The article studies the technological features of calcium sulfide production from phosphogypsum. To ensure the environmental safety of industrial enterprises, closed production cycles creation is necessary. One of the criteria for “green” technologies is industrial waste recycling. Phosphogypsum formed during the orthophosphoric acid production from apatite raw materials by sulfuric acid method can be classified as large-tonnage waste. Phosphogypsum can be considered a mineral with zero mining costs and zero feedstock to produce valuable products. The synthesized materials are characterized using a complex of modern methods such as X-ray phase analysis, and electron microscopy. An environmentally friendly precursor, sucrose, is used as a reducing agent for calcium sulfate. The recovered material is a mixture of calcium sulfate and sulfide. When illuminated with ultraviolet light, it glows yellow-orange. The article presents an integrated approach to the problem of phosphoric acid production waste disposal by marketable products production.

Scientific interest in the processes of forming the structure of magnetic spinels and composites based on them is due to the possibility of synthesis of materials with multifunctional properties. The process of formation of cobalt (II) nanocrystalline ferrite and CoFe2O4/C composite material is studied. The mechanism of formation of structure of materials including a stage of formation of hydroxides of transition elements, precursors on the basis of complex connections of cations of iron and cobalt with citric acid and their subsequent destruction at heating is offered. The synthesized materials were characterized by x-ray phase analysis, electron microscopy, low-temperature nitrogen adsorption, Debye-Scherrer methods. It is shown that cobalt (II) ferrite has a developed surface, the value of the surface area according to the BET method is 16 m2/g, the average size of the crystallites determined by the Debye-Scherrer equation is 4.0 nm. Activated carbon with a specific surface area of 685 m2/g was used to prepare the composite material. The resulting composite material has a surface area of 222 m2/g, the average crystallite size of 1.1 nm. Cobalt (II) ferrite, included in the composition of the composite material CoFe2O4/C, has a slightly higher value of the lattice parameter, compared with pure cobalt (II) ferrite, which is associated with a decrease in the degree of spinel inversion. The synthesized composite material was tested in the process of adsorption of copper (II) cations from an aqueous solution. It is shown that CoFe2O4/C exhibits an increased adsorption capacity for copper (II) cations in comparison with pure activated carbon, despite a decrease in the specific surface area. The result is explained by the involvement of cobalt (II) ferrite in the adsorption process. The obtained materials may be of interest as catalysts, adsorbents.

The paper considers the process of processing phosphogypsum into an inorganic luminescent material. The synthesized materials were characterized using X-ray phase analysis and scanning electron microscopy. It has been shown that phosphogypsum reduced with sucrose exhibits the ability of luminescence under the action of ultraviolet radiation, glowing with yellow-orange light. A process for the recovery of phosphogypsum has been proposed. The results obtained open up the possibility of processing large-tonnage waste into demanded cheap materials.

In modern society, the detrimental effect of industrial production on the environment is intensifying. Contaminated wastewaters of industrial enterprises deteriorate the environmental situation and violate the ecosystem stability. One of efficient methods of dealing with harmful impurities in wastewater is to remove them using adsorption active materials. Oxide systems of ferrites of transition elements are one example of materials with multifunctional properties. The possibility of synthesizing nanoscale cobalt (II) ferrite and a composite material based on it with the CoFe2O4/C composition was studied. The obtained materials were studied using X-ray phase analysis, electron microscopy (SEM), and the BET method of low-temperature nitrogen adsorption. It was established that cobalt (II) ferrite has a developed surface (the surface area measured by the BET method is 16 m2/g, the average crystallite size obtained by the Debye-Scherrer method is 4.0 nm). The mechanism of CoFe2O4 structure formation is considered. The composite material CoFe2O4/C is characterized by a high surface area (222 m2/g, average crystallite size of 1.1 nm) and exhibits increased adsorption ability with respect to copper (II) cations from aqueous solutions. The obtained results are of interest as materials for purification of aqueous solutions.