Papers by Keyword: Silica

Abstract: The decline in conventional oil recovery efficiency necessitates the development of advanced tertiary methods such as Enhanced Oil Recovery (EOR). This study investigates a hybrid nanofluid composed of acetylated cassava starch and silica nanoparticles for application in chemical EOR. Acetylated starch was synthesized to enhance viscosity and thermal stability, while silica nanoparticles were incorporated for their interfacial activity and wettability alteration capabilities. Comprehensive laboratory experiments were conducted to evaluate the hybrid fluid’s physicochemical, rheological, and recovery performance. Characterization using FTIR, XRD, SEM, and TGA confirmed successful functionalization and improved thermal resilience. Rheological tests demonstrated shear-thinning behavior with high viscosity retention. The hybrid fluid also achieved a 57.7% reduction in interfacial tension and altered sandstone wettability from oil-wet to strongly water-wet conditions. Core flooding tests revealed a recovery factor of 68.9%, outperforming starch-only, silica-only, and brine controls. The synergy between the polymer and nanoparticles enhanced colloidal stability, flow performance, and oil displacement efficiency under simulated reservoir conditions. The use of cassava starch as a biodegradable and locally sourced material underscores the environmental and economic viability of the formulation. These findings support the potential of acetylated starch–silica nanofluids as sustainable, high-performance EOR agents.

Abstract: The limited thermal stability of starch-based bioplastics restricts their application in high-temperature environments necessitates the need to reinforce them with thermally robust fillers. This study explores calcined eggshell (CES) and silica as potential bio-based and inorganic fillers to enhance the thermal and structural performance of starch-derived bioplastics. Both materials were characterized using the Brunauer–Emmett–Teller method (BET), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis, and a Scanning Electron Microscope equipped with Energy Dispersive X-ray Spectroscopy (SEM-EDX). BET analysis revealed mesoporous structures in CES and silica, with pore diameters of 2.8 nm and 2.7 nm, and pore volumes of 0.125 cm³/g and 0.132 cm³/g, which favors filler–matrix interactions. FTIR confirmed the presence of hydroxyl and carbonate groups in CES and silanol groups in silica, which promotes compatibility with hydrophilic polymers. Thermal analysis showed both materials to be stable above 600°C, with CES decomposing into thermally inert CaO and silica, exhibiting minimal mass loss post-dehydration. SEM–EDX analysis confirmed high surface area morphologies and dominant Ca and Si elemental compositions for CES and silica, respectively. The findings support the suitability of CES and silica as effective fillers for thermally stable bioplastics, offering environmentally friendly and cost-effective alternatives to conventional additives.

Abstract: This research is centered on an environmentally sustainable sol-gel coating, using silica extracted from rice husk ash (RHA), to foster the persistent deterioration of mild steel cause by corrosion for decades despite all efforts put in place by previous researchers. The research focus, was on the extraction of silica from rice hush to synthesize silica-base sol-gel formulation, doped in a graphene oxide to enhanced its efficiency. The formulated sol-gel coating was applied on the mild steel substrates and then characterized by evaluating its corrosion resistance through electrochemical and surface characterization techniques. Such as XRD, FT-IR, SEM, Tafel Polarization and Adhesion Test, which were carried out on the coated samples. Corrosion test was carried out by immersing coated and uncoated samples in 3.5% NaCl solution for seven (7) days and then conducted a Potentiodynamic polarization and Electrical Impedance Spectroscopy (EIS) test to analyze the corrosion rates, impedance and protection efficiency. It was observed that, the highest inhibition efficiency of 85% was achieved at a concentration of 1.0g/200ml after 7 days of exposure which revealed that, coated mild steel possess higher potential corrosion resistant when compared with the conventional anti-corrosion coating in use. Essentially, this research would definitely promote green chemistry by utilizing agricultural waste materials, avoiding uses of toxic precursors and offering an eco-friendly alternative to conventional anti-corrosion coatings.

Abstract: Polymer Electrolyte Membranes (PEM) is an important component in a Direct Methanol Fuel Cell (DMFC) system that has a primary function as a proton conductor and separator between a cathode and anode. Due to the awareness of the comprehensive methanol crossover issue in the commercially available Nafion membrane, however, the main parameter of PEM for DMFC is low methanol permeability. The chitosan-based inorganic hybrid membrane is a promising organic–inorganic hybrid for the development of high-performance PEM. The study of composite membranes as PEM was initiated with the synthesis of silica from POFA (palm oil fuel ash). Using the phase inversion technique, the chitosan was mixed with silica filler in an acetic solution to produce Ch/Silica composite membrane. Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDX) analysis shows that pure silica has been successfully synthesized from POFA and can interact with chitosan in the layer of the membrane structure which is supported by the Fourier Transform Infrared Spectroscopy (FTIR) spectra results. Water uptake shows a value of 75%, while methanol uptake with a low value of 52%. The addition of silica gives the membrane the ability to reduce methanol crossover as indicated by the low value of methanol permeability of 0.00027 mg cm²s^-1. However, this membrane has good proton exchange performance as indicated by the Ion Exchange Capacity value of 1.56 mmol g^-1. These results indicate that the composite membrane of chitosan with silica from POFA has the potential as PEM in direct methanol fuel cell applications.

Abstract: Methylene Blue (MB) waste is damaging to both humans and the environment. Chitosan is one of the MB adsorbents that may be made from green mussel shells. Because CS compounds have a limited adsorption capacity for MB, a restricted surface area, and poor chemical stability, thus necessitating modification. CS/XG was created by combining the three chemicals silica (SiO₂), tofu pulp, and the anionic substance Xanthan Gum (XG). SiO₂ hydrogel bio-composite with the aid of UV light, can absorb MB by photodegradation. The objective of this paper is to analyze the regeneration and photocatalysis kinetics based on the kinetic rate constant of the bio-composite photodegradation, and to identify the ideal circumstances of MB photodegradation by CS/XG.SiO₂ hydrogel bio-composite with Box-Behnken design. The CS/XG bio-composite was synthesized from chitosan (green mussel shell waste) and xanthan gum (tofu dregs waste) with added SiO₂ to adsorb methylene blue via photodegradation. The use of green mussel shells and tofu dregs is significant as it turns abundant waste into valuable materials, reducing pollution and supporting low-cost, eco-friendly wastewater treatment.The variables were pH, MB concentration, and photodegradation time. The results showed that the optimum condition occurred at pH 9.43; MB concentration 5.054 ppm; and irradiation time 119.67 minutes with % degradation of 94.2%. After the 5th reuse of CS/XG.SiO₂, the % degradation only decreased from 94.2% to 79.4%, indicating good regeneration ability. Analysis of photodegradation kinetics showed accurate modelling using the Modified Elovich model with an R² value of 0.9805 and a photodegradation kinetic rate constant of 0.0010 min^-1.

Abstract: Reverse osmosis (RO), the main technique for desalination, is affected by the quality of the water source. Natural water contains silica, which comes from metal silicates found in the earth's crust. Silica fouling is complicated to manage and often leads to less efficient designs of RO systems for safe operation. This research evaluates the current technologies for treating silica in RO desalination. The pilot project showed considerable water savings, achieving maximum recovery over the longest duration. To enhance water conservation, it is essential to optimize permeate recovery. Water savings were constrained due to silica scaling on the membranes. The chosen membranes can achieve a lower total dissolved solids (TDS) rejection than was required in the initial research, which could enhance water conservation. The additional energy needed for membrane treatment was balanced out by the savings in water costs. To avoid scaling, an antiscalant chemical along with a dosing system was installed next to the membrane system, and this study focused on three methods to mitigate silica scaling: Amonium Bifloride (ABF), a cation ion exchange column (IEX) containing Amberlite-IRC747 (Dupont) resins to eliminate multivalent cations like Ca2+, Mg2+, and Fe3+. Lastly, a simulated anti-scaling test was conducted using a feed solution that was pretreated by MIL-101(Fe) adsorption. Each type of antiscalant suitable for decreasing silica from water possesses distinct characteristics such as pH and other cations. Keywords:, Water conservation, Silica , Anti-Scalant, Amonium Bifloride (ABF), Exchange column (IEX) filled with Amberlite-IRC747 (Dupont), MIL-101(Fe).

Abstract: The increasing demand for metals has led to the growth of the metal industry in Indonesia. This has resulted in a rise in the amount of waste generated. Various methods can be used in the treatment of metal waste, such as flotation, flocculation-coagulation, and adsorption. One biopolymer that can be used for metal removal is chitosan. This study aims to synthesize chitosan from shrimp shell waste, which is then modified with silica to enhance its mechanical strength and stability in acidic conditions using the sol-gel method. The chitosan-silica composite is then immobilized using dithizone to increase the adsorption capacity through immersion variations of 4, 6, and 8 hours. The adsorbent, characterized using Fourier Transform Infrared, showed the presence of bonds in chitosan at wavenumbers 3454 cm^-1 (N-H) and 1647 cm^-1 (C=O), chitosan-silica at wavenumbers 966 cm^-1 (Si-O in Si-OH), 798 cm^-1 (Si-O in Si-O-Si), and 466 cm^-1 (Si-O-Si), and chitosan immobilized with dithizone at wavenumbers 2343 cm^-1 (S-H) and 1083 cm^-1 (S=C). Adsorption was performed by mixing the adsorbent with the waste for 1 hour, then the waste was added with 0.25 ml of phosphoric acid and analyzed using a UV-Vis Spectrophotometer. Based on the results of the study, the highest adsorption efficiency was obtained with the adsorbent variation of 8 hours immersion at 59%, while the adsorption efficiency for immersion times of 4 and 6 hours was 0.3% and 6%, respectively.

Abstract: Synthesis of calcium alginate silica gel based on coral skeleton and wedi awu beach sand has the potential to be used as a product to reduce NaCl levels in seawater. This research aims to maximize the potential of natural materials. The materials used in the manufacture of adsorbents are calcium from coral skeletons used as a constituent of CaCl2, silica extracted from Wedi Awu beach sand, and sodium alginate. The three materials were synthesized into a cross-linked calcium alginate silica gel. Silica extracted from beach sand was mixed with sodium alginate, and then the mixture was dripped into CaCl2 solution. The results obtained are white round-shaped adsorbent gel, which occurs because SiO2 reacts with-O-groups on sodium alginate to form a white mixture, and Ca2+ in CaCl2 will crosslink with sodium alginate when dripped, forming an adsorbent gel. In the FTIR analysis of silica calcium alginate adsorbent gel, there are-OH, C=O, C-O groups that can play an active role in NaCl adsorption. Calcium alginate silica adsorbent gel can produce the highest percent adsorption at a CaCl2 concentration of 0.5 M, with an optimum contact time of 60 minutes, namely for Na + obtained a percent adsorption of 95.24% and on Cl-of 99.19%. The results of concentration and time optimization were then tested with real seawater with a percent adsorption of Na + of 69.33% while on Cl-of 37.26%.

Abstract: This investigation was carried out in a lab setting with the aid of a filter set. This study aimed to lower the level of clean water contamination and assess the filter media's performance in Fitu Village, Ternate City, using physical and chemical criteria. Temperature, turbidity, total dissolved solids (TDS), and odour are physical parameters. While pH, Mn (manganese), and Fe (iron) are the chemical parameters. Sand-activated carbon made of silica and zeolite is the filter medium. One hundred eighty litres of water from a resident's well make up the sample. The physical characteristics, namely the TDS of 1250 mg/L, the turbidity of 27 NTU, and the temperature of 25 °C, show the outcomes of investigating healthy water as raw water in the Kelurahan Fitu. Fe concentration was 1.3 mg/L, Mn concentration was 0.6 mg/L, and pH was 9. Water is passed via silica sand, zeolite, and activated carbon filters before entering the filter after further inspection. According to the results, the TDS has dropped to 897 mg/L, the turbidity has changed to 24, and the temperature is 24 °C. The filtered water meets the chemical standards for Fe concentration with only 0.91 mg/L of Fe, 0.45 mg/L of Mn, and a pH of 7.9. According to the study's findings, inhabitants of Fitu Village in Ternate City can efficiently reduce pollutants and metal levels in their healthy water by employing a filtering system that uses silica sand filter media, zeolite, and activated carbon.

Abstract: This paper presents the synthesis of metallic silver (Ag) nanoparticles immobilized on silica (SiO₂) particles. Ag immobilization was carried out via the Ag mirror reaction using two types of reducing reagents: D-glucose and formaldehyde (HCHO). The effects of Ag immobilization conditions, such as Ag nitrate concentration, SiO₂ concentration, reaction time, and reducing reagent concentration, were investigated. The particle morphology is related to the ionic strength of the solution. As a result, Ag immobilization was successfully performed while minimizing the formation of large metallic Ag nanoparticles and/or the aggregation of metallic Ag nanoparticles in the HCHO system with a reaction time of 5 min and HCHO concentration of 1.5×10^-4 M, producing SiO₂ particles (92.5±7.3 nm) immobilized with metallic Ag nanoparticles 5–15 nm in size.