Calcium silicate is produced from a mixture of silica sand powder, lime, paper pulp, and Portland cement hydrothermally steamed at 180 °C for about 16 h. This material is considered environmentally ...friendly and is popular in countries around the world. In this study, quartz sand was replaced with residual waste sludge from water-filtration plants to produce calcium silicate materials. Nowadays, the residual waste sludge from water-filtration plants is an environmental problem that needs to be treated. The results of determining the properties showed that a sample using 10 w/% residual waste sludge gave the best replacement. This sample had a bending strength of 10.95 MPa, a volumetric density of 1.57 g/cm3, and water absorption of 23.67 %. The results of the analysis of the mineral composition (by X-ray diffraction analysis and Fourier-transform infrared spectroscopy) and microstructure (by scanning electron microscopy) showed that all samples formed tobermorite and xonotlite minerals. The tobermorite and the xonotlite are hydro-silicate-calcium minerals characteristic of calcium silicate materials, which are the synthesis products of chemical reactions of SiO2, CaO, and H2O under hydrothermal conditions. Samples using 5–10 w/% of waste residual sludge have even higher mechanical strength than samples without. Therefore, using waste residual sludge from water-filtration plants to replace part of the sand in producing calcium silicate materials can be considered an effective method to treat environmental problems caused by waste residual sludge.
Abstract Agricultural production in Vietnam annually generates a substantial volume of by-products and waste, with rice husks constituting the predominant fraction. Due to their meager economic ...value, rice husks are typically deemed agricultural waste and are commonly disposed of through incineration or discharge into rivers, contributing significantly to environmental pollution. In this investigation, rice husks were employed as the principal raw material for synthesizing silicon carbide. A blend of rice husks and silica gel in a ratio of 1.4/1 was subjected to sintering in a CO 2 environment within the temperature range of 800 °C–1300 °C for 30 min. The chemical composition of the resultant product post-pyrolysis was ascertained in accordance with the ISO 21068–2:2008 standard. The capacity for SiC formation was further assessed utilizing Fourier transform infrared spectroscopy and x-ray diffraction. The outcomes revealed that the optimal temperature for SiC synthesis was 1200 °C. The composition of the sample post-pyrolysis was determined as 20.4% SiC, 51.2% SiO 2 , and 26.4% C (%wt). The primary phase constituents encompass amorphous carbon, cristobalite, α -SiC, and β -SiC. Scanning Electron Microscopy/ Energy Dispersive x-ray imaging of the product at 1200 °C exhibited dispersed SiC crystals on a SiO 2 -C substrate. The presence of SiC suggests the potential application of the product as a wear-resistant material.
Due to the low melting temperature, the glazes based on the Bi2O3-B2O3-ZnO system are used as coatings on the surface of industrial glass substrates. Moreover, the composition of these coatings does ...not contain PbO, meeting the optical and environmental properties requirements. In this study, TiO2 was used in the Bi2O3-B2O3-ZnO glaze system to improve its photocatalytic ability. This can be considered a four – component glass system Bi2O3-B2O3-ZnO-TiO2. The heating microscopy results show that the melting temperature of the glaze system is 606 °C. The Fourier transform infrared spectroscopy results show that the TiO2 polyhedra are located independently in the structure without participating in forming a glass network. Thanks to that, the photocatalytic properties of TiO2 are maintained. The X-ray diffraction patterns results show that the formed TiO2 nanocrystals are rutile and anatase crystals. The results of determining the band gap energy using UV-Vis show that the band gap energy of the base glaze system increases with the addition of TiO2. The methylene blue decomposition results also showed that the ability to decompose organic increased when TiO2 was added to the glaze coating. The characteristics such as melting temperature, microstructure, and photocatalytic capacity of Bi2O3-B2O3-ZnO-TiO2 white glazes (5 and 10 % weight of TiO2) also were indicated in this paper.
This paper introduces a method for producing red copper glaze by adding copper oxide (CuO) and silicon carbide (SiC) additives to the base glaze. SiC created a reducing environment in situ and ...allowed the glaze to be sintered in an oxidizing furnace environment. Nanocrystals are the determinants of the red color of the glaze. The CuO reduction reaction temperature range of SiC produces a reducing environment in the glaze as detected by the method (DSC). The functional group and phase of nanocrystals were determined by Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) spectroscopy.
Treatment of the sludge from water-purification plants is becoming more and more urgent due to the inability to increase its storage area. To avoid CO2 emissions, the use of non-Portland cement ...binders is recommended. The application of geopolymerization of waste sludge (WS) from water-purification plants is a novel solution. Curing conditions including high temperature, pressure or microwaves enhance the formation of geopolymer bonds. This paper presents the results of a research on the treatment of the WS of the Thu Duc water-purification plant (Vietnam) with the geopolymerization method. Solid phases were prepared by mixing the WS and fly ash (FA). The FA proportions of the solid phases were (10, 40, 70) w/%. The alkali-activated solution (AAS) was a mixture of a 40 w/% NaOH 6M solution and 60 w/% water glass (WG: Na2O.nSiO2 with n = 1.75 and volumetric density r = 1.40 kg/L). The geopolymer materials were mixtures containing an 80 w/% solid phase and a 20 w/% liquid phase of the AAS. Geopolymer samples were formed in a cylindrical steel mold with a diameter of 10 mm at a high pressure. The samples were cured in a 112 W microwave oven for 30 s or in a dryer at 110 °C for 24 h. The compressive strength and volumetric density of both sample groups were determined and compared to each other. The formation of geopolymer bonds was investigated using XRD, FTIR and SEM.
In this study, the sintering mechanism of woodceramics (WCs) from cashew nut shell waste (CNSW) was studied by analyzingchemical reactions and structural changes during the sintering process of of ...CNSW powder, liquefied wood and green bodiesof WCs at 900 oC for 60 minutes in the CO2 atmosphere. The chemical and structural properties of the products wereinvestigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared (FTIR), and scanning electronmicroscope (SEM). The results showed that the decomposition reactions of liquefied wood and CNSW occurred simultaneouslyto form the hard carbon and the soft carbon at high temperature. The sintering mechanism of WCs has been presented. KCI Citation Count: 0
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