich model (R = 0.994), confirmed to the pseudo-second-order model (R > 0.997), and mainly controlled by chemisorption. The density functional theory (DFT) calculations indicating that the Cd binding ability of multi-functional groups modified cellulose was stronger than that of single-functional group modified cellulose. The preferential adsorption sites were analyzed based on the frontier orbital theory (FOT), and they were concentrated on the secondary amino groups and carbonyl sulfides. It is foreseeable that the as-prepared modified-cellulose adsorbent has great potential in heavy metal cadmium removal, and our conclusions could provide significant theoretical guidance in the due bioresource utilization.
重金属污染直接威胁着人类的生命和健康。在这项工作中，我们尝试制备了一种新型的羧基、酰胺、羰基硫和仲氨基接枝纤维素衍生物吸附剂（改性纤维素），用于去除重金属 Cd。XRD、FTIR、C NMR 和 XPS 结果表明，羧基、酰胺、羰基硫和仲氨基成功地接枝到纤维素主链上。研究了各种因素对吸附性能的影响以及吸附机制。改性纤维素对 Cd 的吸附容量相当好，达到 401.1mg/g，比未改性纤维素提高了 3 倍。吸附过程是自发的，很好地符合 Freundlich 模型（R=0.994），证实了准二级模型（R>0.997），主要受化学吸附控制。密度泛函理论（DFT）计算表明，多官能团改性纤维素的 Cd 结合能力强于单官能团改性纤维素。基于前沿轨道理论（FOT）分析了优先吸附位点，它们主要集中在仲氨基和羰基硫上。可以预见，所制备的改性纤维素吸附剂在去除重金属镉方面具有很大的潜力，我们的结论可为生物资源的合理利用提供重要的理论指导。
