Mónica Calero de Hoces

Biosorption of Cu2+ in a packed bed column by almond shell: optimization of process variables

Abstract This paper presents the ability of a low-cost biosorbent, almond shell, to remove Cu(II) ions from aqueous solution. Biosorption capacity of almond shell to removal Cu(II) was studied in a packed bed column. The effect of various parameters, flow rate, initial copper concentration, and mass of biosorbent, was analyzed. A 23 factorial experiment design was carried out to optimize some of the factors directly affecting the biosorption of copper onto almond shell. The results have shown that initial concentration of Cu(II) is the most influential factors in biosorption capacity, while the most important factors in total copper removal are the flow rate and mass of biosorbent. The biosorption capacity of almond shell presented a maximum when the operational conditions are: flow rate, 6 mL/min; initial copper concentration, 100 mg/L; and mass of almond shell, 5 g; while the parameters which give the maximum value of % removal of Cu(II) are: flow rate, 2 mL/min; initial copper concentration, 40 mg/L; a...

Assessment of the removal mechanism of hexavalent chromium from aqueous solutions by olive stone

The objectives of this study were to study the removal mechanism of Cr(VI) by natural olive stone (OS) and to present a sequential-batch process for the removal of total chromium (original Cr(VI) and Cr(III) derived from reduction of Cr(VI) during biosorption at acidic conditions). First, experiments were conducted varying pH from 1 to 4, and showed that a combined effect of biosorption and reduction is involved in the Cr(VI) removal. Then, X-ray photoelectron spectroscopy and desorption tests were employed to verify the oxidation state of the chromium bound to OS and to elucidate the removal mechanism of Cr(VI) by this material. The goal of these tests was to confirm that Cr(III) is the species mainly absorbed by OS. Finally, the possibility of total chromium removal by biosorption in a sequential-batch process was analyzed. In the first stage, 96.38% of Cr(VI) is removed by OS and reduced to Cr(III). In the second stage, approximately 31% of the total Cr concentration was removed. However, the Cr(III) released in the first stage is not completely removed, and it could suggest that the Cr(III) could be in a hydrated compound or a complex, which could be more difficult to remove under these conditions.