The emergence of multifunctional adsorbents and their role in environmental remediation

Abstract

Water pollution is a growing issue which requires various treatment technologies for efficient and effective remediation. Adsorption is one of the dominant wastewater treatment technologies due to its flexible operation and cost effectiveness. Recently, a new class of adsorbents with multiple functionalities has appeared. They are capable of removing various pollutants, and they possess additional functions such as photocatalytic and antibacterial properties. These new types of advanced materials could significantly enhance treatment efficiency and potentially reduce the footprint of wastewater treatment plants. This review presents a detailed discussion of the studies of multifunctional adsorbents, covering the modification and functionalization to incorporate multifunctional properties on the adsorbents and exploring the interplay between various groups of pollutants and adsorbents that affect the pollutants removal efficiency. The multifunctional adsorbents discussed are in four classes: carbon-based, carbon nanomaterial-based, polymer-based, and inorganic-based. Additional functionalities, especially antibacterial and photocatalytic properties, are generally incorporated onto the adsorbents to provide mutual and superimposed benefits that could be advantageous for subsequent treatment processes. Though the performance of multifunctional adsorbents is quite promising, the lack of an in-depth techno-economic feasibility study has hindered upscaling application studies. Future studies in this aspect should clarify the uncertainties and fully materialize the benefits of multifunctional adsorbents in wastewater treatment.