ABSTRACT

Industries produce large amounts of heavy metal waste that are hazardous to the environment. Thus, heavy metal ions such as nickel (II), lead (II), copper (II), cadmium (II), and zinc (II), must be removed from wastewater. One commonly employed method is biosorption, which is the adsorption of metal ions by biomaterials such as polysaccharides. In this review, polysaccharides are classified into four groups: polysaccharide homopolymers, polysaccharide blends, copolymers, and polysaccharide composites. Pristine natural polysaccharides like chitin, chitosan, cellulose, starch, and alginate which have multiple functional groups. Additional functionalization is introduced in the form of blending, grafting, or mixing with various nanomaterials having additional functional group to make it more efficient for heavy metal ion adsorption. Introduction of second component onto the main polymer chain not only introduce functionality but enhance mechanical strength which is one of the vital requirements for the recyclability of adsorbent. Longer the time adsorbent is reused more economical is the removal process of metal ions from wastewater. Heavy metal ions undergo various types of interaction like π-π interactions, dipole–dipole interaction, hydrogen bonding or van der walls force with homopolymer, copolymers, blends, or nanocomposite having anions or electron-rich group. Adsorption process is studied by adsorption kinetics and adsorption isotherms. This review represents the adsorption behavior of chitosan, cellulose, starch, alginate, and their derivatives.

摘要

工业产生大量对环境有害的重金属废物。因此，必须从废水中去除重金属离子，例如镍（II），铅（II），铜（II），镉（II）和锌（II）。一种常用的方法是生物吸附，这是生物材料（例如多糖）吸附金属离子的方法。在这篇综述中，多糖分为四类：多糖均聚物，多糖共混物，共聚物和多糖复合物。天然天然多糖，如几丁质，壳聚糖，纤维素，淀粉和藻酸盐，具有多个官能团。以与具有附加官能团的各种纳米材料共混，接枝或混合的形式引入附加的官能化，以使其对重金属离子的吸附更为有效。将第二组分引入到主聚合物链上不仅引入功能性，而且提高了机械强度，这是对吸附剂可循环利用性的重要要求之一。吸附剂的再利用时间越长，从废水中去除金属离子的过程就越经济。重金属离子会与具有阴离子或富电子基团的均聚物，共聚物，共混物或纳米复合材料发生各种类型的相互作用，例如π-π相互作用，偶极-偶极相互作用，氢键或范德华力。通过吸附动力学和吸附等温线研究吸附过程。这篇综述代表了壳聚糖，纤维素，淀粉，藻酸盐及其衍生物的吸附行为。