Rice Husk Particles Research Articles

Influence of Alkali Treatment and Nanoclay Content on the Properties of Rice Husk Filled Polyester Composites

The effect of alkali treatment and nanoclay addition on the mechanical properties and water absorption behavior of rice husk particle (RHP) reinforced unsaturated polyester (UP) composites was investigated. Thermogravimetric analysis (TGA) indicated that the alkali treatment removed most of the hemicellulose and impurities from the RHP with the tensile strength, tensile modulus, flexural strength and flexural modulus of the resulting composites being improved by alkali treatment. The results indicated that the 5% sodium hydroxide concentration had the optimum performance on mechanical strength and water absorption resistance. Furthermore, the influence of nanoclay addition (1, 3 and 5 wt%) on the properties of optimum alkali treated RHP-UP composites was investigated with the lowest content (1 wt%) of nanoclay showing the highest mechanical performance. However, further addition of nanoclay improved the moisture absorption resistance of the composites. Good interface bonding between the filler and matrix was observed from scanning electron micrographs for the optimum RHP alkali treated and nanoclay dispersed RHP-UP composites.

Preparation of porous titanium materials by powder sintering process and use of space holder technique

It is shown that an adapted powder sintering process can successfully prepare a 24.0%—35.5% porous titanium composite using 20 μm Ti powder and rice husk particles ranging in size between 250 μm and 600 μm. The phase constituents of the porous Ti composite samples were determined by X-ray diffraction (XRD) pattern sintered at 1250 °C. The generation of silicon in the form of a TiSi2 solid solution, injected into the substrate, illustrates the solid solution strengthening effect. The average grain size of the tested sample and the grain boundary area increase along with the silicon content. This indicates that silicon is dispersed within the green compact of Ti. As the distance from a hole becomes greater, the nanohardness increases until it reaches a maximum hardness of 3.5 GPa at approximately 1.5 mm. This may be due to the solid solution strengthening of SiO2. However, nanohardness is 3.3 GPa at a distance of approximately 0.5 mm from a hole's edge. The compressive strength is measured to be in the range of 440 — 938 MPa. The strain reaches 14.8% — 16.6% under compression testing. A large number of cleavage steps appear following a fracture. The observed fracture is a brittle fracture. Porous Ti composites with about 36% porosity have promising potential biomaterial applications, specifically related to bone implants and biological bearings.

Numerical study of hydrodynamics with surface heat transfer in a bubbling fluidized-bed reactor applied to fast pyrolysis of rice husk

The present study investigates the hydrodynamics and heat transfer phenomena that occur during the biomass fast pyrolysis process. A numerical approach that combines a two-dimensional Eulerian multi-fluid model and the kinetic theory of granular flow has been applied to simulate the gas-solid flow in a bubbling fluidized-bed reactor. In this study, rice husk and quartz sand with specified properties were used as biomass and inert material, respectively. Our model was first validated the feasibility using previous findings, then an extensive parametric study was conducted to determine the effects of the major variables, especially the size of rice husk particles, on the flow distribution and the heat transfer between the phases. The concept of standard deviation attributed to the dispersion of solid volume fraction was used to calculate the intensity of segregation. The simulated results indicated that the mixing of binary mixture was strongly affected by different sizes of rice husk particles. The heat transfer occurring inside the fluidized bed was described by the distribution of solids temperature, the variation of surface heat flux and heat transfer coefficient. Both heat transfer quantities were observed to be dominant in the dense bed regions as they strongly depend on the solids concentration in the fluidized bed. The increasing inlet gas velocity promoted the mixing of solid particles, thus resulted in the effective heat transfer from wall to particles and between the particles.

Pretreatment of rice husk in a pilot scale mill for further enzymatic hydrolysis

The effect of the mechanical activation of rice husk on the reactivity of its carbohydrates was studied. The activation was performed in a pilot-scale centrifugal roller mill. The mechanical treatment of the raw material led to an increase in its reactivity due to the increase in the specific surface area and amorphization of the crystalline regions of cellulose. The optimum process conditions of activation, leading to the preparation of a reactive product from rice husk, were determined: rotor frequency 1500 rpm, raw material feed rate 30 kg/h. The rice husk particles were ground to 45–50 μm under these conditions. These changes led to a sevenfold increase of the yield of low-molecular carbohydrates in the complete enzymatic hydrolysis of the material.

KARAKTERISTIK SIFAT MEKANIK KOMPOSIT SERAT BAMBU RESIN POLYESTER TAK JENUH DENGAN FILLER PARTIKEL SEKAM

This paper presents the effect of volume fraction of rice husks on the mechanical properties of bamboo fiber/unsaturated polyester composites. The composite specimens were made from bamboo fiber with fixed volume fraction of 40% and rice husk particle as filler with volume fractions varied 0%, 10%, 20% and 30%. Matrix used was unsaturated polyester resin. Bamboo fibers and rice husk were surface treated using alkali solution 4% (by weight) for 2 hours. The manufacturing process of composite was using hand layup method. The specimens were tested in tension, bending and in impact loading. The results show that the addition of rice husk particles up to volume fraction of 20% does not result in a decrease of tensile strength, but after a volume fraction of 20%, the tensile strength tends to decrease. In bending test, the rice husk volume fraction up to 20% increase the bending strength, but after that then it tends to decrease. However the bending modulus seems unaffected by the volume fraction of rice husk. Similar to the bending modulus, the impact strength is not significantly affected by the volume fraction of rice husk.

Investigation into the morphology, composition, structure and dry tribological behavior of rice husk ceramic particles

To expand the application of rice husk (RH) resource, this study developed carbon-based RH ceramic (RHC) particles using a common high-temperature carbonization method. The morphology, composition, and structure of the RHC particles were characterized with a series of modern analysis technologies and were then compared with those of the initial RH powder and carbonized RH (CRH) particles. The dry tribological behavior of RHC particle adobes (RHAs) was also investigated. Results showed the sheet-shaped morphology of the RHC particles. The graphitization degree of the RHC particles was lower than that of the CRH particles possibly because the phenolic resin (PR) filled the micro-pores of the RH particles, thereby prompting the formation of amorphous carbon in the RHC particles as a result of high-temperature carbonization. The appearance of a hydroxy function group (OH) on the surface of the RHC particles was ascribed to the decomposition of PR at 900°C. The friction coefficients and mass loss rates of the RHAs almost increased with the rise in load and velocity. In addition, the friction coefficients of the RHAs decreased at high load (5N) and velocity (0.261m/s) conditions. Such outcome indicated that the variation of contact area between steel ball and RHA at high load and velocity conditions resulted in the abrasive wear or catastrophic wear.

Mathematical modeling of the Ni(II) removal from aqueous solutions onto pre-treated rice husk in fixed-bed columns: a comparison

One of the efficient techniques for the removal of heavy metals from wastewater is adsorption. In this paper, the adsorption of Ni on a new porous carbonaceous adsorbent, pre-treated rice husk particles, was investigated in both batch and column experiments. The equilibrium isotherm was described well by both the Langmuir and Freundlich isotherm. The Langmuir constants, qm and b, were estimated to be 8.0 and 0.15 l/mg, respectively. Different conditions of flow rate, bed heights, and initial nickel concentrations were considered in the column experiments. It was observed that the adsorption capacity of the packed-bed column and the breakthrough time were increased with an increase in the bed height and a decrease in the flow rate and the influent Ni concentration. The traditional Bohart–Adams, Thomas, and Yoon–Nelson models in accompany with the mass transport model were used to describe the adsorption process in the columns. The experimental breakthrough curves were described satisfactorily by all the aforementioned continuous models. However, the predicted maximum adsorption capacity using Bohart–Adams and Thomas models was less than the one obtained from batch equilibrium experiments. Whereas, there was a good agreement between the batch equilibrium results and the continuous mass transport model regarding the maximum adsorption capacity, indicating the prediction of column performance using batch experiments.

Development of Rice Husk and Wood Dust Filler Based Polyester Resin Based Composites

Rice husk particles are one of the important agriculture waste products and wood dust particles are left to degrade of its own in many wood cutting industries. In the present work, polyester resin based composite laminates are manufactured by filling the mixed solution consisting of polyester resin with rice husk and wood dust fillers into a mould. The tensile test was conducted in a Universal testing machine as per ASTM: D638 standard. The flexural test was conducted in a Universal testing machine as per ASTM: D790 standard. The hardness test was conducted in a Shore hardness tester as per ASTM D2240 standard.

Statistical Analysis and Particle Swarm Based Optimization of Mechanical Properties of Rice Husk and Termite Mound Soil Impregnated Coir–Polyester Composites

The tensile, flexural and impact properties of rice husk and termite mound soil particle impregnated coir fiber–polyester composites were evaluated in order to introduce a new variety of bio particulated natural fiber–polymer composites. In this investigation the problem of matrix cracking which causes quick failure of natural fiber reinforced polymer composites was solved by matrix strengthening using inclusion of bio particulates. The interlaminar bond between constituents of composites was studied using SEM images. The effects of fiber length, particulate content and fiber content on mechanical properties of rice husk and termite mound soil impregnated coir–polyester composites were analyzed using correlation and regression analysis procedures. The statistical interference techniques namely Weibull distribution was used to validate the mechanical properties of the composites. The optimum fabrication parameters for better mechanical properties were envisaged using particle swarm optimization.

Simulation of a Gas-Solid Flow Field in a Two-Stage Rice Husk High-Temperature Pyrolysis and Gasification Cyclone Gasifier

A scheme for using a two-stage cyclone gasifier for high-temperature rice husk pyrolysis and gasification to reduce the tar content in biogas is presented in this study. The two-stage cyclone gasifier consisted of an upper cyclone high-temperature pyrolysis chamber and a lower steam spray gasifier. The staging pyrolysis and gasification process used in this study can increase the carbon conversion efficiency and reduce tar content by increasing the pyrolysis temperature. This process uses part of the produced gas for combustion in an external burner to generate high-temperature (1600 °C) anaerobic flue gas and to provide heat for pyrolysis and gasification. This study simulates the isothermal gas phase and the gas-solid flow field for the upper cyclone chamber, as well as the gas-solid flow field, with steam (heat transfer between the steam and the gas is considered), for the entire gasifier by varying the structural and operational parameters. The optimal parameters for the cyclone gasifier for good mixing and lengthy residence (2.3 to 4.8 s) of the rice husk particles were found to be inlet angles of 20° and 30° with inlet velocities between 40 and 80 m/s.

Effects of Hydrothermal Duration on Synthesized Zeolite Rice Husk Particles

Zeolite particles were synthesized through in-situ extraction of silica from rice husk ash without seeding method in the absence of organic template by a static hydrothermal condition at various duration for 8, 12, and 24h. The effect amorphous silica content on hydrothermal duration of synthesis products was evaluated with X-ray diffraction (XRD), and field emission microscopy (FESEM). The present of zeolite Y without seeding method via XRD analysis show a mixture of zeolite A, Y and P. The transformation of amorphous rice husk particle was increased gradually with the increased of hydrothermal reaction. The FESEM images showed agglomerated cubic-shaped morphology of the powders with increase in crystallization reaction. .

Catalyst and process parameters for the gasification of rice husk with pure CO2 to produce CO

A process for preparing CO with CO2 as gasification agent and rice husk as raw material in the presence of metal oxide catalyst was reported in this paper. Five kinds of catalysts (Fe2O3, CoO, NiO, CuO, and ZnO) supported on γ-Al2O3 were compared in the catalytic gasification, and the effects of reaction temperature, system pressure, catalyst loading, space velocity, and rice husk particle size were also studied. The results show that ZnO/γ-Al2O3 obtained at a calcination temperature of 650°C exhibits the highest activity. The optimal conditions are: 800°C, 0.1MPa, ZnO loading of 7.5%, space velocity of 240h−1, and rice husk particle size of 0.20–0.30mm. Under such conditions, 22.1% of CO content, 22.4% of CO2 conversion, and 71.7% of rice husk conversion are obtained.

Critical parameters in the production of ceramic pot filters for household water treatment in developing countries.

The need to improve the access to safe water is generally recognized for the benefit of public health in developing countries. This study's objective was to identify critical parameters which are essential for improving the performance of ceramic pot filters (CPFs) as a point-of-use water treatment system. Defining critical production parameters was also relevant to confirm that CPFs with high-flow rates may have the same disinfection capacity as pots with normal flow rates. A pilot unit was built in Cambodia to produce CPFs under controlled and constant conditions. Pots were manufactured from a mixture of clay, laterite and rice husk in a small-scale, gas-fired, temperature-controlled kiln and tested for flow rate, removal efficiency of bacteria and material strength. Flow rate can be increased by increasing pore sizes and by increasing porosity. Pore sizes were increased by using larger rice husk particles and porosity was increased with larger proportions of rice husk in the clay mixture. The main conclusions: larger pore size decreases the removal efficiency of bacteria; higher porosity does not affect the removal efficiency of bacteria, but does influence the strength of pots; flow rates of CPFs can be raised to 10-20 L/hour without a significant decrease in bacterial removal efficiency.

Evaluation of alkali–silica reaction in concretes with natural rice husk ash using optical microscopy

The use of rice husk ash as a supplementary cementing material is of great interest to many developing countries where rice production is in abundance. A highly reactive pozzolan is obtained when rice husk ash is burnt under controlled conditions. Previous work showed that it is possible to use residual rice husk ash “as nature” (natural rice husk ash). Nevertheless, it was observed that the incorporation of natural rice husk ash implies risks of expansions and mechanical degradation due to the reactions with alkalis. Based on the performance of slab prototypes placed outdoors during more than 3years, this work analyzes the causes and the damage processes involved in the development of expansions in presence of natural rice husk ash. Optical microscopy observations on thin sections; crack patterns of the slabs and the strength and surface strain evolution along the time were evaluated. Visual and microscope observations showed clear signs of damage due to expansive reactions in concretes incorporating natural rice husk ash when high alkalis contents are available; although not gel was found, numerous cracks and voids were observed close to unburned rice husk particles, as well as high expansions and significant decreases in strength and stiffness. In concretes with alkalis contents lower than 3kg/m3, even with the same percentages of natural rice husk ash, there were no significant decreases in the mechanical properties.

Combined effect of thermoplastic and thermosetting adhesives on properties of particleboard with rice husk core

This study investigated the combined effect of adhesive type and content on the dimensional stability and mechanical properties of three-layer particleboards made from a mixture of wood particles (face layer: 30 wt %) and rice husk particles (core layer: 70 wt %). Two types of thermosetting adhesives, liquid urea-formaldehyde (UF) and phenol-formaldehyde (PF), and thermoplastic adhesive (low density polyethylene: LDPE) powder were used as binder in the experiments. Thickness swelling and water absorption of the particleboards significantly decreased with increasing content of the LDPE powder. The incorporation of LDPE powder into the core layer of particleboard greatly improved the internal bond strength.

Hydrophilicity Effect of Rice Husk Silica on Mixed Matrix PSF Membrane Properties

The effects of two types of additives rice husk silica (RHS) towards membrane hydrophilicity and flux performance were investigated. Different percentages or concentrations of rice husk silica (RHS) additive were used to form a mixed matrix membrane. This flat sheet mixed matrix membrane was prepared via phase inversion technique. The fabricated membrane was characterized by contact angle and surface roughness measurements, whereas the flux permeation was measured using pure water flux. The result demonstrated that the addition both types of rice husk silica have increased the hydrophilicity properties of the mixed matrix membrane. Stronger effect of hydrophilicity is shown upon addition of amorphous rice husk particle where both contact angle and surface roughness were reduced and increased, respectively.

The Characteristic of Synthesized Zeolite Rice Husk Particles via Different Routes

Zeolite particles were synthesized through in-situ extraction of silica from rice husk ash without seeding method in the absence of organic template by a static hydrothermal condition at 100oC/24h at varied ageing 8-24h. The effect of amorphous silica content on ageing time of synthesis products was evaluated with X-ray diffraction (XRD), Fourier transform infrared (FTIR) and field emission microscopy (FESEM). The present of zeolite Y without seeding method by XRD analysis show a mixture of zeolite A, Y and P. The transformation of amorphous rice husk particle gradually increased as early at 8 hours in ageing and increased with increase in ageing reaction. The vibration bands at around 974 cm-1 indicated Si-OH vibrations of the surface silanols, which is the characteristic of mesoporous silica. The FESEM images showed cubic-shaped morphology of the powders increased with increase in ageing reaction.

Physical and mechanical properties of particleboard manufactured from wood, bamboo and rice husk

In this work, the physical-mechanical properties of particleboards manufactured with wood (Eucalyptus grandis), bamboo (Bambusa vulgaris) and/or rice husk (Oryza sativa) particles, combined or not, were assessed. They were produced in the following proportions: 100% wood; 100% bamboo; 100% rice; 50% wood and 50% bamboo; 50% wood and 50% rice husk. In order to characterize the manufactured particleboards, their physical (density; moisture content; water absorption and thickness swelling) and mechanical properties (static bending; internal bonding and screw withdrawal) were assessed. The results indicated that the use of rice husk caused reduction in particleboard quality. Particleboards manufactured with bamboo showed better quality than those using rice husk as raw material. For most parameters, the particleboards manufactured exclusively with wood particles showed similar performance to bamboo and wood-bamboo particleboards.

Effect of Rice Husk Particle Size on Tensile and Density of Recycled PPVC Composite

This study is to measure the effect of various rice husks particle size on density, tensile strength, Youngs modulus and elongation at break of PPVC composite. Rice husk was grind before being sieved to particle sizes of 60 μm, 60 μm < particle size 80 μm, and 80 μm < particle size 100μm. Each size was compounded with PPVC at same filler loading which is 20 % rice husk and being pressed using hot press machine. Tensile strength, Youngs modulus and elongation at break increased as particle size increases. The highest value for tensile strength, Youngs modulus and elongation at break are 21.48 MPa, 1344.88 MPa and 2.29 % respectively. However, it is different for density result which decreased as particle size increases. The results obtained from the study shows that the bigger the size of the rice husks, the better the composite tensile properties.

Heavy metals removal from wastewaters using organic solid waste—rice husk

In this study, the removal of Cr(III) and Cu(II) from contaminated wastewaters by rice husk, as an organic solid waste, was investigated. Experiments were performed to investigate the influence of wastewater initial concentration, pH of solution, and contact time on the efficiency of Cr(III) and Cu(II) removal. The results indicated that the maximum removal of Cr(III) and Cu(II) occurred at pH 5-6 by rice husk and removal rate increased by increased pH from 1 to 6. It could be concluded that the removal efficiency was enhanced by increasing wastewater initial concentration in the first percentage of adsorption and then decreased due to saturation of rice husk particles. Also according to achieved results, calculated saturation capacity in per gram rice husk for Cr(III) and Cu(II) were 30 and 22.5 mg g(-1), respectively. The amounts of Cr(III) and Cu(II) adsorbed increased with increase in their contact time. The rate of reaction was fast. So that 15-20 min after the start of the reaction, between 50 and 60 % of metal ions were removed. Finally, contact time of 60 min as the optimum contact time was proposed.