Toxic Heavy Metals Elimination from Contaminated Effluents Utilizing Various Adsorbents: Critical Mini-Review

Abstract

The release of massive pollutants amounts continuously because of urbanization and industrialization has caused a big ecological problem worldwide. Due to their activities, effluents of many industries: mining operations, paper/pulp, and batteries, release different heavy metals, including Copper (Cu), Lead (Pb), and Nickel (Ni), into the environment. Heavy metals are of big concern due to their high toxicity, big bioaccumulation susceptibility, and serious threat to humans and ecosystems. Compared to organic pollutants, which are highly influenced by biological and chemical degradation, heavy metals have no degradation into end products using these methods. Therefore, the removal of such metals is considered a big challenge in water purification. For metals removal, different techniques have been applied, such as precipitation, ultrafiltration, and coagulation. However, those applications have many drawbacks: low-efficiency, high consumption of reagents, and generation of toxic sludge. In contrast, adsorption considers an effective method for metal removal, owing to the method’s simplicity, economic and versatility, making it the most convenient way for toxic metals removal. Many conventional adsorbents, such as activated carbon and alumina, have been effectively employed. Nevertheless, the biggest disadvantages of using such adsorbents appear to be their price due to high activation costs and limited reusability. Biosorption has lately emerged as a method with several advantages, including minimal cost, ease of use, and great efficacy, even for trace amounts of metallic ions. This paper aims to review the relevant literature regarding the adsorption method for heavy metals removal from wastewater. Different treatments of heavy metals from wastewater and their related features are highlighted. The metals’ toxicity and hazards to health and the environment are also discussed. The application of various materials as bioadsorbents is explored, such as natural adsorbents and industrial and agricultural wastes.