Influence of the pyrokatekhin complex forming agent on the extraction of nickel and nickel hydroxide from galvano slides and the study of characteristics of electrodes made from Ni(OH)2

The problems of enterprises of the chemical and machine-building industries, which have a negative impact on the state of the natural environment, are considered. The galvanic workshops and areas available in their structure belong to categories 1-3 of hazard classes due to the use of solutions and the resulting wastewater containing various heavy metals. On the territory of these workshops, a large amount of galvanic sludge (GS) is formed and accumulates, containing such toxic components as nickel, zinc, iron, copper, chromium, lead, cadmium, etc., which have a high toxic, carcinogenic and mutagenic effect on living organisms. However, when finding an effective method for processing, GS can serve as a source of obtaining valuable components, in particular metals and their compounds. The work carried out selective extraction of nickel ions contained in galvanic sludge into a solution with addition of pyrocatekhin (PC) in the concentration range of 50-250 g/l (step 50 g/l). It was found that the optimal concentration of catechol for the extraction of Ni2+ ions was Cpc = 50 g/l. With an increase in the concentration of PC, the concentration of extracted nickel ions increases (from 12.4 to 18.2 mg / ml), however, at high concentrations of PC (100-250 g / L), a thick suspension is formed, which is practically not amenable to filtration. During the subsequent processing of the resulting solution of 40% NaOH in the range of pH = 7.2 ÷ 9.5, Ni(OH)2 hydroxide was precipitated, which met the requirements of TU 48 3 63 90 “Nickel nitrous hydrate”. It was used as a component of the active mass of nickel-cadmium (iron) battery cathodes. The electrochemical characteristics of the obtained cathodes have been studied and it has been shown that, in terms of their operating parameters, they are not inferior to industrial Ni(OH)2 electrodes. As a result of the experiments, it was found that the proposed technology for extracting nickel hydroxide from metal-containing galvanic sludge can be used to manufacture the active mass of nickel-cadmium (iron) batteries cathodes and is promising.