Recent advances on elemental biosorption

Industrial activities play a relevant role in environmental pollution since their wastes contain high concentrations of toxic elements that can add significant contamination to natural water and other water sources if no decontamination is previously applied. As toxic metals and metalloids are not biodegradable and tend to accumulate in living organisms, it is necessary to treat the contaminated industrial wastewaters prior to their discharge into the water bodies. There are different remediation techniques that have been developed to solve elemental pollution, but biosorption has arisen as a promising cleanup and low-cost biotechnology. Biosorption is governed by a variety of mechanisms including chemical binding, ion exchange, physisorption, precipitation, and oxide reduction. This review presents applications of biosorbents for metals and metalloids removal. Biomaterials including bacteria, fungi, algae, plant derivatives, agricultural wastes, and chitin-chitosan-based materials are considered. Also, bio-nano-hybrid materials, which have superlative sorption properties due to their high surface area coming from the nanomaterials structures and multifunctional capacity incorporated from the several types of chemical groups of biomaterials, are discussed. High metal removal percentages as high as 70-100% can be found in most works reported in the literature, which demonstrates the excellent performance obtained with biosorbents. These, as well as other important aspects linked to biosorption, are fully covered in the present review.