活化木质素炭基材料THM@L对水体中砷的去除机理研究

Arsenic (As) has been considered as the most poisonous pollutant on the blacklist of pollutant. According to the Centers for Disease Control and Prevention (CDC) of the United States and the international cancer research institutions, arsenic has been identified as the first kind of carcinogens. In recent years, the pollution of arsenic has been received the researchers' extensive and special concern because of its long time environmental persistence and biological toxicity properties of the pollution. Because of these features, the arsenic pollution has resulted in serious problems on human health and the ecological environment. Various techniques such as the traditional adsorption experiment and adsorption materials have been developed for the treatment and removal of arsenic pollution. However, the preparation technology and cheap and efficient adsorption material for the pollutant of the complex wastewater environment are the key research problems in the field of efficient arsenic pollutant removal. This study focuses on the arsenic pollution in the river. The toxicant-heavy metal adsorption onto lignin based carbon material (THM@L) will be prepared by the low temperature and microwave assisted method, combined with aqueous H3PO4 activation to improve the adsorption capacity. The activation mechanism of THM@L by H3PO4 will be revealed by lignin molecular microscopic structure characterization. The new method of lignin activation will be set up. The adsorption mechanisms of arsenic onto THM@L will be studied comprehensively by characterization of the lignin molecular microscopic structure and quantified functional groups of THM@L according to 31P NMR and 2 D HSQC NMR spectra analysis, as well as a series of experiments. The project will provide scientific theoretic basis for the arsenic in wastewater pollution treatment, which is also meaningful and helpful for the actual river pollution disposal.

砷(As)位居污染有毒元素黑名单之首，已被确定为第一类致癌物质，因其环境持久性和生物毒性对地球生态环境和人类健康造成了较大的危害，受到了研究人员的特别关注。目前对于水体中As污染去除的研究主要依赖传统的吸附剂，然而吸附材料成本，制备技术及吸附效率已成为制约其大规模应用及高效去除As的瓶颈。本项目拟选用造纸残渣木质素为原料，采用低温微波辅助结合H3PO4高效活化新技术制备木质素炭基吸附材料THM@L，增加木质素分子活性位点，提高其吸附性能；通过分子微观结构及活性基团表征，揭示该活化新技术对木质素分子的作用机制；基于吸附实验，结合原位定量磷谱及二维核磁共振波谱等技术，在分子水平上阐明活化木质素炭材料THM@L对As的吸附机理。本项目的研究将为水体砷污染治理提供科学的理论指导和技术支撑，具有重要的研究意义。

水体重金属污染对地球生态环境和人类健康造成了较大的危害，本项目采用低温微波辅助离子液体技术提取生物质材料中的木质素组分，表征其物理化学结构，制备高性能吸附材料，用于废水中重金属的去除，阐明去除机理及工业化应用障碍。研究内容一：采用微波辅助-离子液体提取技术对桉木中木质素进行提取、分离，结果表明对桉木的提取效率为97.6%，24.6%的木质素（酸不溶木质素）被提取，占总木质素的50%以上，离子液体1-ethyl-3-methylimidazolium acetate ([C2C1im][OAc])对木质素的提取表现出良好的选择性，微波辅助能够提高木质素的提取效率，降解产生的木质素分子量减小，含氧官能团增多，有利于环境污染治理。采用离子液体-水体系（IL-water）从桉木中提取酶水解木质素（EMAL）和碱性木质素(AL),对木质素的结构变化、物理化学性能进行分析、表征，研究发现，离子液体对木质素的降解起到主要作用，含水量的增加，提高了氢键受体β值，导致木质素的降解，木质素结构中含氧功能性基团增多，活化作用增强，有利于对污染物的去除。研究内容二：采用H3PO4等试剂高效活化技术制备木质素炭基吸附材料，增加木质素分子活性位点，提高其吸附性能，研究发现炭基材料表面含氧官能团含量较高，有利于与重金属的结合，H3PO4活化木质素（PA-CL）在吸附5min内对Cr(VI)去除率可达79.2%，40min时达到96.5%，吸附效果较好。发明了一种基于氧化石墨烯和木质素制备水凝胶（LGH）的工艺，改性的木质素磺酸钠/氧化石墨烯复合水凝胶具有吸附率高、抗干扰强等优点，对Cr(VI)的吸附容量高达1743.9mg/g，从分子水平角度阐明活化木质素炭材料对重金属的吸附机理，静电吸附和化学吸附占主导地位，该材料适合对工业废水中重金属离子的去除。研究内容三：对木质素吸附材料的解析循环利用实验表明，经过5次循环吸附后，木质素水凝胶对Cr（VI）吸附效率仍能够达到88%（300mg/L），吸附效果较好。本项目的研究将为木质素应用于水体重金属污染治理及废水资源化提供科学的理论指导和技术支撑，具有重要的研究意义。