Details of hydroxide ion utilization in the treatment of contaminated effluents with zinc

Details of hydroxide ion utilization in the treatment of contaminated effluents with zinc. This work analyzed the treatment of effluent produced by an Atomic Absorption Spectrometer (AAS) containing the heavy metal zinc, utilizing the capacity of Zn2+ to react with hydroxide ion (HO-), forming Zn(OH)(2(ppt)). The content was treated theoretically and experimentally. Theoretically, the thermodynamic parameters were assessed and the solubility of Zn(OH)(2(ppt)) with pH variation was analyzed mathematically. Experimentally, the study analyzed the behavior of the Zn(OH)(2(ppt)) aqueous solution and in nanny solution of discarded effluent with the medium pH. The values of zinc concentration in the different situations were measured using AAS, flame modality, with detection limit (DL) 0.030 mg L-1. The results in the different situations of solution and medium pH for the minimum solubility of Zn(OH)(2(ppt)), in mg L-1, were: theoretical value = 2.3; experimental value for the Zn(OH)(2(ppt)) solution = 0.92; in natural effluent = 0.092, respectively. These values are in compliance with BRAZIL-Conama Resolution number 397/2008.