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The aim of the study was the synthesis of multifunctional TiO2-ZnO oxide systems with desired antibacterial and photocatalytic activity. It was investigated how the TiO2:ZnO molar ratio and the time of hydrothermal treatment affected the physicochemical and structural properties (including morphology, crystalline and porous structure, as well as chemical surface composition) of the synthesized materials. For the first time this type of binary oxide systems were used as antibacterial materials against Gram-positive, Gram-negative and anaerobic bacteria. Moreover, the photocatalytic properties of the obtained materials were verified in the degradation of C.I. Basic Violet 10 dye. The SEM analysis demonstrates that binary oxide materials based on TiO2 and ZnO were found to have spherically and hexagonally shaped particles, characteristic of both oxides. The results of XRD, Raman and HRTEM analysis proved that the molar ratio of the components affects the crystalline structure of the synthesized oxide materials. Analysis of porous structure parameters showed that an increase in the ZnO content leads to a decrease in the BET surface area. Moreover, low-temperature N2 sorption analysis demonstrates that TiO2-ZnO oxide systems have higher surface are than the pure oxides. The TiO2-ZnO oxide systems exhibited very good antibacterial activity against Gram-positive bacteria, especially Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus). The photo-oxidation tests proved that the binary oxide materials (especially the T9Zn1 samples) demonstrates high photocatalytic activity in the decomposition of C.I. Basic Violet 10 (95% after 180 min irradiation) compared with the reference titania sample.

In this paper, a synthesis and physicochemical characterization of a novel magnetite/lignin (Fe3O4/Lig) and magnetite/lignin/polydopamine (Fe3O4/Lig/PDA) materials are presented as a novel and effective platforms for an enzyme immobilization or biosensing application. The hybrid has interesting features like improved thermal and mechanical stability, excellent adhesion for inorganic and organic materials, transferability of electrons and photothermal properties. In order to characterize features of the materials, carried out Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), thermogravimetry analysis (TGA), electrokinetic potential (zeta), and magnetic measurements (SQUID). From the TEM analysis, magnetite/lignin hybrid is proved to be covered by a 2–3 nm uniform layer of polydopamine. In a further study, the resultant functional biomaterial Fe3O4/Lig and Fe3O4/Lig/PDA were used to immobilize glucose oxidase (GOx). The immobilization capacity of 26.92 and 29.24 mg/g were achieved for Fe3O4/Lig and Fe3O4/Lig/PDA, respectively. After mixing of the materials with graphite and ferrocene, the modified carbon paste electrodes CPE/Fe3O4/Lig/GOx/Fc and CPE/Fe3O4/Lig/PDA/GOx/Fc were obtained and they were tested for application as bioelectrochemical glucose sensing system. The linear ranges of CPE/Fe3O4/Lig/GOx/Fc and CPE/Fe3O4/Lig/PDA/GOx/Fc were from 0.5 to 4.5 and 0.5–9.0 mM glucose, respectively. The hysteresis loops of the prepared materials show no coercivity and remanent magnetizations at room temperature, exhibiting typical superparamagnetic behavior.

Coal fly ash (CFA) based-copper ferrite nanocomposites were fabricated, characterized, and applied for the photocatalytic degradation of Methyl Orange (MO) dye. The hydrothermal synthesis route was opted for the fabrication of pristine copper ferrite nanoparticles and its CFA nanocomposites. The prepared photocatalysts were analyzed in terms of structural, surface morphology, chemical state analysis, elemental composition, and optical response. The photocatalytic activity of nanocomposites was investigated sequentially under ultraviolet light (254 nm) and influencing parameters (pH, H2O2 dose, photocatalyst content, dye initial concentration, irradiation time) were studied. The optimized conditions for photocatalytic degradation were found at pH = 5, composite dose = 100 mg/L, H2O2 = 10 mM using CFA nanocomposite and the dye was efficiently degraded within 60 min. The best degradation efficiency of ~98% was achieved using CFA-CuFe2O4 (1:1) under the optimized conditions. The key reactive species ( OH, h+, and e−) for photocatalytic degradation were determined by a radical scavenging experiment and O H radicals were found to be the most effective ones. The kinetic study of Fenton oxidation processes was conducted using Behnajady-Modirshahla-Ghanbery (BMG) kinetic model. Response surface methodology was the statistical tool for the assessment of interaction effect among experimental variables.

Using the by-product biopolymer lignin and nanoparticles of magnetite, well-known for its nontoxicity and magnetic properties, novel nanomagnetite–lignin hybrid materials were synthesized. In the first step, magnetite was produced via a co-precipitation method with hydrothermal treatment, and was found to have a particle size of around 20 nm. Nano–Fe 3 O 4 was then combined with pre-activated lignin to obtain hybrids with various magnetite–lignin ratios, whose physicochemical and magnetic properties were thoroughly analyzed. Thermal analysis showed the hybrids to have higher thermal stability than pure lignin. Based on Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy it was demonstrated that the Fe 3 O 4 and lignin are connected via Fe O C bonds. Further measurements showed the nanomagnetite–lignin hybrid materials to have good magnetic properties. The results of this study suggest that the synthesized hybrids may find practical applications in many fields of science and industry.

A microwave method was used for the synthesis of TiO2-CuO oxide systems. A detailed investigation was made of the effect of the molar ratio of components (TiO2:CuO = 9:1, 7:3, 5:5, 3:7, 1:9) on the crystalline structure and morphology. Transmission electron microscopy (TEM) confirmed the presence of octahedral and rod-shaped titania particles and sheet copper(II) oxide particles; moreover, HRTEM analysis indicated the presence of a heterojunction between TiO2 and CuO. The synthesized materials were analyzed by X-ray diffraction (XRD) and Raman spectroscopy, and two crystalline forms (anatase and monoclinic CuO) were detected. The key element of the work was to determine the photocatalytic activity of the obtained binary oxide systems in the degradation of tetracycline. Photo-oxidation tests proved that the binary oxide materials (especially the (9)TiO2-(1)CuO and (7)TiO2-(3)CuO samples) demonstrate high photocatalytic activity in the decomposition of tetracycline (95% after 90 min irradiation) compared with the reference titania samples. Furthermore, a Z-scheme heterojunction photocatalytic process mechanism was proposed. Another important part of the work was the determination of tetracycline photodegradation products using the HPLC/MS technique.

Processes of adsorption and desorption of a model active substance (octylamine) on the surface of unmodified titanium dioxide (E 171) have been performed. The effects of concentration of octylamine and time of the process on the character of adsorption have been studied and the efficiency of the adsorption/desorption has been determined. The samples obtained have been studied by X-ray diffraction. The nitrogen adsorption/desorption isotherms, particle size distribution and absorption capacities of water, dibutyl phthalate and paraffin oil have been determined. The efficiency of octylamine adsorption on the surface of the titanium dioxide has been found positively correlated with the concentration of octylamine in the initial solution. The desorption of octylamine has decreased with increasing concentration of this compound adsorbed. For octylamine in low concentrations the physical adsorption has been found to dominate, which is desirable when using TiO 2 in the production of pharmaceuticals.

Attempts at modification of silica surface with a polymer (natural latex) directly in the course of the precipitation process have been made. The effects of temperature, non-ionic surfactants and silane coupling agent in preparation of poly[cis-isoprene]-coated silica on the precipitation of polymer/silica composites initiated by ammonium salts (NH4Cl, (NH4)2SO4, NH4HCO3), have been studied. The influence of the process parameters on the quality of the silicas obtained and the character of the polymer adsorption on the silica surface has been determined along with the effect of the surface impregnation with natural latex on physicochemical parameters of the silicas (bulk density, capacities to absorb water, dibutyl phthalate and paraffin oil) and their surface structure.

Studies were presented on production of highly dispersed magnesium silicate at a pilote scale. The process of silicate adsorbent production involved precipitation reaction using water glass (sodium metasilicate) solution and appropriate magnesium salt, preceded by an appropriate optimization stage. Samples of best physicochemical parameters were in addition modified (in order to introduce to silica surface of several functional groups) using the dry technique and various amounts of 3-isocyanatepropyltrimethoxysilane, 3-thiocyanatepropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane. The so prepared samples were subjected to a comprehensive physicochemical analysis. At the terminal stage of studies attempts were made to adsorb phenol from its aqueous solutions on the surface of unmodified and modified magnesium silicates. Particle size distributions were determined using the ZetaSizer Nano ZS apparatus. In order to define adsorptive properties of studied magnesium silicates isotherms of nitrogen adsorption/desorption on their surfaces were established. Efficiency of phenol adsorption was tested employing analysis of post-adsorption solution.

Modified silicas were obtained by precipitation from aqueous solutions of sodium metasilicate and sulphuric acid. For the modification, silane coupling agents with various functional groups were applied, including aminosilane (AEAPTS), glycidoxysilane (GPTS), mercaptosilane (McPTS), and vinylsilane (VTMES). Extensive physicochemical evaluation of the obtained modified silicas was conducted, using FTIR, 29 Si CP MAS NMR and XPS techniques. The silica surface modification was proven to depend upon chemical reactions and to show intensity increasing with a rising concentration of a given modifier. A surface charge of the formed silica dispersions was also examined, by determining their zeta potential. Moreover, surface morphology, dispersion and particle size of the obtained silicas were evaluated, employing TEM electron microscopy and the technique of a dynamic light scattering (DLS). The studies demonstrated that application of hydrophobic type silanes for surface modification of the hydrated silicas restricted the intense tendency for agglomeration in the formed precipitated silicas.

Adsorption of several organic dyes was examined on a modified silica surface. For this purpose, EG-Silica was applied, precipitated from sodium metasilicate solution using carbon dioxide in presence of ethylene glycol. In order to promote their interaction with dyes, the silica surface was modified using silane coupling agents with the amino functional group. Technique of conducting the adsorption process was discussed. Studies on morphology and microstructure were performed employing scanning electron microscopy (SEM). Particle size distribution was also examined using the technique of dynamic light scattering. The SEM micrographs and particle size distributions showed that highly uniform pigments can be obtained employing EG-Silica as a core. Studies on elution of dyes from the silica surface demonstrated that, in general, stable pigments were obtained.

Silicas of highly dispersion degree were obtained. This process includes formation of silica particles and their aggregation. The ethylene glycol solution was used in precipitation process, resulting in a partial blocking of the silica surface hydroxyl groups (silanol groups) and, thus, in a decreased hydrophilicity of silica. Studies on the surface modification of silicas using silane coupling agents are described. The best modifiers were selected, which inducted a change of the silica surface from hydrophilic to hydrophobic. Basic physicochemical analyses of the obtained silicas were performed. The methods of evaluating the degree of surface modification of the silica were presented. Near infrared spectroscopy (NIR) was used to determine the degree of condensation of the silica surface silanol groups. The degree of hydrophobization of silica surface was determined by a calorimetric method. Moreover, studies on morphology and microstructure using transmission electron microscopy (TEM) were performed. Size distribution of primary particles and aggregates and agglomerates structures were determined by ZetaPlus instrument using dynamic light scattering (DLS) method.