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A fast microwave-assisted method was used to grow zinc oxide. The synthesis was carried out under three different pH conditions (8, 10 and 12) with the precipitation agent triethylamine. The obtained materials were comprehensively characterised using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), low-temperature N2 sorption (BET model), and analysis of electrokinetic potential and thermal stability (TGA). It was established that the pH value had a significant impact on the crystallinity, morphology and thermal stability of the final products. The primary purpose of this study was to use the synthesised materials in a process of photodegradation (in the UV light range) of the model organic pollutant – 4-chlorophenol (20 mg/dm3). The photo-oxidation tests showed that the obtained zinc oxide materials exhibit good photodegradation and mineralisation efficiency. Moreover, the kinetics of the photocatalytic degradation of 4-chlorophenol were determined based on the pseudo-first-order model, assuming the Langmuir–Hinshelwood mechanism.

TiO2-ZnO heterostructures with multifunctional photoactive properties were prepared using the two-stage microwave method. The presence of a binary crystalline system (anatase – wurtzite) was confirmed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The multifunctional character of the obtained photoactive materials was evaluated in two different processes – photocatalysis and photovoltaics. Photo-oxidation tests proved that the TiO2-ZnO heterostructures demonstrate high photocatalytic activity in phenol degradation. Furthermore, the prepared titania-based heterojunction systems were employed as precursors of the semiconducting layers in the DSSCs working electrodes. The photovoltaic parameters of the cells, assembled with electrodes post-treated with TiCl4 solution, have been tremendously improved by as much as forty-fold. Additionally, the scientific novelty of the work should be emphasized, resulting from the utilization of microwave-assisted synthetic strategy for the first time to prepare highly efficient photoactive materials with significant application potential in both photocatalysis and photovoltaics (DSSC cells).

It is well known that removal of vanadium ions from the natural environment has become a great challenge in recent years. Due to this fact, the present study concerns the application of binary oxides such as TiO2-ZrO2 (molar ratio 9:1) and TiO2-ZnO (molar ratio 7:3) synthesized by the sol–gel method with calcination at 873 K (TZ1 sample) or by the hydrothermal method at 433 K (TZ2 and T7Zn3 samples), respectively. The fabricated adsorbents were subjected to the detailed physico-chemical analysis including: dispersive properties, morphology, crystalline and textural properties as well as chemical composition. The vanadium(V) ions adsorption on the binary oxides was optimized by the experimental conditions such as pH (2–10), adsorbent dose (0.01–0.1 g), vanadium concentration (10–500 mg/L), agitation time (1 min–24 h) and temperature (293–333 K). The pseudo-first-order (PFO), pseudo-second-order (PSO) and intraparticle diffusion (IPD) kinetic models as well as the Langmuir, Freundlich, Temkin and Dubinin-Raduskievich isotherm models were applied for the description of V(V) adsorption. The adsorption capacities were found to be 129.3 mg/g for TZ1, 170.8 mg/g for TZ2 and to 195.9 mg/g for T7Zn3. The endothermic and spontaneous character of V(V) adsorption on the binary oxides was confirmed by the values of thermodynamic parameters. The best fitting of kinetic experimental data to the pseudo-second-order model was obtained. The maximum desorption yield (%D) was achieved using the 1 mol/L NaOH solution (97.96%-T7Zn3, 75.81%-TZ2, 62.88%-TZ1). Applicability of the inorganic oxides in V(V) and Fe(III) removal from spent catalyst leaching solutions was proved.

A novel TiO 2-ZrO 2 hybrid oxide material enriched with lanthanum via in situ modification was successfully synthesized via a sol–gel process and applied in tetracycline (TC) removal. Lanthanum was introduced to increase the adhesion of organic compound to the TiO 2-ZrO 2 surface, which is beneficial for adsorption capacity and photocatalytic activity. Detailed physicochemical analysis of the hybrid oxide materials was carried out using analytical techniques including energy dispersive X-ray spectroscopy (EDX), Fourier infrared spectroscopy (FTIR), low-temperature N 2 adsorption (BET model) and X-ray photoelectron spectroscopy (XPS). A key aspect of the research was the determination of optimum conditions for tetracycline removal from model solutions by a comprehensive method that combines adsorption and photocatalytic degradation processes. The maximum Langmuir adsorption capacity of the TiO 2-ZrO 2/La system with respect to TC was calculated to be 69.44 mg/g. Additionally, photocatalytic tests showed that 35 mg of TiO 2-ZrO 2/La photocatalyst was able to remove TC from a 10 mg/L model solution in 120 min with 100% efficiency. Thus, it is a very promising material for the treatment of wastewaters containing tetracycline.

Herein, the series of {0 0 1} exposed anatase nanosheets from HF-assisted solvothermal growth synthesis were obtained. The two-dimensional TiO2 were characterized, including both bulk (XRD, DR-UV-Vis, Mott-Schottky) and surface characteristics (N2 sorption, XPS, SEM) with experimental results compiled with Density Functional Theory (DFT) calculations. The effect of alcohol amount and type was studied, demonstrating the crucial role of nucleation rate on the final material properties, which was connected with the possible ligand exchange between F- and ROH in the [TiF6]2- octahedra, leading to further TiO2 condensation through an ether elimination reaction. Highly active 2D nanoparticles were easily obtained for different reaction times when a moderate amount of n-butanol or n-hexanol was introduced to the synthesis. The photoactivity of 2D TiO2 with exposed {0 0 1} facet strongly depended on the photocatalytic available surface area with an increased amount of ortho–hydroxyphenol (catechol) formed as a by-product. Meanwhile, the rise of n-butanol or n-hexanol content during solvothermal reaction or changing it to ethanol allowed to form smaller and more crystalline anatase particles, but their activity was hindered. For these samples, the slow phenol disappearance and no catechol formation occurred due to (i) a lower amount of adsorbed fluorine, (ii) band position shifting towards lower values, and (iii) the surface presence of Ti3+, which prevented the generation of ∙OH radicals. It was also found that changing the nucleation rate by modifying the reaction environment influences the fluorine ions distribution, determining the final properties of 2D structure photocatalyst.

Novel ionic liquid-functionalized mesoporous silicas were synthesized using triblock copolymer Pluronic F127 as a template and I. (3-chloropropyl)trimethoxysilane, which then reacted with the appropriate pyridine derivatives (Q-pSZ series), or II. 1-[3-(trimethoxysilyl)propyl]-3- or −4-undecanoylpyridinium chloride, and 3- or 4-[1-(hydroxylimine)undecyl]-1-[3-(trimethoxysilyl)propyl]pyridinium chloride (SZ series), as a source of IL functional groups. The synthesized materials were characterized by FT-IR, Raman, SEM, XPS, low temperature N2 sorption, and IGC technique. The ability of the fabricated materials as adsorbents was investigated for the removal of Pb(II), Cd(II) and Zn(II) from aqueous solutions and compared with the nonmodified silica. Sorption optimization experiments were performed by changing the factors affecting the metals ions removal, such as pH, temperature, time, metals ions concentration. The optimum pH range for adsorption of Pb(II), Cd(II) and Zn(II) was found to be 4–6 and, the optimum contact time was found to be 15 min and 45 min, for the series materials “Q-pSZ” and “SZ”, respectively. The adsorption isotherms were obtained using concentrations of the metals ions ranging from 50 to 200 mg/L. The adsorption process followed pseudo-second-order reaction kinetics, as well as Langmuir and Freundlich adsorption isotherms. Q-pSZK3 possessed adsorption capacities of 202.3 mg/g for Pb(II), SZ-Ox3 148.6 mg/g for Cd(II) and SZ-Ox4 133 mg/g for Zn(II). This study revealed that the fabricated materials were promising adsorbents for removal especially Pb(II), Cd(II) and Zn(II) from aqueous solutions.

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.

Novel binary and ternary oxide photocatalysts based on titania, zirconia and silica were synthesized via a sol-gel method assisted by a calcination process. The effect of the molar ratio of components as well as the temperature of calcination on the physicochemical and photocatalytic properties of the final products was examined. Particle size distribution (NIBS), scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), Raman spectroscopy, low-temperature N2 sorption, and X-ray fluorescence (XRF) were employed to investigate the dispersion, morphology, crystalline and textural structure as well as the chemical composition of the photocatalysts. Additionally, X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) were used to confirm the chemical surface concentration and the presence of characteristic surface groups of the synthesized materials. The key stage of the research involved evaluation of the photocatalytic behavior of the synthesized materials in the catalytic decomposition of Rhodamine B (RhB) dye. The photocatalytic studies focused on determination of the effect of the type and crystalline structure of the photocatalyst, the pH of the reaction system, and the irradiation time on the efficiency of degradation of RhB in the presence of the synthesized oxide materials.

Due to its exceptional textural, morphological and mechanical properties, mesostructured cellular foam (MCF) silica is a suitable support material for enzyme immobilization. However, the simple and efficient protocol of enzyme immobilization using MCF is often overlooked. Thus, in the presented study, we describe the synthesis, modification and characterization of mesostructured cellular foam silica for use in laccase immobilization. It has been established that the synthesized materials are characterized by high surface area equal to approx. 550 m2 g−1 and pores with diameters of approx. 20 nm, which makes them suitable for effective enzyme binding. Furthermore, immobilization of the laccase onto both, unmodified and Cu-modified MCF has been carried out, resulting in process yield of over 95% and 85%, respectively. Upon immobilization, irrespectively of the support used, laccase retained higher activity (over 80%) at a wider temperature (20–40 °C) and pH (4–7) range, as compared to the free enzyme, which exhibited such high activity only at pH 5 and 30 °C. In addition, the reusability of the laccase immobilized onto MCF + Cu material has also been improved as it still retained approx. 90% of its initial activity after 10 reaction cycles. Finally, the obtained biocatalytic systems have been applied for degradation of tetracycline from aqueous solutions resulting in 100% removal of the antibiotic by the MCF + Cu + lac system due to simultaneous adsorption and biocatalytic conversion.