bioadsorbenti

Bioadsorbenti, or biosorbents, are natural or biologically derived materials capable of removing contaminants from liquids or gases by adsorption. They typically rely on functional groups and porous structures present in biomass to bind pollutants such as heavy metals, dyes, or organics. Biosorption can involve living microorganisms, dead biomass, or biopolymers derived from biological sources.

Sources include agricultural by-products (rice husk, sawdust, banana peels), macro- and microalgae, fungi and yeasts, and biopolymers such as chitosan, cellulose, and lignin. These materials are abundant, often inexpensive, and can be regenerated or reused after desorption in some cases.

Mechanisms include ion exchange, complexation, chelation, hydrogen bonding, electrostatic attraction, and physical adsorption. Dead or inactivated biomass is commonly used to prevent metabolic limitations, while living cells may contribute uptake through metabolism in some systems. The performance depends on pH, ionic strength, temperature, and contact time.

Applications span wastewater treatment, including removal of heavy metals (lead, cadmium, copper), dyes, and radionuclides. Biosorption is frequently evaluated with equilibrium isotherms (Langmuir, Freundlich) and kinetic models (pseudo-second-order). Column studies simulate real-scale treatment. Regeneration and reuse of biosorbents, and proper disposal of spent materials, influence overall sustainability.

Limitations include variability in biomass composition, lower and batch-dependent capacity, and competition from other ions. Ongoing research aims to improve selectivity, develop standardized preparation methods, and integrate biosorbents with conventional treatment to reduce costs and environmental impact.