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SiO2/PLGA(poly(d,l-lactic acid-co-glycolic acid)-based composites were synthesized using the single-stage sol–gel technique in acetone. The composition of the obtained materials was studied by means of the CNHS analysis, pH-potentiometric acid–base titration, zeta potential measuring, IR spectroscopy, TGA, low-temperature nitrogen adsorption method, SEM, EDX analysis, and photon cross-polarization spectroscopy. On the basis of physical and chemical method data, it was found that the synthesized hybrids are spherical samples of up to 250 nm with an organic component content of up to 18.5% (mass.), and an acid groups content of up to 1.47 mmol/g. The composites were applied as adsorbents of Fe (III) ions from aqueous solutions. It was found that the optimum pH value for adsorption was 4.0, and the adsorption equilibrium time was 240 min. The adsorption kinetics was also considered, it was revealed that kinetics obeyed the Lagergren pseudo-second-order model and chemisorption takes place during the adsorption. The results also showed that hybrid composites selectively adsorb Fe (III) ions from aqueous solutions containing the equal amount of Cu (II), Mn (II), Ni (II), and Fe (III) ions (~ 20 mg/l).

We demonstrated the deposition of the architecture of graphene oxide on stainless steel substrate and its potential environmental application. The synthesis and characterization of graphene oxide were described. The controlled formation of graphene oxide coatings in the form of the homogenous structure on stainless steel is demonstrated by scanning electron microscopy (SEM). The structure, morphology and properties of the material were assessed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The morphology and stability of these structures are shown to be particularly related to the pre-treatment of stainless steel substrate before the electrophoretic deposition. This approach opens up a new route to the facile fabrication of advanced electrode coatings with potential use in environmental applications.

Production of environmentally friendly multitasking materials is among the urgent challenges of chemistry and ecotechnology. The current research paper describes the synthesis of amino–/silica and amino–/phenyl–/silica particles using a one-pot sol–gel technique. CHNS analysis and titration demonstrated a high content of functional groups, while scanning electron microscopy revealed their spherical form and ∼200 nm in size. X-ray photoelectron spectroscopy data testified that hydrophobic groups reduced the number of water molecules and protonated amino groups on the surface, increasing the portion of free amino groups. The complexation with Cu(II) cations was used to analyze the sorption capacity and reactivity of the aminopropyl groups and to enhance the antimicrobial action of the samples. Antibacterial activities of suspensions of aminosilica particles and their derivative forms containing adsorbed copper(II) ions were assayed against Gram-positive (Staphylococcus aureus ATCC 25923) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). Meanwhile, antifungal activity was tested against fungi (Candida albicans UCM Y-690). According to zeta potential measurements, its value could be depended on the suspension concentration, and it was demonstrated that the positively charged suspension had higher antibacterial efficiency. SiO2/–C6H5/–NH2 + Cu(II) sample’s water suspension (1%) showed complete growth inhibition of the bacterial culture on the solid medium. The antimicrobial activity could be due to occurrence of multiple and nonspecific interactions between the particle surfaces and the surface layers of bacteria or fungi.

The combination of several methods (X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray analysis, infrared spectroscopy) was applied to study the changes that have occurred during the adsorption of Zn(II) and Mn(II) ions on a carbonized sunflower sample for understanding a mechanism of heavy metals adsorption. Sunflower biochar was obtained from the stem and inflorescences sunflower wastes through pyrolysis at 600 °C for 30 min. According to the infrared spectroscopy and Boehm titration data, this carbonized material has acidic and basic functional groups on its surface, but they do not participate in the metal ions adsorption. However, the synthesized carbon proved to be a sustainable high-effective adsorbent for zinc(II) and manganese(II) ions removal with adsorption capacity 138.3 mg g−1 of Zn2+ and 45.4 mg g−1 for Mn2+. Surface analysis of the carbonized material by energy dispersive X-ray analysis, X-ray diffraction, and X-ray photoelectron spectroscopy indicated the presence of soluble and insoluble inorganic salts, such as KCl, NaCl, NaHCO3, KHCO3, CaCO3, MgCO3. It was established, that during the adsorption process, soluble salts are washed away, and new insoluble ones are formed assisting by Zn(II) and Mn(II) ions. It has been revealed that the adsorptive removal of Zn2+ and Mn2+ is caused by the precipitation mechanism. The efficiency of removing Zn(II) and Mn(II) ions from water contaminated with battery waste by the same mechanism is shown.

This study is focused on a technologically viable and zero-energy green synthesis of zeolite Na-X by aging fly ash from lignite coal (CFA) in alkaline solutions at ambient conditions resemb...

A nanocrystalline zeolite of Na-X type (CFAZ) was synthesized by ultrasonic-assisted double stage fusion-hydrothermal alkaline conversion of lignite coal fly ash. Modified CFAZ with magnetic nanoparticles (MNP-CFAZ) was obtained by adding presynthesized magnetic nanoparticles between the synthesis stages. CFAZs loaded by particles of copper (Cu-CFAZ) and cobalt (Co-CFAZ) oxides were prepared by postsynthesis modification of the parent CFAZ, applying a wet impregnation technique. The parent and modified CFAZs were examined for their phase composition by X-ray diffraction, morphology by scanning electron microscopy, and surface characteristics by N2 physisorption. Comparative studies have been carried out on the adsorption capacity of the starting CFAZ and its derivatives with respect to Cd2+- and Pb2+-ions from aqueous solutions. Adsorption isotherms of Cd2+-ions on the studied samples were plotted and described by the adsorption equations of Langmuir, Freundlich, Langmuir&ndash, Freundlich, and Temkin. The best correlation between the experimental and model isotherms for the parent and modified CFAZ was found with the Langmuir linear model, assuming a monolayer adsorption mechanism. Parent and modified CFAZs were also studied as catalysts for heterogeneous thermal Fenton oxidation of methylene blue. At 90 &deg, C, the higher catalytic activity exhibits the nonmodified sample, but with the decrease in temperature to 60 &deg, C, the modified samples are more effective catalysts.

Rotary rock drilling of rocks deploys a combined action of normal and tangential forces induced by thrust force pressing against the drill bit along with rotation of the bit, delivering the loosening of rock chips from the solid rock mass after crossing its strength limits. Different mechanisms of rock breaking occur during the rock drilling, which depends on the applied thrust force. The highest probability of energy-convenient chipping occurs near the inflection point of the penetration-thrust curve. Energy theories of rock drilling consider the area surrounding the inflection point as the point where the energy necessary to break the unit volume of rock (i.e. specific energy) reaches its minimum. The inflection points of the designed model of penetration depth were fitted with exponential trend lines for two tested drill bits. The area of chipping moves to higher thrust forces due to bit's progressing wear. Indirect assessment and prediction of drill bit wear based on model of penetration depth used in process control enables to reduce the energy consumption and decrease the drill bit wear in underground construction and mining of mineral resources.