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Removal of Arsenic and Heavy Metals from Contaminated Water with Emerging Sorbents

Abstract:

The current research arose due to an oil spill in the Papallacta Sub-basin, in the Amazonian area of Ecuador. Hereby, we were based to implement a baseline of the corresponding waters and sediments by searching an effective and low-cost treatment for the removal of arsenic and heavy metals from the lagoon water matrix. First steps included the synthesis of the hybrid sorbent (double lamellar hydroxides-metal oxides) for the selective removal of arsenical species, removal tests of As and heavy metals from the water matrix using the synthesized hybrid sorbent. Subsequently, the material was calcined and resulted in a material with metal oxides, then these were conditioned with ferric chloride to bind the hydrated iron oxides. In the synthesis of the hybrid sorbent, technical grade and reactive grade reagents were used to reduce the manufacturing costs of hybrid sorbents and four types of sorbents were obtained. The results indicated that the removal of arsenic and heavy metals can be attributed to inner sphere complexes by coulombic reactions and Lewis acid base. Balance tests were conducted applying the Langmuir and Freundlich models, being the Freundlich model the one that presented the best results. The data from the kinetic tests are adjusted to first-order kinetics and a half-life of 60 min. The intraparticle diffusion gives a value of 1.0 × 10–9 cm2/s, which indicates that it is a fast kinetics. Both reactive and technical grade sorbents performed well in reducing arsenic and heavy metals in synthetic water.