Devising a comprehensive technology for treating industrial iron sulfate-containing effluents of galvanic production

Abstract

The object of the research is complex electrochemical and ferritic decontamination of iron sulfate-containing waters. Processing of liquid waste is carried out by electrochemical treatment using two- and three-chamber electrolyzers. This paper investigates the processes of electrodialysis purification of simulated solutions with an FeSO4 compound concentration of 5 g/dm3 and an H2SO4 compound concentration of 300–2100 mg-equiv/dm3. A plate made of stainless steel was used as the cathode, and a plate made of titanium covered with ruthenium oxide and lead was used as the anode. It is shown that the highest current yield of electrodialysis products of 84.5 % was obtained when using a three-chamber electrolyzer with MA-41 anion exchange membranes. It was found that when using the specified electrolyzer, the concentration gradient, the value of which is directly proportional to the difference in the concentrations of the initial solutions filled with the electrode chambers, has a significant effect on the process of separation of impurities. It is shown that for a two-chamber electrolyzer, the current output reaches 72 %, which is explained by the harmful effect of a significant concentration gradient and is manifested in the rapid mechanical blocking of the membrane and the slowing down of the ion migration process, as well as the increase in energy consumption. In a two-chamber electrolyzer, H2SO4 with a concentration of 18.3 % was obtained, which is suitable for repeated use in etching baths. It was found that as a result of electrodialysis separation and additional oxidation, it is advisable to use concentrated iron sulfate solutions for obtaining ferrite material of a crystalline structure with particle sizes of 2–20 μm. Within the framework of the circular economy, an ecologically safe technology for decontamination of industrial iron-containing sulfate solutions of galvanic production using a complex of electrodialysis and ferrite methods is proposed

Development of an innovative catalyst for neutralization of carbon monoxide in multi-chamber kilns of electrode blanks

“…The reactor is a heat-resistant glass tube equipped with an electric heater (5). Temperature control was carried out using a thermocouple (6) with an accuracy of ±1.0 °C, connected to the temperature meter-regulator (7).…”

“…Thus, achieving a high purification efficiency when using smaller doses of the reagent should attract the attention of the water industries, since, firstly, this will reduce chemical costs, and, secondly, reduce the production of ferrite sludges in the event of their storage and, ultimately, save production costs. To compare the efficiency of the catalysts, it is advisable to also obtain iron ferrite (magnetite) and manganese ferrite using solutions of iron sulfate (II) and iron sulfate (III), obtained by electrolysis, as an alternative to iron chloride (III) [6].…”

“…Currently, obtaining potassium ferrate is limited in Ukraine, so its use for obtaining a highly efficient catalyst will be scarce. However, considering the availability of zeolite raw materials for the carrier and spent iron-containing etching solutions [6] for the catalytically active component of the CO oxidation catalyst, the inertness and stability of manganese ferrite and magnetite in the environment, the use of the specified catalysts on the zeolite carrier will allow to comprehensively solve the complex environmental problem of detoxification of toxic gases and sewage waters of metallurgical production.…”

“…Confirmation of this fact is an unacceptable excess of iron ions in the basins of the rivers of Ukraine, recorded as a result of monitoring the state of transboundary rivers within the framework of bilateral agreements [5]. Therefore, to ensure a closed cycle of production within the framework of the circulating economy, it remains relevant to create an environmentally safe technology for neutralizing liquid waste from industrial production containing iron ions [6]. Currently, the attention of scientists is paid to the development of technological methods for the use of iron-containing solutions for the production and subsequent use of nano-and micro-sized iron oxide ferritic compounds with a crystallite size of 100 nm [7].…”