“Plasti-remediation”: Advances in the potential use of environmental plastics for pollutant removal

Abstract

Plastic wastes are introduced into the environment inevitably and their exposure in the environment causes deterioration in its mechanical and physicochemical properties. This leads to the formation of plastic fragments, which are considered as micro and nano plastics when their size is <5 mm and < 10 nm. In recent years, plastic pollution has been reported in all kinds of environments worldwide and is considered a threat to the health of the ecosystem and humans. Besides, plastics serve as vectors for pollutants as they are capable of adsorbing and accumulating pollutants from seawater. However, this particular ability exposes the tendency of exploiting plastic waste as an adsorbent for removing pollutants from polluted water. Considering the problems caused by plastic waste to ecosystems, this concept is very interesting and attractive as a way to protect the environment by recycling or reusing plastic wastes as novel low-cost adsorbents. Meanwhile, studies have begun to exploit and understand the concept of using plastic waste as an adsorbent to remove diverse pollutants such as heavy and radioactive metals, persistent organic pollutants, dyes and oils from aqueous solutions as well as gases e.g volatile organic compounds (VOCs), carbon dioxide (CO 2 ) and hydrogen (H 2 ). This paper, therefore, provides an overview of studies, highlighting the process of adsorbent preparation, plastic/pollutant interaction mechanisms (including kinetic and isotherm models), and factors influencing the removal rates and desorption of pollutants and reusability of the plastic-based adsorbent. Diverse pollutants such as heavy and radioactive metals, persistent organic pollutants, dyes and oils from aqueous solutions as well as gases e.g volatile organic compounds (VOCs), carbon dioxide (CO 2 ) and hydrogen (H 2 ) have been removed by plastic based adsorbent with the modified ones showing higher removal capacity. Desorption and reusability studies have shown that the plastic-based adsorbent is re-generable and stable for dyes and heavy metals (e.g. Pb 2 + ) with high desorption rate (> 80 %) while for low (< 40 %) for phenathrene. Applying plastic waste is a novel potential way of pollutant removal from the environment and therefore a facile sustainable approach. However, the optimization of the method considering the factors affecting the removal rate as well as characterizing the plastic absorbents before and after pollutant adsorption should be conducted. This will help in understanding the possibility of using this concept for field applications. • Diverse pollutants can be effectively removed by plastics. • Modified plastic waste adsorbent were the best class of adsorbents. • Plastics can be used for effective capturing of gases such as VOCs, CO 2 and H 2 . • Environmental factors generally influence removal rate. • Adsorption kinetics and isotherms models were used for studying removal mechanism.