利用生物质制备微纳结构介孔材料及其对活性物质的装载与控释
文献类型：学位论文
| 作者 | 毕磊 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 潘纲 |
| 关键词 | 生物质 微藻 介孔材料 中空微球 物质装载与控释 biomass algae mesoporous materials hollow microspheres loading and unloading of active materials |
| 其他题名 | Fabrication of mesoporous materials with micro/nano architectures using biomass as the precursors and the effect of loading and unloading active materials |
| 学位专业 | 环境工程 |
| 中文摘要 | 生物质作为一类重要的可再生资源，在众多领域都有着广泛的应用。微藻作为生物质资源的一种，不仅具有种类繁多、生物量巨大、易于再生且廉价易得的特点，而且微藻本身就具有高度复杂的微/纳米构造，和丰富的功能基团，经过修饰和处理就可以得到结构和功能多样的微/纳米材料。本研究一方面寻找一种富含氧并可以缓慢释氧的生物质材料，用于改善湖泊底质厌氧状态，减少氮磷的内源释放，控制蓝藻藻华的发生；另一方面为了开发藻资源利用新方法，本文以太湖藻华爆发时产生的蓝藻、提取过油脂的藻渣和绿藻为原料，制备出了中空介孔碳微球、有机/无机复合软胶囊以及铃铛结构多磁性内核介孔微球。本研究所提出的制备中空介孔微球的方法是直接利用藻类天然的球形构造并以其自身物质为主要原料采用反应条件相对温和的水热法处理微藻得到的多孔中空微球。这种合成策略具有无需制备模板、反应步骤少和化学试剂消耗量低等优点，与传统的软、硬模板法相比有了较大的进步。另外还分别研究了上述几种材料在固液体系中氧的装载能力、释氧材料的氧缓释能力以及活性物质的自主封装与控释能力等相关领域的应用。主要得到了以下研究成果： 1）提出了多孔材料悬浊液体系中高载氧量材料的快速筛选方法，并发现采用椰壳制备的活性碳对氧的负载能力明显优于其它材料；提出了直接测定富氧颗粒物材料在水溶液体系中对水中溶解氧贡献量的方法；材料的比表面积和接触角是决定多孔材料在水中载氧能力的关键因素，前两者越大，其在水溶液体系中载氧能力就越强；活性碳对溶解氧的负载主要是以吸附的形式为主，通过常温曝氧的方式，水中活性碳对氧的吸附量可达到2mg/g，多次循环变温可以使溶解氧在活性碳上的负载量提高5%，这种富氧活性碳可作为覆盖材料用于湖泊厌氧底质的改善。 2）采用水热法处理太湖蓝藻制备出了中空介孔碳微球。研究发现，过高的反应温度和较长的反应时间都不利于得到形貌完整的微球。蓝藻经丙酮前处理再经水热反应处理后得到的微球具有较大的比表面积和孔容，但是结构较为松散易碎；而水热反应过程中加入戊二醛后所得到的微球形貌完整，热稳定性得到明显提高，但是比表面积和孔容与未添加戊二醛相比都大幅降低。因此，通过将二者结合使用便可得到球形形貌完整且具有较大的比表面积和孔容的中空介孔碳微球。通过将释氧剂过氧化钙装载于中空碳微球内部制备出了氧缓释微球。研究发现与未包覆微球的过氧化钙相比，包覆有碳微球的过氧化钙可以延长氧在水中的释放时间，同时在一定程度上可以减缓由于直接向水体投加过氧化钙导致的水体pH 过高过快的上升，并具有消减水中磷酸盐浓度的作用。 3）通过对比目前常用的油脂提取剂对藻脂的提取效率，筛选出了藻脂提取效率最高的二氯甲烷/甲醇提取剂，当藻与提取剂的比例为1：20，提取时间为12h，提取温度为25℃，在不破坏藻细胞壁的前提下藻脂提取率达到最大为15.1%。另外，将提取过藻脂的藻渣经6%氢氧化钠和1%的SDS水溶液105℃处理1.5 h后，得到了具有中空结构的羟基磷灰石/聚合物有机/无机复合型微胶囊。而将上述微胶囊经初始pH为10的水溶液200℃水热处理后，便可得到具有磁性的微胶囊。 4）提出了一种简单、绿色的制备多磁性内核铃铛结构介孔微球的合成方法。该方法主要是利用微藻的细胞壁作为中空微球球壳的前驱物，采用水热法合成出具有介孔结构的球壳，并利用藻在水热反应过程中生成的还原性物质将三价铁部分还原成二价铁，在球壳内部形成四氧化三铁纳米内核，从而形成具有介孔壳@多磁性内核的铃铛结构微球。该方法不仅合成步骤简单，而且藻的参与也减少了化学试剂的使用。所得到的微球大小在2.5 μm左右，内含多个平均粒径为30 nm的磁铁矿纳米颗粒，微球内部的容积率达到了70%，同时微球还保留了大量的小球藻的活性基团，有利于进一步的功能化修饰。另外，磁性纳米内核不仅令微球具有快速的磁响应特性，而且利用磁性内核在不同pH条件下表面电性的差异，可以高效的封装和释放BSA。因此，该微球的上述特性使其在活性物质封装、磁性分离以及磁操控靶向给药等领域表现出较大的应用潜力。 |
| 英文摘要 | Bio-resource has wide application in many fields. Microorganism as a resource is abundant, renewable and inexpensive. Furthermore, microorganism exhibits extremely complicated micro/nano architectures and various chemical functional groups, which could be used to fabricate micro/nano materials with multiple functions via modification and process of microorganism. On the one hand, biomass holding a certain quantity of oxygen was chosen as the capping materials for decreasing the nutrient release from the sediment. On the other hand, blue algae from Lake Taihu, algae residue from the green algae after extraction of lipid and green algae were used to fabricate hollow carbon microspheres with mesoporous shell, organic/inorganic composite hollow microcapsules and rattle-type mesoporous microspheres with multiple magnetite nano-particles. Compared with conventional soft-template and hard-template method, our method has many advantages， such as without using templates, simpler procedures and reducing the consumption of harmful chemical agents. Because of algae cell itself is involved as template and reactant in the synthetic process of the hollow microspheres with porous shell. Furthermore, these materials were used to test the capacity of loading oxygen in porous material suspension, the controlled-released effect of oxygen release compound inside the mesosphere carbon microspheres and the effect of bioactive substance auto-loading and unloading in the rattle-type mesoporous microspheres with multiple magnetite nano-particles. The main results are as follows: 1) Proposed the rapid method for evaluation the oxygen loading capacity of porous materials suspensions, and active carbon presented the highest oxygen loading capacity; developed the method for direct determination of the oxygen releasing amount in the porous materials suspensions; BET and contact angle are the key factors for determining the oxygen loading capacity of porous materials suspensions. The higher the BET and the content angle, the better the oxygen loading capacity of porous materials suspensions. Most of the oxygen was adsorbed on the active carbon and the absorbing amount of oxygen in active carbon suspension could reach 2 mg/g. The oxygen absorbing amount could be increased 5% after temperature circulation. The oxygen loading to Active carbon can be used to cap the lake sediment and improve the anaerobic conditions of lake sediment. 2) Hollow carbon microspheres with mesoporous shell have been produced by blue algae from Lake Taihu via hydrothermal treatment. The results show that high temperature and long time hydrothermal reaction are not favorable for the formation of microspheres. The BET and pore volume of microspheres could be improved but the structure is loose by pretreatment blue algae with acetone. However, the adding of glutaraldehyde in the hydrothermal reactive process was favorable for the structure strength but could decrease the BET and the pore volume. Therefore,hollow carbon microspheres with proper BET, pore volume and structure could be produced by the combination of pretreatment blue algae with acetone and the adding of glutaraldehyde in the hydrothermal reactive process. The oxygen controlled-released microspheres were fabricated through loading CaO2 inside the hollow carbon microspheres. Compared with the CaO2, the CaO2 loading to the hollow carbon microspheres could prolong the DO releasing time, avoid the rapid increase in pH and reduce the phosphate concentration in water. 3) Dichloromethane/methanol was chosen as the effective extractant to extract the algae lipid by comparing the extraction efficiency of algae lipid in different organic extractant. The highest extraction rate (15.1%) was obtained without break the cell wall by optimizing the extraction time (12 h), solid/liquid ratio (1:20) and extraction temperature. The hydroxyapatite/biopolymer composition hollow microcapsules were produced by hydrothermal treatment of algae residue with hot 6% NaOH and 1% SDS solution. 4) A novel method was developed to prepare rattle type microspheres with multiple magnetite nano-cores and porous shell. By controlling the hydrothermal synthetic conditions, the cell wall of the Chlorella pyrenoidosa formed the porous biopolymer shell, and the iron precursor (FeIII) was partly reduced and turned into magnetite nanoparticles inside the porous shell with the assistance of Chlorella pyrenoidosa. This method not only simplifies the fabricating steps and supersedes harmful chemical reagents, but also endows the microspheres with a uniform size (~2.5 μm),porous shell (~15 nm), multiple magnetite nano-cores (~25 nm) and high void volume ratio (>70%). The product presents fast magnetic separation and redispersibility as well as pH-switched protein auto-loading (high capacity >600mg/g) and unloading as high performance delivery vehicles. The microspheres may have potential applications including encapsulation of active ingredients, magnetic separation of biological molecules and magnetic drug target delivery. |
| 公开日期 | 2015-06-12 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13455]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 毕磊. 利用生物质制备微纳结构介孔材料及其对活性物质的装载与控释[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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