A Review on the Application of Agri-Food Residues as Biosorbents of Heavy Metal Ions

Surface water contamination is widespread worldwide, including contamination caused by heavy metal cations. These pollutants originate from large volumes of effluents from various industries, agriculture, and municipal sources. Therefore, in recent years, it has become necessary to search for innovative, cheap and efficient techniques to remove these pollutants. This review presents adsorption as the most promising compared with alternatives, such as membrane filtration and electrochemical oxidation. It lists examples of the use of agri-food industry wastes and their chemical, biological and thermal modifications, along with their performance against individual metal ions in aqueous solutions. In addition, various techniques necessary to test the sorption potential of adsorbents are described. Based on the literature, it can be seen that adsorption using plant waste materials is a simple and cost-effective technique that is also in line with the principles of a closed-loop system.