Rice Husk Silica Research Articles

Bismuthite and cassiterite-doped borosilicate glass systems for X-rays attenuation: Fabrication and characterisation

For the first time, X-ray shielding glass (XSG) was fabricated using rice husk (RH) silica, bismuth, and tin mineral ores. The objective was to promote waste valorisation and circular economy by minimising the use of analytical grade silicon and metal oxides in large-scale radiation shielding glass production. The physical, structural, and low-energy X-ray attenuation properties of the new bismuthite and cassiterites-doped glass were characterised using XRD, FTIR, and low-energy mobile X-ray shielding analyses. The X-ray shielding parameters linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), and mean free path (MFP) were comparatively examined alongside commercial lead/barium XSG used in hospital radiology units. XRD results showed that glasses with 0, 5 and 15 wt% dopants contain nanocrytallites measuring 19.43, 38.85 and 42.44 nm, respectively, with peaks in the 2Θ (28°) vicinity. FTIR revealed structural modifications that demonstrate the network modulation capabilities of cassiterite-sourced Sn ions. At 70 kVp tube voltage, the MAC of the 20 wt% dopant glass compares favourably with commercial Pb/Ba glass, while the 25 wt% variant has lower values than commercial Pb/Ba glass at 80 kVp tube voltage. The HVL and MFP of 25 wt% dopant glass compared favourably with commercial glass at 60 kVp X-ray tube voltage, suggesting the new glasses with x = 15, 20, 25 wt% dopants are competitive candidates for viewing window applications in low energy X-ray radiology units. Future studies will investigate the radiation attenuation efficiency of the new glass systems using point gamma sources.

Development of food packaging bioplastic from potato peel starch incorporated with rice husk silica using response surface methodology comprehending central composite design

Rice husk and sweet potato peel are agricultural waste with high potential and economic interest. The utilization of these materials in product development will provide substantial improvement toward waste reduction. Therefore, this study aimed to develop a food packaging bioplastic using potato peel and rice husk. The optimization of three parameters (ratio of silica, the volume of glycerol and volume poured) was set in Design Expert Software version 13 to find the best formulation. The software set eighteen formulations to measure advanced bioplastic thickness, density, and moisture content. The optimum formulation exhibits thickness, density and moisture content with the value of 1.87 mm, 0.196 g/mL and 31.224%, respectively. In response surface methodology, bioplastic formulation was optimized using central composite design (CCD). The statistical model displayed an excellent fit with standard deviation, R2 data. The R2 for thickness was 0.8946, while 0.9516 for density and 0.96 for moisture content. These values were close to 1, indicating the significant effect on the tested conditions to get the optimum formulation.

Optoelectronic and Gamma Ray Attenuation Properties of Ore-based Bi and Sn-doped Borosilicate Glasses

Progress in glass science has given rise to innovative functional glasses, unlocking significant applications for creating cutting-edge materials such as solid-state batteries, solar cells, optical reinforcement, and medical technologies. In this study, rice husk silica, Bismuth (Bi) and Tin (Sn) oxide ores were used to fabricate a novel glass series. The electrical conductivity (i.e., dielectric constant) of the glasses increased with the dopant’s gravimetric levels. The novel glass series also possesses good optical non-linearity with metallisation criteria ranging from 0.35 to 0.40, which points to a novel non-linear optical material. The non-bridging oxygen content in the new glasses exceeds the bridging oxygen, indicating high polarisation. The transmission coefficient decreased with increasing dopant concentration from 0.76 to 0.75, while the reflection loss decreased from 0.37 to 0.38. For the Caesium-137 energy, GS6 has a minimum HVL of ∼5.02 cm, which is ∼20% lower than that of commercial Pb/Ba glass. For the two energies, GS6 has the least MFP, suggesting that the addition of dopants improved the efficiency of the glass attenuation. Process capability analysis based on Caesium-137 (661.7 keV) and overall performance analysis of the fabricated glass series revealed that GS3 glass (15 wt.% dopant) is the optimal material, even outperforming the commercial Pb/Ba glass. Although Cobalt-60 (1,253 keV) yielded comparable outcomes, concentrations beyond 15 wt.% in GS3 showed marginal enhancements in the photon attenuation parameters of the glasses. Hence, the fabricated GS3 and the circular synthesis method of the glasses are cost-effective for low-energy gamma/X-ray shielding. The percentage deviation between the experimental data for MAC and that of Monte Carlo simulations for Cs-137 and Co-60 energies are both within 10%, which validates the methods of this paper.

Synthesis and characterisation of rice husk and palm fruit bunch silica: compositional, structural, and thermal analyses

Synthesis and characterisation of rice husk and palm fruit bunch silica: compositional, structural, and thermal analyses

Tin dioxide coated rice husk silica as lead-acid battery positive additive for enhancing the performance under power-intensive applications

Lead-acid batteries rapidly response to instantaneous high-current, rendering them particularly effective for high-power applications, including power traction batteries, starter batteries, and start-stop systems. However, issues arise during intense working rate (6–10C), causing significant polarization that leads to severe oxygen evolution side reactions and softening and shedding of positive active material (PAM), limiting the battery's cycle life. This study introduces a tin dioxide (SnO2) coated rice husk silica (RH-SiO2) composite as an positive additive in lead-acid batteries. The composite (SnO2/RH-SiO2) has a hierarchical pore structure from RH-SiO2, provides a robust conductive framework. The lattice structure of the SnO2 is similar to that of PbO2, while induces the formation of a PbSnO3 intermediate phase during formation process. SnO2/RH-SiO2 can also accelerates lead dioxide deposition and improves the interphase conversion efficiency, while significantly enhances the transformation of α- and β-PbO2, leading to a 20.7% increase in discharge specific capacity. Compared to a standard battery, up to 3.7 times longer at 100% deep discharge cycle life and 4.7 times longer in start-stop-mode testing. In our finding the SnO2/RH-SiO2 composite serves as a highly effective additive for augmenting the performance and longevity of lead-acid batteries in high-power applications, presenting a significant advancement in battery technology.

Production and Characterization of Silica from Rice Husk: An Updated Review

Rice is regarded as one of the most valuable sources which is consumed by almost fifty percent of the world’s population. Rice husk ash is a by-product substance obtained from the rice husk by thermal and chemical treatment. The non-crystalline nature of silica content in rice husk, which is converted to crystalline silica such as quartz, tridymite, and cristobalite on thermal treatment. It has been an important material which impacts not only enhances the betterment of industrialization but also protects the environment from pollution. The produced silica was characterized by various analyses such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), and Thermal analysis. This review is given attention to integrating and investigating processing, properties, characterization, reactivity, and application of rice husk (RH) and rice husk silica (RHS).

Chemical and structural properties of silica obtained from rice husk and its potential as a catalytic support

The structural and chemical properties of biogenic silica obtained from rice husk using an acid treatment were determined in order to explore its potential as a support in the synthesis of catalysts for the remediation of contaminants in water. Using thermogravimetric analysis (TG-DTG) the total amount of silanol groups on the surface was quantified and by means of DRIFT spectroscopy and TPR-NH3 analysis, the amount of silanol groups present (isolated, geminal and vicinal) were identified and quantified. The silica structure was confirmed by XRD and a silica content of 99.3% was determined by XRF. The zeta potential measurements revealed an isoelectric point at pH 5.4. Finally, the presence of non-bridging oxygen centers – NBO type oxygen defects on the surface of the biogenic silica was identified by DRIFT and EPR spectroscopy techniques. New knowledge is uncovered aimed at the future exploration of rice husk silica produced by a more environmentally friendly method, as a potential support in the synthesis of catalysts.

Rice husk silica blended fillers for engine mount application

The functional properties of engine mounts largely depend on the rubber compound formulation. This study proposes the use of rice husk–derived silica (RHS) blended with carbon black (N772) as an effective and environmentally friendly substitute for fillers used in rubber engine mounts (REMs). CV-60 natural rubber was filled with the blended fillers at various ratios, and their compatibility for use as rubber engine mounts (REMs) was assessed. Grey Relational Analysis was utilised to determine the optimal blend loading levels for use in rubber engine mounts, resulting in 40 phr of N772 and 20 phr of RHS cured at 130 °C and 2.5 MPa for 20 min. The developed REMs and conventional REMs had low vibration data variation during the performance assessment. Their resonance transmissibility was 5.03 and 3.74, corresponding to natural frequencies of 24.27 Hz and 26.94 Hz, respectively. The RHS/N772 REMs had excellent damping characteristics and lower transmissibility in the isolation zone of the vibration isolation curve, which is outside of the resonant frequency region. The efficiency curves showed that the blended fillers are a better and more effective material for REMs at all frequencies, balancing static deflection and vibration isolation.

Investigation of the Properties of Metakaolin-Based Geopolymer Materials Using Ferrisilicates as Additives Synthesised in Sodium Hydroxide Solution or Distilled Water

The main objective of this work is to investigate the behaviour of ferrisilicates prepared from hematite and two silica sources (rice husk ash and silica fume) on the compressive strength of geopolymer materials. Some ferrisilicates were synthesised in 2M sodium hydroxide solution. Others were prepared using distilled water as a solvent. The Fe2O3/SiO2 molar ratio contained in the ferrisilicates is set to 0.2. Metakaolin and sodium silicate solution with a molar ratio of SiO2/Na2O of 1.6 were used as the aluminosilicate and hardener in this work. The control geopolymer compressive strength is 53.34 MPa. For ferrisilicates prepared in alkaline solution using rice husk ash and silica fume, their compressive strength values are 71.91 and 77.72 MPa, respectively. The compressive strengths of the geopolymer materials made from ferrisilicates prepared in distilled water using rice husk ash and silica fume are 74.13 and 44.73 MPa, respectively. In the presence of ferrisilicate obtained by dissolving silica fume and hematite in sodium hydroxide solution, the maximum compressive strength of 77.72 MPa was obtained. When ferrisilicates from the mixture of silica fume, hematite, and distilled water are used as an additive, the minimum compressive strength of 43.73 MPa is achieved. It can be concluded that additives synthesised in an alkaline medium and those obtained in distilled water with rice husk ash improve compressive strength. On the other hand, the compressive strength of the geopolymer material that uses the additive produced with silica fume in distilled water is lower (44.73 MPa).

Unlocking synergies of Mg(OH)2 and rice husk silica as dual additives for tailored pore properties, selectivity, and antifouling performances of PES membrane

This research investigates the synergistic impact of incorporating Mg(OH)2 and rice husk silica additives during membrane fabrication to enhance both selectivity and resistance to fouling. The main objective is to harness the enhanced hydrophilicity provided by both additives to elevate membrane characteristics and performance, while also addressing the individual limitations of each additive when used separately. The introduction of Mg(OH)2 and silica is performed on the polyethersulfone (PES) membrane via blending method. The findings of the research show that combination of Mg(OH)2 and silica as additive result in exceptional attributes of the PES membrane, in comparison to membranes modified with each additive separately. This membrane demonstrates outstanding characteristics, including a remarkable porosity of 60.7 %, and exceptional antifouling capability, as evidenced by an impressive Flux Recovery Ratio (FRR) of 84.7 %, thereby enhancing its practical utility. These collective findings underscore the remarkable potential of combining Mg(OH)2 and rice husk silica as beneficial hybrid additives for membrane fabrication. The synergistic approach holds great promise for enhancing membrane properties and overcoming constraints associated with the individual application of each additive.

Application of Response Surface Methodology (RSM) to Study Transesterification of Palm Oil in the Presence of Zeolite-A as Catalyst

In this research, the application of response surface methodology with central composite design (RSM-CCD) to optimizetransesterification of palm oil in the presence of zeolite-A as catalyst was investigated. Zeolite-A was synthesized from rice husk silica (RHS) and food-grade aluminium foil using hydrothermal method and then characterized using XRD and SEM. The synthesized zeolite was then applied to an optimized transesterification reaction using response RSM with three factorial levels, for three variables including methanol to oil ratio, catalyst load, and reaction time. The experimental results indicate that the yield of 99% was achieved at optimum conditions of methanol to oil volume ratio of 6, catalyst load of 9.6%, and reaction time of 4.3 hours. The results of experiments and predicted results based on the RSM model are in agreement as shown by the p-value less than 0.05 at a confidence level of 95%.

Kinetic and thermodynamic studies on the thermal inactivation of lipase immobilized on glutaraldehyde-activated rice husk silica.

The objective of this study was to obtain sufficient information on the thermal stabilization of a food-grade lipase from Thermomyces lanuginosus (TLL) using the immobilization technique. To do this, a new non-porous support was prepared via the sequential extraction of SiO2 from rice husks, followed by functionalization with (3-aminopropyl) triethoxysilane - 3-APTES (Amino-SiO2), and activation with glutaraldehyde - GA (GA-Amino-SiO2). We evaluated the influence of GA concentration, which varied from 0.25% v v-1 to 4% v v-1, on the immobilization parameters and enzyme thermal stabilization. The thermal inactivation parameters for both biocatalyst forms (soluble or immobilized TLL) were calculated by fitting a non-first-order enzyme inactivation kinetic model to the experimental data. According to the results, TLL was fully immobilized on the external support surface activated with different GA concentrations using an initial protein load of 5mgg-1. A sharp decrease of hydrolytic activity was observed from 216.6 ± 12.4 U g-1 to 28.6 ± 0.9 U g-1 of after increasing the GA concentration from 0.25% v v-1 to 4.0% v v-1. The support that was prepared using a GA concentration at 0.5% v v-1 provided the highest stabilization of TLL - 31.6-times more stable than its soluble form at 60°C. The estimations of the thermodynamic parameters, e.g., inactivation energy (Ed), enthalpy (ΔH#), entropy (ΔS#), and the Gibbs energy (ΔG#) values, confirmed the enzyme stabilization on the external support surface at temperatures ranging from 50 to 65°C. These results show promising applications for this new heterogeneous biocatalyst in industrial processes given the high catalytic activity and thermal stability.

Rice husk fibers and their extracted silica as promising bio-based fillers for EPDM/NBR rubber blend vulcanizates

Bio-based natural wastes could be considered eco-friendly alternatives to conventional fillers for enhancing the properties and reducing the cost of final rubber products. Thus, in the present research, EPDM/NBR rubber blend composites filled with kaolin and mixed with rice husk fibers (RHFs) were prepared. Homogeneity of the EPDM/NBR blends was improved by the incorporation of maleic anhydride (MAH) as a compatibilizing agent (1 phr), as evidenced by scanning electron microscopy (SEM). Of all EPDM/NBR blend ratios investigated, the 25/75 blend revealed good mechanical properties, thermal stability, and the least weight swell at equilibrium (Q%) in motor oil and brake fluid. EPDM/NBR/kaolin (25/75/30) blend vulcanizates containing RHFs at various loadings demonstrated a significant improvement in swelling resistance, primarily in motor oil and brake fluid, accompanied by a slight reduction in the mechanical properties at high RHFs content. That was complemented by the enhancement of thermal stability of the rubber blends, as demonstrated by TGA analysis. Among the filler types investigated (RHFs, silica ash (SA), rice husk silica (RHS), and kaolin), RHFs exhibited the best swelling resistance of the composite vulcanizates in motor oil and brake fluid. In addition, RHS could be used successfully as a supporting filler for carbon black-reinforced EPDM/NBR composite vulcanizates because it enhanced their thermal stability and swelling resistance in the motor oil.Graphical

Mechanical characteristics and regression models of rice husk silica reinforced natural rubber composites

Carbon black and silica fillers have been widely used as reinforcing fillers in tyres and engine mounts. However, both fillers are non-renewable and with REACH legislation in Europe, the USA and elsewhere, where some of these fillers are termed hazardous due to the presence of polyaromatic hydrocarbons (PAHs), there is a need to search for sustainable alternative fillers to wholly or partially replace carbon black as a filler. This research studied rice husks-derived silica (RHS) as a filler in natural rubber (NR). The characteristics of RHS at 50 phr to 90 phr filler loading levels were examined to determine its suitability as a substitute for unsustainable carbon black (N772) fillers used in the rubber industry. Bound rubber content, crosslink density, tensile strength, young modulus, tear strength, shore A hardness, compressive set, and elongation at break were measured. Regression models were generated and the correlation of determination (R2) values was obtained. The RHS composites resulted in maximum tensile strength of 13.20 MPa at 90 phr, tear strength of 119 MPa at 90 phr, shore A hardness of 69 at 90 phr, compressive set of 6.72% at 80 and 90 phr, elongation at break of 453.60% at 80 phr, bound rubber content of 92.14% at 50 phr and crosslink density of 3.87×10-2 mol/cm3 at 70 phr. The results obtained were within the range of those obtained for the carbon black filled composites across various loading levels. The R2 value of mechanical characteristics for the RHS and N772 samples respectively were 50.06% and 62.18% (bound rubber content), 97.62% and 99.85% (tensile strength), 98.44% and 63.97% (tear strength), 89.16 and 97.40% (Shore A hardness), 32.90% and 91.80% (compressive set), a d 50.91% and 46.91% (elongation at break). Rice husk-derived Silica filled natural rubber composites showed favourable mechanical properties and can substitute traditional fillers in tyres, rubber engine mounts, bushings, seals and doormats.

Preparation and Characterization of High-Density Polyethylene (HDPE) Waste filled with Rice husk Silica (RHS) Composites in Gwagwalada metropolis, Abuja, Federal Capital Territory, Nigeria

The adverse effects of use of plastics by human beings are on the increase and become challenging with the growing population. The non-degradability of plastics products such as bottles, cans, cups, bags which resulted into blockage of culverts, drains, suffocating animal’s life. This research focused on recycling of high density polyethylene (HDPE) plastic waste with rice husk silica (RHS) from agricultural waste of rice husks to form eco-friendly polymer composites. Different proportions of 0.5 to 3.0 % rice husk silica (RHS) as filler were melt mixed with maleic anhydride grafted high density polyethylene (HDPE) material and the composite analyzed for tensile and flexural strengths. The tensile strengths ranged values from 10.49 to 13.02 MPa for the resin (vHDPE) and the recycled (rHDPE) composites presented values from 8.30 and 12.41 MPa for 0.5and 3.0% filler loading, respectively. The peak flexural strengths recorded for recycled (rHDPE) and resins (vHDPE) composites are 12.19 MPa and 12.05 MPa for 0.5 and 3.0% filler loading, respectively. The tensile strength of rice husk silica (RHS) filled HDPE waste composites are higher than that of the waste HDPE (control) and thus, the filler reinforced the HDPE. The composite prepared is suitable for use as tiles in building application to solve leaching problems associated with paint coating.

Silica-pyridine sulfonic acid catalyst for cellulose and glucose hydrolysis

An innovative catalyst was developed for the purpose of simplifying the manufacturing process of biofuels without the need for costly materials. The incorporation of pyridine sulfonic acid (PSA) into silica rice husk (RH) was achieved by two distinct strategies, resulting in the production of a heterogeneous catalyst. The first catalyst, RHAPSA@Dir, was prepared using the Sol-Gel technique through a one-pot synthesis approach. The second catalyst, RHAPSA@Ref, was created through post-synthesis means. BET analysis of RHAPSA@Dir showed a significant improvement in surface area to 416 m2/g, while RHAPSA@Ref only exhibited 48.2 m2/g. Upon conducting elemental research on both catalysts, it was observed that the presence of carbon, nitrogen, and sulfur was apparent. The thermal study conducted indicated that approximately 47–48% of organic matter was lost from the silica at the anticipated temperature. The SEM analysis of RHAPSA@Dir revealed that a minor level of pore arrangement was observed. Furthermore, the TEM analysis of RHAPSA@Dir demonstrated that a few particles exhibited spherical nano shapes that were clearly visible. Conversely, the SEM analysis of RHAPSA@Ref showed a rough and porous surface with large particles. Lastly, the TEM micrograph of RHAPSA@Ref revealed spherical particles with an approximate diameter of 6 nm. The use of electron microscopy revealed the presence of spherical nanostructures. Both cellulose and glucose underwent hydrolyzation over the catalysts within 2–6 h at 140 °C. The essential properties of both catalysts were their stability and reusability.

Characterization of reinforced nanohybrid dental composite resin made of nano silica rice husk with the reinforcement utilizing kenaf fiber

Characterization of reinforced nanohybrid dental composite resin made of nano silica rice husk with the reinforcement utilizing kenaf fiber

Statistical Optimization of Faujasite Zeolite Synthesis from Bauxite Alumina and Rice Husk Silica

Statistical Optimization of Faujasite Zeolite Synthesis from Bauxite Alumina and Rice Husk Silica

Durability of alkali-activated slag concrete incorporating silica fume and rice husk ash

To improve the mechanical properties and durability of alkali-activated slag concrete (AASC), as well as to reduce carbon emissions and exploitation of natural resources. This paper attempts to introduce rice husk ash (RHA) and silica fume (SF) into the AASC system. The effects of RHA and SF on the physical properties (water absorption and density), mechanical properties (flexural strength and compressive strength), and durability properties (dry shrinkage, resistance to sulfuric acid attack and carbonation) of AASC are examined. The optimization mechanisms are also explored from the points of pore structure and microstructure analysis. The experimental results suggest that RHA and SF can substantially reduce water absorption and improve the mechanical and durability properties of AASC. Remarkably, adding 10 wt% RHA into concrete can reduce the water absorption by 42%, increase the strength by 9.7–20%, the resistance to sulfuric acid attack by 26.91%, and the resistance to carbonization by 54.4%. Unfavorably, its dry shrinkage increases by 3.2–33%. Microstructural investigations demonstrate that the addition of RHA and SF to the AASC system provides an additional source of silica, which could have a filler effect, pore refinement, and pozzolanic nature. Moreover, RHA has more silica content than SF, and the particle size of RHA is finer and the reaction is more adequate, so the effect is more remarkable. The findings of the study suggest that RHA and SF demonstrate promising prospects in improving the durability and sustainability of AASC.

A preliminary appraisal for utilizing abandoned industrial side streams as alternatives to cement within radiation protection applications

Recently, there has been arising a severe alert regarding climate crisis all over the world. As industrial production capacities have been soaring every passing day, the primary sources of the earth's crust have been depleting like there is no tomorrow. Sustainable and greener suggestions should be followed to overcome the upcoming catastrophic climate change. With this motivation, cement material, whose influence on global warming is excessive, has been studied to be replaced by alternative material systems in different application areas, and radiation shielding applications may be regarded as one of these emerging fields. In this study, the authors were motivated to replace ordinary Portland cement (OPC) with alternative side streams (SS) that have accumulated in nature without any benefits. First, the high-quantity SS were determined and presented as follows: fly ash (FA), blast furnace slag (BFS), red mud (RM), electric arc furnace slag (EAFS), fayalite slag (FS), rice husk ash (RHA), silica fume (SF), ferrochrome slag (FS), and copper mining tailings (CMT). Each side stream's average chemical compositions were obtained, and their theoretical density values were calculated. After that, the theoretical radiation shielding properties were assessed using Phy-X/PSD software within the 0.15–15 MeV photon energy range. Some essential parameters such as linear attenuation coefficient (LAC), half-value layer (HVL), effective atomic number (Zeff), radiation protection efficiency (RPE), and build-up factors (EBF and EABF) paved the way for comparing SS with OPC material. The results for radiation protection demonstrated that high-density-oxide-containing SS like RM, FS, and EAFS could replace OPC material with a good performance. Owing to this replacement, the authors strongly believe that the future can be sustained in a more secure environment without OPC material, but with SS in radiation shielding applications.