褐煤腐殖酸基磁性复合微球的制备及其对重金属离子的吸附性能研究

Lignite resource is abundant in our country. Due to a large amount of humic acid contained in lignite, high efficient utilization of lignite humic acid is an important way to carry out the deep processing and utilization of lignite. At present, the pollution problem of heavy metal waste water becomes more and more serious in our country and many physical or chemical methods have also been applied to treat heavy metal wastewater. However, these methods are hard to at the same time satisfy the demands of a technique with all-around excellence such as high efficiency, low cost and no second contamination. In this project, magnetic composite microspheres based on lignite humic acid are fabricated by the Pickering emulsion droplet template method. Lignite humic acid colloid particles are used to stabilize the oil-in-water type droplets containing magnetic nanoparticles and immobilized on the emulsion droplet surface by chemical crosslinking reaction or interfacial polymerization. Then chemical crosslinked lignite humic acid magnetic composite microspheres and lignite humic acid/conducting polymer magnetic composite microspheres were prepared by solvent evaporation. It is expected to remove the heavy metal ions from wastewater efficiently by using composite microspheres based on lignite humic acid via adsorption process, which is owing to combination between the excellence adsorption characteristics of lignite humic acid and magnetic separation performance. The controlled preparation and formation mechanism of composite microspheres are discussed and their correlations of structure and adsorption behavior for heavy metal ions are also investigated. The results obtained would provide a new preparation approach and basic theory for developing a valuable and applicable adsorption material for heavy metal wastewater. Also, the results would provide a new idea for the comprehensive utilization of lignite resource.

我国褐煤资源丰富，褐煤中含有大量腐殖酸，对褐煤腐殖酸进行有效利用，是开展褐煤深加工与利用的重要途径。目前我国重金属废水的污染问题日渐突出，而现有的物理化学方法很难同时满足效率高、成本与二次污染低等综合性能俱佳的要求。本项目以褐煤腐殖酸胶体粒子稳定的水包油型Pickering乳滴为模板，将磁性纳米粒子包裹在乳滴内，采用化学交联或界面聚合反应将腐殖酸胶体粒子固定在乳滴表面，再通过溶剂挥发制备化学交联褐煤腐殖酸磁性复合微球和褐煤腐殖酸/导电聚合物磁性复合微球；综合褐煤腐殖酸基复合微球优异的重金属离子吸附特性和磁分离性能，实现复合微球对水中重金属离子的高效吸附，净化重金属离子废水；探讨复合微球的可控制备、形成机理及其结构与重金属离子吸附性能之间的"构-效"关系，为发展具有应用价值的重金属废水吸附材料提供新颖制备途径与基础理论依据，并为褐煤资源的综合利用提供一种新的研究思路。

为实现褐煤腐殖酸的有效利用和重金属废水吸附材料的开发，本项目以褐煤腐殖酸胶体粒子及其复合胶体粒子稳定的水包油型Pickering乳滴为模板，制备褐煤腐殖酸基磁性复合微球，并研究其对水中重金属离子的吸附性能。主要研究结果如下：（1）利用褐煤腐殖酸的水溶性与pH值的关系，调节溶液pH < 3获得褐煤腐殖酸胶体粒子，制备出褐煤腐殖酸胶体粒子稳定的水包油型Pickering乳液，并实现了苯乙烯Pickering乳液的循环聚合；制备出褐煤腐殖酸/海泡石复合胶体粒子协同稳定的水包油型Pickering乳液和褐煤腐殖酸/蒙脱土协同稳定的水包油型Pickering乳液，并实现了海泡石纳米纤维包覆聚苯乙烯微球的成功制备；（2）以褐煤腐殖酸胶体粒子稳定的Pickering乳滴为模板，通过“界面聚合+溶剂去除”法制备出腐殖酸/聚吡咯复合中空微球，通过“两步聚合+溶剂去除”法制备出两种花状腐殖酸/导电聚合物/聚苯乙烯磁性复合微球；以腐殖酸/海泡石复合胶体粒子稳定的Pickering乳滴为模板，通过“界面聚合+溶剂挥发”法制备出两种腐殖酸/海泡石/导电聚合物磁性复合微球；以腐殖酸/蒙脱土复合胶体粒子稳定的Pickering乳滴为模板，通过“两步聚合+溶剂挥发”法制备出两种腐殖酸/蒙脱土/导电聚合物磁性复合微球。将七种复合微球用于吸附水中Cr(Ⅵ)离子，表现出优异的吸附性能；（3）以腐殖酸/海泡石复合胶体粒子稳定的Pickering乳滴和腐殖酸/蒙脱土复合胶体粒子稳定的Pickering乳滴为模板，通过壳聚糖的化学交联作用制备出两种化学交联腐殖酸磁性复合微球，将其用于吸附水中Cu（II）离子，表现出优异的吸附性能。在项目执行期间，已发表论文5篇（SCI论文3篇，CSCD论文2篇），待发表6篇。申请国家发明专利3项。培养硕士研究生6名，其中3名已取得硕士学位，3名在读。本项目获得了褐煤腐殖酸基复合微球的可控制备、形成机理及其结构与重金属离子吸附性能之间的"构-效"关系，为发展具有应用价值的重金属废水吸附材料提供新颖制备途径与基础理论依据，并为褐煤资源的综合利用提供一种新的研究思路。