Abstract

PITALUA-SANCHEZ, D. et al. Precipitation of Ag, Hg and Cr for recycling derived from hazardous liquid wastes. RIIIT. Rev. int. investig. innov. tecnol. [online]. 2019, vol.7, n.40, pp.19-35.  Epub Feb 05, 2021. ISSN 2007-9753.

Lab tests generate a large amount of waste, including Ag, Hg and Cr, which are the heavy metals from the determination of the Chemical Oxygen Demand (COD). The liquid waste generated by this parameter shows a high initial concentration of 1133 mg/L of Ag, 2252 mg/L of Hg and 950 mg/L of Cr, exceeding what the Official Mexican Standard NOM-002-SEMARNAT-1996 establishes.

In this paper, a physicochemical procedure was optimized and applied to reduce the concentration of the heavy metals through laboratory experiments and the evaluation of the operating conditions (temperature, contact time and reagent concentration) using a factorial design 23.

The results of the developed technique showed a satisfactory performance obtaining removal efficiencies of 99.99 % for Ag, 99.99 % for Hg and 99.96 % for Cr; the final concentration (0.1 mg/L for Ag, 0.001 mg/L for Hg and 0.36 mg/L for Cr) is below the limits of the Mexican standard. Due to the high removal efficiencies, this technique is adequate and simple to reduce the metals of the COD waste.

Keywords : chromium; COD; hazardous liquid waste; mercury; silver.