机械活化-乳液交联协同制备木薯淀粉磁性微球及其吸附分离镉离子的研究

Starch-based adsorbent for heavy metal ions has such disadvantages as low adsorption capacity, slow adsorption rate, unable to move .directionally and poor solid-liquid separation. In this study, magnetic starch microspheres are prepared in a mechanical activation- inversed emulsion/cross-linking synergistic system with mechanically-activated starch， Fe3O4 and acrylic acid as a raw material. The key theory and technology of preparation of magnetic starch microspheres were studied. Synergistic reaction mechanism among mechanical activation -inverse emulsion/cross-linking are discussed. Preparation mechanism and regulation model of stability of magnetic starch microspheres emulsion system are investigated respectively. The effects of mechanical activation on the macro structure and magnetic properties of microspheres in a mechanical activation - inversed emulsion system are studied with varying reaction conditions. The effects of mechanical activation on chemical reaction activity of starch are studied by monitoring the rheological properties, viscosity, transmittance, and microstructure of magnetic starch microspheres during the reaction. the kinetics of adsorption of magnetic starch microspheres for heavy metals are investigated, and its adsorption mechanism is proposed. The structure-activity relationship between structure of microsphere adsorbents and its adsorption property is discussed. The researches will provide theoretical and technical support for controllable preparation of magnetic starch microspheres and effective treatment methods of serious heavy metal pollution in Guangxi. The important significance is to improve the independent intellectual property rights of processed starch products and to promote the development of processed starch products and starch deep processing.

为改善淀粉基吸附剂吸附容量小、速率慢、无法定向移动和固液分离困难等不足，以木薯淀粉为原料，以Fe¬3O4为磁粒子，丙烯酸等乙烯基单体为共聚单体，采用机械活化-反相乳液交联协同技术制备淀粉磁性微球重金属离子吸附剂，研究淀粉磁性微球制备的关键理论与技术。探讨机械活化-反相乳液交联技术制备淀粉磁性微球的协同反应机制；调变工艺参数，监控聚合过程乳液体系的流变性、粘度、透光率等指标，获得微球结构的调控技术和规律，实现微球可控合成；研究微球对镉等重金属离子的吸附动力学并构建数学模型，研究重金属离子和微球结构作用机理，建立微球结构性能与吸附位点之间的构效关系。研究成果可为磁性淀粉微球的可控合成以及广西地方乃至全国严重的重金属污染的有效治理提供理论和方法，对提高淀粉深加工产品自主知识产权水平，促进广西淀粉深加工行业的发展具有重要意义。

为解决日益严峻的重金属离子废水污染问题和充分利用广西丰富的生物质资源，本项目以木薯淀粉、木薯渣为主要原料，采用机械活化、反相乳液聚合、交联等复合技术构建了三种天然高分子微球吸附剂：多孔磁性淀粉微球（AAM-MSMPM）、PEI修饰磁性淀粉微球（PEI/HMPCR）和木薯渣磁性微球（PEI/HMPCR）。通过扫描电镜(SEM)、X射线光电子能谱(XPS)、振动样品磁强计(VSM)等表征手段对其进行表征分析；结合吸附过程动力学和吸附等温模型，揭示结构性能-吸附-脱附之间的构效关系。主要结论如下：1）多孔磁性淀粉微球对Cd(II)的吸附：与不加致孔剂相比，AAM-MSMPM的粒径从19.21 nm减小7.32 nm，比表面积从7.33 m2·g-1增大35.23 m2·g-1，孔体积从0.03 cm3·g-1增加到0.13 cm3·g-1，对Cd(II)的吸附提供了更多的吸附位点，AAM-MSMPM对Cd(II)的吸附容量最大为210.68 mg·g-1。经过5次吸附-解吸循环实验后，AAM-MSMPM对Cd(II)的吸附容量基本保持不变。吸附过程符合Langmuir等温吸附模型和准二级动力学模型。AAM-MSMPM表面的官能团(-NH2，-COOH，-OH)与Cd(II)之间的相互作用使吸附量增加，当AAM-MSMPM表面大部分吸附位点被Cd(II)占据时，吸附达到平衡。2）PEI修饰磁性淀粉微球对Cd(II)的吸附：pH是影响PEI/MMA-MSM微球吸附效果的重要因素，其最大吸附容量为187 mg·g-1。PEI/MMA-MSM微球对Cd(II)的吸附均是单分子层覆盖过程，化学吸附为主，主要通过共用电子对的方式，使吸附剂中的-NH2和-OH官能团与溶液中的Cd(II)发生相互作用。经过5次吸附-解吸循环时，对Cd(II)的吸附容量仍保持为最初吸附容量的81%。3）PEI修饰木薯渣磁性对Cd(II)的吸附：PEI成功负载到木薯渣微球上，XPS显示吸附前后-NH和-NH2官能团峰消失，O元素结合能增加，在吸附过程中，N通过失氢与氧键合，共用电子对与Cd(II)形成配合物形成配合物。对Cd(II)的最大吸附量为143.6mg·g-1，吸附过程是单分子吸附，吸附受化学吸附和扩散过程共同控制。以上研究成果对重金属离子治理和生物质利用起到了积极的指导作用。