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A series of titanium dioxide (TiO2) modified with 3-aminopropyltriethoxysilane (APTES) was prepared by high-temperature calcination in an argon atmosphere in the temperature range from 800 to 1,000°C. The properties of the obtained samples were compared with those of pure TiO2 annealed under the same conditions. Examining electron paramagnetic resonance (EPR) parameters at room temperature for APTES–TiO2 showed an intense resonance line from defects related to conducting electrons with g eff from 2.0028 to 2.0026 and 1.9052 for temperatures 800, 900, and 1,000°C, respectively, while for pure calcined TiO2, these ERP lines were not observed. With the increase in the calcination temperature to 900°C for APTES–TiO2 samples, the EPR increases linearly. This has been combined with a relatively high anatase content and small crystallites. The EPR line intensity at RT calculated for 1 g of sample showed an almost linear relationship with the photoactivity in removing ORANGE II dyes from water.

In this work, a conversion of carbon dioxide (CO2) into methane, carbon monoxide, as well as hydrogen was investigated. The TiO2/rGO photocatalysts were prepared by two steps: solvothermal method and calcination at 500, 800, and 1000 °C in an argon atmosphere. The obtained samples were characterized by X-ray diffraction (XRD), UV–vis diffuse reflection spectroscopy (UV–vis/DRS), N2 adsorption-desorption and analysis of carbon content. The activity of photocatalysts was evaluated in the photocatalytic reduction of CO2. The TiO2/rGO-10 without calcination showed the highest activity toward CO2 conversion. It was found that all samples after rGO modification exhibited good activity toward H2 generation with high selectivity. The enhanced photocatalytic performance was attributed mainly to the presence of graphene due to its excellent electron transport/collection ability.

In this work, the impact of TiO2 properties on the CO2 adsorption properties of titanium dioxide modified with 3-aminopropyltriethoxysilane (APTES) was presented. The APTES-modified TiO2 materials were obtained by solvothermal process and thermal modification in the argon atmosphere. The prepared adsorbents were characterized by various techniques such as X-ray diffraction (XRD), Fourier transform infrared (DRIFT), thermogravimetric analysis and BET specific surface area measurement. CO2adsorption properties were measured at different temperatures (0, 30, 40, 50 and 60 °C). Additionally, the carbon dioxide cyclic adsorption-desorption measurements were also investigated. The results revealed that modifying TiO2 with APTES is an efficient method of preparing CO2 sorbents. It was found that the CO2 adsorption capacity for the samples after modification with APTES was higher than the sorption capacity for unmodified sorbents. The highest sorption capacity reached TiO2-4 h-120 °C-100 mM-500 °C sample. It was also found that the CO2 adsorption capacity shows excellent cyclic stability and regenerability after 21 adsorption-desorption cycles.

This work aimed to obtain hybrid composites based on photoactive metal oxide and carbon having adsorption properties. The materials, composed of titanium dioxide or zinc oxide and spherical carbon, were obtained from resorcinol-formaldehyde resin, treated in a solvothermal reactor heated with microwaves and then subjected to carbonization, were received. The functional groups of pure carbon spheres (unsaturated stretching C=C, stretching C-OH and C-H bending vibrations), CS/ZnO and CS/TiO

In this work, the impact of APTES-modified TiO2 photocatalysts on antioxidant enzymes (catalase and superoxide dismutase) activity secreted by bacteria was presented. Microbial tests has been examined using Escherichia coli (ATCC 29425) and Staphylococcus epidermidis (ATCC 49461) as model organisms. It was found that APTES-TiO2 affected the activity of antioxidant enzymes. Additionally, obtained APTES-TiO2 photocatalysts were capable of total E. coli and S. epidermidis inactivation under artificial solar light irradiation. The sample modified with the concentration of APTES equals 300 mM (TiO2–4h–120°C-300mM) showed the strongest photocatalytic activity toward both bacteria species. The two-stage photocatalytic mechanism of bacteria response to photocatalysts was proposed.

DC magnetization of a series of titania nanocomposites modified with reduced graphene oxide (rGO) has been investigated. Hysteresis loops observed at room temperature disappeared at low temperatures. At a temperature of about 100 K, a phase transition to the superferromagnetic order state was observed, probably due to the linear expansion and self-reorientation of the magnetic moments. Processes associated with magnetic moment reorientation can cause a hysteresis loop to disappear at low temperatures as well as superferromagnetic ordering. It was suggested that the isolated nanoparticle in the nanopore could be used to create a “compass” at a nanometer-sized level that would be many times more sensitive than the conventional one. Measurements of the zero-field cooling and field cooling modes do not exclude the possibility of the coexistence of a superparamagnetic state.

In this work, a series of TiO2/rGO photocatalysts were obtained by hydrothermal method and calcination at 500 °C. These nanomaterials were prepared with different content of rGO (1–8 wt. %). The samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-VIS/DRS) and surface-enhanced FRaman spectroscopy. The BET specific surface area was also measured. The photocatalytic activity of the photocatalysts was investigated on the basis of methylene blue decomposition under UV-VIS light with high UV intensity. The TiO2/rGO hybrids show enhanced adsorption properties and photocatalytic activity in comparison to references samples. It was found that adsorption plays an important role in methylene blue decomposition due to interactions between methylene blue molecules and aromatic regions from rGO.

The presented work shows the antibacterial activity of TiO2 photocatalysts modified by 3-aminopropyltriethoxysilane (APTES). The APTES-functionalized TiO2 samples were obtained by the solvothermal process followed by calcination. The antibacterial activity of APTES/TiO2 samples was evaluated with two species of bacteria, Escherichia coli and Staphylococcus epidermidis, under artificial solar light (ASL) irradiation. The used bacteria are model organisms characterized by negative zeta potential (approx. −44.2 mV for E. coli and −42.3 mV for S. epidermidis). For the first time, the antibacterial properties of APTES-functionalized TiO2 were evaluated against mono- and co-cultured bacteria. The high antibacterial properties characterized the obtained APTES-modified nanomaterials. The best antibacterial properties were presented in the TiO2-4 h-120 °C-300 mM-Ar-300 °C sample (modified with 300 mM of APTES and calcined at 300 °C). The improvement of the antibacterial properties was attributed to a positive value of zeta potential, high surface area, and porous volume.

Nanocomposites based on nanocrystalline titania modified with graphene-related materials (reduced and oxidized form of graphene) showed the existence of magnetic agglomerates. All parameters of magnetic resonance spectra strongly depended on the materials' modification processes. The reduction of graphene oxide significantly increased the number of magnetic moments, which caused crucial changes in the reorientation and relaxation processes. At room temperature, a wide resonance line dominated for all nanocomposites studied and in some cases, a narrow resonance line derived from the conduction electrons. Some nanocomposites (samples of titania modified with graphene oxide, prepared with the addition of water or butan-1-ol) showed a single domain magnetic (ferromagnetic) arrangement, and others (samples of titania modified with reduced graphene oxide) exhibited magnetic anisotropy. In addition, the spectra of EPR from free radicals were observed for all samples at the temperature of 4 K. The magnetic resonance imaging methods enable the capturing of even a small number of localized magnetic moments, which significantly affects the physicochemical properties of the materials.

A visible-light photocatalytic performance of 3-aminopropyltriethoxysilane (APTES)-modified TiO

Zinc chloride and potassium oxalate are often applied as activating agents for carbon materials. In this work, we present the preparation of ZnO/carbon spheres composites using resorcinol-formaldehyde resin as a carbon source in a solvothermal reactor heated with microwaves. Zinc chloride as a zinc oxide source and potassium oxalate as an activating agent were applied. The effect of their addition and preparation conditions on the adsorption properties towards carbon dioxide at 0 °C and 25 °C were investigated. Additionally, for all tested sorbents, the CO

Zeolite 13X (NaX) was modified through ion-exchange with alkali and alkaline earth metal cations. The degree of ion exchange was thoroughly characterized with ICP, EDS and XRF methods. The new method of EDS data evaluation for zeolites was presented. It delivers the same reliable results as more complicated, expensive, time consuming and hazardous ICP approach. The highest adsorption capacities at 273 K and 0.95 bar were achieved for materials containing the alkali metals in the following order K < Na < Li, respectively, 4.54, 5.55 and 5.94 mmol/g. It was found that it is associated with the porous parameters of the ion-exchanged samples. The Li0.61Na0.39X form of zeolite exhibited the highest specific surface area of 624 m2/g and micropore volume of 0.35 cm3/g compared to sodium form 569 m2/g and 0.30 cm3/g, respectively. The increase of CO2 uptake is not related with deterioration of CO2 selectivity. At room temperature, the CO2 vs. N2 selectivity remains at a very high stable level prior and after ion exchange in co-adsorption process (XCO2 during adsorption 0.15; XCO2 during desorption 0.95) within measurement uncertainty. Additionally, the Li0.61Na0.39X sample was proven to be stable in the aging adsorption-desorption tests (200 sorption-desorption cycles; circa 11 days of continuous process) exhibiting the CO2 uptake decrease of about 6%. The exchange with alkaline earth metals (Mg, Ca) led to a significant decrease of SSA and micropore volume which correlated with lower CO2 adsorption capacities. Interestingly, the divalent cations cause formation of mesopores, due to the relaxation of lattice strains.

The paper presents a modification of titanium dioxide with fumed silica. The SiO2/TiO2 photocatalysts were obtained by the sol-gel method and then were calcined under an argon atmosphere. Various SiO2 weights (2–17.2 wt.%) were used in the materials’ preparation stage. The obtained samples were characterized using advanced analytical methods, such as FT-IR/DRS infrared spectroscopy, X-ray diffraction, SEM scanning electron microscopy, and UV-Vis/DRS spectroscopy. The BET specific surface area and zeta potential of samples were also measured. Based on the obtained results, it was observed that the modification of titanium dioxide with SiO2 effectively inhibited the increase in crystallite size of anatase and brookite during calcination and the decrease in specific surface area values. Moreover, the presence of SiO2 in the nanomaterials contributed to the increase in the size of specific surface area and the change in band gap energy values. The photocatalytic activity was determined based on the decomposition of methylene blue under UV irradiation. Thermal modification in an inert gas atmosphere significantly increased the dye removal rate. It should be noted that all the obtained SiO2/TiO2 photocatalysts showed higher activity compared to the starting TiO2. It was also found that the photocatalytic activity increased along with the increase in SiO2 content in the sample (up to 14.3 wt.% of SiO2). The highest activity was recorded for SiO2(11.1%)/TiO2_400 and SiO2(14.3%)/TiO2_400 samples.

This paper examines the synthesis of the ZnO/carbon spheres composites using resorcinol—formaldehyde resin as a carbon source and zinc nitrate as a zinc oxide source in a solvothermal reactor heated with microwaves. The influence of activation with potassium oxalate and modification with zinc nitrate on the physicochemical properties of the obtained materials and CO2 adsorption capacity was investigated. It was found that in the case of nonactivated material as well as activated materials, the presence of zinc oxide in the carbon matrix had no effect or slightly increased the values of CO2 adsorption capacity. Only for the material where the weight ratio of carbon:zinc was 2:1, the decrease of CO2 adsorption capacity was reported. Additionally, CO2 adsorption experiments on nonactivated carbon spheres and those activated with potassium oxalate with different amounts of zinc nitrate were carried out at 40 °C using thermobalance. The highest CO2 adsorption capacity at temperature 40 °C (2.08 mmol/g adsorbent) was achieved for the material after activation with potassium oxalate with the highest zinc nitrate content as ZnO precursor. Moreover, repeated adsorption/desorption cycle experiments revealed that the as-prepared carbon spheres were very good CO2 adsorbents, exhibiting excellent cyclic stability with a performance decay of less than 10% over up to 25 adsorption-desorption cycles.

Titanium dioxide mixed with reduced graphene oxide (rGO) has been tested in the photoproduction of hydrogen using UV light from water-ethanol combination in gas phase. The presence of the reduced graphene oxide in TiO2/rGO nanocomposites affects the physicochemical properties of hybrid materials, thus enhancing the photocatalytic activity. The obtained catalysts have been characterized for physical-chemical properties using X-ray diffraction (XRD), UV–vis spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM)/high-resolution transmission electron microscopy (HRTEM), and Brauner Emmett Teller (BET). The best photocatalyst has been obtained by mixing anatase and rGO (10 wt%) after calcination at 700 °C. This TiO2-rGO composite exhibited the highest performance with a hydrogen photogeneration rate of 9.5 mmol h-1 g-1.

The iron diet supplements: AproFER 1000 and AproTHEM were subjected to various chemical, microbial and magnetic analysis. The microbial analysis revealed no presence of pathogenic bacteria in the studied products. No significant changes in iron content or forms (bivalent/trivalent) were observed in EPR analysis of supplements stored at different conditions for a long period of time. The chemical and magnetic analysis showed that both AproFER 1000 and AproTHEM contain a high concentration of bivalent iron so they can be used as an iron diet supplements.

This study presents a simple method of titanium dioxide modification by carbon. Monosaccharide (fructose) was used as the carbon source. The pressure modification using fructose caused enhancement of antibacterial efficiency. It was found that prepared photocatalysts were capable of total Escherichia coli and Staphylococcus epidermidis inactivation under the UV-A and artificial solar light, which was attributed to the changes of the surface characteristics, i.e. zeta potential. The best results were observed for the TiO2-F-1%-100 photocatalyst, containing 0.51 wt% of carbon with less negative zeta potential (−18.08 mV). The two-stage photocatalytic mechanism of bacteria destruction by OH radicals was found. Obtained data suggest that fructose-modified photocatalysts may be useful in the development of alternative water disinfectants.

This brief review presents the principal results of studies on the photocatalytic and antimicrobial activity of TiO2/graphene nanohybrid materials with an application for water and wastewater treatment. The impact of different kind of graphene materials on the photoactivity of new hybrid photocatalysts was discussed in detail. It was generally concluded that graphene matrix acts as an acceptor and transporter of electrons photogenerated during TiO2 excitation. Mentioned charge carriers can be freely transferred through the graphene sheets reducing the fast e−−h+ recombination, thus enhancing the photocatalytic performance of TiO2-graphene systems. Additionally, theoretically negatively charged and high surface area of graphene flakes benefits the enhancement of an adsorption rate of pollutants contained in water (especially cationic dyes like methylene blue). Formation of chemical interactions between d orbital in TiO2 and π orbital in graphene impacts on the narrowing of the bang-gap of new hybrid nanocomposites, hence the significant enhancement of photocatalytic activity in the visible region. The occurrence of chemical bonds strongly depends on the type of fabrication method, conditions of preparation, as well as the presence of different functional groups on graphene matrix that greatly facilitates the formation of d−π interactions. The higher amount of reactive oxygen species, especially hydroxyl radicals mainly responsible for the effective oxidation of organic compounds, increases the photocatalytic decomposition rate of degraded pollutants. The effectiveness of OH formation in TiO2/graphene systems could be also attributed to the use of titania nanoparticles with exposed {001} active facets.

TiO2 is the most promising oxide semiconductor extensively used as photocatalyst in solar energy conversion into hydrogen and electric energy as well as in degradation of contaminants in water. To increase its efficiency, carbon dopants are applied. A series of TiO2/graphitic carbon nanocomposites with enhanced photocatalytic performance was synthesized at different temperatures in the 300 – 850°C range in the presence of benzene vapours. To investigate the magnetic properties of these nanocomposites, the dc magnetic susceptibility and electron paramagnetic resonance (EPR) measurementswere carried out. Magnetometry revealed the presence of three very different components: a temperature independent and easily recognized in the high-temperature range, another one in 20 – 100 K range displaying a slow increase with temperature decrease and saturation at low temperatures, and the third one observed at T < 20 K showing a sharp increase with decreasing temperature. Five types of EPR spectra were detected in the investigated samples and attributed to various paramagnetic centres. The role of TiO2 phase composition, nanocrystalline sizes, carbon content in its different forms in establishing static and dynamic magnetic response of our samples will be discussed.

BACKGROUND: One of the main drawbacks of membrane processes is (bio)fouling. Recent attempts to overcome these phenomena focus on incorporation of nanoparticles into polymeric membrane matrices. This paper presents an investigation of the influence of modification of polyethersulfone (PES) ultrafiltration membranes with Ag/titanate nanotubes (Ag/TNTs) on physicochemical characteristics, water permeability and antifouling and antibacterial properties. RESULTS: The modified membranes were prepared via a wet phase inversion method by adding 0.1–1.5 wt% of Ag/TNTs relative to PES into the casting solution. An increase of water permeability with increasing Ag/TNTs content up to 1 wt% was found. The modification contributed to fouling mitigation during ultrafiltration of humic acids solution due to (i) improved hydrophilicity, (ii) presence of Ag/TNTs turbulence promoters and (iii) negative surface charge of the membranes. A correlation between membrane surface roughness, zeta potential and proneness to fouling is discussed. The highest inhibition of bacterial growth, reaching 99.8 and 99.3% for Escherichia coli and Staphylococcus epidermidis, respectively, was observed at the highest Ag/TNTs content. CONCLUSIONS: The introduction of Ag/TNTs into PES membrane structures improved membrane permeability, fouling resistance and antibacterial properties. The most significant improvement was observed in the case of membranes containing the largest quantities of Ag/TNTs. © 2019 Society of Chemical Industry

Sol-gel method was used for preparation of TiO2 having different structure and phase composition. Prepared titania samples were applied for acetaldehyde decomposition under UV light irradiation. The obtained results showed, that TiO2 consisted from mixed phases of anatase and brookite, which was prepared at neutral pH and calcined at 450 °C was the most active. Charge separation of free carriers was investigated by measurements of electron traps density. It was proved, that density of electron traps can be enhanced by nitrogen doping or by coexisting of two phases such as anatase and brookite. However nitrogen doping to TiO2 did not increase of its photocatalytic activity towards acetaldehyde decomposition. Therefore preparation of TiO2 having mixed phases of anatase and brookite appeared to be the most favourable towards elimination of acetaldehyde under UV at ambient conditions. Moreover, temperature of calcination such as 450 °C was the most optimal, because at that temperature total crystallisation of amorphous titnia occurrs and then interparticle contact increases, which facilitates the interfacial charge transfer between titania particles.

Hybrid carbon-TiO2 spheres (TiO2/C spheres) were prepared via the CVD method in the atmosphere of benzene vapours at 800–1000 °C. Structure and morphology of prepared hybrid composites were examined by means of SEM, TEM, XPS, TG, Raman spectroscopy, XRD and UV–Vis/DRS methods. The SEM and TEM analysis confirmed the presence of uncovered rutile crystallites as well as the different forms of carbon-modified TiO2 forms: rutile TiO2/C spheres and thin flakes of graphite and thin graphene sheets. The average thickness of the typical spheres varied between 30 and 40 nm for samples prepared at lower temperatures (800–900 °C), but the carbon core-shell thickness could be even up to 100 nm for samples obtained at 950–1000 °C. The XPS, TG, Raman spectroscopy and XRD measurements allowed to characterize in detail the carbonaceous nature of carbon layers of the fabricated spheres, indicating the graphitic character of TiO2/C hybrids.

This work aimed to obtain hybrid composites based on photoactive metal oxide and carbon having adsorption properties. The materials, composed of titanium dioxide or zinc oxide and spherical carbon, were obtained from resorcinol-formaldehyde resin, treated in a solvothermal reactor heated with microwaves and then subjected to carbonization, were received. The functional groups of pure carbon spheres (unsaturated stretching C=C, stretching C−OH and C−H bending vibrations), CS/ZnO and CS/TiO2 samples were determined by FT-IR analysis. The characteristic bands for ZnO and TiO2 were observed below 1000 cm−1. The thermal oxidative properties are similar for TiO2- and ZnO-modified carbon spheres. We have observed that the increased carbon sphere content in nanocomposites results in starting the decomposition process at a lower temperature, therefore, nanocomposites have a broader combustion temperature range. The effect of the oxides’ addition to carbon spheres on their adsorption properties was evaluated in detail by examining CO2 adsorption from the gas phase. The selectivity of CO2 over N2 at a temperature of 25 °C and pressure of 1 bar (a novelty in testing CS-based sorbents) calculated for 3.00 CS/TiO2 and 4.00 CS/ZnO was 15.09 and 16.95, respectively. These nanocomposites exhibit excellent cyclic stability checked over 10 consecutive adsorption–desorption cycles.

A simple method of hydrogen production through the decomposition of water subjected to UV radiation is presented. Water contained dissolved sodium hydroxide and the solution was saturated with carbon dioxide gas. During saturation, the pH value dropped from about 11.5 to 7-8. The produced bicarbonate and carbonate ions acted as scavengers for hydroxyl radicals, preventing recombination of hydroxyl and hydrogen radicals, and giving priority to the formation of hydrogen gas.In the presented method, the production of hydrogen is combined with the utilization of carbon dioxide.

This work investigated for the first time the role of adsorption in the photocatalytic degradation of methylene blue and Orange II dyes in the presence of 3-aminopropyltriethoxysilane (APTES)-modified TiO2 nanomaterials. It has been demonstrated that the decrease in adsorption has a detrimental effect on photocatalytic activity. APTES/TiO2 photocatalysts were successfully prepared by solvothermal modification of TiO2 in a pressure autoclave, followed by heat treatment in an inert gas atmosphere at the temperature range from 300 °C to 900 °C. It was observed that functionalization of TiO2 via APTES effectively suppressed the anatase-to-rutile phase transformation, as well as the growth of crystallites size during calcination, and reduction of specific surface area (APTES modification inhibits sintering of crystallites). The noted alterations in the adsorption properties, observed after the calcination, were generally related to changes in the surface characteristics, mainly surface charges expressed by the zeta potential. Positively charged surface enhances adsorption of anionic dye (Orange II), while negatively charged surface was better for adsorption of cationic dye (methylene blue). The adsorption process substantially affects the efficiency of the photocatalytic oxidation of both dyes. The methylene blue decomposition proceeded according to the pseudo-first and pseudo-second-order kinetic models, while the degradation of Orange II followed the zero, pseudo-first, and pseudo-second order kinetic models.

In this work, the impact of APTES-modified TiO

This paper describes the investigations on the possibilities of treatment of wastewater generated in an industrial laundry with application of a combined biological-photooxidation- membrane system aimed at water recycle and reuse. The two treatment schemes were compared: 1) scheme A consisting of a treatment in a moving bed biological reactor (MBBR) followed by microfiltration (MF) and nanofiltration (NF), and 2) scheme B comprising MBBR followed by oxidation by photolysis enhanced with in situ generated O3 (UV/O3) after which MF and NF were applied. The removal efficiency in MBBR reached 95&ndash, 97% for the biochemical oxygen demand, 90&ndash, 93% for the chemical oxygen demand and 89&ndash, 99% for an anionic and a nonionic surfactants. The application of UV/O3 system allowed to decrease the content of the total organic carbon by 68% after 36 h of operation with a mineralization rate of 0.36 mg/L&middot, h. Due to UV/O3 pretreatment, a significant mitigation of membrane fouling in the case of both MF and NF processes was achieved. The MF permeate flux in the system B was over two times higher compared to that in the system A. Based on the obtained results it was concluded that the laundry wastewater pretreated in the MBBR-UV/O3-MF-NF system could be recycled to any stage of the laundry process.

This paper describes the investigations on the possibilities of treatment of wastewater generated in an industrial laundry with application of a combined biological-photooxidation- membrane system aimed at water recycle and reuse. The two treatment schemes were compared: 1) scheme A consisting of a treatment in a moving bed biological reactor (MBBR) followed by microfiltration (MF) and nanofiltration (NF), and 2) scheme B comprising MBBR followed by oxidation by photolysis enhanced with in situ generated O3 (UV/O3) after which MF and NF were applied. The removal efficiency in MBBR reached 95–97% for the biochemical oxygen demand; 90–93% for the chemical oxygen demand and 89–99% for an anionic and a nonionic surfactants. The application of UV/O3 system allowed to decrease the content of the total organic carbon by 68% after 36 h of operation with a mineralization rate of 0.36 mg/L·h. Due to UV/O3 pretreatment, a significant mitigation of membrane fouling in the case of both MF and NF processes was achieved. The MF permeate flux in the system B was over two times higher compared to that in the system A. Based on the obtained results it was concluded that the laundry wastewater pretreated in the MBBR-UV/O3-MF-NF system could be recycled to any stage of the laundry process.

Zinc chloride and potassium oxalate are often applied as activating agents for carbon materials. In this work, we present the preparation of ZnO/carbon spheres composites using resorcinol-formaldehyde resin as a carbon source in a solvothermal reactor heated with microwaves. Zinc chloride as a zinc oxide source and potassium oxalate as an activating agent were applied. The effect of their addition and preparation conditions on the adsorption properties towards carbon dioxide at 0 °C and 25 °C were investigated. Additionally, for all tested sorbents, the CO2 sorption tests at 40 °C, carried out utilizing a thermobalance, confirmed the trend of sorption capacity measured at 0 and 25 °C. Furthermore, the sample activated using potassium oxalate and modified using zinc chloride (a carbon-to-zinc ratio equal to 10:1) displayed not only a high CO2 adsorption capacity (2.69 mmol CO2/g at 40 °C) but also exhibited a stable performance during the consecutive multicycle adsorption–desorption process.

Selenium is one of the trace elements playing a crucial role in a proper function of living organisms. Selenium intake varies, largely based on the selenium content of food. The daily Se intake recommended for adults amounts to 55 μg per day. The mean level of selenium in the population varies considerably between countries. Recent studies on the selenium dietary intakes in Poland showed that it is not sufficient to meet the daily requirement for this microelement so it is strongly recommended to employ selenium supplementation. The commercial product SEL-BRCA1® being a selenium diet supplement was subjected to chemical and microbial analysis to determine its stability in storage time and conditions. Basing on the obtained results it can be stated that the stability of studied supplement, stored in the closed bottles, can be confirmed for the period of time up to 45 months after the production date and it is not recommended to store opened bottles for the period of time longer than 12 months. The studied supplement showed a very high microbial stability what underscores its usefulness as human medicines.

Co-modified TiO2 photocatalysts (TiO2-N,C) were added to commercial gypsum to obtain self-cleaning building material. The gypsum/TiO2 composite were also studied towards their mechanical properties. The highest photocatalytic activity was obtained for gypsum samples containing TiO2/N,C photocatalyst treated at 100–300 °C, attributed to high anatase phase participation, relatively high nitrogen and carbon content and high BET surface area (ca. 170–270 m2/g). In this case (300 °C) the model pollutant (azo dye) degradation rate was 85% and 70% after 15 h of UV and vis irradiation, respectively. Higher compressive strength values was observed for gypsum sample loaded with photocatalysts treated at higher temperatures (600–800 °C), attributed to rutile phase presence and large crystallite size. The grinding operation during gypsum/TiO2 composite preparation can contribute towards the increase of compressive strength (even 40%) by reduction of gypsum particle size whereas photocatalyst particles act as the effective fillers of void spaces in gypsum material.

Large, laboratory scale biological treatment tests of real industrial wastewater, generated in a large industrial laundry facility, was conducted from October 2014 to January 2015. This research sought to develop laundry wastewater treatment technology which included tests of a two-stage Moving Bed Bio Reactor (MBBR); this had two reactors, was filled with carriers Kaldnes K5 (specific area – 800 m2/m3) and were realized in aerobic condition. Operating on site, in the laundry, reactors were fed actual wastewater from the laundry retention tank. The laundry wastewater contained mainly surfactants and impurities originating from washed fabrics; a solution of urea to supplement nitrogen content and a solution of acid to correct pH were added. The daily flow of raw wastewater Qd varied from 0.6–1.0 m3/d. Wastewater quality indicators showed that the reduction of pollutants was obtained: BOD5 by 95–98%, COD by 89–94%, the sum of anionic and nonionic surfactants by 85–96%. The quality of the purified wastewater after the start-up period met legal requirements regarding the standards for wastewater discharged into the environment.

The gypsum building material was enriched with photocatalytic properties for indoor air purification. The photocatalytic additive to gypsum was TiO2 modified with carbon from various sources. The photocatalytic activity of gypsum plates was performed towards NO x removal. Carbon doping into TiO2 improved not only total degradation of NO x on corresponding gypsum plates but also NO2 selectivity was changed, limiting the production of toxic NO2. The exhibition of photocatalysts on the visible and ultraviolet irradiation has been also carried out to examine their durability. First, the stability of modifying element – carbon in TiO2 structure was analysed, indicating on the gradual reduction of carbon content with irradiation time, especially when the carbon source was cyclic hydrocarbon. Second, the photocatalytic activity of the gypsum plates was performed at each stage of the ageing process. Based on this insight, the correlation between carbon content in modified photocatalysts loaded to gypsum plates and photocatalytic activity of them was described in detail.

In this paper titanium dioxide carbon modification with benzene as a carbon source is presented. A TiO2/graphitic carbon nanocomposites were synthesized by thermal modification in the presence of benzene vapours at different temperature (300–700 °C). The new materials were characterized by a various techniques, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-vis/DR), surface-enhanced Raman spectroscopy. BET specific surface area was also measured. The photocatalytic activity of obtained nanocomposites was measured by the decomposition of acetic acid and methylene blue under UV–vis irradiation. The results show that photocatalytic activity increasing with increase in carbon concentration and temperature of modification. It can be noted that adsorption degree has a very high impact on methylene blue decomposition. The highest photocatalytic activity was found for the photocatalyst modified at 600 °C contains 1.13 wt% of carbon. It should be noted that, the influence of crystallite size, crystal structure changes and specific surface area for photocatalytic activity are presented.

Carbon spheres were prepared by carbonisation of phenolic resin spheres obtained using a modified Stober method in a microwave assisted solvothermal reactor. Preparation process involved water–ethanol, ammonia water, resorcinol, potassium oxalate and formaldehyde. The mixture was stirred for 24 h at room temperature and then subjected to a pressure treatment, in which the solution was treated in a microwave assisted solvothermal reactor for 15 min at a pressure of 1–3 MPa. The proposed synthesis resulted in a material containing microporous carbon spheres having high surface area (from 1178 to 1648 m2/g), with diameters from 200 to 350 nm, total pore volume from 0.49 to 0.78 cm3/g, and high CO2 adsorption capacity from 3.86 to 5.03 mmol/g measured at 0.1 MPa and 25 °C. Taking into account the properties of the obtained material, it can be applied as a sorbent for CO2 capture.

A comparison of effectiveness of two advanced oxidation processes, photocatalysis and ultraviolet (UV) irradiation enhanced with H2O2 addition, coupled with ultrafiltration (UF) for treatment of secondary effluent (SE) from a municipal wastewater treatment plant (WWTP) is presented. The results were compared with photolysis – UF system. The concentration of H2O2 in the UV/H2O2 – UF mode ranged from 0.03 to 0.3 g/L, the photocatalyst TiO2 P25 loading was changed from 0.5 to 2 g/L. A ceramic membrane with ZrO2 separation layer was used. No significant influence of photocatalyst or H2O2 concentration on permeate flux was observed, however, both PMR (photocatalytic membrane reactor) and UV/H2O2 – UF systems were less prone to fouling than the photolysis – UF one. Adsorption was found to be an important stage of total organic carbon (TOC) removal in PMR, while UF contributed mainly to photocatalyst rejection with minor effect on the overall treatment efficiency. The highest TOC removal of organic contaminants after 5 h of operation was found at 1.5 gTiO2/L in PMR (61%) and 0.15 gH2O2/L in UV/H2O2 – UF process (65%). The quality of permeate obtained in both systems was comparable, the product of the latter one exhibited lower ecotoxicity towards crustaceans Thamnocephalus platyurus than the PMR permeate.

In this study, a series of TiO2/rGO photocatalysts were obtained with a two-step procedure: a solvothermal method and calcination at 300–900 °C in an argon atmosphere. It was noted that the presence of rGO in photocatalysts had an important role in the changes in crystallite size and specific surface area. In TiO2/rGO samples, different surface functional groups, such as C−Cgraph, C−Caliph, C−OH, C=O, and CO(O), were found. It was observed that rGO modification suppressed the anatase-to-rutile phase transformation. The photocatalytic activity of the obtained nanomaterials was investigated through the decomposition of methylene blue under UV and artificial solar light irradiation. It was found that the adsorption degree played an important role in methylene blue decomposition. The experimental results revealed that TiO2/rGO samples exhibited superior removal efficiency after calcination for methylene blue compared toTiO2 without rGO, as well as a commercial photocatalyst KRONOClean 7000. It was noted that photocatalytic activity increased with the increase in the calcination temperature. The highest activity was observed for the sample calcined at 700 °C, which consisted of 76% anatase and 24% rutile. This study clearly demonstrated that TiO2/rGO samples calcined in argon can be used as efficient photocatalysts for the application of methylene blue decomposition.

In this paper, the antibacterial activity of titanium dioxide modified with reduced graphene oxide (rGO) was presented. TiO2/rGO photocatalysts were prepared by the hydrothermal method under elevated pressure at 180°C and heated at 100°C in Ar flow. The obtained photocatalysts were characterized by means of XRD, FTIR/DRS, UV-vis/DR, Raman spectroscopy and scanning electron microscopy (SEM). The carbon content was also examined. FTIR/DRS and Raman analysis confirmed the presence of rGO in the TiO2 structure, suggesting a successful modification. The antimicrobial photoactivity of photocatalysts was conducted against E. coli under an artificial solar light. The results show that all TiO2/rGO photocatalysts exhibited an antibacterial activity higher than unmodified TiO2. The best result was found for sample with 1.5wt% additive of reduced graphene oxide. In this case, total inactivation of E. coli was noticed after 75min of irradiation. It was found that the presence of rGO in sample improves the antimicrobial activity.

A hybrid nanocomposites containing nanocrystalline TiO2 and graphene related materials (graphene oxide and reduced graphene oxide) were successfully prepared elevated pressure using hydrothermal method. The structural and textural properties as well as the presence of different carbonaceous structures on the surface of obtained nanocomposites have been characterized by means of XRD, FTIR/DRS and Raman spectroscopy. FTIR/DRS analysis allowed to find characteristic peaks of graphene oxide: epoxy stretching at 1229 cm−1 and alkoxy stretching vibration at 1059 cm−1. In the spectrum of nanocomposites containing rGO, all the bands decreased or even disappear. It can be indicated that GO was successfully reduced to rGO. SEM studies showed difference between graphene oxide (aggregated, crumpled, non-transparent) and reduced graphene oxide (thin and transparent) flakes. The Time Resolved Microwave Conductivity analysis have been utilized to investigate the excess of charge-carrier lifetimes in TiO2-graphene oxide and TiO2-reduced graphene oxide hybrid nanocomposites. It was generally concluded that modification of starting TiO2 with carbonaceous precursors leads to the slight increase of intensity of the TRMC signals, indicating that more electrons are induced in the conduction band of hybrid nanocomposites. It is also worth mentioning that the decay of studied signals of modified powders depends on added carbon precursor, indicating that the type of deposited species may affect the slight or significant suppression of recombination or charge-carriers trapping.