Considerable attention has been paid recently to the development of comprehensive recycling of industrial wastewater, which provides for an appropriate degree of purification for both organization of circulation water supply, and subsequent disposal of waste of water treatment. The improved ferritization process, which allows decreasing original concentration of nickel ions in depleted electrolytes of nickel plating from 50–100 g/dm³ to <0.2 mg/dm³, was presented. The experimental ferrite-reactor with the use of the traditional thermal and electromagnetic pulse method of activation of ferritization process in the range of generating frequencies of up to 0.9 kHz was developed. Economic benefits of the use of the electromagnetic pulse activation compared to the high temperature one were identified. Kinetics of extraction of nickel and iron ions from aqueous solutions was explored. The impact of the basic technological parameters of ferritization at different ways of activation was experimentally determined. The most effective results of treatment of highly concentrated wastewater were achieved using the electromagnetic pulse (T=20 °C) and thermal (T=70 °C) way of activation of the ferritization process at the original ration of concentration Fe²⁺/Ni²⁺ within 3/1–4/1, total concentration of ions of heavy metals of 20–25 g/dm³, original pH of the reaction mixture of 9.5 and duration of ferritization process of 15 min. Research into phase composition and physical properties of ferritization sediments was performed. Comparative analysis of sediment volumes at different ways of compaction was carried out. Sediments are mainly characterized by the crystalline structure, ferromagnetic properties, and considerable chemical resistance. This provides for actual environmental ways of recycling, which makes it possible to avoid the loss of valuable and, at the same time, toxic metal – nickel. The proposed comprehensive process of recycling liquid industrial waste prevents pollution of the environment, ensures effective and efficient use of water, raw materials, and power in the system of galvanic production.

Development of ferritization processing of galvanic waste involving the energy­saving electromagnetic pulse activation of the process

Development of a technology for utilizing the electroplating wastes by applying a ferritization method to the alkaline­activated materials

The efficiency of the AC-magnetic field usage for resource-saving activation of the reaction mixture in the ferritization process with the extraction of heavy metals ions from galvanic waste has been confirmed. The one of the key parameters of the ferritization process—the ratio of the concentration of iron ions to the total concentration of other metal ions on the quality of galvanic waste processing has been investigated. It is determined that under the optimal processing conditions (ratio of concentrations of iron ions to other heavy metal ions 3.5 ÷ 4/1) the residual concentrations of heavy metal ions decrease to the values: Fe^2+;3+—0,1; Ni^{2 +—}0.26; Cu^{2 +}—0.2; Zn^{2 +}—0.19 mg/dm³. It is established that the AC-magnetic field activation provides the metal ions extraction degree of 99.96%, and also has undeniable energy advantages in comparison with thermal technique: the energy consumption is reduced by more than 60%. This indicates the suitability of purified water for reuse in galvanic production due to the requirements for the heavy metal ions content. Also, the structural studies of ferritic sediments shown that samples obtained at the ratio of heavy metal ions concentrations 4/1 phases characterized by the maximum content of crystalline ferromagnetic ferrite (Ni_0.53Cu_0.3 Zn_0.17Fe₂O₄) ≥ 76% were detected.

Development of technology of utilization of products of ferritization processing of galvanic waste in the composition of alkaline cements

This study presents a sustainable approach to recycling exhausted etching solutions through ferritization, using various activation methods and aeration rates. The process transforms industrial waste into valuable magnetic sorbents, supporting circular economy principles. Structural and chemical analysis of the ferritization products revealed the formation of ferromagnetic crystalline phases, including lepidocrocite (ɣ-FeOOH), ferrooxygite (δ-FeOOH), and magnetite (Fe₃O₄). Increasing the aeration rate and use of ultrasound treatment enhances Fe₃O₄ content and iron ion removal efficiency. The adsorption capacity of the recycled materials for Zn²⁺ removal was assessed under different pH conditions using mechanical mixing and ultrasound treatment. The highest level of Zn²⁺ removal (92.0%) was achieved at pH 8 with ultrasound-activated sorbents containing 61.3% δ-FeOOH and 38.7% Fe₃O₄. At pH 10, magnetite-based sorbents achieved over 98.9% Zn²⁺ removal, enabling the treated water’s reuse in industrial rinsing processes. Electron microscopy and X-ray fluorescence confirmed the presence of fine, spherical magnetite and zinc ferrite particles. These findings underscore the potential of ferritization-based recycling as an eco-friendly and efficient strategy for heavy metal removal from galvanic wastewater.