Search Results (6)

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. Full article

Predictive modelling is very important for water pollution management. In this study, based on an electromagnetic field-enhanced vertical flow artificial wetland and using the actual measured data as inputs to the model, the ammonia nitrogen (NH₄⁺-N) effluent concentration of this wetland system was analyzed by Pearson’s correlation analysis to be related to six key factors, which were the NH⁺-N raw water concentration, the chemical oxygen demand (COD) raw water concentration, the treatment time, the magnetic field strength, the aeration time, and the electric field strength. Then, different artificial neural network models were constructed for comparison and the constructed models were evaluated based on statistical parameters. The results show that the PSO algorithm can improve the prediction effect of the BP neural network, but the prediction accuracy of the CNN model is better compared to the others. The prediction accuracy of the RF model is the highest compared to the others, and the evaluation parameters of R2, RMSE, and MAE of the test set are (0.9446, 2.4328, and 3.0943), respectively. The prediction error of this model is the smallest, and the model can predict the concentration of electric and magnetic fields in a wetland system with high accuracy compared to other models. This model can more accurately predict the NH₄⁺-N effluent concentration of the magnetic field-enhanced wetland system, which can provide a certain basis for the study of the management of water pollution. Full article

Every year, metallurgical enterprises generate a massive amount of toxic exhausted high-concentration etching solutions. Application of the ferritization process to recycle exhausted etching solutions can help to prevent environmental pollution. It enables a cost-efficient use of water at an industrial plant and allows the plant to obtain products from toxic industrial waste and utilize it. The aim of the study was to analyze the qualitative and quantitative composition of the formed sediment and its grain size composition. Variable study parameters were the initial pH values of the solutions, the initial concentrations of total iron, and the duration of the aeration process of the reaction mixture. Thermal activation and alternating magnetic fields were used to activate the ferritization. The XRD showed that the formed sediments contained phases of γ-FeOOH, δ-FeOOH, Fe₃O₄, and γ-Fe₂O₃. Granulometry analysis showed that these sediments were highly dispersed and heterogeneous. Chemically stable phases of magnetite were obtained in the composition of sediments, with an initial concentration of iron in the reaction mixture of 16.6 g/dm³, a pH of 11.5, and a process duration of 15 min. The study results demonstrated the feasibility of further study and possible use of such sediments with a high magnetite content for the production of materials with ferromagnetic and sorption properties. Full article

Raising yields and agricultural production efficiency is the primary goal of realizing modern agriculture. As a low-cost and environmentally friendly technology, activated water has the potential to increase crop yields and improve water and fertilizer use efficiency, but much research is still needed to make this technology widely available in the field. Hydroponic experiments were conducted to investigate the effects of magnetized water, aerated water, and magnetized aerated water on rice and wheat seedling and root growth. The results showed that aerated water irrigation significantly increased plant height by 5.1–9.6%, leaf area by 21.1%, and aboveground biomass by 14.8–16.3%, respectively. Aerated water irrigation also significantly promoted rice root biomass, maximum root length, total root length, total root surface area, and especially the proportion of roots less than 0.5 mm in diameter, indicating that aerated water enhances the growth of rice seedlings mainly by promoting root growth, especially fine root (D ≤ 0.5 mm) growth. The maximum root length and total root volume of wheat roots under magnetized water irrigation treatment were increased by 7.7–8.6% and 17.2%, respectively, resulting in a significant increase in aboveground dry biomass by 13.6%. Magnetized water and magnetized aerated water irrigation also promoted the growth of rice seedlings and roots. In contrast, aerated water and magnetized aerated water irrigation exhibited an inhibitory effect on the growth of wheat seedlings and roots. Therefore, activated water has different effects on different crops in hydroponics, and more research is needed in the future to determine the conditions for the application of activated water in agriculture. Full article

The aim of this work was to investigate magnetic field (MF) usage for urban water treatment. Currently, the popular method of ground water purification includes water aeration and filtration, which are expensive and energy intensive. MF is not used for drinking water treatment but mostly for boiler and cooling water at industrial water plants or in farming for plant growth. The authors decided to test it at a small water treatment station in Poland. An MF generator was placed on the pipe between raw water intake and aeration. The results proved higher efficiency in water treatment, especially in hardness, turbidity, Fe, Mn and NH₄ removal. Full article

The purpose of this study was to recycle basic oxygen furnace (BOF) slag in the production of autoclaved aerated concrete (AAC), and to examine the influence on the properties of AAC products. The magnetic substances in the BOF slag accounted for about 15 wt.% and the magnetic proportion increased as the particle size decreased. The nonmagnetic portion of the BOF slag was acquired by a magnetic separation process and its major constituents were Ca (~42 wt.% as CaO) and Si (~35 wt.% as SiO₂), which are the essential elements of AAC. When using the BOF slag for AAC production, the bulk density and compressive strength of the specimens decreased as the amount of slag increased. The results of the performance analysis revealed that at appropriate water–solids ratios, using 15 wt.% or less of the BOF slag was beneficial to the properties of the AAC products. In general, it should be feasible to recycle the BOF slag in the production of AAC. However, the foreign elements introduced by the BOF slag can alter the formation and structure of hydrates, including tobermorite, and thus affect the properties of the AAC product, a potential issue that needs to be addressed. Full article