Rice Husk Silica Research Articles

Nano Powder SiO2 from Rice Husk and its Industrial Applications: A Concept of Wealth from Waste

The rice Husk (RH) is a renewable biomass product and through thermochemical processes like pyrolysis and gasification, silica-rich RH is transformed into biofuels (such as bio-oil, vapors, and charcoal) and biochar at the same time. RH catalysts can convert bio-oil into more renewable biofuel (biodiesel). Using RH silica materials to purify gas or undergo catalytic reforming, vapors from the breakdown of organic waste can be transformed into syngas, which have more value and can be utilized to create energy or make chemicals. Biochars created from RH are usually used to produce materials for silicon batteries, mend soil, clean up pollutants, and accomplish other things. This study looked at recent improvements in how RH silica products are created and how they can be used in the future, notably in manufacturing materials that benefit the environment and save energy. RH-silica compounds have environmental benefits, can eliminate organic and heavy metal contamination through integrated processes and adsorption, and are used as a catalyst in fertilization, and water purification, including gas cleaning. Lastly, biomass with a lot of silica could be a source of cheap starting materials for creating high-value silica/silicon compounds that can be employed in the actual world.

MCM-41 from rice husk silica as a support for Ni catalyst in the emission-free production of H2 by CH4 cracking.

Selecting a sustainable source of silica from biomass waste was the research challenge that was put forth in this investigation. Herein, the MCM-41 support has been synthesized using a renewable rice husk and explored as a support for Ni-Cu catalyst in the production of zero-emission H2 through CH4 pyrolysis. The role of Cu promoter was investigated by doping different amounts of Cu loading to 30wt%Ni/R-MCM-41catalyst, which improved the catalytic performance in terms of CH4 conversion and stability. An optimum Cu loading of 3wt% addition to 30wt%Ni/R-MCM-41 catalyst demonstrated the best catalytic performance compared to all the catalysts in terms of hydrogen yield (15,218mol H2/mol Ni) and carbon formation rate. The Ni-Cu alloy formation was confirmed by X-ray diffraction, H2-temperature programmed reduction, and pulse chemisorption studies, as demonstrated by decreased H2 uptake (from 41 to 33μmol/gcat) and enhanced N2O (from 89.2 to 138.3μmol/g) uptakes, which results in a significant improvement in the availability of the surface metal species (both Cu and Ni), which in turn contributed to increase the CH4 cracking performance and stabilization of Ni species. Additionally, doping Cu results in better carbon nanotube production, as shown by the lowest ID/IG ratio from the Raman spectroscopic analysis.

Augmented barrier properties of poly (lactic acid) composite packaging film reinforced by antibacterial hybrid bio‐filler: Extending the shelf life of fruits

AbstractThis work investigates the construction of biodegradable packaging film based on polylactic acid (PLA) reinforced with a novel antibacterial hybrid nanofiller to improve barrier and mechanical properties. The study focuses on incorporating silver‐ingrained silica particles (Ag–In–Si) into PLA matrix to prepare the packaging film (Ag–In–SiPLA) that has superior antibacterial, and barrier property with negligible oxygen and water vapour penetration. The Ag was synthesized using natural neem leaf extract as a reducing agent. To ingrain silver over rice husk silica (Si) an in situ technique was adopted. Hence called Ag‐In‐Si bio‐filler. The Ag–In–SiPLA films were fabricated using melt blending and sheet extrusion methods by means of a micro‐compounder. The addition of rice husk silica served the purpose of cost‐effectiveness of the packaging film along with the enhancement of the oxygen and water barrier properties of the films. The optimized sample (PLA loaded with 3% Ag–In–Si), exhibited optimum transparency, moisture resistance, and barrier properties compared with control PLA film. The experiments on Muntingia calabura (Jamaica cherry) preservation have verified the remarkable effectiveness of Ag–In–SiPLA films in preserving their quality for an extended period. These biodegradable packaging films, composed of food‐grade materials and sustainable ingredients, have the potential to provide a compostable and environmentally friendly solution for various packaging applications. This research shed light on the antibacterial Ag–In–SiPLA film as a long‐term, high‐performance fruit packaging solution.Highlights Novel antibacterial PLA composite with enhanced barrier and mechanical properties. Silver‐ingrained silica particles improve antibacterial and barrier properties. Green synthesis of silver using neem leaf extract Melt blending and sheet extrusion used to create cost‐effective packaging films. Ag–In–SiPLA films extend Muntingia calabura preservation, proving effective.

Intensification of n-butyl ethanoate synthesis using ultrasound over ammonium sulphate supported on silica extracted from rice husk ash as an efficient heterogeneous catalyst

ABSTRACT The silica extracted from rice husk ash was used as support to load ammonium sulphate ((NH4)2SO4) (10–40 wt.%) and ammonium sulphate supported on rice husk silica ((NH4)2SO4/RHS) catalysts were characterised by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and scanning electron microscope (SEM) with EDS techniques. The catalyst was further used to convert butan-1-ol to n-butyl ethanoate in an ultrasonic batch reactor. The study demonstrated the influence of ultrasound and operating parameters on the conversion. The maximum conversion of 88.77% was attained at the optimal operating conditions of temperature 353 K, molar ratio 1:2 (ethanoic acid to butan-1-ol), catalyst loading 4% (w/w), duty cycle 75% and ultrasound power 80 W. When compared with the conventional process, the reaction time was reduced by 54% in ultrasound-assisted synthesis over conventional synthesis. It has been observed that intensification benefits as it lowers reaction time for the ultrasound-assisted approach.

Flexural strength and viscosity of dental luting composite reinforced with zirconia and alumina

Objectives Optimum flexural strength and viscosity are essential for longevity while efficiently handling dental luting composite. This study aims to investigate the effects of zirconia and alumina on the flexural strength (FS)and viscosity of dental cement made of silica rice husk. Materials and Methods Study groups with different percentages of weight (wt.): Group 1 (3 wt.% zirconia), Group 2 (3 wt.% alumina), and Group 3 (3 wt.% zirconia and 2 wt.% alumina), negative control specimen (0 wt.% zirconia/ alumina) and Rely-X U200 (3M ESPE). A universal testing machine and a rheometer were used to test FS and viscosity, respectively. One-way ANOVA and post-hoc Bonferonni test were used for data analyses. Results and Discussion FS and viscosity for Group 3 (3 wt.% zirconia and 2 wt.% alumina) were significantly higher compared to the negative control (p<0.05). Conclusion: Adding zirconia and alumina improved flexural strength without compromising the viscosity of dental luting composite. This experimental dental luting cement using hybrid fillers could be an alternative to resin luting cement. Bangladesh Journal of Medical Science Vol. 23 No. 04 October’24 Page : 1048-1053

Ultrafine GGBS and Fly Ash as Cement Replacement for Sustainable Concrete

The construction industry is one of the major contributors to environmental degradation. Hence, it requires eco-friendly practices to make concrete more sustainable. This can be achieved by addition of mineral admixtures as a cement replacement. This process helps the environment in two ways: by reducing the carbon dioxide emission through cement replacement and by utilizing mineral admixtures such as fly ash, Ground Granulated Blast Furnace Slag (GGBS), metakaolin, rice husk ash and silica fume, which are all industrial wastes or by-products. Hence, this approach lowers the greenhouse effect and global warming by reducing carbon dioxide emissions and prevents environmental contamination by utilizing industrial wastes. This experimental study aims to find the perfect combination of mineral admixtures such as fly ash and ultrafine GGBS to maximize cement replacement in concrete without compromising its mechanical properties and achieving a more sustainable concrete for day-to-day practice. For this study, the fly ash percentage was maintained at 20% for all trials, with the ultrafine GGBS percentage varying from 15% to 30%. Keywords: Sustainable Concrete; Ultrafine GGBS; Fly ash; Mineral Admixture.

Rice Husk Silica Liquid Enhances Autophagy and Reduces Overactive Immune Responses via TLR-7 Signaling in Lupus-Prone Models.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by widespread inflammation and multi-organ damage. Toll-like receptor 7 (TLR-7) and autophagy have been implicated in SLE pathogenesis. Rice husk silica liquid (RHSL) has shown potential for modulating inflammatory responses, but its effects on SLE have not been thoroughly investigated. This study aims to evaluate the impact of RHSL on immune responses and autophagy in cell culture experiments, focusing on its effects on TLR-7 signaling, cytokine production, and autophagy modulation. RAW264.7 cells and human peripheral blood mononuclear cells (PBMCs) from healthy donors and SLE patients were used. Cells were stimulated with LPS or TLR-7 agonists and treated with RHSL. Cell viability was assessed, and cytokine levels (TNF-α and IL-6) were measured by ELISA. Autophagy-related proteins (LC3II, ATG5-ATG12) were analyzed by Western blotting. The effect of autophagy inhibition was studied using 3-methyladenine (3-MA). A concentration of 100 μg/mL RHSL did not affect cell viability but significantly reduced the TNF-α production in TLR-7 agonist-stimulated RAW264.7 cells (compared to TLR-7 alone, 3.41 ± 0.54 vs. 6.72 ± 0.07 folds) and PBMCs (compared to TLR-7 alone, 0.97 ± 0.19 vs. 1.40 ± 0.33 folds). RHSL enhanced autophagy, as evidenced by increased LC3II (4.35 ± 1.08 folds) and ATG5-ATG12 (7.07 ± 1.30 folds) conjugation in both RAW264.7 cells and SLE patient-derived PBMCs. The reduction in TNF-α production by RHSL was attenuated by 3-MA, indicating that autophagy plays a role in this process. RHSL also inhibited the translocation of phosphorylated NF-κB into the nucleus, suggesting a mechanism for its anti-inflammatory effects. RHSL exhibits potential as an immunomodulatory agent in SLE by enhancing autophagy and modulating TLR-7 signaling pathways. These findings suggest that RHSL could offer therapeutic benefits for managing inflammatory responses in SLE and warrant further investigation into its clinical applications.

Formation of incipient anodes in localized mortar repairs with the addition of rice husk silica

The objective of this work was to investigate how incipient anodes can be detected and monitored in localized repair areas using mortars with added rice husk silica. Three repair conditions were tested on prismatic specimens: without repair, with repair without rice husk silica addition, and with rice husk silica addition in the mortar. Corrosion potential and electrical resistivity tests were conducted. The corrosion potential test showed no variation along the bar, while the electrical resistivity test showed varied values depending on the repaired and non-repaired zones. It was concluded that adding rice husk silica to the mortar made the corrosion potential more electronegative due to the greater difference in electrical resistivity compared to the substrate, contributing to the formation of incipient anodes.

Catalytic pyrolysis of polystyrene over rice husk silica-derived traditional and hierarchical green MWW zeolites

This work aimed at the green synthesis of MWW zeolites using rice husk silica as an alternative raw material. It was also performed a post-synthesis desilication procedure with NaOH and CTABr aiming to obtain MWW zeolites with improved accessibility. The set of characterization techniques (XRD, 27Al MAS NMR, N2 physisorption, SEM, TEM, and Pyridine-FTIR) revealed the phase purity and combined structure of micro-mesopores after desilication. The zeolites were evaluated as catalysts for polystyrene pyrolysis, producing benzene, toluene and ethylbenzene, besides styrene monomers, and dimers. Without any catalyst, polystyrene produces only styrene monomers, dimers and trimers. The desilication increases the amount of Brønsted and Lewis sites and the external area, catalyzing the production of polyaromatics and naphthalene derivatives. The activation energy decreased for the catalyzed reactions, reflecting other reaction pathways.

A review of the use of rice husk silica as a sustainable alternative to traditional silica sources in various applications

A review of the use of rice husk silica as a sustainable alternative to traditional silica sources in various applications

Invitro Activity of Mineral Trioxide Aggregate Modification from Rice Hull Ash Silica and Calcium Oxide from Clamshells

The impact of SrO particles and hydroxyapatite (HA) on the characteristics of Mineral Trioxide Aggregate (MTA) from silica Rice Husk Ash (RHA) and Precipitated Calcium Carbonate (PCC) from clam shell has been studied in this research. Silica and calcium oxide are used as material to form tricalcium silicate (C3S) and dicalcium silicate (C2S) in MTA. Bi2O3 and SrO were added in MTA with 18% (w/w) total percentage. MTA was made with a sol-gel process and used catalyst NH3. After synthesis, material was calcined at 1000 oC for 3 h. HA was added at percentages of 3, 6, and 9% in 5% SrO modified MTA to see the effect of its addition on the material. The modified MTA (MTA-SrO-HA) were hydrated water using water to powder method with ratio of 3:1. The MTA-SrO5/HA6 showed higher compressive strength and dentine interaction to the commercial MTA (Proroot brand) in days 3 and 7. This material had potential as a root canal filling in dental endodontic treatment.

A novel biogenic porous core/shell-based shape-stabilized phase change material for building energy saving

The application of phase change materials (PCMs) for thermal storage in construction can effectively reduce building energy consumption. However, high costs and vulnerability to leaks have hindered their application. The present study proposes two approaches for the synthesis of porous supporting matrices derived from rice husk, resulting in the formation of rice husk silica (RHS) and rice husk carbon (RHC). Then, n-octadecane and the porous materials were combined by vacuum impregnation, while the leakage resistance performance of the composite PCMs was enhanced by applying epoxy resin coating to create a shell-core structure. The results show that the n-octadecane/RHS and n-octadecane/RHC composite PCMs exhibit high latent heat potential of 106.5 J/g and 116.3 J/g, respectively. Both porous supporting structures provided the PCMs with robust structural stability and exceptional thermal conductivity. The thermal conductivity of the n-octadecane/RHS composite PCMs and n-octadecane/RHC composite PCMs reached 0.52 W/(m K) and 0.41 W/(m K), respectively. The thermal properties of the biogenic porous core/shell-based shape-stabilized PCMs were characterized by an analog T-history method, and the results demonstrated that the composite PCMs exhibited excellent and rapid heat storage and exothermic capabilities. After undergoing 300 complete heating and cooling cycles, the composite PCMs demonstrate exceptional thermal reliability and possess a high enthalpy capacity. Finally, the impact of the pore structure of RHS and RHC on the crystallization behavior of n-octadecane was discussed. Both composite PCMs can be regarded as environmentally friendly construction materials with promising thermal and acoustic properties.

Removal of silica in rice husk derived Ni/biochar modifies reaction intermediates formed and minimizes coking in steam reforming of glycerol

Metal/biochar catalyst features with the advantages for easy recovery of chemical energy of biochar carrier and metal species via simply combustion. Another unique feature of biochar carrier is intrinsic inorganic species, which might also interact with metal species in resulting catalyst. This was investigated herein by synthesis of the Ni/biochar with rice husk-derived biochar carrier pretreated with NaOH for removal of SiO2 and evaluation of the resulting catalysts in steam reforming of glycerol. The solid phase reactions between NaOH and biochar (mass ratio: 2) plus subsequent washing removed 94.6% of ash (mainly SiO2). This formed Ni/biochar of fragmented surface with specific surface area increasing from 207.8 to 457.4 m2g-1 and simultaneously increasing mesopore percentage from 15.5% to 24.0%. NaOH treatment also effectively removed significant portion of both Lewis and Brønsted acidic sites but created abundant alkaline sites. These drastically enhanced nickel dispersion and activity for steam reforming. In-situ IR characterization suggested enhanced adsorption/activation of CO2 and H2O over Ni/biochar treated with NaOH (Ni/biochar-NaOH), which mitigated accumulation of coke precursors bearing CO or CC via accelerated gasification reactions. This led to the reduced amount of coke (mass ratio to catalyst) from 193.4% to 94.7% over Ni/biochar treated with 2-fold of NaOH or to 111.3% over Ni/biochar treated with 1-fold of NaOH. The coke formed was mainly catalytic type in form of carbon nanotube over Ni/biochar-NaOH. The superior resistivity to coking originated from developed pores, enhanced Ni dispersion and abundant alkaline sites from the NaOH treatment.

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 (1253 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.

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.

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.