INFLUENCE OF CHEMICAL MODIFICATION ON THE COMPOSITION AND PROPERTIES OF ORGANOMINERAL COMPOSITE MATERIALS
Keywords:sodium humate, phosphogypsum, polyacrylamide, chemical modification, organomineral composite materials, carboxyl and phenolic group, ion exchange, complexation
Introduction. The structure characteristic and polyfunctionality of humic substances makes it possible to obtain new products by chemical modification. The aim of this work is to study the regularities of sodium humate modification processes with phosphogypsum and phosphogypsum with polyacrylamide (PAA) mixture, to establish the composition and properties of obtained organomineral composite materials. Methods. Chemical analysis, infrared spectroscopy, differential thermal analysis and scanning electron microscopy. Results and discussion. The possibility of obtaining new types of products by modifying sodium humate with phosphogypsum and its mixture with PAA is shown. The dependence of the composition and properties of obtained organomineral composite materials on the modifier nature has been revealed. The chemical modification has been shown to increase the content of COOH groups to 0.24 mg-eq/g, phenolic OH groups to 1.83 mg-eq/g, total pores to 0.44 cm3/g, static exchange capacity to 27.25 mg-eq/g, P2O5 to 1.34%, nitrogen up to 1.71% and the humic acid yield - up to 42.83%. The reaction between sodium humate and phosphogypsum proceeds leads to an increase in the content of total, digestible and water-soluble forms of P2O5. Conclusion. It has been established that the use of phosphogypsum for humic substances modification contributes to the phosphorus production waste processing. Organo-mineral materials obtained by modifying sodium humate acquire growth-stimulating, fertilizing, reclamation, water-retaining, and sorption properties. The complexity and multi-component composition of synthesized compositions is determined by DTA, IR, SEM methods. It has been shown that when sodium humate is modified with phosphogypsum, ion exchange reactions and complex formation occur.