Chitosan and chitosan-based nanomaterials in decontamination of pharmaceutical waste

Clean water is constantly demanded and should be accessible to all living organisms and human. However, water resources are threatened by toxic, mutagenic, and carcinogenic pollutants originating from various sources such as wastewaters from manufacturing industries, agriculture, municipal activities, and hospitals. The existing wastewater treatment systems are unable to completely eliminate certain types of pollutants, such as synthetic dyes and pharmaceutical compounds. As a result, these accumulated contaminants escape into water resources, posing risks to the environment, aquatic ecosystems, wildlife, and human health. Pharmaceutical compounds, commonly used in medications and health treatments, are now recognized as emerging environmental contaminants due to their presence in wastewater and water systems. Among the various methods available, adsorption and photocatalysis have been extensively studied due to their high efficiency, simple implementation, and utilization of environment-friendly materials. In particular, chitosan-based materials have gained significant attention as potential adsorbents and photocatalysts due to their biodegradability, biocompatibility, nontoxicity, and environment-friendly nature. Chitosan-based materials possess multiple functional groups that readily interact with synthetic dyes and pharmaceutical compounds through hydrogen bonding. Additionally, they can be easily modified chemically with photoactive compounds, allowing them to act as catalysts in the photocatalytic degradation of synthetic dyes and pharmaceutical compounds. This chapter aims to describe and discuss the recent advancements and applications of chitosan-based materials as adsorbents and photocatalysts in wastewater remediation. It covers the adsorption kinetics and isotherms, as well as the proposed adsorption mechanism of pharmaceutical compounds on chitosan-based materials. Furthermore, the chapter explores the photocatalytic degradation of pharmaceutical compounds in the presence of chitosan-support organic photoredox, such as Rose Bengal– or Eosin Y–conjugated chitosan. Finally, it addresses the research challenges that lie ahead in utilizing chitosan-based materials for the removal of emerging contaminants from wastewater.