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Synthesis of Silver Nanoparticles and Silver-Gold Binary System by Galvanic Replacement in an Ultrasonic Field

The conditions for the synthesis of colloidal solutions of silver nanoparticles by galvanic replacement in an ultrasonic field and the AgAuNP binary system by galvanic replacement have been studied. It has been shown that colloidal solutions of stabilized nanoparticles with absorption maxima at 410 nm (AgNPs) and 540...560 nm (AgAuNPs) are formed in solutions of sodium polyacrylate and metal precursors of AgNO3 and H[AuCl4]. The synthesized AgAuNPs are spherical in shape and their size does not exceed 20 nm.

Degradation of Congo Red Using Periodate, Activated by Ultrasound and Iron(II)

The periodate, activated by the combination of ultrasound and Fe(II), was used for oxidative degradation of an anionic diazo dye of congo red (CR). The effect of the main factors (the initial pH, the molar ratio of CR:KIO4:FeSO4, the amount of Fe(II), and the specific power of ultrasonic cavitation treatment) on its degradation efficiency was analyzed.

Demulsification Methods for Heavy Crude Oil Emulsions. A Review

Demulsification (dehydration) is one of the most important problems in the oil industry. The peculiarity of heavy oil emulsions is their high stability since heavy crude contains a significant quantity of resins and asphaltenes. This paper provides an overview of the issue of heavy oil emulsion dehydration, emphasizing the importance of understanding their properties to develop appropriate demulsification methods. The use of environmentally friendly demulsifiers was an object of special attention.

Activated Periodates and Sodium Percarbonate in Advanced Oxidation Processes of Organic Pollutants in Aqueous Media: A Review

The methods of periodates and sodium percarbonate activation are considered for planning strategic approaches to increasing the efficiency and intensity of oxidative degradation of organic pollutants in aquatic environments. A classification of periodate activation methods is proposed, including activation methods by external energy effects, catalytic activation methods, and other activation methods (e.g., by hydrogen peroxide, by hydroxylamine, activation in alkaline medium). Activation methods for sodium percarbonate were divided into homogeneous and heterogeneous activation methods.

Perspectives of Treatment of Water Environments from Pollutants with Ultrasound-Activated Bentonites

The paper analyzes the perspectives for natural sorbents to be used in environmental technologies. The object of the study is the clay rock from the left side of the upper Pivdennyi Bug river (in the vicinity of the Khmelnytskyi city). The rock was enriched in montmorillonite by centrifugation of a clay suspension to obtain the fraction with a size of less than 5∙10-6 m. The researchers defined the mineral composition of the enriched clay based on the findings of the X-ray diffraction and complex thermal analyses.

Characterization, Antioxidant Activity, and In Silico Molecular Docking of Chitosan from Snail Shell Waste by Ultrasonic Technique

Snails are often found in Indonesia, especially at Kediri, but the snail shell has no commercial value. This research report describes the characterization and antioxidant activity of chitosan from snail shell waste (chitosan-SSW) by ultrasonic technique and analyzes the potential of chitosan as an inhibitor of receptors of free radicals using an in silico molecular docking method.

Synthesis of Antibacterially ActiveSilver Nanoparticles by Galvanic Replacement on Magnesium in Solutions of Sodium Polyacrylate in an Ultrasound

“Green” synthesis of silver nanoparticles (AgNPs) by a galvanic replacement (GR) on magnesium in solutions of sodium polyacrylate (NaPA) under ultrasound (42 kHz) is reported. The mechanism of combined action of GR and ultrasound on the formation of nanoparticles is proposed. Synthesized solutions of AgNPs are characterized by an absorption maximum at 410 nm, the value of which does not depend on the concentrations of precursors (AgNO3 and NaPA) and the duration of the process. The dimensions of nanoparticles that have a spherical shape do not exceed 30 nm.

AN INFLUENCE OF CAVITATION PHENOMENA ON THE DESTRUCTION PROCESSES OF ORGANIC AND BIOLOGICAL POLLUTIONS IN THE WATER

The regularities of cavitation treatment of food and chemical industries wastewater from organic and biological contaminants in the presence of gases of different nature were studied. The optimal temperature range 313K - 318 K for cavitation wastewater treatment was established. It is shown that the process of cavitation destruction of organic compounds can be described by a first - order kinetic equation.

Establishment of the Regularities of the Concentrations Change of Microorganisms and Water-Soluble Compounds in Polluted Water after Ultrasound Treatment

The regularities of the change of the concentration of microorganisms and water-soluble organic compounds in the polluted water in the conditions of cavitation treatment and the influence of the amount of biological water pollution on the value of the chemical oxygen consumption are investigated.

INFLUENCE OF ULTRASOUND ON THE SYNTHESIS OF SILVER NANOPARTICLES BY GALVANIC REPLACEMENT IN SODIUM POLYACRYLATE SOLUTIONS

Sonogalvanic replacement and galvanic replacement synthesis of silver nanoparticles (AgNPs) by magnesium scrap in sodium polyacrylate solutions were studied. It was found that during these processes in NaPA solutions silver is practically not deposited on the magnesium surface. Sodium polyacrylate provides stabilization of AgNPs with the formation of yellow solutions with maximum absorption of ~415 nm.