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IDENTIFICATION ARSENIC (V) BY CYCLIC VOLTAMMETRY AND RECOVERY OF ARSENIC BY ELECTRODEPOSITION.

IWRA World Water Congress 2017 - Cancun Mexico
1. Water, sanitation and health
Author(s): Haydeana Isabel Navarro Solis
Aline del Carmen Gonzalez Canchola
Genoveva Rosano Ortega
Sofia Esperanza Garrido Hoyos
Pedro Avila Pérez

Haydeana Isabel Navarro Solis
Universidad Popular Autonoma de Puebla
haydeanaisabel.navarro@upaep.mx
Aline del Carmen Gonzalez Canchola
Universidad Popular Autonoma de Puebla
alinedelcarmen.gonzalez@upaep.edu.mx
Genoveva Rosano Ortega
Universidad Popular Autonoma de Puebla
genoveva.rosano@upaep.mx
Sofia Esperanza Garrido Hoyos
Instituto Mexicano de Tecnología del agua
sgarrido@tlaloc.imta.mx
Pedro Avila Pérez
Instituto Nacional de Investigaciones Nucleares
pedro.avila@inin.gob.mx


Keyword(s): cyclic voltammetry, electrodeposition, waste water
Article: Poster:

Abstract

In this research the identification and recovery of As present in the waters of rejection from reverse and deionization osmosis by cyclic voltammetry and electrodeposition is proposed, which have advantages over traditional techniques, such as low cost and recovery for new processes creating a safe and sustainable management of As. Arsenic contamination is a global problem. Prolonged exposure through contaminated water and food consumption can cause serious health damage or death. WHO recommends 0.010 mg L-1 (10 μgL-1) maximum limit As for drinking water. The presence of arsenic in natural waters is usually associated with natural and anthropogenic sources. In response to the problems mentioned, the need arises to monitor the concentration of arsenic in contaminated water, by techniques of high sensitivity at low concentrations arises.

There are different technologies to remove arsenic as reverse osmosis and capacitive deionization, however these processes generates waste water with high concentrations of As, 0.76 to 10 mg L -1, commonly called water rejection thereof having as final disposal environment.
The voltammetric methods for the quantification of arsenic are a viable option since they have high sensitivity, selectivity and low cost. The voltammetric method of chemical analysis is based on the interpretation of the current intensity curves - potential (I vs. E), generated from the electro oxidation or electro reduction of species in solution.

For detection of arsenic a conventional cell, a reference electrode (RE), of Ag0/ AgCl, a working electrode (WE) of platinum and an auxiliary electrode graphite (EC) in a potential range from +800 to -500 mV at a scan rate of 100 mV s-1of  were used. Calibration curves for As (III and V) with a R2 of 0.95 were performed with concentrations of 100 to 1 mg L-1 for As (V) the pH was adjusted to 2 with HCl and was used as background electrolyte 0.001 M KCl and 0.01 M KI which reduces the as (V), for As (III) it was used as background electrolyte with 0.01 M NaSO4 and 0.0001 M CuSO4, pH 5. The electrodeposition was conducted in water with synthetic concentrations of 1, 3, and 5 mg L-1 of As, pH 2.5 to 1.5 V in periods of 30 to 120 minutes using electrodes of copper and iron. In both methods the oxygen is displaced from solution by high purity nitrogen 99.9%.
For both cases the magnitude of the anodic peak is proportional to the concentration of As in solution, which is oxidized and reduced. Electrodeposition is feasible in acid and efficiency observed oscillates around 60%.

 

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