Physico-chemical properties of silicon dioxides obtained by extraction from sulfuric acid solutions from acid decomposition of nepheline

The synthesis of silica was carried out by extraction from a silica-containing solution from the decomposition of nepheline using acetone and ethanol, followed by gelatinization of the organic phase. The structural and surface properties of the obtained sample of SiO2 were studied and the pH of the isoionic point of their surface was determined. It was found that the use of extraction does not have a destructive effect on the specific surface of the SiO2 xerogel and allows preserving its original microporous structure.

Selectivity of extraction of rare earth metals from sulfuric acid media by neocarboxylic acid hydrazides

The effect of Fe3+, Al3+, and PO43- ions on the efficiency of extraction of REM ions from sulfuric acid solutions was studied. The effectiveness of the HD1519 reagent for the concentration and selective extraction of REM ions is shown.

Chemical, electrochemical and surface studies of new metal–organic frameworks (MOF) as corrosion inhibitors for carbon steel in sulfuric acid environment

The effects of [Co2 (SCN) 4(hmt)2(H2O)6. H2O] (SC1) and [Co (CN)6 (Me3Sn)3(H2O). (qox)] (SCP2) MOF as corrosion inhibitors on C-steel in 0.5 M sulfuric acid solutions are illustrated utilizing mass reduction (MR), electrochemical [potentiodynamic polarization (PP), and AC electrochemical impedance (EIS)]. The experiments revealed that as the dose of these compounds rose, the inhibition efficacy (IE percent) of C-steel corrosion improved, reaching 80.7–93.1% at dose 25 × 10−6 M for SC1 and SCP2, respectively. IE percent, on the other hand, dropped as the temperature range grew. SC1was adsorbed physically and chemically (mixed adsorption) but SCP2 was adsorbed physically on the surface of C-steel and conformed to the Langmuir adsorption isotherm equation. The PP studies revealed that these compounds act as mixed kind inhibitors. To establish the morphology of the inhibited C-steel surface, scanning electron microscopy (SEM), energy transmitted X-ray (EDX), and atomic force microscopy (AFM) studies were used. All tested experiments were in good agreement.

Leaching of Zinc for Subsequent Recovery by Hydrometallurgical Techniques from Electric Arc Furnace Dusts and Utilisation of the Leaching Process Residues for Ceramic Materials for Construction Purposes

Steel is one of the most widely used materials in the past and today. Various techniques are used to recycle this material, including the electric arc furnace. This process has several advantages, but it also has a major disadvantage, namely, the generation of waste such as electric arc furnace dusts. Electric arc furnace dusts are classified as hazardous waste due to their high percentage of heavy metals, including zinc. Consequently, in the present research, the leaching of zinc for recovery with sulfuric acid solutions at ambient temperature and atmospheric pressure is evaluated, as well as the reuse of the leaching process residue as a raw material for ceramic materials. The sulfuric acid solutions were 0.125, 0.25, 0.5, and 1 molar, using clay for ceramic conforming and percentages of the leaching residue from 0–50%. The results showed that the optimum solution was 1 molar sulfuric acid, recovering all the zinc in the sample in 36 h. Furthermore, it was found that the clay-conformed ceramics with less than 40% leaching residue showed acceptable physical and mechanical properties according to standards. Therefore, this research develops a new environmental hydrometallurgy in which metallic elements of interest are valorized and the production of waste is avoided, reducing the deposition of hazardous waste in landfills and the extraction of raw materials for the manufacture of construction materials.

Synthesis and study of the extraction properties ofnew phosphorus-containing extractants of heavy metals

The metallurgical industry is one of the cornerstones of contemporary chemical science and industry and it is developing rapidly in many countries. The widespread introduction of metal extraction, concentration and separation as the most productive methods entails the need to search for and create new effective metal extractants. Among the compounds, suitable for use as extractants, the most widespread are organic phosphites and phosphates, which allow performing extraction processes with good selectivity and efficiency. The purposes of this article include finalizing the optimal synthesis conditions and developing larger batches of 4,5-dimethyl-2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane and 5,5-dimethyl-2-(2,2,3,3,4,4,5,5- octafluoropentoxy)-1,3,2-dioxaphosphorinane, and study of the extraction properties of the obtained phosphorus- containing heterocyclic compounds in the separation of uranium from the commercial desorbate. The synthesis of new representatives of the indicated polyfluoroalkylated five- and six-membered heterocyclic phosphorus compounds was conducted using the interaction of 2-chloro-1,3,2-dioxaphospholane with trifluoroethanol and the substitution–cyclization reaction of polyfluoroalkylated dichlorophosphite with 2,2-dimethyl- 1,3-propanediol. Reactions easily proceed in triethylamine–hexane or pyridine–diethyl ether systems at temperatures ranging between minus ten to room temperature, with the output of target heterocycles of 53–57%. The studies of extraction properties of synthesized poly-fluorinealkylated dioxaphospholane and dioxaphosphorinane show that the use of these phosphorus-containing heterocyclic compounds as extractants allows extracting a technically valuable metal up to 12.4 and 15.2%, respectively. Nitric and sulfuric acid solutions of commercial desorbate of hydrometallurgical production in Kazakhstan were used as feedstock in the extraction process.

STUDY OF SORPTION OF RHENIUM IONS ON SOLID EXTRAGENTS

In this work, the aim is to study the possibility of extracting rhenium from sulfuric acid solutions by sorption of impregnated sorbents based on polystyrene-divinylbenzene (MN202) and an organic reagent MAB (2-amino-1-methylbenzimidazole).New sorbent based on MN202 (Purolite) impregnated with organic reagents have been obtained and investigated. The sorbent characteristics determined using SEM, XRD and FTIR methods. The optimal conditions for the sorption of rhenium (VII) ions for the "element-sorbent" systems have been established. Under static conditions, the sorption of rhenium on impregnated sorbents in a sulfuric acid solution was studied in the periodic system with respect to the contact time, sulfuric acid concentration, the ratio of the solid phase to liquid, and the initial concentration of rhenium. For the first time, the kinetics of sorption of rhenium (VII) ions with the obtained solid extractants has been studied. The kinetic parameters of the chemical reaction on the surface of the impregnate have been determined. Based on the processing of the integral kinetic curves of sorption, it was found that the sorption process proceeds in accordance with second-order models.