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Ceramic membranes based on SiC have a number of advantages, namely high surface hydrophilicity, good water permeability and negative surface charge, which leads to better performance during their operation, but they require high sintering temperatures due to covalent bonds. The use of sintering agents can significantly reduce the final sintering temperature. The aim of this work was to synthesise ceramic membranes based on silicon carbide and to study the effect of liquid glass on their mechanical, electrical and antibacterial properties. The physicochemical properties of SiC ceramic membranes were investigated by diffraction analysis and scanning electron microscopy. It was found that, regardless of the type of carbonate, only two phases are identified: the main phase of the initial mixture, silicon carbide and the phase added to the mixture, corundum. The obtained SiC ceramic membranes are macroporous, as indicated by the transport properties (9.03–18.66 cm3/(min-cm2)) and the results of electron microscopy (13–20 μm). SiC ceramic membranes obtained are characterised by high strength (16.3–46.8 MPa). Studies of antibacterial properties have shown that SiC-based ceramic membranes do not exhibit antibacterial properties, but modification of ceramic membranes with titanium oxide inhibits the growth of gram-negative bacteria. The results of this study are useful for enriching the knowledge about the production of silicon carbide membranes and are aimed at further research and development of selective membranes (micro- and ultrafiltration) based on them.

In the current study we used the grape pomace extract (GPE) based on deep eutectic solvent (DES) as reducing and capping agent for synthesizing of small (< 10 nm) gold nanoparticles. Organic compounds were extracted with L-proline/Lactic acid-based deep eutectic solvent. The synthesized AuNPs by DES-based GPE were characterized using UV–visible spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectrometry. UV–visible absorbance spectral value at 423 nm confirmed the formation of AuNPs. The FTIR analysis revealed that carbonyl and hydroxyl groups of grape pomace extract were involved in reducing and capping of the DES grape pomace extract—AuNPs. The SEM analysis revealed that the synthesized gold nanoparticles were irregularly spherical with diameters ranging between 5 and 7 nm. The formation of gold nanoparticles was further confirmed by the EDX spectrum which revealed signals from Au (1,7–2,4 keV). The obtained DES-GPE-based gold nanoparticles displayed significant antibacterial activities against E. coli, B. subtilis, antifungal effect against Candida albicansyeast, and showed phytotoxicity influence in a concentration-dependent manner. The antibacterial activity of obtained DES-GPE-based gold nanoparticles against Bacillus subtiliswas the strongest. Mitotic index estimated by A. cepacytotoxicity method showed that AuNPs had negligible cytotoxic effects.

Herein, new function-oriented deep eutectic solvents (DESs) with on l-proline or betaine and DL-lactic acid were designed extraction of polyphenol compounds from grape pomace. The formations of new hydrogen between the two components of DESs were evidenced by FTIR and 1H NMR spectra. Physicochemical characteristics of deep eutectic solvents under the effect of water on density, viscosity, electrical resistance have been revealed. The betaine-based DES could changes the electrical resistance depending on the concentration of water. The feasibility of using ultrasound-assisted extraction of phytochemicals combined with betaine-based and proline-based DES as a green chemistry technique to improve extraction of green (polyphenols) compounds from grape pomace was evaluated. Grape pomace extracts were analyzed by LC-DAD-MS to identify extracted compounds and analyze the impact of type DES on compound chemical profile. LC results indicated that ultrasound-assisted extraction of phytochemicals using betaine-based and proline-based deep eutectic solvent application allowed enhanced hydroxycinnamic acids extraction, while the use of proline-based DES resulted in a more diverse compound profile. The highest recovery efficiencies were recorded with DESs giving the highest total phenolic content (80–92 mg EGE//g d.w), total flavonoid content (47–51 QUE/g d.w), antiradical activity (80% at 100 mg/ml) and reducing power (310–468 mg ASE/g extract). Scanning electron microscope (SEM) results further verified DESs intensified the destruction of cell wall structure, and thereby allowed greater release of polyphenolic from grape pomace.

This paper presents a synthesis of silver nanoparticles by the novel method with grape pomace extract obtained by eco-friendly “green” solvent, namely, deep eutectic solvent (DES). The electrical conductivity of deep eutectic solvents was measured, and the width of electrochemical stability window was evaluated depending on water content in the solvent (0–25%). The DES was used to obtain the extract, and the latter was used in synthesis nanoparticles. The bands found in the FTIR spectrum were found to be associated with phenolic compounds. Grape pomace extract (GPE-DES) were analyzed by HPLC-DAD-MS to identify extracted compounds. The phytochemical profile of GPE-DES exhibits a high amount of the hydroxycinnamic acids (~23%), followed by anthocyanins (~19%). Furthermore, caffeic acid (164.5 μg/g), gallic acid (792.4 μg/g), and (+)-catechin (511.3 μg/g) were quantified with HPLC. A sharp absorbance peak at 436 nm was found using a UV-visible spectrophotometer, confirming the presence of AgNPs. The extensive spectroscopic study enabled the identification of synthesized AgNPs. The silver nanoparticles with round shape were noticed on the scanning electron microscopy micrographs with the particle size in the range of 10–20 nm. High antibacterial potential has been proven against gram-positive spore-forming B. subtilisand gram-negative bacteria E. coliwith 9 mm and 16 mm zone inhibition, respectively, observed by agar well diffusion method. Mitotic index (MI) and chromosomal aberrations (CAs) were assessed by Allium cepaassay. The synthesized silver nanoparticles do not induce cytogenotoxic and genotoxic changes in Allium cepaL. with nanoparticles at concentration up to 10%. The silver nanoparticles are biocompatible and non-toxic.

Deep eutectic solvents (DESs) have been explored as an alternative to hazardous solvents to extract phenolic compounds. The aim of this work was estimate the performance of choline chloride-based DESs regarding the extraction of phenolic compounds of tomato pomace and determination of their antioxidant activity. “Green” choline chloride-based DESs coupled with ultrasound-assisted extraction were performed to extract. The solvents were choline chloride:1,2-propanediol (1:2 v/w):water (10% w/w) and choline chloride:lactic acid (1:2 v/w):water (10% w/w).The phytochemical constituents of tomato pomace extracts were verified with a combination of high-performance liquid chromatography coupled to diode-array detection and tandem mass spectrometry (HPLC–DAD-MS). The total antioxidant activity of the extracts was assessed using phosphomolybdenum (PM) method. The redox behavior of tomato pomace extracts was evaluated by means of cyclic voltammetry. The DES-based tomato pomace extracts were used as the antioxidant agent to develop a natural cosmetic formulation (colloidal solutions). The ζ-potential, colloidal stability, and the antioxidant, antimicrobial, and antifungal activity were studied. The antioxidant activity of the cosmetic emulsions has been studied by means of cyclic voltammetry. The tomato pomace extracts contain significant quantity of phenolic acids and flavanols (26–37% of the total compounds). Chlorogenic acid was detected as the main phenolic compound in tomato pomace extracts (ranging from 37.23 to 52.33 μg/g). The total antioxidant power of the extracts varies in the range at 408 to 511.18 μg/g extract. Choline chloride-based DESs have low values of oxidation potentials. Zeta-potential of obtained colloidal solutions (cosmetic formulation) varies from − 0.0102 to − 0.0594 mV indicating the moderate stability of obtained cosmetic emulsions. The following ranking of antioxidants was obtained: cosmetic emulsions with extract obtained by choline chloride:lactic acid deep eutectic solvent > cosmetic emulsions with extract obtained by choline chloride:1,2-propanediol deep eutectic solvent. Antibacterial and antifungal activity of the cosmetic emulsions with DES extracts relative to Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli), and Candida albicanswound pathogens were studied. Thus the DESs could serve as solvents to produce a phenolic-rich tomato extract could be readily applicable to cosmetic formulations.

Graphical abstract:

The influence of an ultrasound intensity (28 kHz, 1.11-7.48 W/cm2), water hardness (as CaCO3, 125-275 mg/l) and temperature (15-30degC) 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.

•Quebracho tannin extract (QE) was introduced as a component for steel protection as inhibitor and an efficient rust conversion agent.•Use of DPPH, ABTS and FRAP methods to assess the antioxidant properties of Quebracho tannin extract.•-Anticorrosive protection depends on tannin extract concentration and is due to an organic film formed on steel surface.•Tannin primer can good protect steel in salt spray chamber.

•Iron corrosion products can adsorb chloride ions and increase surface chloride concentration.•Rust and scale deposition influence on pitting resistance of AISI 316 steel was tested.•Rust deposition on stainless steel does not reduce pitting resistance in 2.8 g/L NaCl.•Scale deposition on stainless steel does not influence pitting resistance in 35 g/L NaCl.

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.