Revisión bibliográfica de estudios realizados en Colombia y Latinoamérica, relacionados con la adsorción de cromo hexavalente y mercurio en disoluciones acuosas y muestras reales, empleando adsorbentes naturales e isotermas de adsorción

Abstract

Bioadsorption is a technique that allows the capture of metal ions, thanks to the living or dead biomass that allows the accumulation of pollutants such as heavy metals present in effluents, soils and air (Tovar et al., 2015). Heavy metals are chemical elements with a density greater than 7g / cm3 (INHEM, 1992), which have an impact on the environment due to their high toxicity and complex elimination, since living organisms and ecosystems tend to accumulate in tissues at very low concentrations (<2 g) (INHEM, 1992; Netzahuatl, Muñoz et. al, 2010). As established by Resolution 0631 of 2015, where the range of heavy metal in discharges made to public sewers or surface waters should be 0.001 to 3.0 mg / L (Article 20, Ministry of Environment and Sustainable Development); These are: Lead, Mercury, Hexavalent Chromium and Cadmium (Beltrán P. and Gómez R, 2016). Waste of natural origin plays an important role in the remediation of contaminated effluents (Vendruscolo et al., 2016). Avocado, yucca, orange, lemon, rice, pineapple, pine bark, sawdust, palm bagasse, cocoa husk, among others (Sala and García, 2010) are natural removal materials with a low cost for the treatment of heavy metals, thanks to variations in their cellular composition, which can be composed of amino, hydroxyl, carboxyl, sulfate, polysaccharide groups (such as starch, glycosides, among others), and / or biopolymers such as lignin, hemicellulose and cellulose. These functional groups allow the metal to adhere to the cell wall and then accumulate inside it, facilitating the extraction of these types of contaminants. In this work, the removal capacity of the different types of natural biomass to eliminate Mercury (II) and Chromium (VI) in aqueous solutions will be investigated, taking into account experiments carried out in Colombia and Latin America during the last ten years, where it is shown the experimental parameters that affect the adsorption process, such as pH, dosage and initial concentration of the metal, temperature, removal time, particle size of the bioadsorbent and contact time. Later, the use of Freundlich and Langmuir mathematical models will be observed to demonstrate the adsorption capacity of biomass in removal percentages.