Mixed Hydroxide Research Articles

Preparation of Ni-Cu-C composite catalysts prepared from mixed nickel and copper hydroxides for selective hydrogenation of 4-nitrophenol

A high-performance Ni-Cu-C composite catalyst was prepared from mixed nickel hydroxide and copper hydroxide, which were obtained by coprecipitation, by thermal treatment with acetylene-containing gas at 120 °C followed by hydrogen reduction at 180 °C. The characterization results of XRD, TEM, XPS, and H2-TPR measurements confirmed the presence of nickel carbide (Ni3C), copper carbide (CuxC), Cu, and Ni in the matrix of amorphous carbon in the composite catalyst. The mild preparation temperature and the porous carbon shell layers prevented the nano-sized particles from aggregation. The formation of interstitial Ni3C and CuxC significantly enhanced the dissociation of molecular hydrogen, accelerating the selective hydrogenation of 4-nitrophenol (4-NP) to yield 4-aminophenol (4-AP) at relatively mild conditions (80 °C and 1.0 MPa hydrogen pressure). The catalytic performance of the composite catalysts depended strongly on the Ni/Cu molar ratio, with an optimal Ni/Cu molar ratio of 4. In addition, the composite catalyst showed high conversion and selectivity to the corresponding aniline in the selective hydrogenation of other nitroarenes, including nitrobenzene, 4-nitrotoluene, 4-nitrochlorobenzene, 4-nitrobenzaldehyde, 4-nitroacetophenone, and 2-nitroaniline. The catalyst offers a novel approach to rational design and preparation of high-performance abundant metal catalysts for selective hydrogenation of nitroarenes.

Removal of Impurities from Nickel and Cobalt in Mixed Hydroxide Precipitate with Solvent Extraction Using Di(2-Ethylhexyl) Phosphoric Acid

ABSTRACT This study investigates the removal of major impurities, namely Fe, Al, Zn, and Mn, in a solution produced by sulfuric acid leaching of mixed hydroxide precipitate from the Ni and Co via solvent extraction using di(2-ethylhexyl) phosphoric acid (D2EHPA). The results of extraction experiments showed that the extracted Ni, Co, Fe, Al, Zn, Mn, and Mg increased as the equilibrium pH, D2EHPA concentration, and O/A ratio increased. The optimum extraction condition was achieved at a pH of 3.5, a 20% (v/v) D2EHPA concentration, and an O/A ratio of 1, with a complete (>99.9%) extraction of Al, Fe, Zn, and 97.33% Mn with co-extracted Ni and Co of 22.32% and 29.13%, respectively, in a single extraction stage. Complete Mn removal can be achieved in two extraction stages. Co-extracted Ni and Co can be scrubbed out using a mild sulfuric acid solution at a pH of 1.2 with only less than 2% of the Al, Fe, Zn, and Mn co-scrubbed. McCabe-Thiele diagrams of the scrubbing processes were constructed, and the results showed that Ni and Co can be scrubbed out using a mild acidic solution at a pH of 1.2, O/A ratio of 1, and temperature of 40°C for 10 min of mixing. Zn and Mn can be stripped completely using 0.5 M sulfuric acid solution at an O/A of 1 and temperature of 40°C for 10 min of mixing, while Fe and Al remained unstripped. Fe and Al can subsequently be stripped via reductive stripping.

Cradle to gate life-cycle assessment of battery grade nickel sulphate production through high-pressure acid leaching

The rising global demand for high-purity nickel (Ni) sulphate, primarily used in lithium-ion batteries, is largely met by processing Indonesian laterite ores via hydrometallurgy. However, this supply chain is associated with significant environmental challenges and lack of transparent industrial data. This study uses a cradle-to-gate life cycle assessment (LCA) approach to quantify the greenhouse gas (GHG) emissions and energy use associated with the production of mixed hydroxide precipitate (MHP) from low-grade Indonesian laterites via high-pressure acid leaching (HPAL), which is then refined in China for the production of battery-grade nickel sulphate hexahydrate (NiSO4·6H2O, NSH). Fifteen impact categories are analyzed using established impact assessment and allocation (mass and economic) methods. The analysis reveals that feed preparation/HPAL and purification are the stages that contribute most to environmental impacts and in particular to global warming potential (GWP). Mass allocation results in higher environmental impacts, with 36.8 kg CO2-eq per 1 kg of Ni in NSH for GWP, compared to 33.8 kg CO2-eq per 1 kg of Ni in NSH when economic allocation is used. Sensitivity analysis shows a potential reduction (up to 13 %) in key impact categories if production of NSH is fully integrated in Indonesia or a greener electricity mix is used. Overall, our results indicate that the production of MHP in Indonesia and its refinement to NSH in China has a GWP about two times higher than the global average. Given the limited number of LCA studies for the production of battery-grade nickel, this study highlights major environmental concerns for the NSH production process from Indonesian laterites and identifies opportunities for improvement, towards a more sustainable global battery supply chain.

Effect of pH neutral on the separation of nickel and cobalt from laterite leaching solution using cyanex 272

Abstract Nickel and cobalt are the most common elements in the earth’s crust that naturally occur in laterite ores. Nickel and cobalt from laterite ores are recovered as products such as mixed hydroxide precipitate (MHP) and mixed sulphide precipitate (MSP). This research focuses on how the nickel laterite leach solution can be processed directly for solvent extraction without going through the precipitation stage. The nitric acid leach solution obtained from the laterite ore is used to extract nickel and cobalt. A cyanex 272 extractant and kerosene mixture will be used as an organic solvent for direct extraction. The raw material used was Indonesian laterite ore from Halmahera Island, which contained Ni (1.72%), Co (0.155%), Fe (26.17%), and other minor elements. The effect of pH in a neutral condition was investigated on the extraction efficiency, distribution coefficient, and separation factor. Nitric acid (1M) was applied as the leaching reagent. The variables include pH variations (6.8; 7.0; 7.2; 7.4; 7.6), 20% cyanex 272, and O/A ratio (1:1/v:v) at 20 minutes with a stirring speed of 500 rpm. Optimum results were obtained at pH 7.4 variation with an extraction efficiency of 69.26% for cobalt and 0% for Ni, respectively. At these optimum conditions, the highest distribution coefficient value is the element cobalt at pH 7.4, and the result is 2.253 with a separation factor (∞). The optimum condition focuses on removing cobalt from the organic phase, not nickel.

Methods of Producing Disordered Rocksalt Cathode Materials

Li-rich cation-disordered rocksalts (DRX) have attracted attention as a promising new class of Co-free Li-ion battery cathodes. Current synthesis and optimization routes of DRX materials often require the use of high-energy ball-milling, which creates inhomogeneous distributions and non-ideal particle morphologies. A new technique to synthesize DRX materials was developed at Materials Engineering Research Facility (MERF) by forming a mixed transition metal hydroxide precursor material through aqueous co-precipitation before calcining the precursor with a Li-source. Such a method enables a controllable and scalable route to synthesize DRX materials.

Influence of Phosphate on Arsenic Adsorption Behavior of Si-Fe-Mg Mixed Hydrous Oxide.

The arsenic adsorption performance of silicon (Si), iron (Fe), and magnesium (Mg) mixed hydrous oxide containing a Si: Fe: Mg metal composition ratio of 0.05:0.9:0.05 (SFM05905) was investigated. SFM05905 was synthesized by the co-precipitation method. Batch experiments on arsenic adsorption were conducted at various temperatures and concentrations. Adsorption isotherms models were represented by a linearized equations and were insensitive to temperature change. The anion selectivity of SFM05905 at single component was high for arsenite (III), arsenate (V), and phosphate (PO4), indicating that PO4 inhibits arsenic adsorption. The adsorption amount of As (III), As (V), and PO4 were compared using a column packed with granular SFM05905, and an aqueous solution was passed by a combination of several anions that are single, binary, and ternary adsorbate systems. As (III) had the highest adsorption amount; however, As (III) and PO4 were affected by each other under the ternary mixing condition. Although the adsorption amount of As (V) was smaller than that of As (III), it was not affected by other adsorbates in the column experiments. Finally, although the adsorption of both arsenic continued, the adsorbed PO4 gradually desorbed.

Leaching of Nickel and Cobalt from a Mixed Nickel-Cobalt Hydroxide Precipitate Using Organic Acids

Nickel (Ni) and cobalt (Co) are strategic metals that have found applications in a wide range of metallurgical and industrial uses. In this study, the dissolution of a mixed nickel–cobalt hydroxide precipitate using organic acids (citric, oxalic, and malic acid) was investigated. Citric acid was found to be the best leaching agent yielding the following dissolution rates: 91.2% Ni, 86.8% Co, and 90.8% Mn. Oxalic acid resulted in low dissolution, which is likely due to the formation of insoluble metal oxalates. The impact of acid concentration, leaching time, and temperature on metal dissolution was systematically examined. The optimal dissolution conditions were identified as 0.5 M citric acid at 30 °C for 30 min, utilizing a 1/20 solid/liquid ratio and a stirring speed of 400 revolutions per minute (rpm). The attempt to use oxidants, such as potassium permanganate (KMnO4) and hydrogen peroxide (H2O2), to achieve selective dissolution in an organic acid environment was not successful, which was different from that in the sulfuric acid case. As for the leaching kinetics in the organic acids, it seems that the leaching of Ni correlates with the Shrinking Core Model, specifically regarding porous-layer diffusion control. Based on the experimental results, the activation energy for the leaching of Ni was estimated to be 3.1 kJ/mol.

Improving electrochemical performance of Ni-rich layered cathode material with combining Co-enriched compositional gradient and radial microstructure

Ni-rich complex layered oxides LiNixMnyCozO2 (x > 0.85) with a combined Ni/Co concentration gradient and radially oriented elongated plate-like primary particles were synthesized with hydrothermal microwave-assisted treatment of an as-prepared mixed hydroxide precursor with aqueous solution of Co source and urea followed by a high temperature annealing with a Li source. The radial distribution of plate-like primary crystallites in microwave-treated materials was achieved through Co-enrichment at the surface, which likely triggered the surface-to-bulk growth of plate-like particles rather than isotropic octahedral crystallites. The Co-modified cathode materials demonstrate greatly improved cycling stability (capacity fade per cycle of 0.04 ± 0.01%) compared to unmodified Ni-rich NMCs (capacity fade per cycle of 0.13 ± 0.02%) with similar Ni concentration, as well as good rate capability (215, 210, 199, 189, 178 and 160 mAh/g at C/10, C/5, C/2, 1C, 2C, and 5C rates at 2.7–4.3V vs Li/Li+). Enhanced electrochemical performance is linked to the improved mechanical integrity, which was achieved through radial microstructure organization of the agglomerates triggered by Co concentration gradient, suppressing the intragranular crack formation.

MDCK-Adaptive Mutation of A169S Changes Glycosylation Pattern of Hemagglutinin and Enhances MDCK-Based H7N9 Vaccine Virus Production without Loss of Antigenicity and Immunogenicity.

The adaptation of egg-derived H7N9 candidate vaccine virus (CVV) in the mammalian cell line is an approach to developing a high-growth virus strain for the mass production of vaccine manufacturing. The adaptive mutations that occur in hemagglutinin (HA) are critical to the activity and potency of the vaccine virus. Previously, we identified a new mutation of A169S in the HA protein of an MDCK-adapted H7N9 vaccine virus (A/Anhui/2013, RG268); however, whether and how this mutation affects vaccine potency remain to be investigated. In this study, we serially passaged RG268 in MDCK cells and found that the HA titer and the TCID50 of the passaged virus RG268-M5 were 4-fold (HA units/50 μL) and 3.5-fold (log10 TCID50/mL) higher than those of the original CVV. By inspecting tandem MS spectra, we identified a new glycosylation site at N167 near the receptor binding site of the HA protein of RG268-M5. Flow cytometry results revealed that RG268-M5 could efficiently infect MDCK cells and initiate viral protein replication as well as that of RG268. Though the new glycosylation site is in the antigenic epitope of viral HA protein, the HI assay result indicated that the antigenicity of RG268-M5 was similar to RG268. Additionally, immunizing mice with RG268-M5 mixed aluminum hydroxide could induce potent antibody responses against the homologous and heterologous H7N9 viruses in vitro whereas the titers were comparable with those from the RG268 group. These results provide in-depth structural information regarding the effects of site-specific glycosylation on virus properties, which have implications for novel avian influenza vaccine development.

Enhancing the oxygen evolution reaction activity of CuCo based hydroxides with V2CT x MXene.

The oxygen evolution reaction (OER) is a key reaction in the production of green hydrogen by water electrolysis. In alkaline media, the current state of the art catalysts used for the OER are based on non-noble metal oxides. However, despite their huge potential as OER catalysts, these materials exhibit various disadvantages including lack of stability and conductivity that hinder the wide-spread utilization of these materials in alkaline electrolyzer devices. This study highlights the innovative chemical functionalization of a mixed copper cobalt hydroxide with the V2CT x MXene to enhance the OER efficiency, addressing the need for effective electrocatalytic interfaces for sustainable hydrogen production. The herein synthesized CuCo@V2CT x electrocatalysts demonstrate remarkable activity, outperforming the pure CuCo catalysts for the OER and moreover show increased efficiency after 12 hours of continuous operation. This strategic integration improved the water oxidation performance of the pure oxide material by improving the composite's hydrophilicity, charge transfer properties and ability to hinder Cu leaching. The materials were characterized using an array of materials characterization techniques to help decipher both structure of the composite materials after synthesis and to elucidate the reasoning for the OER enhancement for the composites. This work demonstrates the significant potential of TMO-based nanomaterials combined with V2CT x for advanced innovative electrocatalytic interfaces in energy conversion applications.

Comparative study of mixed ammonium fluoride complex-derived single metal hydroxides based on cobalt and nickel for energy storage applications

Zeolitic imidazolate framework 67 (ZIF67) have been intensively applied as efficient active materials for energy storage. Structure directing agents (SDA) play important roles on morphology and electrochemical performance of active materials. Incorporating SDA in synthesis is expected to confine growth of ZIF67 derivatives and create efficient active materials. Ammonium fluoride (NH4F) has been widely applied as an effective SDA for synthesizing active materials in electrochemical systems. Inspired by the confiner of NH4+ and the conductive agent of F−, two novel SDA of ammonium hydrogen fluoride (NH4HF2) and ammonia borane fluoride (NH4BF4) are introduced to synthesize Ni-based or Co-based ZIF67 derivatives via a one-step solution process at room temperature. Substituting 2-methylimidazole with HF2− and BF4− improves conductivity of ZIF67. Effects of NH4HF2 to NH4BF4 ratio for synthesizing ZIF67 derivatives are investigated. The main compositions of ZIF67 derivatives are cobalt and nickel hydroxides. The largest specific capacitance (CF) of 1112.4 F/g is attained for the optimized Ni-based ZIF67 derivative (NiHB) at 20 mV/s. An asymmetric supercapacitor with the NiHB and activated carbon electrodes shows a maximum energy density of 32 Wh/kg at the power density of 750 W/kg, and the CF retention of 70% and Coulombic efficiency of 90.6% after 10,000 cycles.

Dual-atomic-sites anchored on nanosized hollow polyhedron to boost oxygen reduction reaction in acidic electrolyte

Fe and Co dual atomic sites anchored on a hollow carbon nanocage (Fe/Co–N–C) have shown notable advantages in improving the activity and stability toward the oxygen reduction reaction (ORR) in the acidic media. However, it is yet challenging to design such nanostructured Fe/Co–N–C electrocatalysts in a simple manner. In this research, hollow polyhedral carbon nanocages modified by Fe, Co-dual metal atoms are designed from ZIF-8 which involves cage-inclusion of mixed metal salts and conversion to mixed metal hydroxides before high-temperature pyrolysis. The optimized Fe/Co–N–C demonstrated one of the best acidic ORR performances, exhibiting a half-wave potential (E1/2) of 0.81 V (vs. RHE) in 0.5 M H2SO4, and a slight decay of 13 mV in E1/2 after 10,000 cycles. Compared to Fe–N–C counterpart, the improved ORR performance of Fe/Co–N–C is attributed to the synergism between Fe-Nx and Co-Nx active sites, which are attested by various characterizations and control experiments.

Synthesis of nano-architectured copper-cobalt layered double hydroxide for energy storage applications

The uprisal in demand for alternative energy storage devices because of the expeditious depletion of natural resources is pushing the research frontiers to develop clean and efficient energy sources. Supercapacitors are drawing colossal attention due to its high-power density, low cost, and wearable properties. Herein we report the preparation of mixed copper-cobalt Layered double hydroxide (LDH) Cu1Co1 and Cu2Co1 (CC1 & CC2) in (1:1) and (2:1) molar ratios respectively by the sonochemical method and the prepared samples are characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), and High-Resolution Transmission Electron microscopy (HR-TEM) analysis. An imperceptible change in the concentration causes a difference in their morphology which is established by SEM images. To unleash the potential of Cobalt-based LDH a thorough study of their morphology is carried out meticulously which may usher us to develop novel supercapacitor electrodes. The specific capacitance of the constructed asymmetric devices CC1 and CC2 was found to be 28F/g and 50F/g.

Karakterisasi Spektroskopi Raman pada Purifikasi Mixed Hydroxide Precipitate dari Baterai Lithium Bekas

Electrical energy storage batteries are a form of this supporting technology. Lithium batteries are considered the most suitable battery technology for many types of electronic devices today. Waste of used batteries will also increase as LIB production increases. The recycling process is one way to dispose of used batteries because they contain high levels of heavy metals, which pose a significant risk. The most common treatment method for battery recycling is hydrometallurgy. The most important of the various hydrometallurgical steps is the leaching process. The mixed hydroxide precipitate (MHP) will be the product of the precipitation on the NMC metal. Na2SO4 is always an impurity present in MHP products. Therefore, the MHP still needs to be purified to achieve the highest possible purity so that it can be used as a cathode in battery manufacturing. Raman’s spectroscopic was used to analyze the characteristic of MHP purification with variation 30, 50, 70 and 90 oC.

Highly atom-economic synthesis and scale-up production of zinc-aluminum layered double hydroxides

ZnAl layered double hydroxides (LDHs) has been widely applied as functional additives in polymers. The common coprecipitation method used to synthesize ZnAl LDHs has an atomic utilization of only 44.35 %, and is accompanied with the formation of sodium salt by-product, ZnO impurities and lots of waste water. In this work, we proposed a green and cost-effective synthesis route with 100 % atom economy to prepare ZnAl LDHs from mixed metal oxides and hydroxides. Pure ZnAl LDHs was synthesized at 120 °C. A dissolution-nucleation-diffusion reaction mechanism was proposed through structural and morphological studies and reaction kinetics calculations. The prepared ZnAl LDHs exhibited excellent smoke suppression properties, with a reduction in the smoke density of PVC from 705 to 340. This proposed method was successfully scaled-up and applied on a 1000 t/a industrial production line, providing a valuable opportunity for the reaction design and large-scale preparation of LDHs and other inorganic compounds.

Different metal precursor based rapid synthesis of α-Ni(OH)2-type Ni-Co-Mn layered double hydroxides and its use as electrodes for high performance energy storage devices

Improvement in the specific capacity of battery type electrode material is vital for creating hybrid devices with superior electrochemical performance. To accomplish this, mixed metal hydroxides, Ni0.7Co0.2Mn0.1(OH)2, are synthesized via a simple co-precipitation method by rapid pH switching using chloride, nitrate, acetate and sulphate salts of Ni, Co and Mn. P-XRD analysis confirmed the formation of pure and highly crystalline materials stabilized in the α-Ni(OH)2 structure. Finely divided particle type microstructure with sub 100 nm size and homogenous distribution of elements are confirmed by FESEM and EDX analysis, respectively. Among the studied samples, the layered hydroxide synthesized using chloride salts (Ni0.7Co0.2Mn0.1 LDH-Cl) shows the highest specific surface area of 58.8 m2 g−1 and pore volume of 0.083 cc g−1. The compound exhibited a high specific capacity of 978 C g−1 at 1 A g−1. The observed capacity is much higher than all other double hydroxides studied here and those we have come across in the literature reports on similar metal hydroxides. The diffusion dominance (b = 0.55) and quantitative separation of diffusion and capacitive capacity at different scan rates for Ni0.7Co0.2Mn0.1 LDH-Cl is also studied by CV analysis. Nyquist plot equivalent circuit fitting shows low charge transfer resistance (Rct = 17.6 Ω) and Warburg impedance (Zw = 35 Ω) for Ni0.7Co0.2Mn0.1 LDH-Cl. The high-capacity retention of 90 % for 5000 CV cycles at 100 mV sec−1 and 99 % for 1000 GCD cycles at 5 A g−1 for Ni0.7Co0.2Mn0.1 LDH-Cl confirm its potential for use as a battery type electrode material for practical applications.

A Liquid and Waste-free Method for Preparing Single Crystal Positive Electrode Materials for Li-ion Batteries

Nickel-rich layered positive electrode materials are normally made by a “co-precipitation-sintering” method. Mixed transition metal hydroxides called “precursors” are prepared by co-precipitation to ensure homogeneous cation mixing at the atomic level and to create spherical particles which ensure high-performance poly-crystalline materials. Single crystal materials, which show better capacity retention in long-term cycling can be made from the same mixed transition metal hydroxide precursors by sintering at a higher temperature which inevitably destroys the spherical morphology present in the initial precursors. Here we describe a method for single crystal positive electrode material production which we call “all-dry synthesis” since it does not require the use of any liquid and creates no waste unlike the co-precipitation method. The exemplary reaction between Ni, MnCO3, and LiOH·H2O was studied in situ by synchrotron XRD in order to define a proper heating scheme for the all-dry process. The crystal structure, particle morphology, surface residual impurities, and electrochemical performance of materials prepared by the “all-dry synthesis” method are equivalent to or even better than those of materials made using a conventional co-precipitation method.

Use of Highly Dispersed Mixed Metal Hydroxide Gel Compared to Bentonite Based Gel for Application in Drilling Fluid under Ultra-High Temperatures.

In order to solve the problem of poor dispersion and stability of mixed metal hydroxide (MMH), a kind of mixed metal hydroxide-like compound (MMHlc) gel was synthesized for use as the base mud in drilling fluid instead of bentonite gel. Na2CO3, Na2SiO3, and C17H33CO2Na were used as precipitants to form MMHlc with larger interlayer spacing and smaller particle size. MMHlc was synthesized by the coprecipitation method at 25 °C with a metal molar ratio of Mg:Al:Fe = 3:1:1. The performance evaluation of the treated drilling fluid showed that MMHlc (S2) synthesized using Na2SiO3 as the precipitant had the characteristics of low viscosity, low filtration, and a high dynamic plastic ratio at 25 °C, which fully met the requirements of oil field application, and it maintained its excellent properties after being aged at 250 °C for 16 h. Linear expansion and rolling recovery experiments showed that the S2 sample had excellent rheological properties and good inhibition. X-ray diffraction and FT-IR experiments showed that S2 had the most complete crystal structure, its interlayer distance was large, and its ion exchange capacity was strong. The thermogravimetric experiment showed that the S2 crystal was stable and the temperature resistance of the crystal could reach 340 °C. Zeta potential, particle size analysis, SEM, and TEM results showed that S2 is a nanomaterial with a complete morphology and uniform distribution. The drilling fluid of this formula had the characteristics of low viscosity, low filtration loss, and a high dynamic plastic ratio, and it met the conditions for oil field application. Considering these results, the new MMH prepared by our research institute is a drilling fluid material that can be used at ultra-high temperatures and can provide important support for drilling ultra-deep wells.

Contribution of Obi Island Reducing the Carbon Footprint in the Transport Sector

Transportation is one of the main sectors contributing to greenhouse gas (GHG) emissions that cause global climate change. One of the decarbonization strategies from the transportation sector that can be implemented is by switching to a sustainable mode of transportation, especially battery electric vehicles (BEV). Since mid-2021, Obi Island has been producing Mixed Hydroxide Precipitate (MHP). It is an intermediate product of limonite nickel ore processed using hydrometallurgical processing techniques through the first refining plant in Indonesia using High Pressure Acid Leaching (HPAL) technology. The MHP will be processed into Nickel Sulfate (NiSO4.6H2O) and Cobalt Sulfate (CoSO4.7H2O), the primary precursor materials for electric vehicles. The potential GHG emissions reduction in the transportation sector from the processing of limonite nickel ore in Obi Island is 2.04 MtCO2 in 2022 to 21.02 MtCO2 in 2040 with a total accumulation until 2040 of 344.56 MtCO2.

A Comprehensive View of the Optimization of Chromium (VI) Processing through the Application of Electrocoagulation Using a Pair of Steel Electrodes.

In the presented article, an electrocoagulation method using a steel cathode and a steel anode was used to obtain chromium from laboratory-prepared model solutions with known compositions. The study aimed to analyze the effect of solution conductivity, pH, and 100% efficiency of chromium removal from the solution, as well as the highest possible Cr/Fe ratio in the final solid product throughout the process of electrocoagulation. Different concentrations of chromium (VI) (100, 1000, and 2500 mg/L) and different pH values (4.5, 6, and 8) were investigated. Various solution conductivities were provided by the addition of 1000, 2000, and 3000 mg/L of NaCl to the studied solutions. Chromium removal efficiency equal to 100% was achieved for all studied model solutions for different experiment times, depending on the selected current intensity. The final solid product contained up to 15% chromium in the form of mixed FeCr hydroxides obtained under optimal experimental conditions: pH = 6, I = 0.1 A, and c (NaCl) = 3000 mg/L. The experiment indicated the advisability of using a pulsed change of electrode polarity, which led to a reduction in the time of the electrocoagulation process. The results may help in the rapid adjustment of the conditions for further electrocoagulation experiments, and they can be used as the optimization experimental matrix.