Papers by Keyword: Self-Cleaning

Abstract: Black limestones were used as structural and ornamental stones in the facades of the four madrasas at Sultan Hasan mosque. Regrettably, the studied black limestone blocks have significantly suffered from deterioration mechanisms, causing severe damage forms such as discolouration, salt crystallization, cracking, fissuring, flaking, granular disintegration, and microbial growth. Examination and analysis of the studied black limestone were performed using polarizing light microscope, scanning electron microscope equipped with EDS, X-ray diffraction, and fungal investigation. The current research mainly presents an experimental study to evaluate the efficiency of nanocomposites prepared from SRC-220 (fluorinated polyurethane) and TiO₂ NPs in the treatment of the studied black limestone. The prepared TiO₂ nanocomposites were used for the treatment of experimental black limestone samples. The effect of TiO₂ nanoparticle concentration on the properties of the fabricated nanocomposites was comparatively tested. Experimental study was implemented using transmission electron microscope, scanning electron microscope, atomic force microscope, static water contact angle, colourimetric investigation, abrasion resistance, self-cleaning activity, and fungistatic efficiency. The results proved that the addition of TiO₂ nanoparticles into SRC-220 pure polymer produced multifunctional nanocomposites characterized by high transparency, good consolidation effect, superhydrophobicity, self-cleaning, and antifugal efficiency. Moreover, it was demonstrated that the concentration of TiO₂ nanoparticles significantly affects the obtained properties of the prepared nanocomposites.

Abstract: Cotton fabric is a textile material that is valued for its strength, breathability, absorbency, and potential for many textile products. In this study, titanium dioxide (TiO₂) was synthesized by the sol-gel method, and cotton fabric was coated with TiO₂ by the dip-coating method in an ultrasonic bath for self-cleaning applications. The characteristics of the coated cotton fabric were determined by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray, and tensile strength. The photocatalytic activity of cotton fabric treated with TiO₂ nanoparticles was followed by the degradation of three organic compounds, such as tea, coffee, and red wine, under solar, UV, and xenon light conditions. The results showed that stains of organic compounds were successfully decomposed by more than 50%, and the light conditions significantly affected the self-cleaning ability of fabric. The higher energy of light leads to improved degradation of stains on the treated fabric. With the ability to self-clean, cotton fabric may have great potential for commercialization in the textile industry for high-end products.

Abstract: Due to their ability to combine the physical separation of membrane filtration with organic degradation in one unit, photocatalytic membranes have demonstrated enormous potential for application in energy-efficient water purification and wastewater treatment. Titanium dioxide (TiO₂) is the substance most frequently utilized to create photocatalytic membranes. However, TiO₂'s use is constrained by its substantial band gap (3.2 eV). On the other hand, tungsten trioxide (WO₃) has a fairly small band gap (2.7-2.8 eV) which makes it able to absorb visible light, making the photocatalytic process more efficient. This article examines recent developments in WO₃ photocatalytic membranes for wastewater treatment and water purification with a focus on the photocatalytic mechanism, photocatalytic membrane fabrication and development. The mechanism of WO₃ semiconductor in pollutant removal is explained in detail. Blending, coating and grafting methods, which are three methods commonly used when fabricating photocatalytic membranes, are discussed. Likewise with the development of WO₃ photocatalytic membranes using pure WO₃, heterojunction or doping with metal.

Abstract: The dust accumulation and dirt particles always degrade the transparency of glass, later hampers its various applications such as photovoltaic panels, building glass, and car-windshield. In this study, the hydrophilic self-cleaning coatings have been developed by using the nanocalcium Carbonate particles (nanoCaCO₃) and hydrophilic micro-titanium dioxide particles (µ-TiO₂). The presence of oxide groups, CO^-3 and TiO^2- forms a strong attraction of glass to polar water molecules. At the weight ratio of 1: 1 in the CaCO₃ to TiO₂ mixture, it forms a great hydrophilic property in which the water contact angle (WCA) of coated glass has been recorded as low as 11.46 ±0.85°. The coated glass also showed high transparency in UV and Visible regions. The optical transmission of coated glass was above 89% at the wavelength of 300-400nm and above 97% at the wavelength of 400-800nm. Due to its hydrophilic property, the coated glass is capable of removing the dust particles away via the water stream. The hydrophilic coating spontaneously forms the water-thin film after contact with coated glass without the presence of UV light.

Abstract: In this work, TiO₂ was applied to cotton fabric by a sol–gel-hydrothermal process. A combination of 3-(trihydroxysilyl) propyl methylphosphonate monosodium salt solution (TPMP) and (3-aminopropyl)triethoxysilane (APTES) was used as a matrix to enhance the interfacial interaction between TiO₂ and surface of the cotton fibres. During the hydrothermal treatment, silver nitrate (AgNO₃) or reduced graphene oxide (rGO) were added to produce Ag-doped TiO₂- or rGO-coupled TiO₂-coated textiles. The successful application of all investigated components on cotton fabric was confirmed by the analysis of SEM and EDS. The results of UPF determination and self-cleaning activity showed excellent performance of both studied nanocomposite coatings, whereas the use of rGO proved to be better than Ag.

Abstract: In this study, Chitosan-Xyloglucan encapsulated Titanium dioxide was prepared by in-situ method for coating Silk fabric. FT-IR XRD characterized the functional groups and formation of crystallization of composite film. SEM analysis showed the immobilization of composite film on the surface of silk fabric. The coated silk fabrics were stained with methylene blue, and the stain removal efficiency was evaluated. The results showed that the composite film was deposited onto the silk fabric. The functional groups showed peaks around 1635 to 1636 and 400 to 500 cm^-1 that indicate the presence of C=N groups of Chitosan-Xyloglucan and Ti-O groups of TiO₂ on the composite, respectively. The XRD results indicated that the TiO₂ prepared by the sol-gel method was an anatase crystalline structure. The mechanical properties showed the composite film was superior to the Chitosan-Xyloglucan, TiO₂, and uncoated silk fabric. Finally, the methylene blue degradation capability was investigated. The coated silk fabric has insignificantly removing methylene blue stain than the untreated silk fabric, but it is noticeably repellent to stain.

Abstract: This research is a continuing study on F9-filter development via Ag-TiO₂ coating to promote volatile organic compounds (VOCs) removal and antibacterial activity. Problems of poor adhesion and uniform distribution of coating material on the filter surface were observed, so the addition of a polymeric surfactant (PS), which behaves as both a binder and a surfactant, was applied in this study in order to solve such problems. Dip coated F9-filter samples with a selection of Ag-TiO₂ suspension were characterized and tested. Environmental scanning electron microscope was used to characterize uniform coating distribution on an air filter. Self-cleaning test was performed in accordance with ISO 27448. The results showed that Ag-TiO₂ with PS dip coating on air filters provide good adhesion and high uniformity. It is also found that self-cleaning capability of Ag-TiO₂ with PS coated filter is increasing with increasing of Ag-TiO₂ and PS concentrations. Within a scope of this work, only visible light can drive Ag-TiO₂ to undertake photocatalytic activity. Hence, improvement of Ag-TiO₂ coating on F9- filter is confirmed when PS is applied.

Abstract: This paper presents the results of a study on one-component dry mix used for the preparation of silicate-based facade paint with self-cleaning properties. The advantages of the developed composition include the ease of the mix preparation and application, increased adhesion of the coating to the base, and improved aesthetic qualities of the coating provided by its ability to self-clean due to the addition of nanotitanium dioxide, which enhances photocatalysis. In the course of the research work, the optimal quantitative content of the main components and functional additives was established. Studies of the facade paint microstructure were carried out. Infrared spectral and differential thermal analysis of the composition confirmed the significant weather resistance of the facade paint, which is ensured by deep carbonization of the constituent components with their transformation into calcium carbonates, characterized by increased water resistance and chemical stability. Key words: facade coating, silicate paint, self-cleaning, photocatalysis, microstructure

Abstract: In this study, sheet-like MnO₂/ZnO microflower (MnO₂/ZnO) loaded on cotton fabric was prepared via a facile reflux-thermal deposition combined technique. The coated fabric and as-fabricated particles were analyzed through numerous characterization techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), tensile strength, Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) as well as photoluminescence (PL) measurements. The optical trait of the ZnO was significantly improved by the addition of MnO₂ that extended reflectance edges in the visible light region. The treated cotton fabric greatly inhibited the growth of Escherichia Coli bacteria and Aspergillus Niger fungi as testified by the zone of inhibition surrounding the fabric samples. The self-cleaning outcomes also demonstrated that 3% MnO₂/ZnO/fabric presented highest visible light photodegradation of phenol among the samples. The promising performance of the cotton fabric coated by MnO₂/ZnO composite was related to the reactive oxygen species produced by the heterojunction photocatalytic mechanism under exposure of visible light.

Abstract: This article presents research and development on innovative photoactive admixtures for concrete and cement-based plasters for the finishing of concrete surfaces finished this year. The goal of the development was to provide the resulting surfaces of these newly developed materials with a self-cleaning ability stemming from photocatalytic reaction during exposure to UV radiation. The specific function of all these products is based on the photocatalytic oxidative mineralization of all organic structures present on the surface, i.e., their gradual transformation into the final simple inorganic compounds, which are carbon dioxide, water and the corresponding mineral acids. This research and development was carried out as part of a project supported by the Czech Ministry of Industry and Trade, in the TRIO programme; and in cooperation of BETOSAN s.r.o., the Technical University of Liberec, the Institute of Inorganic Chemistry of the Czech Academy of Sciences and the J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences. The first type of developed material is a photocatalytically active admixture in powder form, allowing the preparation of concrete surfaces with photocatalytic properties. The second type of developed material is a photocatalytically active cement-based plaster, intended primarily for application to a concrete substrate. Two final versions of both materials were developed. In the case of the plaster this means preparation of two colour variants, specifically white and grey. For the powder concrete admixture two types with different application procedures were developed. This means one version of admixture mixed throughout the entire volume of the concrete and second variant applied only in the surface layer of the concrete. We anticipate mainly exterior applications on the self-cleaning outer shell of buildings, as well as treatment of the surface layer of various structures such as bridges, noise barriers, traffic barriers and tunnels. The developed materials can also be used in interiors under specific conditions, with anticipated uses in the health care and food processing industries.