Chitin and Chitosan for Water Purification

The interest in developing new and more efficient materials and technologies for the removal of different pollutants from wastewater is constantly growing. To this end, chitin and chitosan have attracted the attention of many researchers because of their interesting removal capacities for certain hazardous pollutants such as water-soluble organics (phenols, dyes, pesticides, herbicides, etc.) and heavy metal ions. Moreover, these biocompatible and biodegradable carbohydrate polymers fall in the category of low-cost sorbents that are abundant and renewable resources. Nevertheless, the limited solubility of chitin and the high sensitivity to pH of chitosan generate some feasibility issues. In this respect, many studies suggest the chemical modification of chitin and chitosan, in order to develop derivatives and composites with improved properties for water purification purposes. In this chapter, chitin and chitosan, together with their derivatives and composites, are reviewed from the perspective of water purification applications, underlining their advantages for the removal of representative organic pollutants and heavy metals from aqueous solutions. Likewise, the principles and mechanisms governing the purification processes such as adsorption, coagulation/flocculation and ultrafiltration are detailed.