A Critical Review on Abatement of VOCs By Adsorption: Adsorbent Types and Their Characteristics

Volatile organic compounds (VOCs) are considered one of the hazardous air pollutants that are discharged from various anthropogenic and natural sources, which have the potential to cause catastrophic damage to both the health of human beings and the environment. Over the years, many control methodologies have been developed to get rid of the menace of VOCs. Adsorption has emerged as one of the popular control techniques for the treatment of gas streams containing VOCs. The cost-effectiveness on account of low energy consumption and high efficiency are the two major factors that give adsorption an edge over other techniques like oxidation (thermal and catalytic), condensation, absorption, membrane separation, etc. The VOCs abatement by adsorption, in terms of adsorption capacity, relies on the properties of the adsorbent material such as surface area, pore structure, and presence of functional groups. This review paper encompasses a variety of adsorbent materials (carbon-based, oxygen-based, organic polymers, and composite materials) that are used by numerous investigators to treat different types of VOCs. MOF-based composite materials are future adsorbents as an alternative to zeolites and activated carbon, but further research to address the problem of costly treatment steps is the need of the hour. Magnetic composite materials are also emerging adsorbents for the VOCs removal, which have attracted the attention of many researchers. This comprehensive review of adsorbents enables budding researchers to cautiously scrutinize and select the appropriate adsorbent depending on the characteristics of the target VOCs.