Photocatalytic Activity of TiO

TiO2-WO3 photocatalysts were prepared in a vacuum evaporator by impregnation of TiO2 with WO2 dissolved in an H2O2 solution (30%) and followed by calcination at 400 and 600∘C. XRD analyses showed that at 400∘C monoclinic phase of WO3 was dominated whereas at 600∘C both monoclinic and regular phases of WO3 were present. Modification of TiO2 by WO3 caused increasing in the absorption of light to the visible range. TiO2 and photocatalysts modified with low amount of WO3 (1–5 wt.%) showed high adsorption of Acid Red (AR) on their surface and enhanced photocatalytic activity under UV irradiation. Under visible light irradiation, TiO2-WO3 photocatalysts prepared at 400∘C were more active for AR decomposition than those prepared at 600∘C suggesting that monoclinic phase of WO3 is more active under visible light than regular WO3. Although TiO2-WO3 photocatalysts appeared to be active under visible light for decomposition of AR, the UV irradiation was more efficient

Photocatalytic Activity and Mechanical Properties of Cements Modified with TiO2/N

In this paper, studies of the mechanical properties and photocatalytic activity of new photoactive cement mortars are presented. The new building materials were obtained by the addition of 1, 3, and 5 wt % (based on the cement content) of nitrogen-modified titanium dioxide (TiO2/N) to the cement matrix. Photocatalytic active cement mortars were characterized by measuring the flexural and the compressive strength, the hydration heat, the zeta potential of the fresh state, and the initial and final setting time. Their photocatalytic activity was tested during NOx decomposition. The studies showed that TiO2/N gives the photoactivity of cement mortars during air purification with an additional positive effect on the mechanical properties of the hardened mortars. The addition of TiO2/N into the cement shortened the initial and final setting time, which was distinctly observed using 5 wt % of the photocatalyst in the cement matrix

The Increase of the Micoporosity and CO2 Adsorption Capacity of the Commercial Activated Carbon CWZ-22 by KOH Treatment

The chemical modification of CWZ-22—commercial activated carbon (AC) with KOH‐ to enhance CO2 adsorption was examined. The effect of different impregnation ratios KOH:CWZ-22 from 1 to 4 was studied. The ACs were characterized by CO2 and N2 sorption, Fourier transform infrared (FTIR), SEM, and XRD methods

Hybridization of Advanced Oxidation Processes with Membrane Separation for Treatment and Reuse of Industrial Laundry Wastewater

A new attempt to treat and reuse the industrial laundry wastewater using biological treatment followed by advanced oxidation processes (AOPs) and membrane separation is presented. Three various configurations of the hybrid systems were investigated: (1) biological treatment in a Moving Bed Biofilm Reactor (MBBR) – photocatalysis with suspended TiO2 P25, enhanced with in situ generated O3 – ultrafiltration (UF) – nanofiltration (NF); (2) biological treatment in MBBR– photocatalysis with immobilized TiO2 P25, enhanced with in situ generated O3 – UF - NF; (3) biological treatment in MBBR – photolysis/ozonation (with in situ generated O3) – UF – NF. For comparison purpose the wastewater was additionally treated in the MBBR – UF – NF mode (4). Application of AOPs contributed to the UF membrane fouling mitigation during treatment of the biologically pretreated laundry wastewater. The highest improvement of the UF permeate flux was found in case of the MBBR effluent treated with application of the immobilized TiO2 bed which was attributed to the highest efficiency of mineralization observed for that system. Since the applied wastewater contained significant amounts of inorganic ions, mainly Na+ and Cl-, the NF as the final polishing step was proposed. The quality of NF permeate was independent on the AOP mode applied and, moreover, significantly higher than the quality of water currently used in the laundry. It was concluded that the NF permeate could be recycled to any stage of the laundry system. Taking into consideration that application of TiO2 increases the overall treatment costs and that although the O3/UV pretreatment is less efficient than photocatalysis, it still allows to improve the UF permeate flux for ca. 35% compared to the direct UF of the MBBR effluent, the MBBR – UV/O3 – UF – NF system was proposed as the most beneficial configuration for the treatment and reuse of the industrial laundry wastewater

Photocatalytic decomposition of surfactants on nitrogen modified TiO

In these studies advanced oxidation processes such as: photolysis, ozonation and photocatalysis for anionic and cationic surfactants decomposition were used. Nitrogen modified titanium dioxide and commercial TiO2-P25 were used for photocatalytic tests. UV-C lamp and different dose of ozone: 186, 383, 478 and 563 mg/(dm3·h) were used. The optimal system for anionic and cationic surfactants decomposition was connection of ozonation with UV-C irradiation

Improved Self-Cleaning Properties of Photocatalytic Gypsum Plaster Enriched with Glass Fiber

In the study the self-cleaning properties of photoactive gypsum plasters are presented. The modified gypsum plasters were obtained by addition of 1 and 3 wt.% of nitrogen-modified titanium dioxide (TiO2/N) and 0.1, 0.3, and 0.5 wt.% of glass fiber. The self-cleaning ability of the obtained materials was tested during two dyes decomposition: Methylene Blue (MB) and Reactive Orange (RO). It was found that presence of glass fiber increased photocatalytic activity of modified gypsum plasters, which may be due to the fact glass fiber may act as ducts for light and transport it to sites screened by TiO2 or glass fiber can retard charge recombination. Moreover, unexpectedly the addition of glass fiber did not increase the mechanical properties of modified gypsum plasters, which may be because gypsum does not strongly adhere to the surface of glass fibers

Application of modified concrete to remove surfactants from water

In these studies two types of modified concretes in photocatalytic mineralization of anionic surfactant sodium dodecylbenzenesulfonate (NaDBS) were used. Commercial TiO2-P25 and nitrogen modified TiO2-N as photocatalysts for concrete modification were employed. The studies were conducted in the special designed reactor which was a simple model of the secondary settler used at the sewage treatment plant. The mineralization of anionic surfactant NaDBS after 18 h of UV light irradiation amounted to 48% for concrete modified by TiO2-P25 and 37% for concrete modified by TiO2-N

Formation of Combustible Hydrocarbons and H2 during Photocatalytic Decomposition of Various Organic Compounds under Aerated and Deaerated Conditions

A possibility of photocatalytic production of useful aliphatic hydrocarbons and H2 from various organic compounds, including acetic acid, methanol, ethanol and glucose, over Fe-modified TiO2 is discussed. In particular, the influence of the reaction atmosphere (N2, air) was investigated. Different gases were identified in the headspace volume of the reactor depending on the substrate. In general, the evolution of the gases was more effective in air compared to a N2 atmosphere. In the presence of air, the gaseous phase contained CO2, CH4 and H2, regardless of the substrate used. Moreover, formation of C2H6 and C3H8 in the case of acetic acid and C2H6 in the case of ethanol was observed. In case of acetic acid and methanol an increase in H2 evolution under aerated conditions was observed. It was concluded that the photocatalytic decomposition of organic compounds with simultaneous generation of combustible hydrocarbons and hydrogen could be a promising method of “green energy” production