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The influence of magnesium anode dissolution in pipe filled with potable water on the steel corrosion rate was investigated. Steel corrosion rate was measured using the weight loss technique, and linear polarization resistance measurements were used to estimate the formation kinetics and protective abilities of the phase layer on the metal surface. The cathodic current distribution along steel pipe was measured using a microammeter and compared with the computer model. The results clearly demonstrate that the reduction of metal corrosion rate is at least 2.8 times in the region where cathodic protection distributes inside the pipe. However, for the remaining part of the metal pipe, the reduction of corrosion rate of 1.5 times was obtained due to the formation of the phase layer on the metal surface that leads to the reduction of oxygen supply. The results obtained in the study can be further applied for designing and maintenance of water supply systems. [ABSTRACT FROM AUTHOR]

The production of low-cost ceramic membranes from natural materials has attracted more and more attention in recent years, as it allows them to reduce their cost while maintaining their advantages. The aim of this study was the synthesis of ceramic membrane supports from kaolin of Ukrainian origin and their characterization. The choice of such a raw material as kaolin was dictated by its characteristics, which were investigated by X-ray and chemical analysis, the nitrogen adsorption/desorption method and thermogravimetric analysis. Ceramic membrane supports were prepared by dry pressing method followed by sintering at 950 °C. The phase composition, morphological structure and structural-adsorption characteristics of the synthesized supports has been established. The effect of the content of boric acid on the electrical resistance of the membrane support has been studied. The ceramic supports after modification of silver demonstrated bactericidal and antifungal effects on Gram-negative (Escherichia coli) and Candida albicans wound pathogens. [ABSTRACT FROM AUTHOR]

The new molecular nickel(II) complex, namely, {4-bromo-2-[({N′-[(2-oxidobenzylidene)amino]carbamimidoyl}imino)methyl]phenolato}nickel(II) N,N-dimethylformamide solvate monohydrate, [Ni(C15H11BrN4O2)]·C3H7NO·H2O, (I), crystallizes in the triclinic space group P\overline{1} with one molecule per asymmetric unit. The guanidine ligand is a product of Schiff base condensation between aminoguanidine, salicylaldehyde and 5-bromosalicylaldehyde templated by Ni²+ ions. The chelating ligand molecule is deprotonated at the phenol O atoms and coordinates the metal centre through the two azomethine N and two phenolate O atoms in a cis-NiN2O2 square-planar configuration [average(Ni--N/O) = 1.8489 Å, cis angles in the range 83.08 (5)-95.35 (5)°, trans angles of 177.80 (5) and 178.29 (5)°]. The complex molecule adopts an almost planar conformation. In the crystal, a complicated hydrogen-bonded network is formed through N--H...N/O and O--H...O intermolecular interactions. Complex (I) was also characterized by FT-IR and ¹H NMR spectroscopy. It undergoes an NiII ↔ NiIII redox reaction at E1/2 = +0.295 V (vs Ag/AgCl) in methanol solution. In a thin film with a free surface, complex (I) shows a fast photoelectric response upon exposure to visible light with a maximum photovoltage of ∼178 mV. [ABSTRACT FROM AUTHOR]

Extracts from the blackcurrant and apricot pomaces were obtained by ultrasound-assisted extraction. Characterization by LC-MS and HPLC methods were performed and total phenolic compounds (TPC), total flavonoid compounds (TFC) and antioxidant activity were assayed. LC-MC and HPLC analysis indicated the presence of phenolic compounds, hydroxycinnamic acids and flavonoids. Various experimental models including iron (III) reducing capacity, total antioxidant capacity, DPPH radical scavenging activity and ABTS•+ radical cation scavenging assay were used for characterization of antioxidant activity of extracts. The blackcurrant and apricot pomaces extracts were tested using cyclic voltammetry (CV). [ABSTRACT FROM AUTHOR]

The component profiles of apricot, grape, and black currant pomace extracts have been analyzed using HPLC coupled to diode-array detection and tandem mass spectrometry (HPLC-DAD-MS). The predominant components in grape, apricot, and black currant pomace extracts were phenolic acids and flavonols. The redox behavior of apricot, black currant, and grape pomace water extracts was evaluated by means of cyclic voltammetry. Also, individual substances mainly present in the extracts were analyzed. The results of electrochemical testing were compared to traditional chemical techniques of potassium ferricyanide reduction (FRAP) and phosphomolybdenum assay, and fair agreement was established. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assays were applied in order to estimate antioxidant activity. The reducing power of the grape extract was found to be higher than that of the apricot and black currant extracts in both potassium ferricyanide reduction (FRAP) and phosphomolybdenum methods. [ABSTRACT FROM AUTHOR]

Agrifood by-products are a key element within Europe's sustainable strategies. Valorization and reuse of zero-waste technologies are becoming more popular, and they are commonly named as "second-generation food waste management." The present study is directed to the valuable extracts of "green" organic compounds from the by-products of fruit and berry/vegetable crops, which can be revalorized in sustainable chemical technology and engineering, namely, in the production of "green" synthesis of nanoparticles and for the inhibition of corrosion and scaling of metals in corrosive media. Numerous types of agrifood by-products (rapeseed pomace, sugar beet pulp, fodder radish cake, grape pomace, and pomegranate peels) were investigated. The waste extracts for corrosion and scale inhibitors of mild steel in tap water were prepared by the conventional extraction method that uses 2-propanol and characterized by gas chromatography-mass spectroscopy (GC-MS). Inhibition of scaling and corrosion was investigated in thermal scaling conditions on the surface of the electrode manufactured from mild steel. The LPR technique was applied to measure the corrosion rate, and the scaling rate was determined gravimetrically. The extracts were found to inhibit the corrosion rate 2-3 times, while only radish cake extract inhibited both the corrosion and scaling rates. The waste extracts to produce nanoparticles were prepared by the ultrasound-assisted water extraction with subsequent oxidation by oxygen purge and characterized by liquid chromatography-mass spectroscopy (LC-MS). The aqueous grape pomace and pomegranate peel extracts were screened for total phenolic content (TPC) and total flavonoid content (TFC). The reduction capacity of the extracts was assessed using ferric reducing power (FRAP) and phosphomolybdenum (PM) assays. AgNPs were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. The particle size of AgNPs ranged between 40 and 50 nm. The antimicrobial activity of AgNPs was tested against Escherichia coli using the agar diffusion method and optical density. [ABSTRACT FROM AUTHOR]

Plate heat exchangers are widespread type of equipment that suffers from pitting corrosion in chloride containing solutions. Anodic behaviour of AISI 316 stainless steel was tested in 3.5% NaCl solution in conditions of ultrasound vibration (27 kHz, 10 W). The potentiodynamic sweep, potentiostatic technique, and galvanostatic technique were used coupled with surface morphology investigation after polarization. The pitting potential increased from 0.26 ± 0.02 V/SSCE to 0.42 ± 0.05 V/SSCE, and repassivation potential increased from 0.03 ± 0.01 V/SSCE to 0.18 ± 0.04 V/SSCE when vibration was applied. The anodic current at applied potential in pitting region was two orders of magnitude lower in conditions of ultrasound vibration. A possible mechanism of vibration influence on pitting is proposed, which is the elimination of pit covers from the vibrating surface, vibration-induced electrolyte motion in and out of the pits, and repassivation of active metal inside the pits. [ABSTRACT FROM AUTHOR]

The water flow rate and galvanic current distribution in the T-shape junction of steel pipes were investigated using the multielectrode array approach. The inner surface of polypropylene pipes junction was divided into 15 separate sections, and a steel plate was placed in every section to form a single inner surface. The tap water flow rate varied between 0.28 and 0.57 m/s, and the water distribution in the junction was between 5 : 1 and 1 : 5. The galvanic current flowing through each steel electrode was mapped on the 3D model of the T-shape junction. Two differential aeration pairs were found with high anodic current densities. [ABSTRACT FROM AUTHOR]

An eco-friendly and low-cost method for synthesizing and capping silver nanoparticles with aqueous extracts of apricot and currant wastes is reported. The chemical profiles of the extracts were analysed using liquid chromatography-mass spectrometry (LC-MS). Total phenolic content and total flavonoid content of extracts were determined. The antioxidant activity of the synthesized nanoparticles was evaluated by DPPH (1,1-diphenyl-2-picrylhydrazyl) power assays. Cyclic voltammetry study was performed to determine the reducing ability of the aqueous extract of the black currant and apricot pomaces. Characterization of AgNPs was carried out using energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible spectroscopy. Zeta potential of obtained colloidal solutions varies from −33.41 to −24.23 mV indicating the moderate stability of synthesized nanoparticles. The synthesized nanoparticles efficiently demonstrated a bactericide effect on Escherichia coli. [ABSTRACT FROM AUTHOR]

A new electrode to study both scaling and corrosion processes of mild steel in tap water was developed. Two identical steel rings are placed on the outside of a glass tube which is heated from inside with an electric spiral; the rings are connected to a corrometer to form a two-electrode corrosion probe. The corrosion rate variations with scale thickness, scale deposition time, and solution composition are measured using the linear polarization resistance technique. The deposited scale was formed of calcite crystals of 50–100 μm as established with SEM and XRD. The scale layer of 0.2 mm formed in tap water within 90 hours reduces the steel corrosion rate from 0.8 to 0.1 mm/year and serves as a barrier layer to prevent further corrosion. [ABSTRACT FROM AUTHOR]

Corrosion rate of mild steel in tap water during 4300 h was estimated by LPR and weight-loss methods coupled with OCP measurements. The LPR results were found to be overestimated compared to the weight-loss data within initial 2000 h of exposure. The electrochemical activity of the rust separated from the metal surface was studied by cycling voltammetry using a home-built powder graphite electrode. High redox currents corresponding to the initial 2000 h of exposure were detected. Rust composition was characterized with IR and XRD, and the highest amounts of electrochemically active β- and γ-FeOOH were again detected for the initial 2000 h. Current consumption in rust transformation processes during LPR measurement in the galvanostatic mode accounts for overestimation of the corrosion rate. The time dependence of rust electrochemical activity correlates with OCP variation with time. During initial 2000 h, OCP values are shifted by 50 mV to cathodic side. For the period of a higher rust electrochemical activity, the use of a reduced B is suggested to increase accuracy of LPR technique in tap water. [ABSTRACT FROM AUTHOR]

The influence of an ultrasound intensity (28 kHz, 1.11-7.48 W/cm²), water hardness (as CaCO3, 125-275 mg/l) and temperature (15-30°C) on the nucleation-growth process of calcium carbonate on the surface of a cylinder mild steel electrode rotated at 500 rpm was studied. The deposition kinetics was analyzed by chronoamperometry; the calcareous layer was characterized by gravimmetry and scanning electron microscopy. The water hardness was found to determine the crystallization kinetics of calcium carbonate influencing both the deposition rate and crystal morphology, so that a porous layer of vaterite was formed in soft water and highly protective calcite scale was built up in hard water. While temperature accelerates crystallization, faster crystallization leads to the formation of a more porous layer with vaterite inclusions due to limitations in calcium supply. Ultrasound accelerates formation of a calcite at intensities lower than 2.23 W/cm². At higher ultrasound intensities, a significant change in carbonate crystallization occurs. Insufficient calcium concentration in the pre-electrode layer promotes formation of vaterite crystals in the growing calcite layer increasing porosity and scaling time. The results obtained could be applied in industry to solve both scale and corrosion problems of heat-exchange equipment by regulation carbonate layer thickness and porosity. [ABSTRACT FROM AUTHOR]

Flow rate influence on corrosion rate of mild steel St3 in tap water (total hardness and total alkalinity equal 4) at 50 °C was studied in a loop setup using LPR and weight loss techniques. The flow rate increase from 0.19 to 0.45 m/s reduces corrosion rate by 2.8 times within 150 h of testing; relative amounts of magnetite and calcite in the surface deposits decrease and increase, respectively, according to XRD. The division of the surface into cathodic and anodic zones is confirmed by SEM. A plausible explanation of the flow rate influence on corrosion rate reduction is suggested. [ABSTRACT FROM AUTHOR]

Production of silver nanoparticles (Ag-NPs) to increase photocatalytic activity of commercial TiO 2 (P25) and antibacterial activity of surgical sutures was studied. А new method of "green" synthesis of Ag-NPs from aqueous extract of grape skin (oxidation product), which is pre-processed by oxygen and ultrasound is reported. Also, a new method of electrochemical modification of surgical sutures was used. Characterization of Ag-NPs was carried out using energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV–visible spectroscopy. Zeta-potential of obtained colloidal solutions indicated the moderate stability of synthesized nanoparticles. The X-ray powder diffraction (XRD) analysis confirmed the crystallographic structure of the synthesized Ag-NPs. The component profile of grape skin extract has been analyzed using HPLC coupled to diode-array detection and tandem mass spectrometry (HPLC-DAD-MS/MS). In this study absorbable sutures were functionalized with biosynthesized AgNPs through an electrochemical and chemical deposition. Morphological analysis of Ag-NPs-coated surgical sutures was performed by SEM and Energy Dispersive X-Ray Spectroscopy (SEM-EDX) in order to evaluate the presence and distribution of silver deposited on the sutures. The sutures demonstrated bacteriostatic and antifungal effects on Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) and Candida albicans wound pathogens. The study revealed that electrochemical deposition of Ag-NPs on nylon surgical sutures did not alter the mechanical properties of the sutures but conferred antibacterial properties. The modified TiO 2 powders with biosynthesized Ag-NPs were characterized by XRD pattern, SEM, their photocatalytic properties, and their antibacterial activities were studied. The results of the antibacterial activity studies showed that TiO 2 modified using green approach possessed higher antibacterial activity against Gram-negative bacteria in comparison with TiO 2 modified by the impregnation method. [Display omitted] • Phytochemical syntheses of Ag-NPs using grape skin extract (GSE). • To increase the reducing ability of the GSE, it was preliminarily oxidized. • The characterization of Ag-NPs was performed by UV–Vis, FTIR, and SEM. • Modified TiO 2 with Ag-NPs showed antibacterial and photocatalytic activities. • The surgical AgNP-coated sutures demonstrated bacteriostatic and antifungal effects. [ABSTRACT FROM AUTHOR]

The new mol-ecular nickel(II) complex, namely, {4-bromo-2-[({ N '-[(2-oxidobenzylidene)amino]carbamimidoyl}imino)methyl]phenolato}nickel(II) N , N -di-methyl-formamide solvate monohydrate, [Ni(C 15 H 11 BrN 4 O 2 )]·C 3 H 7 NO·H 2 O, (I), crystallizes in the triclinic space group P with one mol-ecule per asymmetric unit. The guanidine ligand is a product of Schiff base condensation between amino-guanidine, salicyl-aldehyde and 5-bromo-salicyl-aldehyde templated by Ni 2+ ions. The chelating ligand mol-ecule is deprotonated at the phenol O atoms and coordinates the metal centre through the two azomethine N and two phenolate O atoms in a cis -NiN 2 O 2 square-planar configuration [average(Ni-N/O) = 1.8489 Å, cis angles in the range 83.08 (5)-95.35 (5)°, trans angles of 177.80 (5) and 178.29 (5)°]. The complex mol-ecule adopts an almost planar conformation. In the crystal, a complicated hydrogen-bonded network is formed through N-H⋯N/O and O-H⋯O inter-molecular inter-actions. Complex (I) was also characterized by FT-IR and 1 H NMR spectroscopy. It undergoes an Ni II ↔ Ni III redox reaction at E 1/2 = +0.295 V ( vs Ag/AgCl) in methanol solution. In a thin film with a free surface, complex (I) shows a fast photoelectric response upon exposure to visible light with a maximum photovoltage of ∼178 mV., (© Vassilyeva et al. 2022.)