热带亚热带农产品加工余渣的高值化改性、表征及机理研究

As the typical tropical and subtropical farm products, pineapple and tea produce large amount of residue when being processed into various forms of products. This project proposal is planned to carry out the research on the modification and characterization of cellulose and hemicellulose in the residue of the processed tea and pineapple products via chemical and physical methodology so as to obtain theoretical support for the high-value utilization of tea and pineapple residue. The work is arranged as three aspects: Firstly, the chemical modification of tea and pineapple fibers is to carry out to prepare metal adsorbents. The fibers are modified with succinic anhydride in different solvents and then the adsorption behavior and dynamics of the modified fibers are studied. Secondly, physical modification of tea and pineapple fibers is to carry out by means of puffing, flash evaporation and high pressure treatment, and then the study on the adsorption behavior and dynamics of the modified fibers. Thirdly, research on the preparation of hydrogel from the modifed tea and pineapple peel fibers with ionic liquids, including, the preparation, adsorption and sustained-release kinetics of the prepared hydrogels. .This project is proposed based on scientific and technological innovation. The aim is to utilize effectively the residue and by-products of the tropical and subtropical farm products to prevent, control and manage environmental pollution. So, this project is of multiple significance in environmental pollution control and further processing of farm products.

菠萝及茶叶是我国典型的热带和亚热带农产品，其深加工形式丰富，并且在深加工过程中产生大量余渣。本项目拟对其余渣纤维素及半纤维素进行改性、表征及机理方面的研究，为高值化利用获得理论支撑。一：研究菠萝皮渣和茶渣纤维半纤维的化学改性以制备金属吸附剂。通过在不同的溶剂中，菠萝皮渣和茶渣纤维半纤维与琥珀酸酐改性反应，研究其对不同金属离子和染料色素吸附行为、动力学；二：研究菠萝皮渣和茶渣纤维半纤维的物理改性或物理化学改性。以膨化、超高压处理手段或高压蒸汽闪爆处理后再醚化和胺化，制备金属离子和染料色素吸附剂，研究其吸附行为和动力学；三：研究在离子液体中制备菠萝皮渣和茶渣纤维水凝胶，分析和表征其对药物的吸附与缓释动力学，多种添加物的影响及其药物缓释效应。.本项目立足于科技创新，将容易造成污染的热带亚热带农产品加工余渣高值化改性，用于治理环境污染；对解决农产品深加工的问题，引导现代农产品深加工发展具有多重意义

项目由原计划4年调整为一年。主要对菠萝、茶叶、荸荠等热带亚热带农产品加工余渣进行高值化改性、表征及机理研究，为研究新型纤维素水凝胶、金属和染料吸附剂提供理论支撑。工作包括3个方面：.1：菠萝皮渣作为金属离子吸附剂的改性、表征及机理研究：将菠萝皮渣纤维素分别在在吡啶和二甲基亚砜试剂中与琥珀酸酐化学改性，得到多种菠萝皮渣纤维改性产物：MPPF-PY、MPPF-DMRT、MPPF-DM70； MPPC-PY、MPPC-DMRT、MPPC-DM70。对改性产物进行傅立叶红外光谱（FTIR）和X射线衍射（XRD）表征，然后研究了MPPF-DM70、MPPC-DM70对Cu2+、Cd2+ 和 Pb2+ 重金属离子的吸附行为并利用FTIR分析其吸附机理。发现（1）：溶剂二甲基亚砜比吡啶更有利于将羧基官能团引入菠萝皮渣纤维素，同时证明羧基参与改性分子的吸附功能。（2）：FTIR和XRD分析发现：在吡啶溶剂中菠萝皮纤维素与琥珀酸酐的改性反应发生于纤维外层的非晶区，而二甲基亚砜溶剂更容易使菠萝皮纤维素与琥珀酸酐在结构内发生改性反应。（3）：菠萝皮渣改性后具有更高的Cu2+、Cd2+ 和Pb2+ 吸附容量。MPPF-DM70、MPPC-DM70对Cu2+、Cd2+ 和Pb2+ 的吸附容量分别在pH5.5、7.5和5.5时最大。（4）：二级动力学分析表明改性菠萝皮渣纤维素对Cu2+、Cd2+ 和Pb2+ 的吸附遵循Pseudo 模型。.2：用离子液体AMIMCl溶解菠萝皮渣纤维素制备出菠萝皮渣纤维素水凝胶，研究水凝胶的润胀动力学和对药物的缓释过程，并研究聚乙二醇、聚乙烯醇、卡拉胶、水溶性淀粉对水凝胶质构的影响。发现（1）：菠萝皮渣纤维素水凝胶的硬度、黏性以及回复性随着纤维素含量的增加而显著提高。冻融循环能够提高水凝胶的质构和机械特性；聚乙烯醇可以降低水凝胶的硬度和黏性；卡拉胶的添加可以提高水凝胶的硬度；而水溶性淀粉可以显著降低水凝胶的硬度和黏性。（2）：载药率和缓释动力学研究表明，冷冻干燥、聚乙二醇、聚乙烯醇、卡拉胶、水溶性淀粉可以提高水凝胶载药率。水凝胶的药物缓释分快速释放和缓慢释放阶段，释放率达99%。.3：茶渣和荸荠皮渣纤维的醚化和季胺化改性显著提高对三种工业染料、Cu2+、Pb2+和Cd2+的吸附效果。吸附符合假二级动力学模型及Langmuir和Freundlich等温模型.