Ukrainian State University of Chemical Technology

Sustainable development goals emphasize the need for cost-effective removal of nitrates from water of sources where there is no centralized tap water supply.This paper describes the properties of the carbonate system in the filtrate of the point of use handy submersible denitrifying biofilter.Device has a U-shaped design with open tops of both elbows and operates in displacement (piston) mode.These allows getting up to 5 L of denitrified water daily in one gulp, reducing the concentration of nitrate ions in the water by 96-98% from its initial value of $3\cdot 10{̂-3}M-1.2\cdot 10{̂-2}M$3·10-3M-1.2·10-2M and the water hardness to reduce depending of initial nitrate concentrationThe denitrification process occurs with the consumption of Et alc. as a bacterial food substrate injected to water and accompanies by the accumulation of alk. bacterial exometabolites in the filtrate.During the microbiol. transformation of $3\cdot 10{̂-3}M$3·10-3M nitrate ions into nitrogen gas, the filtrate enriches with $2.6\cdot 10{̂-3}M$2.6·10-3M bicarbonate ions and $3.9\cdot 10{̂-4}M$3.9·10-4M of hydroxyl ions.This results in a reduction of filtrate hardness from 3.75 mg-eq/L to 1.87 mg-eq/L when in contact with atm. air.Phys. experiments and math. modeling verified the concentrations of carbonate components and calcium ions in both the initial and denitrified water.

The controlled synthesis of gold nanoparticles (Au NPs) via a green method, without the use of addnl. reducing agents, has been successfully achieved.This study introduces a novel approach to the synthesis of Au NPs using a liquid-phase plasma process in a natural matrix-sodium alginate.The influence of precursor concentration and plasma discharge time on nanoparticle characteristics was systematically examined, demonstrating high catalytic and antibacterial efficiency.The synthesis was conducted by generating anode-type plasma between two electrodes, with the cathode immersed in an aqueous sodium alginate solution containing a gold precursor.It was established that under plasma-chem. synthesis conditions, sodium alginate functions exclusively as a stabilizer and does not act as a reducing agent, thus not accelerating nanoparticle formation.The impact of plasma discharge duration (3-10 min) and gold (III) chloride trihydrate precursor concentration (0.06-2.5 mmol/L) on Au NP morphol., size (22-75 nm), and optical absorption properties was investigated.It is recommended to synthesize nanocapsules in this range of processing times and initial precursor concentrationsTo control the particle size, the initial precursor concentration should be varied.The synthesized nanoparticles exhibited diverse morphologies, including spherical, hexagonal, and triangular, depending on precursor concentrationComparative anal. of nanoparticle dispersions synthesized with and without sodium alginate highlighted the role of the natural matrix in nanoparticle stabilization.The catalytic activity of Au NPs was demonstrated in the reduction of methylene blue (MB) to leucomethylene blue (LMB) in water at room temperatureIt was established that plasma-chem. obtained nanoparticles without a stabilizer will exhibit higher catalytic properties in comparison with the stabilized: the rate constants are calculated to be 0.25 and 0.12 min-1.Addnl., significant antibacterial activity against E. coli was observedThe environmental sustainability of the synthesis approach for photocatalytic dye degradation was assessed using AGREEpre tools, confirming its eco-friendliness.This study provides insights into a scalable and sustainable method for producing Au NPs with potential applications in catalysis, biomedicine, and environmental remediation.

The development of an efficient and highly productive synthetic protocol for preparation of new 2,5-diamino-1,3,4-thiadiazole derivatives functionalized with N-(2,2,2-trichloroethyl)carboxamide group was reported.The method of their preparation was based on the reaction of oxidative dehydrosulfurization of N-(2,2,2-trichloro-1-(2-(phenylcarbamothioyl)hydrazine-1-carbothioamido)ethyl)carboxamides and N-(1-(2-carbamothioylhydrazine-1-carbothioamido)-2,2,2-trichloroethyl)benzamide under the action of a mixture of iodine and triethylamine in DMF.This reaction took place at room temperature for two hours and allowed obtaining the target products with a 69-75% yield.Using the developed protocol, ten new derivatives of 1,3,4-thiadiazole were obtained.Their structure was proven by IR,¹H NMR,¹³C NMR, ¹H-¹H COSY, ¹H-¹³C HSQC, ¹H-¹³C HMBC spectroscopy and LC/HRMS spectrometry.