Biosorption of Arsenic(III) from Aqueous Solutions by Modified Fungal Biomass of Paecilomyces sp.

The biosorption of As(III) on iron-coated fungal biomass of Paecilomyces sp. was studied in this work. It was found that the biomass was very efficient removing the metal in solution, using Atomic Absorption, reaching the next percentage of removals: 64.5%. The highest adsorption was obtained at pH 6.0, at 30°C after 24 hours of incubation, with 1？mg/L of modified fungal biomass. 1. Introduction Arsenic, a common element in nature, is a naturally occurring contaminant of drinking water and can be found in the earth’s crust, ground, and marine water and in the organic world as well. It is mobilized through a combination of natural processes such as weathering reactions, biological activity, and volcanic emissions [1, 2] as well as through a range of anthropogenic activities such as gold mining, nonferrous smelting, petroleum refining, combustion of fossil fuel in power plants, and the use of arsenical pesticides and herbicides [3, 4]. Contaminated groundwater by arsenic is a well-known environmental problem that can have severe human health implications. Chronic exposure to arsenic concentrations above 100？ppb can cause vascular disorders, such as dermal pigments (Blackfoot disease) and skin, liver, and lung cancer [5, 6]. An arsenic concentration of 10？μg/L has been recommended by World Health Organization as a guideline value for drinking water [7]. Arsenic is found in soils and natural waters, mainly, in the form of arsenate [As(V)] and arsenite [As(III)]. The distribution between dissolved As(III) and As(V) is dependent on redox potential and pH. Under oxidizing conditions, the predominant specie is As(V), which exists as deprotonated oxyanions of arsenic acid ( , , and ). Under reducing conditions, As(III) is thermodynamically stable and exists in solution as arsenious acid, a neutral, uncharged molecule ( ) that only forms deprotonated oxyanions at pH > 9.2 ( and ) [8]. The As(III) species are more toxic than As(V). At the pH of most natural soils and water, As(III) is not strongly adsorbed on most mineral surfaces because is electrically neutral compared with the negatively charged of As(V) oxyanions [9]. Iron oxide-coated sand was used in many studies for arsenic removal, and the results were positives [10], and with modified [iron(III) loaded] orange juice industrial residue, [11], with Penicillium purpurogenum [12], enhancement in arsenate removal by chemically (polyelectrolyte, dodecylamine, and cetyltrimethylammonium bromide) modified Penicillium chrysogenum compared with the unmodified biomass [13], the biovolatilization of As by Aspergillus