A review on renewable biosorbents for the removal of pollutants by the adsorption process

This article reviews various researches in the field of eco-friendly and cost-effective renewable biosorbents, modification of their surface properties, adsorption operating conditions, adsorption isothermal and maximum adsorption capacity of these adsorbents. Is. Among the renewable biosorbents, green adsorbents can better achieve the goal of the circular economy of the future, where there will be no waste. Among the examined renewable biosorbents, the adsorbents obtained from agricultural wastes are the best adsorbents due to their high adsorption capacity due to the presence of abundant carboxyl and hydroxyl groups on the surface of their pores, easy access, non-toxicity and low price. Modification of biosorbents by using minerals and organic acids leads to an increase in the number of active sites in the adsorbent, which increases their adsorption capacity. Some methods of modifying the properties to increase the absorption capacity of the combination of green adsorbents with other adsorbents, modification with acidic compounds, inoculation of different functional groups on the surface of the adsorbent, and the combination of mineral and metal adsorbents with natural and synthetic polymers have been used in order to increase the adsorption capacity. By chemically modifying green adsorbents and creating cross-links, the properties of these adsorbents and their adsorption capacity and selectivity can be improved. The isothermal model of Langmuir and Freundlich has shown a better agreement with the adsorption equilibrium data in renewable biosorbents. The optimal value of the ratio of adsorbent to pollutant can have the best result in removal.