Composite of Natural Polymers and Their Adsorbent Properties on the Dyes and Heavy Metal Ions

Natural polymers such as chitosan, chitin, cellulose, alginate, pectin, and lignin produced by renewable organic resources are regarded as greener, sustainable, and eco-friendly materials. On account of their superior structural characteristics, abundant availability, nontoxicity, and ease of modification these naturel polymers are being used in the removal of dyes and heavy metal ions which can be carcinogenic, mutagenic, allergenic and toxic. However, to remove these contaminants, there are still challenges as pure natural polymers suffer from low surface area, low recovery and more solubility in water. Chemical modifications that lead to natural polymer composite formations have attracted much interest since the feauters they posses such as higher surface areas, porosities, reactivities as well as less solubility in water. In other words, natural polymer composites have better adsorption capacities towards dyes and heavy metal ions compared to the pure natural polymers. This review summarizes the appropriate literatures corresponding to the studies which include the applications of natural polymer composites for the removal of dyes and heavy metal ions in the last few years. A series of low cost natural polymer composites have been reviewed for their adsorption performance, adsorption mechanism, reusable feature, and the experimental conditions such as solution pH, contact time, dose amount, temperature.