Determinación de la concentración de Pb(II) a través de voltametría, por incidencia del vertimiento de una mina de carbón sobre la quebrada El Alisal, ubicada en el Páramo Guerrero (Cogua, Cundinamarca)

Abstract

In this work, Pb(II) was determined in eight water samples from acid drainages. They were taken at four points between El Alisal stream and the "San José" coal mine, located in the Guerrero moor - Cogua, Cundinamarca, through square wave- anodic stripping voltammetry. The cell configuration consisted of a 0.1 M acetate buffer electrolyte (pH 4.5) and three low-cost electrodes: pencil lead graphite electrode modified with bismuth as work electrode (WE), 3M Ag/AgCl as a reference electrode (RE) and platinum wire as an auxiliary electrode (AE). The parameters of the technique used were: Deposition from -1.4 to 0.0 V for 3 minutes in constant agitation, quiet time of 10 s and square wave swept with initial potential: -1.4 V, final potential: 0.0 V, pulse size: 40 mV, step size: 13 mV, frequency: 50 Hz and electrode area of 0.0314 cm2. The determination of the concentration was made through the standard addition method, adding 10 μg/L to 50 μg/L of lead (II) from a standard solution of 100mg⁄(L ). The voltammetric technique used presented voltammograms with high coefficients of determination, finding on average lead concentrations of 10.36 μg⁄(L )on the pipe that draws water inside of the coal mine, 4.64 μg⁄(L )in the water outlet of the treatment system, 0.0 μg⁄(L ) upstream of El Alisal stream and 1.53 μg⁄(L ) downstream the point of confluence between the water discharge and the stream, determining that the coal mine fulfills the maximum permissible concentration of lead (II) in the punctual discharges of coal and lignite mining over surface water bodies, stipulated in resolution 631 of 2015.