A critical review on the separation of heavy metal(loid)s from the contaminated water using various agricultural wastes

Novelty statementThis review provides new information and insights on the potential utilization of agriculture-based biosorbents for the removal of contaminants, especially heavy metal(loid)s from toxic water/wastewater, as well as their mechanisms, adsorption efficiency, and regeneration ability. For practical perspective, biosorbent adsorption efficiency was elucidated by using various types of wastewater and economic analysis studies. Wastewater contamination with heavy metal(loids)s has become a worldwide environmental and public health problem due to their toxic and non-degradable nature. Different methods and technologies have been applied for water/wastewater treatment to mitigate heavy metal(loid)-induced toxicity threat to humans. Among various treatment methods, adsorption is considered the most attractive method because of its high ability and efficiency to remove contaminants from wastewater. Agricultural waste-based adsorbents have gained great attention because of high efficiency to heavy metal(loids)s removal from contaminated water. Chemically modified biosorbents can significantly enhance the stability and adsorption ability of the sorbents. The two mathematical models of sorption, Freundlich and Langmuir isotherm models, have mostly been studied. In kinetic modeling, pseudo-second-order model proved better in most of the studies compared to pseudo-first-order model. The ion exchange and electrostatic attraction are the main mechanisms for adsorption of heavy metal(loid)s on biosorbents. The regeneration has allowed various biosorbents to be recycled and reused up to 4-5 time. Most effective eluents used for regeneration are dilute acids. For practical perspective, biosorbent removal efficiency has been elucidated using various types of wastewater and economic analysis studies. Economic analysis of adsorption process using agricultural waste-based biosorbents proved this approach cheaper compared to traditional commercial adsorbents, such as chemically activated carbon. The review also highlights key research gaps to advance the scope and application of waste peels for the remediation of heavy metal(loid)s-contaminated wastewater.

Automated summary

This review provides new information and insights on the utilization of agriculture-based biosorbents for contaminant removal, particularly heavy metal(loids), from water/wastewater. The review discusses the mechanisms, adsorption efficiency, and regeneration ability of biosorbents, as well as their practical application and economic analysis. Biosorbents obtained from agricultural waste have shown high efficiency in removing heavy metal(loids) from contaminated water, and chemically modified biosorbents enhance their stability and adsorption capacity. The study also highlights the main mechanisms of adsorption and the preferred eluents for regeneration. Economic analysis shows that agricultural waste-based biosorbents are a cheaper alternative to traditional commercial adsorbents. The review identifies research gaps for further development and application of waste peels in heavy metal(loids)-contaminated wastewater remediation.