Papers by Keyword: Silica

Abstract: Silica can be utilized as a DSSC anti-reflection layer material due to its wide storage, low refractive index, and harmlessness. Pumice is a volcanic shaft rock made of silica and alumina. Here, silica was extracted from pumice at 800°C and various aging times of 18 and 24 hours to be used as an anti-reflection in the fabricated DSSC. The extraction results were characterized by XRD and SEM-EDX, revealing that the highest silica content of 79.56% was obtained at the aging time of 24 hours. It was then deposited on the opposite of the FTO active area using the spin coating with varied layer numbers (1 and 2). A UV-Vis spectrophotometer was performed on the sample to observe the transmittance of the FTO without and with silica anti-reflective coatings. It showed that the 1 layer of silica had the highest transmittance. The DSSC performance was tested by an I-V meter to determine current, voltage, and efficiency. It demonstrated that, as it had the highest transmittance value, the fabricated DSSC with 1 layer of silica efficiency by 0.15% compared to the one without anti-reflection coating. Therefore, it could be concluded that the addition of anti-reflection could improve the efficiency of DSSC.Keywords: Pumice, Silica anti-reflection layer, DSSC

Abstract: Vietnam is one of the largest rice producers in Southeast Asia, generating substantial quantities of rice husk as a by-product of rice milling. Currently, rice husk is predominantly disposed of as agricultural waste. This study investigates the utilization of rice husk to synthesize silicon carbide (SiC) and crystal silica (SiO₂). The device for the experiment was built by the authors with simple accessories. SiC and crystal SiO₂ from rice husk were synthesized successfully at low temperatures compared to a chemical reaction of silica reduced by carbon. The research outlines the production conditions for achieving a little SiC from recycled rice husk and explores potential development pathways for applying this technology in structural and material manufacturing industries. The characterization of the synthesized SiC was measured using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Abstract: Desert soils present some issues that need improvement. Some of these are high permeability and collapsibility potential. These problems are due to the uniform particle size distribution and the lack of particle edges. Soil improvement is required to mitigate these issues. Cement is widely used for soil stabilization but has environmental issues since it is a significant source of CO₂ emissions and requires high energy consumption. In this study, the calcined shale material is utilized as a partial replacement for cement to reduce the permeability and compressibility of soils more sustainably. The study considers three cement doses of 5%, 10%, and 15% and four calcined shale percentages of 10, 30, 50, and 70%. A series of falling head permeability and one-dimensional consolidation tests were conducted to examine the performance of cement and calcined shale as stabilizers. The results of the study indicate that the addition of 30% calcined shale as a partial replacement of cement has the most significant effect on the conductivity and compressibility of the soils. An increase in cement content decreases the permeability and compressibility of the soil due to the hydration of cement. Conversely, the conductivity and consolidation of the soil are initially decreased with an increase in the calcined shale up to 30% and then start to increase. In summary, this study reveals that the presence of CS and cement has a substantial effect on the conductivity and compressibility of the soils.

Abstract: Sidoarjo mud contains 48.3% silica which is considered as the biggest impurity when compared to the content of rare earth metals which are 0.3% Eu and 0.02% Yb. The hydrothermal process is used to bind silica as a form of silica extraction activity in the Sidoarjo mud so that the Rare Earth Elements are purified further because their uses are urgently needed. This process compares the alkalis in the form of Na₂CO₃ and K₂CO₃ which are basic salts which will then be compared to the most optimum conditions of the two alkalis. Each alkali will be processed under operating conditions following the Taguchi method which aims to minimize research and optimize research results. Based on the research results, it was found that K₂CO₃ provided better silica recovery than Na₂CO₃ under operating conditions with a K₂CO₃ concentration of 2 M, 1 hour soaking time, 700°C melting temperature and 3 hours melting time, giving 95.24% silica recovery. In addition, by using the Taguchi method it can be analyzed that the main factors affecting the melting of the alkali are the melting time, the concentration of the alkali, the temperature of the melting, and the immersion time.

Abstract: Polyethersulfone membranes were fabricated using non-solvent-induced phase separation (NIPS) with silica and nanocellulose additives extracted from rice husk ash and genjer (Limnocharis flava). N-methyl pyrrolidone served as the solvent. The study aimed to prepare membranes with diverse characteristics by incorporating various combinations of additives. Silica acted as a pore-forming agent, while nanocellulose enhanced membrane hydrophilicity. Characterization techniques included Fourier-transform infrared spectroscopy (FTIR) for functional group analysis, which revealed the presence of C-S, Si-O, and Si-O-Si vibrations in the membranes. Additionally, scanning electron microscopy (SEM) was employed to examine the surface and cross-sectional structure of the membranes. To assess membrane performance, a flux test was conducted. The membrane containing 2% nanocellulose and 1% silica exhibited the highest flux value of 21.37 L/m².h, corresponding to a permeability of 21.37 L/m².h.bar. Based on these results, the membrane with 2% nanocellulose and 1% silica is considered optimal due to its superior performance.

Abstract: The silica element in palm ash has the potential to be an alternative source of silica material to replace mineral silica, making it more environmentally friendly and reducing production costs. This research aims to utilize silica from palm ash waste as an abrasive material in brake friction composites. The silica from palm ash was isolated by a leaching process using 1 M HCl solution at a temperature of 70 °C for 90 minutes. Isolated silica was then characterized by X-ray fluorescence (XRF). The composition of silica was varied by volume fraction (0, 2, 4, and 6%). The mixing process of the powder mixture was conducted using a chopper mixer for 5 minutes, The powder mixture is then hot compressed using uniaxial hot pressing at a pressure of 47 MPa and a temperature of 165 °C for 15 minutes. Post-curing of the samples was carried out at a temperature of 165 °C for 10 hours. The samples were characterized by density, porosity, hardness R-scale, friction coefficient, and specific wear rate. The research results showed that the palm ash was successfully purified with a silica content of 27.3% to 57.2%. Increasing volume fraction of palm ash silica decreases in density and hardness, while porosity increases. The sample with 4% volume of palm ash silica exhibited better friction performance and a lower specific wear rate. Palm ash silica has the potential to replace the silica mineral for brake friction composites.

Abstract: Silica is a hydrophilic reinforcing filler for rubbers, whilst styrene butadiene rubber (SBR) is a hydrophobic synthetic rubber. The interaction between silica and SBR is relatively weak causing a poor silica dispersion inside the SBR matrix. The amide substances such as stearamide and oleamide have been used as additives to solve the problem of poor degree of silica dispersion. Both additives were laboratory prepared by reacting stearic acid and urea for stearamide; oleic acid and urea for oleamide. Each of those additives was compounded with SBR and other curing chemicals separately and vulcanized using a semi-efficient vulcanization formulation. It was found that both additives have acted as curative additives and plasticisers for the silica-reinforced SBR compound/vulcanisate. They have improved processing properties which have improved the coefficient of vulcanization of the silica-reinforced SBR. Based on the torsion properties; they also have a successful role as plasticisers which have the capabilities to reduce the viscousness and to improve the dispersion of silica reinforcing filler in the compound of SBR. The morphological (scanning electron microscopy) study has confirmed that the compound of SBR-silica with stearamide or oleamide has morphology images with better silica dispersion.

Abstract: Calcium carbonate (CaCO₃) and silica are two types of additives for rubber. Through the implementation of a typical semi-efficient (Semi-EV) vulcanisation formulation, those additives were added separately into the compound of natural rubber (NR). The CaCO₃ or silica was added as the reinforcing filler and, incorporated into NR at a constant concentration i.e., 30 parts per hundred NR (phr). It was found that the CaCO₃ or silica have successfully provided an increase in mechanical properties including a greater tensibility (tensile strength) and abrasion resistance of the compound of NR. However, as hydrophilic fillers, the CaCO₃ or silica is hard to disperse homogeneously and hence, lauryl alcohol was used to improve their dispersion degrees. It was combined into the NR compound with varied concentrations such as 1, 3, 5 and 7 phr. Therefore, the effect of lauryl alcohol concentration on the processing and reinforcement properties of CaCO₃ or silica-filled NR was investigated. It could be found that lauryl alcohol has increased the rate coefficient of vulcanisation (Rv) of the CaCO₃ or silica-filled-NR. The greater the lauryl alcohol concentration; the greater the Rv value, tensile strength, and abrasion resistance. Overall, lauryl alcohol has a successful function as a plasticizing agent which increased the reinforcement effects of the fillers on NR through the increasing of crosslink density of CaCO₃-NR or silica-NR especially at the 5 phr of addition.

Abstract: This study focuses on the influence of soybean oil (SO) modified by TESPT silane coupling agent as an environmentally friendly processing oil on the properties of the silica-reinforced rubber compounds. A proton nuclear magnetic resonance (¹H-NMR) spectroscopy confirmed that a novel processing oil based on silane-modified SO was successfully prepared in the laboratory. It was found that the unsaturated structures in SO reduced after modification. The properties of the rubber compounds with different types of processing oils were investigated by comparison to the rubber compound without processing oils. The addition of processing oils into the rubber compounds reduced filler-filler interactions within the rubber matrix due to a shielding effect of silica surfaces by processing oils. The silane-modified SO could react with the silanol group on the silica surfaces, leading to a hydrophobicity of silica surfaces. So, the use of silane-modified SO showed lowest filler-filler interactions. In addition to the filler-filler interactions, the presence of processing oils in the rubber compounds reduced the viscosity of the materials as indicated by minimum torque received from a cure curve. The levels of filler-filler interactions in the rubber compounds correlated well with the viscosity. The crosslinking points within the rubber matrix of the oil-added compounds were lower than the one without processing oil. Furthermore, the mechanical properties of the rubber compounds with and without processing oils were considered. The processing oils did not affect the tensile strength, but strongly improved elongation at break.

Abstract: Imprinted ionic synthesis through the sol-gel process for Ni (II) adsorption has been carried out. Sodium silicate from rice husk ash (NaSiO_3(RHA)), N¹-(3 Trimethoxysilylpropyl) diethylenetriamine (TMPDT) and Ni (II) are stirred, then 6 M HCl is added until a gel forms. Furthermore, 0.1 M EDTA and 0.1 M HNO₃ were added to the dry gel to release Ni (II) to form-imprinted ionic material (SiO₂-TMPDT-Ni-Imp). The material was characterized using FTIR, SAA, and SEM-EDX. FTIR characterization of SiO₂-TMPDT-Ni-Imp indicated the appearance of-OH, -CH, -Si-O-and-NH absorption. The SAA characterization results show a surface area of 18.091 m2/g, a total pore volume of 0.033 cc/g, and an average pore radius of 16.739 Å. The optimum conditions for Ni (II) adsorption by SiO₂-TMPDT-Ni-Imp are pH four and a contact time of 100 minutes. The appropriate adsorption kinetic model for the absorption of Ni (II is pseudo-second order with an adsorption capacity of 6.9 mg/g. Keywords: Silica, imprinted ionic, rice husk ash, adsorption, Ni (II)