Rice Husk Research Articles

Exploring the Synergistic Effects of Industrial and Agricultural Waste in Concrete

Concrete is widely used in the construction industry due to its cost-effectiveness and superior properties compared to other materials. However, the increasing consumption of Ordinary Portland Cement (OPC) due to infrastructure growth and residential construction has raised environmental concerns. Cement production contributes approximately 7% of global carbon dioxide emissions, exacerbating climate change. Additionally, the large-scale mining of finite natural resources like limestone and river sand for fine aggregate has led to environmental degradation, prompting governments, particularly in developing nations, to regulate sand mining. These challenges highlight the urgent need for sustainable alternatives in concrete production. Research has explored supplementary cementitious materials such as fly ash, slag, silica fume, rice husk ash, and metakaolin, demonstrating enhanced strength, reduced permeability, and improved hydration properties in blended cement concrete. However, many locally available pozzolanic materials remain underutilized due to limited characterization and assessment. Aggregates, which constitute the majority of concrete volume, are extensively extracted, leading to severe environmental impacts. With sand and gravel being the most extracted resources globally, their depletion surpasses even biomass and fossil fuel extraction. In response, researchers and organizations are focusing on sustainable alternatives for concrete production by recycling industrial waste and by-products.

Synthesis of MCM‐41 and SBA‐15 from rice husk silica and their carbon replicas for hydrogen adsorption

AbstractBACKGROUNDRice husk, an abundant agricultural by‐product, presents a promising renewable silicon source for producing carbon‐based materials through sustainable and eco‐friendly approaches. Among emerging clean energy solutions, hydrogen storage remains a critical challenge for the practical deployment of hydrogen energy systems. This study explores the use of rice husk‐derived silica to synthesize mesoporous nanostructured silicon materials and their corresponding carbon replicas. The goal is to develop efficient materials for hydrogen adsorption, with performance surpassing that of other biomass‐derived carbons synthesized under comparable conditions – thereby offering a competitive and sustainable solution for hydrogen storage.RESULTSA cost‐effective, sustainable synthesis route was developed to produce siliceous templates MCM‐41 and SBA‐15 using cetyltrimethylammonium bromide and Pluronic P123 as surfactants. Their carbon replicas – rice husk ash (RHA)‐MCM‐41 and RHA‐SBA‐15 – were fabricated via a nanocasting method employing sucrose as a carbon source. The resulting materials were characterized using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption techniques. Notably, the synthesized mesoporous carbons, RHA‐CMK‐3 and RHA‐RMCM‐41, exhibited high surface areas ranging from 800 to 1400 m2g−1 and featured both mesoporous and microporous structures.CONCLUSIONThe synthesized carbon replicas demonstrated significant hydrogen adsorption capabilities. Among them, RHA‐CMK‐3 showed the highest hydrogen storage performance, reaching 3.6 wt% at 196.15 °C and 10 bar. These findings highlight the potential of rice husk‐derived nanostructured carbons as efficient and sustainable materials for hydrogen storage applications. Moreover, the obtained materials exhibit hydrogen adsorption capacities surpassing those of other biomass‐derived carbons synthesized under similar conditions, reinforcing their competitive advantage for energy storage solutions. © 2025 Society of Chemical Industry (SCI).

Utilizing Agro-Waste as Aggregate in Cement Composites: A Comprehensive Review of Properties, Global Trends, and Applications

Amid growing environmental concerns and the increasing demand for sustainable construction practices, the exploration of alternative materials in building applications has garnered significant attention. This paper provides a comprehensive review of the use of agricultural waste as an aggregate in cementitious composites, with a particular focus on palm kernel shells, coconut shells, hazelnut, peanut and pistachio shells, stone fruit shells and pits, date and grape seeds, rice husks, maize (corn) cobs, and sunflower seed shells. For each type of agro-waste, the paper discusses key physical and mechanical properties, global production volumes, and primary countries of origin. Furthermore, it offers an in-depth analysis of existing research on the incorporation of these materials into cement-based composites, highlighting both the advantages and limitations of their use. Although the integration of agro-waste into construction materials presents certain challenges, the vast quantities of agricultural residues generated globally underscore the urgency and potential of their reuse. In line with circular economy principles, this review advocates for the valorization of agro-waste through innovative and sustainable applications within the construction industry.

Growth Of Oil Palm (Elaeis guineensis Jacq.) In Pre Nursery With Planting Media Composition And Concentration Of Micro Fertilizer

Planting media and micronutrients are important aspects of plant growth. Planting media rich in organic matter and micronutrients such as B and Cu are essential nutrients that must be fulfilled for oil palm plants (Elaeis guineensis Jacq). This study aims to determine the growth of oil palm in early nurseries with the composition of planting media and the concentration of microfertilizer application and determine the best treatment interaction for oil palm seedling growth. The research was conducted at UPT BPP Tungkal Jaya Kec. Musi Banyuasin from December 2023 to March 2024. The design used was a two-factor Randomized Block Design with three replications, each replication consisting of 48 plants so that there were 144 experimental units. The treatments consisted of (M0P0) 100% soil + 0 ml/plant vs (M1P1) 85% soil + 15% rice husk charcoal + 2 ml/plant vs (M2P2) 75% soil + 25% rice husk charcoal + 4 ml/plant and (M3P3) 50% soil + 50% rice husk charcoal + 6 ml/plant. The data obtained were analyzed using ANOVA, if there was a significant effect, it was continued with the Honest Real Difference test at the 5% level. The results showed that the composition of planting media had a significant effect on oil palm growth such as stem diameter, number of leaves, plant height, wet weight, dry weight and root length. However, microfertilizer concentration did not show a significant impact on growth. The interaction between growing media and microfertilizer affected certain variables such as leaf area, wet weight and root length.The conclusion of this research is that M3 planting media and P3 microfertilizer are effective in increasing the growth of oil palm seedlings. The use of organic planting media, loose and providing sufficient nutrients for plants found in the community environment

Novel Sub-grade Soil Improvement using Marble Dust and Rice Husk Ash: Prediction and Validation via Machine Learning Models

Novel Sub-grade Soil Improvement using Marble Dust and Rice Husk Ash: Prediction and Validation via Machine Learning Models

Experimental study on dynamic mechanical properties of hybrid fiber reinforced concrete at different temperatures

This paper quantitatively explores the regulatory effects of rice husk ash content, polypropylene fiber, and steel fiber volume fractions on the mechanical properties of hybrid Fiber reinforced concrete (HFRC) through a series of orthogonal design experiments. Using the Split Hopkinson Pressure Bar (SHPB) technique, the dynamic mechanical behavior of HFRC and ordinary concrete (OC) under various temperature gradients was examined, revealing the interactive influence mechanisms of temperature and strain rate on the dynamic mechanical properties of HFRC. The results indicate that the steel fiber content predominantly determines the compressive and tensile strengths of HFRC, while polypropylene fiber plays a crucial role in enhancing the tensile performance of HFRC. Optimal mechanical performance was achieved with 12% rice husk ash content, 0.1% polypropylene fiber volume fraction, and 0.5% steel fiber volume fraction, resulting in a 10.41% and 50.22% increase in compressive and tensile strengths, respectively. Under high-temperature conditions, HFRC exhibited significantly superior mechanical properties compared to OC, particularly in terms of dynamic response characteristics. As the temperature increased, the dynamic compressive strength, dynamic increase factor, and peak toughness of HFRC initially decreased and then increased, consistently maintaining levels higher than those of OC. This research provides a solid scientific basis for enhancing the disaster resistance of concrete structures in fire environments.

Agro-Waste Driven Green Synthesis and Characterization of Silver Nanoparticles Using Oryza sativa and Spent Coffea robusta

Research background. Agricultural waste was utilised to synthesise silver nanoparticles (AgNPs) via green synthesis, a sustainable alternative to traditional synthesis techniques that use hazardous chemicals and extensive processing. AgNPs were produced from spent coffee grounds, Coffea robusta, and rice husks, Oryza sativa, both prevalent agricultural wastes rich in bioactive substances including proteins, flavonoids, and phenolic acids, which act as natural reducing agents. Experimental approach. The formation and stability of AgNPs were confirmed using various methods. UV-Vis spectroscopy displayed surface plasmon resonance (SPR) peaks at 450 nm, signifying AgNP formation, while FTIR identified functional groups responsible for the bio-reduction and stabilisation of nanoparticles. XRD confirmed the crystalline, face-centred cubic structure. Zeta potential analysis showed stable dispersion, and particle size analysis highlighted consistent sizing. The antibacterial activity of AgNPs was assessed by testing their effectiveness against both gram-positive and gram-negative bacteria. Results and conclusions. Synthesis of AgNPs from spent coffee grounds and rice husks rich in biomolecules served as effective reducing and stabilizing agents. FTIR analysis identified functional groups involved in nanoparticle reduction and stabilization, while XRD verified their face-centred cubic (FCC) crystalline structure. Zeta potential measurements demonstrated stable dispersions, with particle sizes of approximately 187 nm spent coffee ground-AgNPs and 198 nm for rice husk-AgNPs. The synthesized AgNPs also exhibited strong antibacterial activity against both gram-positive and gram-negative bacteria. Novelty and scientific contribution. The green synthesis approach for AgNPs utilising agriculture waste such as spent coffee grounds and rice husks as natural reducing and stabilizing agents. This study highlights the innovative use of biomolecule-rich materials, producing stable AgNPs with strong antibacterial properties, and establishes a sustainable foundation for advancing nanotechnology applications.

Comprehensive characterization of Ecuadorian lignocellulosic biomass in terms of their candidacy for bioenergy purposes

Abstract Bioenergy underpins a wide variety of technologies to transform biomass into fuels, chemicals, and biomaterials through sustainable routes. Significant advances in biomass valorization towards understanding their potential for energy production have occurred over the last decades. However, the complexity gap to utilize the entire lignocellulosic biomass simultaneously, remains overwhelming largely, which severely impedes the development of a bioresources-based economy. The exploration of complex characteristics of lignocellulosic biomass fractions, including both chemical and structural aspects, is imperative. In the present study, 17 Ecuadorian lignocellulosic biomass were prepared and extensively characterized to understand their compositional and structural characteristics through analytical approaches such as carbon–hydrogen–nitrogen–sulfur analysis, bomb calorimetric, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy. Regarding volatile matter content, all biomass sources presented remarkable levels ranging from 65.01 to 86.13%. Ash content was found in a range of 5.67 to 17.53%. Results show that the banana pseudostem displayed the highest cellulose content (59.56 %). The lowest cellulose content was recorded in oil palm kernel shell (9.55%). The largest calorific value was found in sugarcane bagasse (22.62 MJ kg-1), while the minimum (12.50 MJ kg-1) was found in banana rachis. The highest crystallinity index was observed in rice husk followed by rice straw and plantain pseudostem. These results provide scientific guidance of the potential of collected biomasses as promising candidates for bioenergy production and related industrial applications.

Mechanisms of Cu2+ Immobilization Using Carbonyl Iron Powder–Biochar Composites for Remediating Acidic Soils from Copper Sulfide Mining Areas

Soil heavy metal contamination poses critical challenges to ecological sustainability in mining regions, particularly in acidic soils from copper sulfide mines. This study developed a sustainable remediation strategy using a carbonyl iron powder–biochar composite (CIP@BC) derived from agricultural waste (rice husk) and industrial byproducts. The composite was synthesized through an energy-efficient mechanical grinding method at a 10:1 mass ratio of biochar to carbonyl iron powder, aligning with circular economy principles. Material characterization revealed CIP particles uniformly embedded within biochar’s porous structure, synergistically enhancing surface functionality and redox activity. CIP@BC demonstrated exceptional Cu2+ immobilization capacity (910.5 mg·g−1), achieved through chemisorption and monolayer adsorption mechanisms. Notably, the remediation process concurrently improved key soil health parameters. Soil incubation trials demonstrated that 6% CIP@BC application elevated soil pH from 4.27 to 6.19, reduced total Cu content by 29.43%, and decreased DTPA-extractable Cu by 67.26%. This treatment effectively transformed Cu speciation from bioavailable to residual fractions. Concurrent improvements in electrical conductivity (EC), cation exchange capacity (CEC), soil organic matter (OM), and soil water content (SWC) collectively highlighted the composite’s multifunctional remediation potential. This study bridges environmental remediation with sustainable land management through an innovative waste-to-resource approach that remediates acidic mine soils. The dual functionality of CIP@BC in contaminant immobilization and soil quality restoration provides a scalable solution.

The performance of hybrid materials for the biodegradation of dichloromethane using Pseudomonas aeruginosa, coconut shell, rice husk, and metal organic framework.

The industrial effluents containing volatile organic compounds manipulate the purity of the environment. Dichloromethane emerges as the toxic malodor that causes carcinogenicity, mutagenicity and teratogenicity. The aim of the present study was to find out the potency of hybrid materials for the removal of dichloromethane using raw rice husk, coconut shell, metal organic framework and Pseudomonas aeruginosa. The identification of bacteria was done by biochemical methods and 16SrRNA test. The characterization of adsorbents was done using sophisticated fourier transform infrared, field emission scanning electron microscopy and x-ray diffraction technique. The particle size of adsorbents was calculated using the Scherrer equation. The analysis of the final concentration of dichloromethane in hybrid materials was done by gas chromatography-flame ionization detector. The removal percentage obtained using Pse + RRH, Pse + CSAC, Pse + MOF (UiO-66(Zr), Pse + RRH + CSAC, Pse + RRH + CSAC + MOF (UiO-66)(Zr) was 96.87%, 99.80%, 97.63%, 97.35%, 98.08%, respectively with 50mg/L of dichloromethane concentration. On the other hand, the removal percentage obtained using Pse + RRH, Pse + CSAC, Pse + MOF (UiO-66(Zr), Pse + RRH + CSAC, Pse + RRH + CSAC + MOF (UiO-66)(Zr) was 96.5%, 99.5,% 96.5%, 97.0%, 98.09, with 200mg/L of dichloromethane concentration. The removal percentage obtained using alone Pseudomonas aeruginosa with 50mg/L and 200mg/L of dichloromethane was 93.78% and 92.33% respectively. The maximum removal percentage was achieved by a hybrid material using Pseudomonas aeruginosa and coconut shell.

Diseminasi Briket Ramah Lingkungan sebagai Solusi dari Limbah Sekam Padi

The majority of people in Balongsari Village, Megaluh District, Jombang Regency work as farmers. The rice harvest every harvest period produces very abundant agricultural waste. One of these agricultural wastes is rice husks. A common habit of farmers in this area is burning rice husks. This has an impact on environmental pollution, which comes from the smoke from burning rice husks. The purpose of this activity is to provide a solution for managing rice husk waste so that it is more useful. Proper processing of agricultural waste, namely rice husks, will produce various processed products, namely alternative fuel sources to replace kerosene or LPG gas or firewood. The objects of community service activities are youth of Karang Taruna and farmer groups. The results of this service activity are (1) Obtaining alternatives to replace fuel oil, (2) Reducing rice husk waste, (3) Providing added value to rice husks so that they become more useful. During the activity, participants were very enthusiastic about participating in the event from beginning to end, as evidenced by the results of the questionnaire after the activity, namely 90% of participants were very enthusiastic.

Performance of agro-waste sugarcane bagasse ash in concrete under durability tests

The concrete industry frequently uses waste material known as sugarcane bagasse ash (SCBA) because of its excellent pozzolanic qualities. Cement is a rare and essential component of concrete construction that is in high demand all over the world. Meanwhile, carbon dioxide (CO2) is generated widely due to the infrastructure development in the construction sector. To lower CO2 emissions, concrete must contain less cement. Replacing some of the cement in concrete with agricultural wastes such as rice husks and sugar cane bagasse significantly reduces the material’s environmental impact. Therefore, this study focuses on the durability performance of concrete with sugarcane bagasse ash as a partial replacement for cement at 5%, 10% and 15% by weight. The durability of the concrete was studied through the electrical resistivity test, rapid chloride infiltration test, initial surface absorption test, as well as carbonation after 7 days and 28 days. It was observed that the SCBA is a pozzolanic substance with good binder qualities that may be utilised in concrete mixtures to partially replace costly cement.

Study on the mechanical properties of rice husk ash-based geopolymer-regenerated mortar reinforced by polyimide fiber and carbon fiber after high-temperature exposure

Study on the mechanical properties of rice husk ash-based geopolymer-regenerated mortar reinforced by polyimide fiber and carbon fiber after high-temperature exposure

Performance of agro-waste cementitious material in the high-strength reinforced concrete applications: a review

The rapid urbanisation and rising demand for high-performance concrete (HPC) have driven research towards sustainable, environmentally friendly, and cost-effective alternatives to traditional cement. Agricultural waste cementitious materials, such as fly ash, rice husk ash, and bagasse ash, have been used as cementitious material due to their pozzolanic properties. This review explores the feasibility of incorporating these agro-waste materials in high-strength reinforced concrete (HSRC) applications, focusing on their effects on the durability, sustainability and mechanical properties of concrete. Previous studies indicate that the partial replacement of cement (5–10%) with such waste materials can enhance the mechanical strength due to the additional calcium silicate hydrate (C-S-H) gels, which improve its microstructural densification. Moreover, this material’s fineness improves the durability by reducing its permeability, enhancing the sulphate and chloride resistance, and mitigating the alkali-silica reaction (ASR). Utilising agricultural waste also significantly lowers the related carbon emissions, minimises industrial waste disposal, and promotes sustainable construction practices. However, challenges such as the variability of the chemical composition, proper processing (grinding and calcination), and standardisation issues must be addressed for broader implementation. This review provides a comprehensive analysis of agro-waste cementitious materials in HSRC, highlighting their benefits and limitations while emphasising the need for further research to optimise their performance and reliability in structural applications.

Teredinibacter turnerae secretome highlights key enzymes for plant cell wall degradation

Carbohydrate-active enzymes (CAZymes) are crucial in the sustainable production of fuels and raw materials from recalcitrant plant cell wall polysaccharides (PCWPs). Teredinibacter turnerae, a symbiont of wood-boring shipworms, is a prolific degrader of plant biomass, largely due to the extensive CAZyme repertoire in its genome. To identify key enzymes involved in PCWP utilization, we analyzed the secretomes of T. turnerae E7MBN strain grown on sucrose, major PCWPs (cellulose, xylan, and pectin), and residual rice hull biomass using mass spectrometry-based proteomics. Our results show that T. turnerae E7MBN exhibits minimal enzyme secretion across various carbon sources, where secretomes mostly display similar functional profiles. Enzymatic complexity varied with the substrate, with cellulose-grown secretome being the most complex and comprising the majority of secreted CAZymes. These CAZymes contain domains that primarily target cellulose, hemicellulose, or pectin, notably including multicatalytic enzymes that are consistently found in the secretome and are likely central to biomass degradation. In contrast, the xylan-grown secretome displayed a more specific response, secreting only a single bifunctional hemicellulase, E7_MBN_00081, also identified as a core component of the bacteria’s enzymatic repertoire. Meanwhile, the pectin-grown secretome consists of multiple tonB-dependent receptors, which, along with isomerases, are considered common secretome constituents. E7MBN also demonstrated the capability to utilize rice hull biomass, predominantly secreting proteins previously identified under cellulose. Protein-protein interaction network analysis further revealed functional associations between CAZymes and several uncharacterized proteins, which include CBM-containing redox enzymes and a putative xylan-acting protein, thus offering new insights into their potential role in lignocellulose degradation. Overall, our work contributes to our understanding of enzymatic strategies employed by T. turnerae for PCWP deconstruction and highlights its potential as a promising source of CAZymes for sustainable biomass conversion.Graphical abstract

Biosynthesis of Nanozeolite Impetus and Their Solicitation in Friedel-Crafts Alkylation and Acylation Reaction

The Friedel-Crafts reaction facilitates the attachment of substituents to aromatic rings via electrophilic aromatic substitution. Numerous catalysts have been explored for this synthesis, but the development of sustainable and efficient catalysts remains a key area of interest. Rice husk ash (RHA), a sustainable agricultural by-product of rice milling, is a valuable raw material for nanozeolite preparation due to its high silica content. Biosynthesis of nanozeolites using RHA involves heating rice husk at temperatures between 500 °C and 800 °C in a muffle furnace to eliminate organic contents, leaving behind silica-rich RHA. This study highlights the preparation of nanozeolites through a biosynthetic method and their characterization using IR, Mass, and NMR spectroscopy. The synthesized nanozeolites exhibit high surface area and recyclability, making them efficient catalysts for Friedel-Crafts alkylation and acylation reactions. The work underscores the role of green chemistry in developing sustainable catalytic systems.

Valorisation of rice husk ash as an activator in the preparation of alkali-activated cements based on electric arc furnace slag

Rice husk ash (RHA) was employed as a silica source to produce an alternative sodium silicate solution through the dissolution of varying quantities of RHA in an 8 M NaOH solution. The solution was employed in the production of alkali-activated cements based on electric arc furnace slag (EAFS). Solutions were prepared with varying activator modules (Ms, molar ratio SiO₂/Na₂O) of 0.60, 0.85, 1.00, and 1.15. As control samples, slags were activated with 8 M NaOH (Ms = 0.0) and with 8 M NaOH in conjunction with commercial sodium silicate (Ms = 1.0). Mechanical, physical, mineralogical (XRD, FTIR), and microstructural (SEM/EDS) tests were conducted to characterize the obtained pastes. The results of the FTIR and SEM analyses indicated that the SiO₂/Na₂O ratio exerts a significant influence on the reaction products formed. At Ms values higher than 0.85, the predominant reaction product was observed to be a more cross-linked hybrid gel (N,C)-A-S-H. Lower modules resulted in the predominant formation of C-A-S-H gel and a more porous structure with lower mechanical properties. Pastes activated with the alternative RHA solution and Ms = 1.0 exhibited a composition, microstructure, and strength that was similar to or superior to those prepared with conventional commercial activators.

Evaluating The Impact of Partially Replacing Cement with Rice Husk Ash and Metakaolin on the Rheological Behavior and Mechanical Strength of Self-Compacting Concrete

Although self-compacting concrete (SCC) is a unique concrete that can spread and fill formwork without the need for mechanical vibration, researchers are now using supplementary cementitious materials (SCMs) to partially replace cement in SCC production because of the high cement content required to produce SCC. Based on the aforementioned, the rheological and strength properties of SCC admixed with Rice Husk Ash (RHA) and Metakaolin (MK) at 0.4, 0.5, and 0.6 water-cement (W/C) ratios was investigated. The materials used in the study are cement, water, fine aggregate, coarse aggregate, Metakaolin (MK), Rice Husk Ash (RHA), and superplasticizer. Mechanical tests were conducted on the cement, fine and coarse aggregate, RHA and MK. SCC was produced by partially replacing cement with RHA and MK separately and in blend at 2.5, 5, 7.5, 10, 12.5, and 15 %, yielding a total of four hundred and twenty (420) concrete cubes, and all cubes were cured for 3, 7, 14, 28, 56, 90, and 120 days before crushing. The Marsh cone test was adopted to determine the optimum superplasticizer (SP) content, while the rheological tests conducted on the fresh SCC are the slump test, V-funnel test, L- Box test, and J-Ring test, whereas the mechanical tests conducted on the hardened SCC are the compressive, flexural, and split tensile strength test. Results from the findings showed that the rheological properties of SCC admixed with RHA and MK separately and in blend at 0.9 % superplasticizer content, exhibits adequate workability and flowability at 0.4, 0.5, and 0.6 water-cement ratios. Also, at 0.4, 0.5, and 0.6 W/C ratios, the maximum compressive strength of SCC was achieved at 5- 10 % for RHA, and 5-15 % for MK, and was achieved at 10 % when MK and RHA was used in blend. More also, the maximum 28 days split tensile strength was achieved at 7.5-10 % for RHA, and 10 % for MK, and was achieved at 10 % when MK and RHA blend replaced cement. Furthermore, the maximum 28 days flexural strength was achieved at 12.5-15 % for RHA, and 15 % for MK, and was achieved at 12.5 % when MK and RHA blend replaced cement. Hence it was concluded that the workable rheological, and maximum strength properties of SCC can be achieved when blend of RHA and MK replaces cement between 10 – 12.5 %.

Determination of Optimal Culture Medium Conditions for Mass Production of Beauveria bassiana Clone EF 46

The issue of food safety has become a major concern due to the use of chemical pesticides, which have deleterious effects on human health, the environment and biodiversity. Biological pest control, which uses entomopathogenic agents, is an alternative that is more respectful of the health of living beings and the environment. This study aimed to determine the optimal culture medium parameters for the indigenous strain Beauveria bassiana clone EF 46, aiming to facilitate the development of biopesticides. Potato Dextrose Agar (PDA) medium was used to evaluate the influence of physical (temperature, photoperiod, pH) and nutritional (carbon and nitrogen sources) parameters on the sporulation of B. bassiana. Concurrently, rice husk supplemented with different types of starch flours was used to determine the best substrate for solid-state fermentation. This study revealed that the optimal physical parameters for sporulation were: a temperature of 25 °C, an alkaline medium with a pH of 9, and a 12h: 12h light/dark photoperiod. Regarding nutritional parameters, fulvic acid and baker's yeast were identified as the best carbon and nitrogen sources, respectively. Concerning the culture substrate for solid-state fermentation, yellow corn flour proved to be the best supplement for rice husk.

Experimental Investigation on Surface Roughness, Hardness and Tensile Strength of Rice Husk (RH) as a Filler for Formulation of Polethylene-Terephthalate Glycol (PETG) 3D Filament Title of Manuscript

Three-dimensional (3D) printing is one of the most widely used additive manufacturing techniques which is able to produce physical objects from geometrical illustrations using the applicable material. Polyethylene Terephthalate Glycol (PETG) is an additively manufacturable polymer material which is gaining attention for its excellent mechanical and chemical properties. However, it has mechanical limitations that restrict its broader use in 3D printing. Thus, reinforcing with natural fibers like rice husk (RH), an agricultural byproduct, show potentials in improving polymer composites. Nonetheless, their potential when blended with PETG for 3D printing applications are insufficiently explored, emphasizing the need for a systematic investigation. Henceforth, the present work seeks to formulate a 3D printing filament using PETG with RH powder that aims to enhance the mechanical properties of 3D-printed filament. This work also finds the mechanical interactions between varying ratios of PETG and RH to determine optimal composition for enhanced properties focusing on surface roughness, hardness and tensile strength. The PETG/RH filaments were produced from crushed raw RH and pellet form PETG. The varying ratios of RH at 0%, 2%, 6%, and 10% were blended with PETG into an extruder. The roughness of the surface was evaluated by direct imaging. The smoother filament was observed when loading up to 6 wt.% RH. In hardness and tensile strength test, the hardness and strength increased with loading up to 6 wt.% RH. This paper presents the results of optimal ratios of PETG/RH at 6 wt.%, as it improves surface roughness, hardness and tensile strength of PETG. This study adopted the same stance and claimed that the fiber’s tensile strength and hardness increased along with its weight until an optimal level. However, further increase in the sample leads to a stronger fiber-fiber bond which it weakens the interfacial bond of fiber-matrix. Weak interfacial bond of fiber-matrix resulting in inefficient load transfer, hence decrease the sample’s mechanical properties.