Abstract
In recent years, the extraction of gold has become important for the development of nations. However, mining wastewater represents an environmental problem due to its high content of free cyanide-based compounds and weak and strong cyanocomplexes for the use of sodium cyanide to obtain gold from minerals. The experimental data presented show the performance of the elimination of one of the strongest cyanocomplex that can appear in mining wastewater ([Co(CN)6]3−)([Co(CN)6]3-)<math><mrow><mo>(</mo> <msup> <mrow><mrow><mo>[</mo> <mrow><mtext>Co</mtext> <msub> <mrow><mrow><mo>(</mo> <mtext>CN</mtext> <mo>)</mo></mrow> </mrow> <mn>6</mn></msub> </mrow> <mo>]</mo></mrow> </mrow> <mrow><mn>3</mn> <mo>-</mo></mrow> </msup> <mo>)</mo></mrow> </math> by the ultraviolet C activation of persulfate (PS). The removal of total cobalt in solution was used as an indicator of the elimination of the cobalt cyanocomplexes that appear as transformation products from the degradation of [Co(CN)6]3−[Co(CN)6]3-<math> <mrow> <msup> <mrow><mrow><mo>[</mo> <mrow><mtext>Co</mtext> <msub> <mrow><mrow><mo>(</mo> <mtext>CN</mtext> <mo>)</mo></mrow> </mrow> <mn>6</mn></msub> </mrow> <mo>]</mo></mrow> </mrow> <mrow><mn>3</mn> <mo>-</mo></mrow> </msup> </mrow> </math> . The data evidence that strong cyanocomplexes can be eliminated from mining wastewater. The experimental runs were divided into two parts: as a first step, the influence of the UVC light was elucidated. Afterward, five initial concentrations of persulfate ion (0.1, 0.3, 0.5, 0.7 and 0.9 g/L of PS), two pH values (11 and 13) and two additional initial concentrations of contaminant (25 mg/L and 75 mg/L of [Co(CN)6]3−[Co(CN)6]3-<math> <mrow> <msup> <mrow><mrow><mo>[</mo> <mrow><mtext>Co</mtext> <msub> <mrow><mrow><mo>(</mo> <mtext>CN</mtext> <mo>)</mo></mrow> </mrow> <mn>6</mn></msub> </mrow> <mo>]</mo></mrow> </mrow> <mrow><mn>3</mn> <mo>-</mo></mrow> </msup> </mrow> </math> ) were examined to find the optimal parameter where the highest Co removal is obtained.