Rice Hull Ash Research Articles

Influence of rice hull ash and levels of p and k on growth performance of rice grown in sandy loam soils of Chikkamangaluru district of Karnataka

A field experiment was conducted at Agricultural and Horticultural Research Station, Bhavikere, Chikkamangaluru, Karnataka State from 2018-2019 to know the influence of rice hull ash and levels of p and k on growth performance of rice grown in sandy loam soils. The treatments comprised of the recommended dose of RHA (2 t ha-1), FYM (7.5 t ha-1) and varied levels of P and K with rice as test crop and tried in RCBD with eleven treatments and three replications. Results of the field experiment showed significant increase in growth attributes (plant height, tillers per plant and dry matter accumulation), with treatment receiving application of recommended dose of RHA, FYM and NPK.

Mechanical Properties of Recycled Polypropylene Macro Flat Fiber Reinforced Concrete with Rice Hull Ash as Partial Replacement to Cement

Due to urbanization, the use of concrete in construction and waste production are arising that resulted to negative impact in environment. There are several studies utilizing cementitious material as substitute to cement and plastic waste as additive to concrete which has potential in increasing the strength. This study utilized recycled polypropylene macro fiber (RPPMF) as a reinforcement and rice hull ash (RHA) as substitute to cement. Varying percentage of RHA (10%, 15%, and 20%) and RPPMF (0.5%, 0.75%, and 1.0%) were incorporated in the concrete mix. Compressive and flexural strength results showed that the combination of RHA and RPPMF has a significant effect in the strength of concrete. Based from the results, the concrete with 10% replacement of RHA and 0.5% addition of RPPMF is theoptimum which has the highest compressive strength of 19.47 MPa with an increase of 13.40%, and a maximum flexural strength test of 3.7 MPa with an increase of 18.62%. Furthermore, the concrete with 10% replacement of RHA for both with additive of 0.75% and 1% RPPMF also attained higher flexural strength than of normal mix with 18.07% and 3.45% increase, respectively. It can be recommended to use for basement foundation walls and slabs, walks, patios, steps, and stairs. Also, it can be used for street roads because it reaches the standard strength of normal mix concrete and lessen the cracks due to addition of RPPMF.

Effect of Different Media on Germination and Seedlings Performance of Chili Pepper (Capsicum annum)

The production of vegetable seedlings is an important business for some farmers in most parts of the world with poor media being a major constraint. An experiment was conducted to investigate the effect of different media on germination and nursery performance of chili pepper at the Department of Horticulture, Kwame Nkrumah University of science and Technology (KNUST). A Randomized Complete Block design with six treatments and three replications was used in the study. Media treatments were used either alone or in combination and they were: topsoil only, rice hull ash only, rabbit waste only, topsoil and rice hull ash (1:1), topsoil and rabbit waste (1:1) and topsoil and river sand (1:1). There were significant differences in germination percentage, seedling height, number of leaves and stem girth as function of the media treatments. The different media however did not affect days to 50% germination significantly. Comparatively, the highest and the lowest germination percentages (77.50% and 62.00%) were obtained by nursing seeds in the mixture of topsoil and rice hull ash as well as rabbit waste only respectively. In terms of growth characteristics, plant height and number of leaves were highest in seedlings nursed in topsoil and rice hull ash mixture (18.36 cm and 13.23 cm) respectively at the end of the study period. The highest stem girth was seedlings nursed in topsoil (3.129 mm) at the end of the experiment. Plants nursed in rabbit waste only had the lowest growth performance in terms of plant height (2.75 cm), number of leaves (4.50) and stem girth (1.27 mm) at the end of the experiment. Growth medium consisting of a mixture of proportion of topsoil and rice hull ash is therefore recommended for growing chili pepper seedlings since this combination improved both germination and subsequent growth as compared to the other media used in the experiment. Rice hull ash is not recommended to be used alone in raising chili pepper seedlings since it has a high pH which decreases seedling growth. Partially decomposed rabbit waste is also not suitable to be used as nursery medium because it retards seedling growth.

Ecological Fickerts Used in the Dimension Stones Polishing Reinforced with Silica from the Rice Hull Ash

The processing stages of the dimension stones industry uses inputs mainly from petroleum-derived chemicals that can cause damages to the environment and to the human health. Therefore, there is a need to develop more ecological and sustainable technologies aiming to replace the conventional inputs by less aggressive ones. From this, ecological fickerts made from polyurethane castor oil resin (Ricinus communis L.), silicon carbide (SiC), silica from rice hull ash (RHA) and synthetic diamonds were developed in order to compare them with the epoxy resin fickerts currently used in industry. For such, each half of a Brazilian granite slab was polished using each different type of fickerts and the gloss measures results were compared. It was found that the side of the slab polished using the ecological fickerts presented brightness values about 10 Gloss Units (GU) greater than the other side polished with the conventional abrasives. In addition, the ecological fickerts presented lower wear values, and consequently lower mass loss compared to the conventional ones. These results indicate that the ecological fickerts are a good alternative to the dimension stones polishing, even considering sustainability aspects and more eco-efficiency inputs materials.

Insertion of Silicon Carbide as Cutting Element in Ecological Fickerts for Dimension Stone Polishing

The dimension stone polishing consists of eliminating the surface roughness of the slabs with the use of fickerts. The main tools used for this activity are composed of epoxy resin, derived from petroleum, which contains chemical elements with harmful potential to the environment and human health. To overcome this problem, it is necessary to develop new technologies with the lowest environmental impact in the life cycle, from the raw material acquisition to the waste disposal. This study aims to contribute to the improvement of an ecological fickert developed by the Centre for Mineral Technology (CETEM). The fickerts presented here are composed of castor oil resin, silicon carbide and silica from rice hull ash. Two different compositional formulas were used for the preparation of the pieces that were tested in an industrial polishing machine. The results showed that the formula with higher percentage of fillers showed better performance, expressed by the relation between the loss of mass of the pieces and the increase of gloss on the surface of the slab. Other particularities of the product, as the high abrasion resistance of the matrix that reduced the cutting function, could be solved by choosing a filler with a lower hardness. This fact allows to infer that this line of research presents great potential of applicability in the dimension stones market.

Synthesis of La and Ce modified X zeolite from rice husk ash for carbon dioxide capture

The porous material adsorbent X zeolite was prepared by using agricultural waste rice hull ash (RHA) and modified by ion-exchange into the rare earth metal zeolite of La and Ce. A series of characterization results, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, N2 adsorption–desorption and pore size analysis, illustrated the effects of ion exchange modification on crystal, pore structure and morphology. The CO2 adsorption experiment was operated, and the adsorption amount of NaX and LaLiX was 6.14 and 4.36mmol/g at atmospheric pressure, respectively. Three isotherm models were used to fit the pressure swing adsorption data. The Toth and DSL models were more accurate due to their ability to express heterogeneity. The isosteric heat and selectivity were obtained by the corresponding models and calculations. The results explained the mechanism of heat and gas uptake during adsorption and desorption. The CO2/N2 selectivity of LaNaX has enhanced more than three times. All modified zeolite samples maintained above 96.5% of initial adsorption after 20 adsorption–desorption cycles. The adsorption heat releases properties and long-term stability of the modified zeolite are superior. It demonstrates that such adsorbents can be used for long-term capture and separation of CO2 from the industrial exhaust gas.

Utilization of Coal Fly Ash and Rice Hull Ash as Geopolymer Matrix-cum-Metal Dopant Applied to Visible-Light-Active Nanotitania Photocatalyst System for Degradation of Dye in Wastewater

Geopolymer (GP) spheres made from coal fly ash (FA) and rice hull ash (RHA) waste products are utilized as both support matrix and dopant applied to titania (TiO2) photocatalyst for organic dye degradation in wastewater. Processing of FA and RHA via suspension-solidification method resulted in GP spheres with nanoporous morphology. The nanocrevices enabled low-energy sol-gel TiO2 coating technique because they served as anchoring sites on the geopolymer surface that favored rigidity and larger surface area. The GP-TiO2 system has been characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Diffuse reflectance spectroscopy revealed a narrowing of the GP-TiO2 system optical band gap due to the interaction of metal dopants contained in RHA and FA with TiO2, thus making the GP-TiO2 system a visible-light-active photocatalyst, as confirmed by methylene blue dye degradation measured through UV-Vis spectroscopy.

Sorption-desorption profile of Au(III) onto silica modified quaternary amines (SMQA) in gold mining effluent

This work aim to study sorption-desorption of Au(III) onto silica modified quaternary amines (SMQA) in gold mining effluent. Synthesis SMQA was conducted by methylation silica modified ammine (SMA) that synthesized by sol-gel process of silica gel (SG) from rice hull ash and APTMS. Characterizations this material by FT-IR, XRD, SEM-EDS and GSA analyzer show that the material has characteristic parameter of SMQA. Sorption study of sorption Au(III) on SMQA was carried out by batch system with optimum pH 5. Sorption capacity was 74.47 mg/g (Langmuir) with 24 kJ/mole sorption energy (electrostatic interaction). Kinetics sorption studies by Lagergren, Ho, and RBS models shows that the sorption Au(III) in this research have the suitable condition with RBS models. Sorption study reveal that –N+(CH3)3 is the most responsible site for Au(III) sorption. Desorbed Au(III) in batch system using Na2S2O3, SC(NH2)2, and KSCN as desorption agent in HCl solution was there are no significant different value (Na2S2O3 = 94.2 %; SC(NH2)2 = 95.2 %; KSCN = 95.2 %). However, for safer eluent it was recommend to use Na2S2O3 or SC(NH2)2. The reusability of SMQA was four times sorption-desorption cycle before at fifth cycle desorbed Au(III) was decreased. The application of SMQA in gold mining effluent by column system (SPE) sample in Sarolangun, Jambi, Indonesia shows that recovered Au(III) was 0.000593 % in 2 g sample.

Reducing excess phosphorus in agricultural runoff with low-cost, locally available materials to prevent toxic eutrophication in hoar areas of Bangladesh

Two potential sorbent materials were investigated for their ability to remove excess phosphate from agricultural runoff in Bangladesh. Because they are low in cost, locally available, and require few extra resources to prepare, they offer viable strategies to prevent hazardous algal blooms that can catastrophically take out fish and water bird populations. The first material is rice hulls that have been burned, calcined and enhanced with FeCl3. The second, and more appealing, is iron-rich Sylhet sands that are simply washed. Sorption trials were run in both batch and column modes. Optimal conditions for phosphate removal were pH 5 and a 3-h contact time. Fe-treated rice hull ash removed 78.5% of the phosphate from a 5-ppm test solution. The Sylhet sand achieved a 49.6% reduction. When an actual sample of runoff from the Tangua hoar was subjected to the sorbents, the rice hull ash removed 83.8% and the Sylhet sand removed 83%. Both materials showed signs of being re-useable. With the rice hull ash, 42.9% of the phosphate could desorbed while with the Sylhet sand, 71.6% of the phosphate was desorbed. Once desorbed, 74% of the phosphate could be recovered for fertilizer feed stock by precipitating it out as ferric phosphate, FePO4.

Crescimento e produtividade de cultivares de tomate cereja utilizando substratos de base ecológica

The objective of this study was to evaluate the influence of substrates on the growth and yield of Cascade and Samambaia cherry tomato cultivars under protected environment. A completely randomized experimental design with six treatments and four replications was adopted. The treatments consisted of six substrates resulting from the combination of soil (CS), bovinemanure (BM), rice husk (RH) and rice hull ash (RA), in the proportions: S1 -70% SC + 10% BM + 10% RH + 10% RA; S2 -60% SC + 20% BM + 10% RH + 10% RA; S3 -50% SC + 30% BM + 10% RH + 10% RA;S4 -60% SC + 30% BM + 10% RH; S5 -70% SC + 20% BM + 10% RH; and S6 -100% SC. Plant growth, yield and development parameters were evaluated. Cherry tomato growth and yield changed according to the substrate characteristics. The substrate composed by soil was not efficient, presenting the lowest values for all the vegetative and reproductive parameters studied. The substrates made from alternative ecologically based residues are interesting and alternative sources for tomato cultivation aiming at the reuse of the matter and the sustainability of the production system.

Silica depleted rice hull ash (SDRHA), an agricultural waste, as a high-performance hybrid lithium-ion capacitor

The partial removal of SiO2from rice hull ash (RHA, an agricultural waste) is a simple, low cost, eco-friendly method of producing high-performance electrode material for hybrid-lithium ion capacitors.

LixSiON (x = 2, 4, 6): a novel solid electrolyte system derived from agricultural waste

A novel solid electrolyte system, LixSiON (x = 2, 4, and 6), derived from agricultural waste, rice hull ash, by polymer precursor syntheses.

Hierarchically pure and M (Cu, Ni)-impregnated ZSM-5 zeolites for the isomerization catalysis of n-hexane and 1-hexene

Conversion of bio-waste into high value catalytic materials is an option in the quest of maintaining sustainable environment. Here, we report an elaborated analysis of the catalytic activity of synthesized hierarchical pure and M (Cu, Ni)-impregnated ZSM-5 zeolite structures from the rice hull ash (RHuA), which is an abundant bio-waste material in most rice producing regions. To achieve the desired characteristics of ZSM-5 framework for metal (i.e., Cu and Ni) impregnation, an organic template-free method synthesis was designed. Further, the catalytic performance of the metal impregnated ZSM-5 in the isomerization of n-hexane and 1-hexene were carried out in a continuous flow stainless steel fixed bed reactor. Three (3) metal impregnation percentages, namely 1, 3 and 5% of Cu/Ni were investigated and compared in respect to the metals. The isomerization of higher alkanes/alkenes is crucial in petroleum industries to increase the octane number of gasoline. Reaction parameters of interest were catalyst amount, reaction temperature, weight hourly space velocity (WHSV), and reaction time were optimized and the obtained results are elaborately discussed. The Ni-ZSM-5 have superior catalytic activity compared Cu-ZSM-5, although the catalytic activity of ZSM-5 zeolite increases with the loading percentage for both Cu and Ni. To explain the metal loading effects on catalytic activity of the ZSM-5, density functional theory calculations were done through adsorption-desorption mechanistic approach. This combined experimental and theoretical investigation strongly validated the reliability of the results.

Green routes to silicon-based materials and their environmental implications

Abstract The “greening” of silicon chemistry is fundamentally important for the future of the field. Traditional methods used to make silicon-based materials rely on carbon rich processes that are highly energy intensive, cause pollution, and are unsustainable. Researchers have taken up the challenge of developing new chemistries to circumvent the difficulties associated with traditional silicon material synthesis. Most of this work has been in the conversion of the “green” carbon neutral biogenic silica source rice hull ash (RHA, ~85 % silica) into useful silicon building blocks such as silica’s, silicon, and alkoxysilanes by using the inherently higher surface area and reactivity of RHA to sidestep the low reactivity of mined silica sources. This is a review of the work that has been done in the area of developing more environmentally benign methods for the synthesis and use of silicon containing materials to eliminate the negative impact on the environment.

The unusually formation of porous silica nano-stalactite structure by high temperature heat treatment of SiO2 aerogel synthesized from rice hull

The SiO2 aerogel has attracted the attention of many researchers in recent years in terms of energy saving due to its properties such as very low density, high porosity, and superior insulation. The primary purpose of this study was to synthesize SiO2 aerogel. For this purpose, the sodium silicate obtained from rice hull ash was used as pre-initiator and dried at ambient pressure and SiO2 aerogel was synthesized. BET surface area of the obtained SiO2 aerogel was found as 241 m2/g. The difference of this study is the structures obtained after this stage. After obtaining SiO2 aerogel, it was subjected to heat treatment at a high temperature to increase the BET area of aerogel and after examining under SEM, it was noticed that some uncommon structures that have not seen before formed. After observing nano-stalactite type structures in the sample, the study was expanded on the causes of the formation of these structures. It was seen that this structure forming after heat treatment was a stalactite composed of SiO2 nanoparticles having a crystal structure. This study examined the formation mechanism and some properties of this structure which was not encountered in previous studies. Brunauer-Emmett-Teller (BET), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis were conducted in order to determine the physical and chemical properties of both synthesized SiO2 aerogel and nano-stalactite type structure.

Synthesis and characterization of L-Arginine modified silica by sol-gel method prepared rice hull ash

The synthesis of L-arginine modified silica using 3-glycidoxypropyl-trimethoxysilane (GPTMS) as linking agent has been done through sol-gel process. Sodium silicate (Na2SiO3) from rice hull ash (RHA) as the silica source precursor, L-arginine solution 0.9 M with various volume ratios and the linking agent were mixed to form a gel labelled SiO2(RHA)-Arg. The synthesis was successfully carried out in the form of bone white solids. Furthermore, SiO2(RHA)-Arg were characterized using Fourier transform infrared (FTIR) spectrophotometer, elemental analyser, thermogravimetric analyser (TGA) and 29Si-NMR. FTIR spectra of SiO2(RHA)-Arg shows two new peaks at 1672 and 1583 cm-1 confirming NH2 and C=O groups, respectively. Elemental analysis indicates that the mol ratio of GPTMS: L-arginine is 5: 1. TGA analysis explains that the ratio of SiO2: GPTMS: Arg is 5:5:1. The analysis of 29Si-NMR indicate that the silica binds two molecules of GPTMS. The results of SiO2(RHA)-Arg characterization show that silica atom binds two molecules of GPTMS, and every molecule of GPTMS binds five L-arginine molecules.

The effects of nanosilica fertilizer concentration and dose of rice hull ash on the characteristic of soybean leaves (Glycine max L. Merril)

Utilization of nanosilica fertilizer and rice hull ash in soybean cultivation is an environmentally friendly cultivation that supports sustainable agriculture. The purpose of the research was to analyze the effects of nanosilica fertilizer and dose of rice hull ash on characteristics of soybean leaves. The study was arranged as factorial design with two factors. The first factor was nanosilica fertilizer, consisted of four levels (0, 1.25, 2.5- and 3.75-ml l−1). The second factor was dose of rice hull ash consisted of four levels (0, 1, 2 and 3-ton ha−1). Each treatment combination was repeated three times. Concentration of nanosilica individually affect the number of leaves at 29 and 43 days, leaf area and the leaf area index at 43 days. There was interaction between nanosilica fertilizer and rice hull ash on leaf thickness, stomata density, trichome density and silica content in leaves. Combinations of 1.25 ml l−1 nanosilica and 1-ton ha−1 rice hull ash gave the highest leaf thickness, combination of 1.25 ml l−1 nanosilica and 2-ton ha−1 rice hull ash gave the highest stomata density and silica content in leaves. Combination of 1,25 ml l−1 nanosilica fertilizer and 3-ton ha−1 rice hull ash gave the highest trichome density.

Synthesis of geopolymer spheres with photocatalytic activity

Geopolymer is an emerging “green” cementitious material which has a potential to valorize waste such as rice hull ash (RHA). Geopolymer is a kind of alkali-activated material which forms from the reaction of alumino-silicates in an alkaline solution. This study uses RHA as the raw material for alkaline activator while metakaolin (MK) serves as a geopolymer precursor to synthesize the so-called geopolymer sphere. Then its capacity as a porous matrix was explored upon incorporation of TiO2 nanomaterial using horizontal vapor phase growth (HVPG) technique to enhance its photocatalytic property. Indication suggests that the synthesized MK-geopolymer spheres activated with RHA-based water glass solution (WGS) were comparable to that of commercial WGS. Furthermore, the geopolymer spheres were successfully coated with TiO2 in the form of nanocrystals. Its photocatalytic activity was evaluated in terms of methylene blue degradation. This material’s potential environmental application for water purification and wastewater treatment will be investigated for future works.

Preparation of Water Repellent Layer on Glass Using Hydrophobic Compound Modified Rice Hull Ash Silica

In this study water repellent layered glass has been prepared by coating silica (SiO2) combined with a hydrophobic silane compound. SiO2 was extracted from rice hull ash and two silane compounds, namely hexadecyltrimethoxysilane (HDTMS) and trimethylchlorosilane (TMCS) were used. Coating was performed through two deposition techniques, i.e. one step (mono-layer) and layer by layer (LBL, multi-layer). The effect of silane to SiO2 mole ratio, silane type and layer number on the glass characters was evaluated. Characterization included hydrophobicity, transparency, surface roughness and stability of coating. Results showed that increasing the mole ratio of silane to SiO2 and the layer number increased the hydrophobicity of the glass surface. The optimum mole ratio was 5:1 and the significant increase of contact angle occurred at lower mole ratio, but the stability tends to be increased at higher mole ratio. For HDTMS-SiO2 layer, the technique of LBL technique produced a coating with higher hydrophobicity and transparency than single-stage one. The LBL technique produced the highest water contact angle of 103.7° with transmittance of 96%, while for TMCS-SiO2 layer the one stage technique produced hydrophobic layer with higher water contact angle of 108.0° and transparency about 94.52%. The prepared hydrophobic glasses were relatively stable in polar and non-polar solvents, but unstable to ambient conditions.

Synthesis, characterization and CO2 adsorption of NaA, NaX and NaZSM-5 from rice husk ash

NaA, NaX and NaZSM-5 zeolites were prepared by using silica extracted from rice hull ash as a raw material, and they were investigated for CO2 adsorption performance as an adsorbent in order to solve the problem of suppressing the global warming. Three zeolites were synthesized by hydrothermal methods with seed technology, and a series of characterization methods, including XRD, FTIR, nitrogen adsorption-desorption and SEM, were used to demonstrate their advantages compared to traditional hydrothermal methods. The maximum equilibrium adsorption capacity of NaA-RS, NaX-RS and NaZSM-5-RS was 1.46, 3.12 and 2.20 mmol/g at 0 °C and 101.3 kPa, respectively. The CO2 and N2 adsorption isotherms recorded at different temperatures were perfectly fitted by the Dual-site Langmuir model. The CO2/N2 selectivity and Henry's law constants were calculated to demonstrate that the samples have a stronger affinity for CO2, especially at low pressures. The isosteric heat of CO2 and N2 adsorption of the three zeolites was calculated, which was indicated that they were in an excellent potential for adsorption and separation of CO2 in industrial flue gas.