Ferrite Process Research Articles

Influence of plasma synthesis parameters on the magnetic, structural and photocatalytic properties of copper ferrite

CuFe2O4 cubic copper ferrite nanoparticles were synthesized by a new plasma method, the advantage of which is the short duration of processing and cost-effectiveness. To select optimal synthesis conditions, central compositional rotatable experimental planning was used. Using the methods of X-ray phase analysis, vibration magnetometry, electron microscopy, and UV spectroscopy, the sizes of crystallites, the intensity of peaks in X-ray diffraction patterns, dislocation density, saturation magnetization, coercive force, and the degree of degradation of 4-nitrophenol were determined. To study the effect of pH on the composition of the resulting copper ferrites, cyclic voltammetry was used. The kinetics of the ferritization process under the influence of a plasma discharge has also been studied. A mechanism for ferritization in the Cu2+-Fe2+-SO42--OH- system has been proposed.It was found that single-phase nanodispersed powders of cubic copper ferrites with a saturation magnetization Ms 78–93 Emu/g can be obtained by plasma treatment at 300 s and pH 12. Copper ferrite with an admixture of Cu2O is formed at pH = 8.The maximum values of the coercive force correspond to regimes in which the minimum dislocation density is observed. The saturation magnetization depends on the crystallite size. The crystallite size of the resulting powders is in the range of 225–500 A. The results showed that the processing time is the parameter that has the greatest impact on the structural and magnetic characteristics of copper ferrite; the pH of the reaction medium affects them to a lesser extent.

Influence of Technological Factors on the Formation and Transformation of Iron-Containing Phases in the Process of Ferritization of Exhausted Etching Solutions

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.

Efficient removal and transformation of Cr(VI) from alkaline wastewater to form a ferrochromium spinel multiphase via a modified ferrite process

Chromium-containing wastewater causes serious environmental pollution due to the harmfulness of Cr(VI). The ferrite process is typically used to treat chromium-containing wastewater and recycle the valuable chromium metal. However, the current ferrite process is unable to fully transform Cr(VI) into chromium ferrite under mild reaction conditions. This paper proposes a novel ferrite process to treat chromium-containing wastewater and recover valuable chromium metal. The process combines FeSO4 reduction and hydrothermal treatment to remove Cr(VI) and form chromium ferrite composites. The Cr(VI) concentration in the wastewater was reduced from 1040 mg L−1 to 0.035 mg L−1, and the Cr(VI) leaching toxicity of the precipitate was 0.21 mg L−1 under optimal hydrothermal conditions. The precipitate consisted of micron-sized ferrochromium spinel multiphase with polyhedral structure. The mechanism of Cr(VI) removal involved three steps: 1) partial oxidation of FeSO4 to Fe(III) hydroxide and oxy-hydroxide; 2) reduction of Cr(VI) by FeSO4 to Cr(III) and Fe(III) precipitates; 3) transformation and growth of the precipitates into chromium ferrite composites. This process meets the release standards of industrial wastewater and hazardous waste and can improve the efficiency of the ferrite process for toxic heavy metal removal.

Effective purification of high concentration chromium-containing wastewater and preparation of chromium ferrite

The formation of valuable ferrite in one step by adding ferrous sulfate to chromium-containing wastewater without adjusting to acidic conditions was studied under simple mechanical equipment. The process can not only solve the problem of heavy metals removal from wastewater, but also achieve the purpose of chromium resource recovery. Increasing temperature and pH can further promote the formation of chromium ferrite while prolonging the reaction time has no significant effect on the product’s performance. The response surface method (RSM) was utilized to optimize the process of ferrite formation: the Fe<sup>2+</sup>/Cr<sup>6+</sup> mole ratio of 7, pH value of 10.5, and temperature of 100℃, on which formed ferrite has a high saturation magnetization of 41.28 emu/g with Cr(VI) removal ratio around 100%. TCLP (Toxicity Characteristic Leaching Procedure) tests showed that the chromium concentrations leached from the solid were below the limit of 5 mg/L by USEPA. The molecular formula of chromium ferrite can be expressed as Fe<sub>3-x</sub>Cr<sub>x</sub>O<sub>4</sub> (where x is about 0.45), which has the potential to be recycled as a favorable material. The ferrite process has a low activation energy of 20.8 kJ/mol, which is an economical and environmentally friendly method for synthesizing ferrite from wastewater.

Influence of citrate/tartrate on chromite crystallization behavior and its potential environmental implications.

The ferrite process has been developed to purify wastewater containing heavy metal ions and recycle valuable metals by forming chromium ferrite. However, organic matter has an important influence on the crystallization behavior and stability of chromite synthesized from chromium-containing wastewater. We focused on the influence and effect mechanism of two typical organic acid salts (citrate (CA) and tartrate (TA)) on the process of chromium mineralization. It was found that the presence of organic matter leads to the increase of the residual content of Cr in CA system (0.50mmol/L) and TA system (0.61mmol/L) in the solution, and the removal of chromium was mainly due to the surface adsorption of Fe(III) hydrolysate. The decreased crystallinity of mineralized products is ascribed to the completion of organic compounds with Fe(II) and Fe(III), which hinders the formation of ferrite precursors. There was bidentate and monodentate chelation between -COO- and metal ions in the CA system and TA system respectively, which resulted in a stronger affinity between CA and iron. This study provides the underlying mechanism for Cr(III) solid oxidation by the ferrite method in an organic matter environment and is of great significance to prevent and control chromium pollution in the environment.

DEVELOPING A TECHNOLOGY FOR PRODUCING RHENIUM ALLOYED MARAGING POWDER STEEL

One of the main trends of modern metallurgy and material science is the creation of new steels, alloys and composite materials with functional properties used in transport technology, nuclear energetics, military industry, etc. A modern technology for obtaining ammonium perrhenate from molybdenite concentrates containing rhenium produced in Republic of Armenia has been developed. The mechanism and kinetics of the ferritization process in the Fe2O3–NiO–CoO–MoO3 oxide system are revealed, as a result of which a technology for the synthesis of complex oxide [Ni1-x,Cox](Fe1-x,Mox)2O4 is developed. Also, the mechanism and kinetics of recovery of the mixture, prepared from synthesized complex oxide and ammonium perrhenate (NH4ReO4) is revealed. It is shown that rhenium, being a very active metal and dissolving in the Fe-Ni-Co-Mo system, forms solid solutions and rhenium intermetallides, increasing the strength, hardness, impact strength, heat resistance, corrosion resistance and frost resistance of the powder steel. As a result of comprehensive expert research, a technology has been developed for producing high-strength maraging powder steels alloyed with rhenium, which includes production of ammonium perrhenate from rhenium-containing molybdenite concentrates, synthesis of complex oxides from metal oxides, preparation of a mixture, recovery, which is accompanied by production of steel powder alloyed with rhenium, pressing, sintering and hot extrusion of porous compacts and heat treatment processes. It is shown that the resulting powder steel in terms of its physical, mechanical and technological properties is not inferior to standard steels, and in some cases, surpasses them.

Energy-saving technology for processing of exhausted etching solutions with obtaining of ferromagnetic compounds

Exhausted etching solutions are the waste of industrial enterprises and contain toxic pollutants that have a detrimental effect on the environment. Currently, the processing of these solutions to obtain marketable products is important. The paper presents the results of research on the application of the ferritization method for processing of exhausted etching solutions of steel surfaces. Energy-saving activation of the process by alternating magnetic fields was used, which has undeniable advantages compared to traditional thermal activation. The influence of the initial concentration of iron ions in the reaction mixture of ferritization process and the methods of its activation on the treatment quality of exhausted etching solutions was studied. It was established that the best degree of extraction of heavy metal ions from exhausted etching solutions by ferritization is achieved when the reaction mixture is activated by alternating magnetic fields at an initial concentration of iron ions of 6.6 g/dm3 . At the same time, the residual concentration of iron ions in purified solutions does not exceed 0.03 mg/dm3 , that corresponds to degree of purification of solutions of 99.999%. Those solutions can be reused in situ. The qualitative and quantitative composition of ferritization sediments was studied. Phases of ferroxygite δ-FeOОН, magnetite Fe3O4 and maghemite ɣ-Fe2O3 were detected by X-ray phase analysis in the sediments. It was established that at the initial concentration of iron ions of 26.6 g/dm3 with thermal activation of the reaction mixture and 16.6 g/dm3 with alternating magnetic fields activation, the sediment exclusively contains the magnetite phase. The results of the study indicate the possibility of further use of sediments for the production of important industrial products and materials containing ferromagnetic compounds. The implamitation of improved ferritization process in industrial enterprises will allow to achieve decrease of energy consumption compared to known technologies of exhausted etching solutions processing.

Effect of zinc ion on synthesis of chromium-containing spinel from wastewater and insight into the synthesis mechanism

Stable spinel can be synthesized in chromium-containing wastewater by ferrite process, which can not only realize the purification of chromium-containing wastewater, but also make chromium resource in the wastewater recycle. However, zinc ion often exists in the chromium-containing wastewater, and easily enters the spinel structure when the wastewater is treated by the ferrite process. Therefore, the effect of zinc ion on the synthesis of chromium-containing spinel from the wastewater was investigated, and the synthesis mechanisms was revealed. The quality of the filtrate, stability and magnetic properties of products synthesized at different initial concentrations of zinc ion were examined, and the results verified that moderate zinc ion enhanced the stability of chromium and magnetic properties of synthetic products, but excessive zinc ion reduced the quality of the filtrate. The synthetic path of products was illustrated by examining the stability and crystal evolution of synthetic product, monitoring the potential and pH, testing the dissolved oxygen, and analyzing the contents of metal ions in the filtrate. The synthesis mechanism was further confirmed by SEM-EDS and mössbauer spectra, and the results demonstrated that the gained solid products were mainly composed of goethite and spinel. It was deduced that the molecular formula of synthetic spinel wasFe3.243+(Fex2+⋅Fe2-x3+⋅Cry3+)O1.5y-0.5x+7.86 in the absence of zinc ion. However, the molecular formula of synthetic spinel was (Zn0.52+⋅Fe2.743+)(Fex2+⋅Fe2-x3+⋅Cry3+)O1.5y-0.5x+7.61 in the presence of zinc ion. The study laid a theoretical foundation for the industrial application of ferrite process in the chromium-containing wastewater.

Determining the rational parameters for processing spent etching solutions by ferritization using alternating magnetic fields

This paper reports the results of studying the application of a ferritization method for the integrated purification of used etching solutions. A feature of this work is the use of energy-saving activation of the process by alternating magnetic fields. Its advantages are shown in comparison with traditional thermal activation. The influence of magnetic induction amplitude and key technological parameters of ferritization on the quality of cleaning an etching solution has been studied. The qualitative and quantitative composition of sediments obtained after the ferritization of etching solutions was investigated. Used etching solutions are large-tonnage waste of industrial enterprises. They contain harmful pollutants that have a detrimental effect on the environment. It is promising to treat these solutions in order to obtain valuable commodity products. It is established that with an optimal value of magnetic induction amplitude of 0.1 Tl, the degree of extraction of iron ions from the solution reaches a value of 99.99 %. The best values for the main technological parameters of the process have been determined: the concentration of iron ions in the reaction mixture is 6.6 g/dm3; pH, 11.5; the duration of ferritization is 15 min. The residual concentration of iron ions in purified solutions does not exceed 0.3 mg/dm3. Thus, according to the norms of current standards, they can be reused in production. Comparative analysis indicates the advantages of electromagnetic activation of the reaction mixture. The phases of magnetite Fe3O4 and iron monohydrate δ ‒ FeOОН were detected by the method of X-ray phase analysis in ferritization sediments. It is established that with an amplitude of 0.1 Tl, the sediment contains only magnetite. The study's results indicate the possibility of further use of sediments for the manufacture of important ferromagnetic substances. The application of the improved ferritization process in production will achieve less energy consumption compared to well-known processing technologies

Study of influence of initial concentration of heavy metal ions on the quality of fertization processing of electroplating sludge

Influence of the key parameter for the ferritization process - initial total concentration of heavy metal ions (СƩ) on the quality of galvanic sludge processing has been experimentally studied. It was determined, that at СƩ = 5.33 g/dm3 and electromagnetic pulse activation of the ferritization process, the lowest values ​​of residual concentrations of heavy metal ions in the purified solution were obtained: for iron – 0,10; nickel – 0,19; copper – 0,12; zinc – 0,10 mg/dm3. The obtained values ​​correspond to the average degree of extraction of these ions of 99,97%. The purified solution is suitable for reuse in electroplating facilities. As a result of structural studies of sediment samples, it was found that at total heavy metal concentration of 5,33 g/dm3 in the ferritization reaction mixture, regardless of the method of activating the process, phases containing crystalline ferromagnetic phases of ferrites (Ni, Cu, Zn) Fe2O4 exceeds 92%. The efficiency of resource-saving electromagnetic pulse activation of the reaction mixture in the ferritization process is confirmed. Using this method of activation, energy consumption is reduced by 1,5 times compared to thermal one. The proposed resource-saving ferritization technology prevents environmental pollution, ensures the rational use of raw materials and energy, as well as allows to obtain marketable products from industrial waste.

Adsorptive behavior of thallium using Fe3O4-kaolin composite synthesized by a room temperature ferrite process

Thallium (Tl) contaminants pose serious threats to the ecological environment and human health due to its acute/chronic poisoning on the health of most organisms even at low concentrations. To find a rapid and efficient technology in removing Tl from waters thus becomes a crucial issue. A magnetic Fe3O4-kaolin composite (denoted by FKC) with high specific surface area (133.7 m2/g) was successfully synthesized via a simple and low-cost technique for Tl(I) removing from various water media. The HRTEM images confirmed the existence of lattice fingers Fe3O4 and displayed that a large number of Fe3O4 nanoparticles dispersed on the surface of kaolin sheets. Compared with kaolin or Fe3O4 alone, FKC enhanced obviously the adsorption rate and capacity of Tl(I) over a wide pH range (4.5–9.0). The maximum adsorption capacity of FKC for Tl(I) was 19,347 mg/kg (calculated by Langmuir model), which was almost one hundred times and two times higher than those of kaolin and Fe3O4, respectively. Importantly, FKC was observed to have a great potential in removing Tl(I) from surface water, groundwater, and tap water in more alkaline conditions. By applying the external magnetic field, FKC could be recovered efficiently (99%) and rapidly (20 s). Moreover, Tl L3-edge XANES spectra revealed that Tl(I) was adsorbed on the FKC and would not be converted to more toxic Tl(III). The cations (CaCl2, NaCl, and KCl) and the ionic strength with concentrations of 0.001–1.0 mol/L showed a great influence on the adsorption of Tl(I) by FKC, implying that this adsorption was dominated by outer-sphere surface complexation at investigated pH values. The information provided is essential for designing a rapid and effective scavenger for removing Tl in various natural waters.

Influence of aeration rate and method of process activation on the degree of purification of zinc-containing waste water by ferritization

The aeration rate for the degree of purification of highly concentrated galvanic wastewater from zinc and ferrum ions was investigated using various activation methods. It is shown that the intensity of aeration has a significant effect on the quality of wastewater treatment and the characteristics of water treatment sludge. The efficiency of the use of an energy-saving method for activating the ferritization process with the use of electromagnetic pulses for the extraction of zinc ions from wastewater has been confirmed. It was determined that with an increase in the aeration rate to 3.5 dm3/min per 1 dm3 of the reaction mixture and the use of thermal activation of the process, the residual concentration of zinc ions remains within the range of 0.12÷0.2 mg/dm3. In this case, the concentration of ferrum ions decreases to values of 0.08÷0.14 mg/dm3. It was found that at an aeration rate of 2.5 dm3/min and the use of pulsed electromagnetic (EMP) activation, the residual concentrations of heavy metal ions decrease to values of 0.08÷0.16 mg/dm3. Comparison of the results indicates the advisability of using low rates of aeration of the reaction mixture. This, together with the use of resource-saving EMR process activation, allows to achieve a significant reduction in energy costs. The quantitative phase composition of ferritization precipitates was determined, in which the crystalline phases of zinc ferrite Zn2Fe2O4 and magnetite Fe3O4, as well as ferrum oxyhydroxide FeO (OH) and sodium sulfate Na2SO4, prevail. It is found that with an increase in the volumetric aeration rate, the proportion of the ferrite phase increases. At an aeration rate of 2.0 dm3/min, more than 85 % of the zinc ferrite phase was found in the sediments. Taking into account the qualitative and quantitative composition of precipitates, it is recommended to use them in the production of building materials. The experimental results obtained make it possible to provide a comprehensive processing of liquid galvanic waste.

FERRITATIVE WASTEWATER TREATMENT FROM CHROMIUM (VI) COMPOUNDS USING ELECTROMAGNETIC PULSE ACTIVATION

Issues related to the prospects of implementing the latest technologies aimed at achieving energy efficiency in the field of water supply, resource conservation in material-intensive processes at industrial enterprises and prevention of environmental pollution are considered. A study of ferritative wastewater treatment from chromium compounds, which belong to the first class of danger. The efficiency of thermal and electromagnetic pulse activation of the process is compared. Appropriate experimental setups were developed and the main parameters of the purification process were studied and determined: the ratio of iron (II) and chromium (VI) ions, magnetic field strength, frequency of electromagnetic pulses, ferritization process duration, temperature and pH of the reaction mixture.
 The expediency of using electromagnetic pulse activation of the reaction mixture by passing electromagnetic pulses through the reaction mixture has been studied and scientifically substantiated. Rational values ​​of the strength and frequency of the electromagnetic field when using this method of activation, which are 0.01 - 0.14 Tl and 1 Hz, respectively, as well as the ratio of concentrations of heavy metal ions Fe2 + / Cr6 + = 10/1 for washing water chrome plating line . It is shown that purified water meets the requirements of category 1 when reused in production. The results of X-ray diffraction analysis of ferritization sediments showed that stable crystalline phases, such as chromium ferrites and magnetite, are formed with increasing magnetic field strength. The chemical resistance of sludge allows them to be safely disposed of. It is established that this method of electromagnetic pulse activation is not inferior to thermal, and the technical and economic calculations confirmed a significant reduction in industrial costs in its application

Wastewater treatment of industrial enterprises from copper compounds by feritization

The article is devoted to solving an urgent problem - the development of effective methods of water purification from heavy metal ions from industrial wastewater.
 Today more emphasis on technologies that allow recycling of precious metals, the organization of return water supply and receipt safe disposal of sludge. Experimental studies of copper ions extraction from industrial wastewater of galvanic production by ferritization method have been carried out. The process of formation of ferromagnetic compounds of copper and iron has been studied. The results of X-ray diffraction analysis of the mineralogical composition of the samples and phase transformations that occur during aging and during the experiment are presented. The lattice constant of the α-ferite phase is calculated. X-ray diffraction analysis confirmed the presence of ferite compounds and metallic copper. In this case, in the process of "aging" of the samples, the amount of the ferrite phase and metallic copper increases. Electron microscopic analysis confirmed that in the surface layer changed due to the formation of new phases, copper-containing iron oxides, the formation of cement copper and cuprospinel simultaneously exist.
 The influence on the course of the ferritization process of its conditions - the concentration and ratio of copper and iron ions, temperature, pH of the medium, the consumption of oxidant - oxygen is studied. The optimal parameters of the ferritization process for wastewater treatment from copper with an initial concentration of up to 10 g / l are determined. The possibility of formation of copper ferrite without aeration at a temperature of 200 C is shown.
 The study of physicochemical properties of sediments formed during ferritization is performed.
 Studies have shown that the residual concentration of copper in the solution after the application of the proposed technology is in the range from 0.14 to 0.6 mg / l. The efficiency of copper removal is 99.98%.
 It is established that at the process temperature within 50… 700 C, the ratio
 Cu: Fe = 1: 2.7, pH = 8.8… 10.5 and aeration intensity 4… 8 l / min precipitates are formed, which consist in the vast majority of ferrites and metallic copper.

Removal and recycling of hexavalent chromium from alkaline wastewater via a new ferrite process to produce the valuable chromium ferrite

Current technologies for removal of Cr(VI) are generally fit for acidic wastewater. In this study, a new ferrite process for removal and recycling of Cr(VI) from alkaline wastewater to produce the valuable chromium ferrite has been developed. The results show that this new ferrite method is a one-step process which can be divided into two successive reactions including Cr(VI) reduction to form coprecipitation (Cr0.25Fe0.75(OH)3) and subsequently magnetic conversion of Cr0.25Fe0.75(OH)3 induced by Fe2+ under the same alkaline condition. The total Fe/Cr mole ratio of 5:1 is at least required for the chromium ferrite transformation. Increasing temperature and pH can enhance the interaction of Fe2+ with Cr0.25Fe0.75(OH)3 and further promote the formation of chromium ferrite, while suppressing the generation of nonmagnetic by-product goethite. Almost pure chromium ferrite is formed under proposed optimum conditions (Fe/Cr = 7:1, 65 °C and pH of 9) with Cr(VI) removal ratio around 100%. The Cr(VI) remained in the filtrate can be reduced to 0.01 mg/L which is much lower than the limits concentration for surface water (≤0.05 mg/L). The chromium ferrite product whose molecular formula can be expressed as Cr0.5-xFe2.5+xO4 (where 0 ≤ x < 0.5) presents good magnetic properties and has the potential to be recycled as a useful material.

Research of heavy metals leaching from sediments after feritization processing of galvanic sludge

Possibility of environmental safety increasing for industrial enterprises as a result of resource-saving technology implementation for processing galvanic sludge is considered. An experimental study of stability for sediments after ferritization processing of galvanic sludge and exhausted technological solutions was carried out. As a result of dynamic leaching of heavy metal ions, the immobilization properties of sediments were determined, which were obtained at different technological parameters of the ferritization process. It is shown that the level of immobilization of heavy metals in ferritic sediments has significantly higher values in comparison with sediments of traditional wastewater neutralization. It was found, that the precipitate obtained at following key parameters of reaction mixture for the ferritization process: the total concentration of heavy metal ions 10.41 g/dm3; ratio of concentrations of iron ions to total concentration of other heavy metals ions 4/1 and pH value of 10.5, is characterized by the highest degree of immobilization of heavy metals in the sediments of 99.96% mass. Using the results of a complete factorial experiment, regression equation for the leaching of heavy metal ions (iron, nickel, copper and zinc) from ferrite sediments was obtained: ratio of iron concentrations to the total concentration of other heavy metals and the pH value of reaction mixture. The adequacy of coefficients of regression equations was evaluated according to the criteria of Student and Fisher, which with 95% reliability correspond to the experimental results of the study. The proposed calculation algorithm provides an opportunity to increase efficiency and automation of ferritization process. Subsequent use of the research results will allow to implement reliable utilization of ferritized galvanic waste by application them into the row materials for obtaining alkaline cements for special purposes.

Determination of influence of pH on reaction mixture of ferritation process with electromagnetic pulse activation on the processing of galvanic sludge

This paper considers prospects for increasing the level of environmental safety of industrial enterprises as a result of the implementation of resource-saving technology of processing galvanic sludge using the ferritization method. The effectiveness of the use of electromagnetic pulse discharges for resource-saving activation of the ferritization process with the extraction of heavy metal ions from sludge (Fe, Ni, Cu, Zn) has been confirmed. The influence of key parameters of the process such as the pH value of the reaction mixture and the initial concentrations of metals in the solution on the quality of processing galvanic sludge by ferritization has been experimentally investigated. It was determined that with an increase in the pH value from 8.5 to 10.5 the residual concentrations of metal ions decrease to the values of 0.1÷0.25 mg/dm3 regardless of the total initial concentrations. It has been established that the technique of electromagnetic pulse activation ensures an adequate degree of extraction of metal ions of 99.9 %; it also has indisputable energy advantages compared to the thermal method: energy costs are reduced by more than 60 %. That indicates the suitability of purified water for reuse in galvanic production in terms of the requirements for the content of heavy metal ions in it. In addition, the structural studies of ferritization sediment samples have been carried out. The sediment is characterized by the maximum content of crystalline ferromagnetic phases of ferrite. It was established that an increase in the pH of the initial reaction mixture leads to an increase in the ferrite phase in sedimentation: at pH=10.5, phases were detected, which are characterized by a maximum ferrite content (exceeding 76 %). The proposed resource-saving ferritization process prevents environmental pollution, ensures efficient and rational utilization of raw materials and energy in the industry; it also makes it possible to obtain commodity products from industrial waste.

Investigation of the influence of electromagnetic field strength on the quality of water purification from heavy metals by ferritization method

To date, one of the components of the global problem of water pollution has been the uncontrolled discharge of wastewater from industrial enterprises that use in their work technological solutions of heavy metals, including galvanic. Among the main components of wastewater generated in galvanic industrial enterprises, about 70% is zinc and its compounds, and the most toxic of the heavy metals contained in process solutions are Cr VI compounds. In view of this, it is important to improve the ferritization treatment of wastewater from zinc and chromium ions. A laboratory installation for the ferritization process with electromagnetic pulse activation (EMI) has been developed. This method of activation provides not only a reduction in energy costs, but also the appropriate degree of extraction of heavy metal ions, which allows you to get an aqueous solution that can be used in a circulating water supply system, and sludge disposed of as additives for alkaline cements. The influence of the strength of the electromagnetic field on the degree of extraction of zinc and chromium ions from wastewater by ferritization has been studied. It is determined that the best degree of purification from heavy metal ions is achieved at an electromagnetic field of 0.14T.

Efficient mercury removal from flue gas using high-quality spinel mixed ferrites obtained from wastewater

High-quality spinel mixed ferrites (M-Fe) are obtained from the electroplating wastewater, which are then used as adsorbents for the removal of elemental mercury (Hg 0 ) in the flue gas to simultaneously realize the purpose of waste resource utilization and pollution control. In the “ferrite process”, through adjusting the dosages of ferrous sulfate (FeSO 4 ·7H 2 O), the chromium (Cr) in wastewater can be fully recycled to synthesize the M-Fe adsorbents with good crystal morphology and chemical stability, and they can be easily separated by applying a magnetic field. Hg 0 removal experiments indicated that the feeding mass ratio of FeSO 4 ·7H 2 O: Cr 6+ and temperatures had great influence on mercury removal efficiency, and the M-Fe adsorbents with FeSO 4 ·7H 2 O: Cr 6+ mass ratio of 100: 1 (M-Fe (100)) had the highest Hg 0 removal performance with nearly 100% at 100℃. In addition, M-Fe (100) presented good sulfur resistance, which remained above 90% Hg 0 removal efficiency after SO 2 injection, and it can recover activity when stopping SO 2 . The XPS and desorption dynamics analysis showed mercury existed in the form of physically and chemically adsorbed states. Adsorption kinetic studies manifested that surface active sites were the adsorption rate controlling step, and inner active sites played an important role in mercury adsorption process. Mercury equilibrium analysis indicated mercury amount during adsorption and desorption process was approximately identical, manifesting M-Fe (100) was well recyclable magnetic adsorbent.

Investigation of the ferritization process in the Co2+–Fe2+–SO42−–OH− system under the action of contact non-equilibrium low-temperature plasma

Investigation of the ferritization process in the Co2+–Fe2+–SO42−–OH− system under the action of contact non-equilibrium low-temperature plasma