Advances in microalgae and their derivative composite for heavy metal adsorption

Heavy metals are harmful and non-decomposable pollutants from industrial activities that remain in the environment for an extended period, endangering life within the ecosystem. The need for affordable and effective strategies to manage heavy metal pollution is a constant requirement. Adsorption is a popular choice because of its versatility, affordability, and effective results. Heavy metals have been removed using a variety of materials over the years, with varying degrees of success. The number of adsorbent materials is affected by the nature and varieties of functional groups, surface area, microporosity, and stability. Microalgae serve as promise resource for adsorbing heavy metals due to their simple production process, diverse and plentiful negatively charged functional groups, and extensive specific surface area. Nevertheless, utilizing microalgae comes with several disadvantages, such as the inconsistency in microalgae species that exhibit different physical structures and biomass properties. The low density of microalgae can also result in the creation of secondary pollutants. In addition, microalgae exhibit weak chemical resistance and mechanical strength. To address some of these challenges, a number of techniques has been developed including microalgae biochar, microalgae biochar composite, microalga-bacterial consortium, and a host of others.