Avaliação da capacidade de remoção da ureia em água por oxidação com hipobromito

Abstract

Urea is an organic contaminant on ultrapure water production for semiconductors, remove it is hard due to its molecular characteristics of non-volatile, tough oxidation, non-ionic, high soluble and low molecular weight. This paper had been studied the dissolved urea oxidation by hypobromite, formed in situ from reaction between sodium bromide and sodium hypochlorite. The experimental tests evaluated the hypobromite formation through the time of hypobromite formation, the urea removal was quantified by TOC data (total organic carbon), on this case were performed different conditions of hypobomite concentrations, pH of solution containing urea, time of urea oxidation and bromate concentration. Either the pH, as the time of hypobromite formation do not affect the amount of urea reduced. Otherwise, the hypobromite concentration and bromide sodium concentration interfered its results. The hypobromite is capable to reduce main part of urea dissolved in water when in absence of others NOM (natural organic matter). The best results on this study were achieved with ultrapure water used as solvent, hypobromite concentration of 3 mgL-1.