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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.

The investigations on the influence of humic acids (HAs) being representatives of Natural Organic Matter (NOM) and inorganic salts (NaHCO3, Na2HPO4 and Na2SO4) representing inorganic ions in natural waters, on fouling and stability of a polyethersulfone ultrafiltration membrane in a photocatalytic membrane reactor (PMR) are reported. The influence of inorganic ions on the permeate flux was dependent on their concentration and was more significant at higher salts content. The HCO3− ions contributed to the permeate flux decline to the highest extent, which was attributed to both a higher feed pH and a formation of a dense fouling layer. In the presence of SO42− the permeate flux was higher than in case of other ions which was explained in terms of lower thickness of the fouling cake caused by repulsion of TiO2 particles by the membrane under such conditions. The most severe decrease of the permeate flux observed in the presence of a mixture of HAs and inorganic salts was attributed to the formation of a thick fouling cake caused by bridging effect between HAs molecules and TiO2 particles under high ionic strength conditions. The inorganic salts contributed also to a decrease of HAs decomposition rate due to the hole and hydroxyl radicals scavenging effect of the ions. It was found that the conditions prevailing in the PMR contributed to the loss of the membrane separation properties towards dextrans due to the abrasive action of TiO2 particles. However, the extent of the observed decrease in the dextrans rejection was dependent on the feed composition.

Three commercial activated carbons (ACs) supplied by Carbon, Norit and Desotec were modified by acid treatments. A significant CO 2 capacity improvement of up to 36% was achieved. It was found that higher CO 2 uptakes were related to removal of inorganic impurities i.e. mineral matter and increase of the submicropores volume i.e. smaller than 0.8 nm. Sorbents were thoroughly characterized in terms of texture and chemical composition. CO 2 uptake was determined by BET isotherm measurement carried out at 273 K and pressure of up to 0.95 bar. The enhancement of CO 2 uptake was observed especially for ACs with the highest initial mineral matter content. It was found that mineral matter in ACs plays the role of a ballast and additionally blocks adsorption places and submicropores volume thus lowers CO 2 uptake. On the other hand it was proven that mineral matter may prevent the structure from collapsing and thus can stabilize high SSA. The AC surface oxidation effect on CO 2 uptake was determined by comparison of ACs treated with HCl and HNO 3 . Both acids remove mineral matter content to the same degree, but detailed X-ray photoelectron spectroscopy (XPS) study revealed that in case of HNO 3 treatment, AC surface was more oxidized which correlated with higher CO 2 uptake. However observed uptake increase was attributed to increase of the submicropores volume.

The investigations on the influence of TiO2 photocatalyst (Aeroxide® P25) loading, feed cross-flow velocity (CFV) and feed water composition on the fouling of ceramic TiO2 ultrafiltration membrane and removal of humic acids (HA) in a photocatalytic membrane reactor (PMR) are presented. Moreover, the stability of the ceramic membrane after 400 h of operation in the PMR is discussed. In case of model solution of HA in ultrapure water it was revealed that by an increase of TiO2 loading from 0.5 to 1.5 g/dm3 the membrane fouling can be avoided. Alkaline conditions (pH 9) had a negative influence on the permeate flux and humic acids removal, whereas at pH 3 and pH 6.5 no membrane fouling was noticed. In the presence of HCO3−, SO42− and HPO42− at both low and high concentrations the membrane fouling was more severe than in the absence of these species, what was attributed to a lower efficiency of HA removal in the feed. Addition of Ca2+ and Mg2+ to the feed containing the inorganic anions allowed to improve the efficiency of HA removal and reduce membrane fouling. After 400 h of PMR operation a deterioration of membrane separation properties was observed what was attributed to the abrasive action of photocatalyst particles.

A simple way of preparation of Ni-modified and Ni,N-co-modified rutile TiO 2 from an industrial grade amorphous titanium dioxide via impregnation followed by calcination at 1073 K in argon (Ni–TiO 2 ) or ammonia (Ni,N–TiO 2 ) atmosphere with different Ni:TiO 2 ratios is presented. New materials were characterized by means of: XRD, XPS, elemental analysis, UV–Vis/DR spectroscopy, SEM, EPR and N 2 adsorption at 77 K. The photocatalytic activity of the materials was studied during decomposition of acetic acid under irradiation with UV or Vis light with wavelengths longer than 400 nm or 450 nm. The obtained results suggest the occurrence of a charge transfer between TiO 2 and NiTiO 3 phases resulting in a relatively high activity of XNi–TiO 2 materials under the irradiation up to 400 nm. A band-gap narrowing of TiO 2 after ammonia treatment was proved on the basis of UV–Vis/DR spectra for all the co-modified samples. The influence of Ti 3+ ions on the band-gap narrowing and consequently photocatalytic activity of XNi,N–TiO 2 and possible electron transfer from rutile conduction band to metallic Ni is here discussed.

A simple method of preparation of visible-light active rutile-TiO2 photocatalysts is presented. New materials were obtained by modification of a commercial amorphous titanium dioxide via impregnation followed by calcination at 800 C processes. Series of Fe-modified TiO2 with different Fe:TiO2 ratios (1, 5 and 10 wt.% of Fe) were obtained by impregnation with Fe(NO3)3 followed by calcination in argon atmosphere. Nitrogen-modified TiO2 was prepared by calcination of the commercial titania in ammonia atmosphere at 800 C. Finally (Fe,N) co-modified samples were prepared by combining impregnation with calcination in ammonia atmosphere. The materials were characterized by the following methods: Xray power diffraction (XRD), X-ray photoelectron spectroscopy (XPS), elemental analysis, UV-Vis/DR spectroscopy, scanning electron microscopy (SEM) and N2 adsorption at 77 K. The photocatalytic activity of the new materials was studied during oxidative decomposition of acetic acid under visible light irradiation using mercury lamp and a cut-off filter providing wavelength longer than 400 nm. Additionally, the so-called action spectra measurements of photocatalytic activity as a function of irradiation wavelength were conducted. The results revealed an excellent increase in the visible light photoactivity of the co-modified samples in comparison with the single-modified ones, which was ascribed to the synergistic effect of the N,Fe rutile co-modification. Nitrogen caused a band-gap narrowing allowing absorption of longer wavelengths from visible light region, whereas iron increased the efficiency of charge separation. As a result, a significantly improved photocatalytic performance of the materials was observed.

Porous carbons loaded with MgO, prepared through one-step process from mixtures of poly(ethylene terephthalate) and natural magnesite, were examined as sorbents for SO 2 gas contained in air at low temperature. Influence of pore structure, inorganics loading, humidity, and temperature, on the efficiency of the gas removal is presented and discussed. Performance of the hybrid sorbent materials increased along with MgO loading, temperature of the bed, and moisture content. As found, removal of SO 2 by the prepared sorbents is due to synergic effect involving adsorption on porous material and chemical interaction between the gas and MgO. Possible mechanism of the SO 2 removal process is proposed on the basis of XPS spectroscopy measurements.

Photocatalytic membrane reactors (PMRs) seem to be a very promising method of solving problems concerning separation of photocatalyst as well as products and by-products of photodegradation from the reaction mixture. In the presented studies an anatase-phase TiO2 was applied for degradation of Acid Yellow 36 (AY36) in the PMR coupling photocatalysis and direct contact membrane distillation (DCMD). The effect of different process parameters such as dye concentration, reaction temperature and photocatalyst loading on the effectiveness of degradation of AY36 was investigated. Moreover, in order to compare the effectiveness of AY36 photodegradation during photocatalysis alone and the hybrid process, additional experiments without application of MD were conducted. The addition of TiO2 to a feed did not affect the permeate flux, regardless of the process conditions applied. The flux remained constant and equal to the maximum permeate flux during about 400 h of experiments. The highest decolorization of AY36 solution during hybrid process was observed at the highest photocatalyst loading applied (0.5 g TiO2/dm3). The increase of the reaction temperature from 313 to 333 K resulted in an increase of the photodegradation rate of AY36. After 5 h of the hybrid process the effectiveness of dye degradation calculated on a basis of AY36 mass in a feed solution amounted to 31, 36 and 42% for the reaction temperatures of 313–333 K. Similar results were obtained when photocatalysis was conducted in the MD installation but with disconnected MD module. It was found that an improvement of AY36 photodegradation could be achieved by a decrease of initial dye concentration. Comparing the results obtained in a conventional slurry photoreactor and in the PMR and taking into account both, the rate of azo dye degradation and the quality of the product, it could be concluded that more beneficial configuration seems to be the PMR.