Performance Evaluation of Novel Eco-Materials Composed of Millet Husks, Rice Husks, and Polystyrene

Managing agricultural waste and expanded polystyrene (EPS) poses significant environmental and economic challenges. This study aims to create composites from millet husks, rice husks, and recycled EPS, using a manufacturing method that involves dissolving the polystyrene in a solvent followed by cold pressing. Various particle sizes and two binder dosages were investigated to assess their influence on the physico-mechanical properties of the composites. The mechanical properties obtained range from 2.54 to 4.47 MPa for the Modulus of Rupture (MOR) and from 686 to 1400 MPa for the Modulus of Elasticity in Bending (MOE). The results indicate that these composites have potential for applications in the construction sector, particularly for wood structures and interior decoration. Moreover, surface treatments could enhance their durability and mechanical properties. This research contributes to the valorization of agricultural and plastic waste as eco-friendly and economical construction materials.

Study of Rice Husks and Expanded Polystyrene Composites for Construction Applications

In the current context of environmental challenges, this study focuses on developing innovative and eco-friendly composites using rice husk and recycled expanded polystyrene. This dual-responsibility approach valorizes a by-product like rice husk, often considered waste, and reuses polystyrene, a plastic waste, thereby contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene into a solvent to create a binder, which is then mixed with rice husk and cold-compacted into composite materials. The study examines the impact of two particle sizes (fine and coarse) and different proportions of recycled polystyrene binder. The results show significant variations in the mechanical characteristics of the composites, with Modulus of Rupture (MOR) values varying from 2.41 to 3.47 MPa, Modulus of Elasticity (MOE) ranging from 223.41 to 1497.2 MPa, and Stiffness Coefficient (K) from 5.04 to 33.96 N/mm. These characteristics demonstrate that these composites are appropriate for various construction applications, including interior decoration, panel claddings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only highlights the recycling of agricultural and plastic waste but also provides a localized approach to addressing global climate change challenges through the adoption of sustainable building materials.

Antioxidant Activities and Characterization of Polyphenols from Selected Northern Thai Rice Husks: Relation with Seed Attributes

Rice production generates a significant amount of agricultural waste. This study aimed to give results related to the existence of antioxidant phenols in agricultural waste of selected Northern Thai rice varieties. The antioxidant activities, contents of total flavonoids and phenolic compounds in the ethanolic rice husk extract were evaluated. The highest antioxidant activities were found in the variety PES1CMU, with 2,2’-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid and 2,2-diphenyl-1-picrylhydrazyl as 679.66 and 4.16 mmol/(L·g) trolox equivalent, respectively, ferric reducing antioxidant power as 0.87 mmol/(L·g) Fe2+, total phenolic content as 29.90 mmol/(L·g) gallic acid and total flavonoid content as 12.16 mg/g catechin equivalent. Polyphenol compounds were identified mainly by standard polyphenols using the liquid chromatography mass spectrometry, with the highest contents of phytic acid, o-coumaric acid, naringin and kaempferol. The non-glutenous and wetland ecotypes of rice husk samples were the richest in antioxidant activities and polyphenol contents characterized by using principal component analysis. The glutenous rice husk contained higher antioxidant activities than the rest. Interestingly, quercetin is a significant phenolic compound that positively correlated with the overall antioxidant activities of rice husk. This finding will be relevant for future application of rice husk antioxidant components in the production of functional ingredients as well as for the food and pharmaceutical industries.

Controllable conversion of rice husks to Si/C and SiC/C composites in molten salts

Direct conversion of biomass to functional materials is an ideal solution to relieve challenges in environmental and energy sustainability.We herein demonstrate a molten salt thermoelectrolysis of rice husks(RHs)mainly consisting of organic mass and biosilica to achieve high-efficiency and upgraded utilization of both Si and C in RHs.By coupling pyrolysis of organic mass with electrochemical reduction of silica in molten salts,the thermoelectrolysis of RHs in molten CaCl_(2)-NaCl at 800℃ refines the RHs and acidleached RHs to SiC nanowire/C(SiC-NW/C)and Si nanoparticle/C(Si-NP/C),respectively.The present study highlights the molten salt thermoelectrolysis for reclamation of biomass wastes in an affordable and controllable manner.

Adsorption Property of Ni-TiO_2-SiO_2 Synthesized by Using Rice Husks as Silicon Source and Template to Gentian Violet

[Objective] The aim was to study the adsorption property of adsorbent Ni-TiO2-SiO2 synthesized by using rice husks as silicon source and template to gentian violet.[Method] The renewable dye adsorbent Ni-TiO2-SiO2 was synthesized by using rice husks as raw material,and the adsorption property of Ni-TiO2-SiO2 to gentian violet was studied.[Result] The adsorption rate of Ni-TiO2-SiO2 to gentian violet reached about 90% after 1 h.In 100 ml gentian violet solution with concentration of 25 mg/L and pH=8,Ni-TiO2-SiO2 with dosage of 0.07 g had the best adsorption effect.More importantly,Ni-TiO2-SiO2 as adsorbent could be used repeatedly,and couldn’t lead to secondary pollution due to leaking.[Conclusion] The study could provide references for practical engineering application.

Complexes of Rice Husks Ash for Oxidation of Cyclohexene

The cheap raw rice husks and the products of their thermal degradation WRHA （white rice husk ash） and BRHA （black rice husk ash）, after vigorously grounding and mixing, can successfully be used as a catalyst support to replace the existing expensive ones. The aim of the present research is to prepare new metal-immobilized complexes based on rice husks and to study their catalytic activity in the oxidation of cyclohexene with tert-butylhydroperoxide. The corresponding metal complexes were obtained by interaction of RRH （raw rice husks） or thermally treated WRHA in air atmosphere. The complexes were obtained from aqueous solutions of various salts such as FeCl2.4H2O, COCl2.6H2O, VOSO4.5H2O and Na2MoO4.2H2O at room temperature. The rice husks-supported metal complexes were identified by infrared spectroscopy. The structure of the iron-containing polymeric materials was evaluated by Mossbauer spectroscopy. The catalytic activity of the molybdenum-containing complex catalyst in the principal epoxidation reaction was higher than that of the vanadium-containing one, whereas, the opposite order of activities was found for the side reaction of allylic hydroxylation of cyclohexene. Under selected reaction conditions, the yields of the principal reaction products cyclohexene oxide （1,2-epoxycyclohexane） and 2-cyclohexene-1-ol were 36.4% and 22.7%, respectively.

Global Kinetics of Rice Husks in an Inert Atmosphere: A Case Study of Kyela, Tanzania

A thermogravimetric analyzer was used to conduct a kinetic investigation of rice husk pyrolysis. The major goal is to investigate the reaction kinetics of rice husk at various heating rates in an inert 99.5 percent nitrogen atmosphere. Kinetics’ importance can be explained by the fact that it provides evidence for chemical process mechanisms. Understanding reaction mechanisms can help you figure out the best way to get a reaction to happen. Furthermore, it is of fundamental scientific interest. The samples were heated at different heating rates of 5, 10, 20, and 40 K min-1 from ambient temperature to 973 K. The thermal degradation characteristics and the kinetic parameter were determined. The values show that the activation energy (Ea) and pre-exponential factor (A) vary with heating rates and temperature.

A Study on the Combustion Characteristics and Greenhouse Gas Emissions from Rice Husks with Varied Heat Fluxes

This paper analyzes the combustion characteristics and greenhouse gas emissions from varied heat fluxes with rice husks. In general, rice husks burnt outdoors at a lower temperature range of 300-400 ℃, which cannot assure complete combustion, thus generating a large volume of toxic air pollutants. A heat flux of 40 kW/m^2, with a cone calorimeter, is the equivalent to the 700 ℃ of an incinerator. The test result shows that the mass reduction rate of the sample at this or at a higher temperature condition was 99.5% or higher, meaning that the sample was almost completely combusted. In this study using rice husks, the amount of carbon dioxide, which is a greenhouse gas, discharged were 1.57-3.61 kg/kg. This is as high as 10 times, than produced in other studies. When the rice husks are burnt outdoors, they are not completely combusted as the combustion temperature remains low, and the rice husk residuals are continuously being combusted in a smoldering phase which creates a large volume of carbon dioxide and carbon monoxide. Therefore, it is recommended to burn rice husks at 700 ℃ or higher to minimize the carbon dioxide and carbon monoxide emissions.

Rice Husk at a Glance:From Agro-Industrial to Modern Applications

Excessive waste production has led to the concept of a circular bioeconomy to deliver valuable by-products and improve environmental sustainability.The annual worldwide rice production accounts for more than 750 million tons of grain and 150 million tons of husk.Rice husk(RH)contains valuable biomaterials with extensive applications in various fields.The proportions of each component depend primarily on rice genotype,soil chemistry,and climatic conditions.RH and its derivatives,including ash,biochar,hydrochar,and activated carbon have been placed foreground of applications in agriculture and other industries.While the investigation on RH’s compositions,microstructures,and by-products has been done copiously,owing to its unique features,it is still an open-ended area with enormous scope for innovation,research,and technology.Here,we reviewed the latest applications of RH and its derivatives,including fuel and other energy resources,construction materials,pharmacy,medicine,and nanobiotechnology to keep this versatile biomaterial in the spotlight.

Fabrication of PMMA nanocomposite biomaterials reinforced by cellulose nanocrystals extracted from rice husk for dental applications

The primary objective of global studies is to develop the properties and durability of polymers for various applications.When it comes to dental disability,denture base materials must have sufficient mechanical and tribological performance in order to withstand the forces experienced in the mouth.This work aims to investigate the effects of the addition of low content of cellulose nanocrystals(CNC)on the mechanical and tribological performance of the polymethyl methacrylate(PMMA)nanocomposites.Different weight percent of CNC(0,0.2,0.4,0.6,and 0.8 wt%)were added to the PMMA matrix followed by ball milling to evenly distribute the nanoparticles reinforced phase in the matrix phase.The findings emphasize the significant impact of CNC integration on the performance of PMMA nanocomposites.By increasing the content of the CNC nanoparticles,the mechanical properties of PMMA were improved.In addition,the tribological outcomes demonstrated a significant reduction in the friction coefficient besides an enhancement in the wear resistance as the weight percentage of nanoparticles increased.The surface of the worn samples was investigated by utilizing SEM to identify the wear mechanisms corresponding to the different compositions.In addition,a finite elment model(FEM)was developed to ascertain the thickness of the worn layer and the generated stressed on the surfaces of the nanocomposite throughout the friction process.

Investigation of the Fermentation Mode of Rice Husk for the Stabilization of Earth Plaster

Despite its low resistance to humidity, adobe remains the most widely used material for housing construction, particularly in developing countries. The present study aims to assess different modes of use of fermented RH and to evaluate their influence on the behavior of raw earth for application in plaster. The influences of two types of RH are evaluated: granular rice husk (RHg) and powdered RH (RHp). The clay mainly consists of clay (40%), silt (22%), and sand (38.4%), with a small proportion of gravel (0.24%). Its liquidity limit is 40% and the plasticity index is 26.5%. The mixtures were designed using earth and each of the two rice husks at the volumetric content of 10%, 15% and 20% of the total volume mixed with water 36.5%, 38.5% and 40.3% and fermented for three weeks. Each fermented mixture was added to the soil to form the paste, and 40 × 40 × 160 mm3 test speciments were made for characterization. The results generally show an improvement in the physico-mechanical properties and water resistance of the mortars containing fermented RH, with an optimal content between 10% and 15%. The powdered RH improved the performance of the mortar better than granular RH.

The Influence of Rice Husk Ash on Mechanical Properties of the Mortar and Concrete: A Critical Review

Increasing the population and infrastructure in both emerging and developed countries requires a considerable amount of cement, which significantly affects the environment. The primary materials of concrete (‘cement’) production emit a large quantity of CO2 into the environment. Also, the cost of conventional building materials like cement gives motivation to find geopolymer waste materials for concrete. To reduce harmful effects on the environment and cost of traditional concrete substance, alternative waste materials like rice husk ash (RHA), ground granulated blast-furnace (GGBS), fly ash (FA), and metakaolin (MK) can be used due to their pozzolanic behavior. RHA waste material with a high silica concentration obtained from burning rice husks can possibly be used as a supplementary cementitious material (SCM) in the manufacturing of concrete, and its strong pozzolanic properties can contribute to the strength and impermeability of concrete. This review paper highlights a summary of the positive effect of using RHA as a partial substitute for cement in building construction, as well as its optimal inclusion of enhanced mechanical properties like compressive strength, flexural strength, and split tensile strength of mortar and concrete.

Lignocellulose aerogel and amorphous silica nanoparticles from rice husks

Rice Husks(RHs)are one of the most abundant sources of biomass in the world due to rice consumption.Lignocellulose and silica are two of the main components of RHs,which allow RHs to be applied in different areas.Lignocellulose can be partially dissolved in 1-butyl-3-methylimidazolium chloride(BMIMCl),which is a simple way of competing with the traditional extraction methods that suffer from high chemical consumption.A lignocellulose freeze gel is obtained via a cyclic liquid nitrogen freeze-thaw(NFT)process.Multi-functional self-assembled lignocellulose aerogel is obtained after CO_(2) supercritical drying.Based on the aerogel’s special properties,two routes are developed for practical applications.On one hand,the aerogel is coated to exhibit a superhydrophobic property that can be applied as an absorbent for oil spills.On the other hand,a carbon aerogel is synthesized via a pyrolysis process,resulting in a porous amorphous carbon.The residue after partially dissolving lignocellulose in BMIMCl is further calcined to obtain amorphous silica nanoparticles,achieving a comprehensive application of RHs.

Reinforcement of Thermoplastic Starch Films with Cellulose Fibres Obtained from Rice and Coffee Husks

Cellulosic fibres from coffee(CF)and rice(RF)husks have been obtained applying chemical treatments and characterized as to their microstructure and thermal behaviour.These materials have been incorporated into glycerol plasticised thermoplastic starch(TPS)films obtained by melt blending and compression moulding at 1 wt%,5 wt%and 10 wt%.Microstructure,thermal behaviour and optical,tensile and barrier properties of the composites were analysed.Both kinds of micro-fibres improve the film stiffness while reduced the film stretchability.However,CF better maintained the film ductility at 1 and 5 wt%.A network of fine oriented fibres was observed on the surface of the films,while internal fibres exhibited a good adherence to the polymer network.The water vapour permeability of TPS films was not reduced in composites,although oxygen permeability was lowered by about 17%.Film transparency decreased by fibre addition in the UVVIS range.Thermal stability of composites was slightly higher than net TPS films.

Mechanical properties of a clay soil reinforced with rice husk under drained and undrained conditions

Fiber-reinforced soils have been increasingly used in geotechnical engineering.Over the years,research has sought to understand and investigate the influences of fibers as reinforcement in soilefiber mixtures.This study assessed the behavior of clayey soil in the city of Curitiba(Paraná,Brazil),adding rice husk fiber(RHF),an industrial waste from Cooperativa Agroindustrial in Alegrete(Rio Grande do Sul,Brazil).To evaluate the effect of the presence of natural RHF on the mechanical behavior of compacted soil,aspects such as the influence of fiber content and the drained and undrained behaviors of the soil were evaluated through unconfined triaxial compression tests.The following tests were realized:soil granulometry,specific mass of solids and Atterberg limits.Specimens were produced in quadruplicate for the soil and mixtures using the RHF contents of 0.5%,0.75%,1%and 1.5%to determine the unconfined compressive strength(UCS).Triaxial tests were realized on a pure soil specimen and the specimens with 1%RHF under confining pressures of 50 kPa,100 kPa,200 kPa and 400 kPa.The interactions at the interface between husk surface and soil were analyzed using scanning electron microscopy(SEM).In UCS tests,specimens with RHF percentages of 1%and 1.5%presented the highest results,with an increment of 36%compared to the soil without RHF.The results of the consolidated drained triaxial compression tests show that in terms of effective stress,there was a small difference in the strength of the compacted pure soil and soil with the addition of RHF.For the undrained tests,the strength increased with the inclusion of husk,with a reduction of 50%in cohesion and an increment of 22%in friction angle for specimens containing RHF compared to the soil without RHF additions.

Effectiveness of Rice Husk and Sugarcane Bagasse Ashes Blended Cement in Improving Properties of Concrete

This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m3) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO2 which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)2 crystals, converting it into CaH2O4Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.

Characteristics of Rice Husk-Admixed Conplast SP 430 Concrete

Experimental work was mounted using 5.7 mL of the Conplast SP430 admixture and rice husk ash(RHA)at replacement levels of 0 to 50%at 10%intervals by wt.%of cement.It is on the performance of Conplast SP 430 admixture and its effects on concrete and concrete with rice husk ash.Concrete specimens were cast and cured for 3 to 90 days and subjected to slump and mechanical characteristics tests.Data generated from the experiments were analyzed and sensitivity analysis of the concrete mix was determined using the Minitab 18 Statistical Package.The results showed that CP with concrete improves the workability of the concrete and reduces water absorption.The reverse was the case when RHA was used with the admixture which may be an issue of compatibility.The statistical characteristics restrict good and within the specified limits.

Effectiveness of Rice Husk and Sugarcane Bagasse Ashes Blended Cement in Improving Properties of Concrete

This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m3) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO2 which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)2 crystals, converting it into CaH2O4Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.

Preparation and characteristic analysis of rice husk high boiling solvent lignin

Rice husk high boiling solvent lignin （RHL） was prepared by high boiling solvent method, and its characteristics was analyzed by using chemical composition analysis, infrared spectroscopy, and ^1H-NMR and ^13C-NMR spectroscopy. The optimum prepared condition was that the rice husk with 70%-90% aqueous solution of 1, 4-butanediol was mixed with autoclave, under a certain weight ratio of solid raw material and solvent, heated to 200-220℃ for 1.0-3.0 h, then water-insoluble RHL was separated from the liquor reaction mixture by water precipitation. Results suggested that the lower digestion temperature and concentration of 1,4-butanediol were both unfavorable for extracting lignin. Chemical weight-average molecular weight of RHL was 1939 g·mol^-1, and the residual polysaccharide content was 5.12%. The ^1H-NMR spectra of RHL showed the relative intensity ratio, aliphatic over aromatic methoxyl groups, situated at 3.5-3.8 and 3.8-4.0 ppm, respectively. The results from ^13C-NMR spectra showed that β-O-4 bond and β-5 carbon-carbon linkage were the major linkages between RHL units. The C9-formula of RHL was calculated by the experiment data.

Preparation and activity research of ecological nano mineral admixture from rice husk charcoal

The rice husk ash （ RHA） and silica （ Si02） nanoparticles are prepared from rice husk charcoal （RHC） by the methods of ventilated calcining and chemical precipitation, respectively, to remove the residual carbon which is harmful to cement composites. The structures and morphologies of these products are investigated by the Fourier transform infrared spectroscopy, X-ray diffraction, scanning/ transmission electron microscopy and N2 adsorption- desorption analyzer. The results show that the as-produced RHA and Si02 nanoparticles exist in amorphous phase without residual carbon, and exhibit porous structures with specific surface areas of 170.19 and 248. 67 m2 /g , respectively. The micro particles of RHA are aggregated by numerous loosely packed Si02 gel particles with the diameter of 50 to 100 nm. The Si02 nanoparticles are well dispersed with the average size of about 30 nm. Both the RHA and Si02 nanoparticles can significantly reduce the conductivity of saturated Ca（OH）2 solution and increase the early strength of the cement composites. They also exhibit high pozzolanic activity, indicating that they can be used as ecological nano mineral admixtures.