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.

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.

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.

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.

Development and Characterization of Particle Boards Based on Sorghum Husk

This study tackles current environmental challenges by developing innovative and eco-friendly particle boards utilizing sorghum husk, combined with recycled expanded polystyrene (EPS). This dual eco-responsible approach valorizes sorghum husk, often deemed agricultural waste, and repurposes EPS, a plastic waste, thus contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene within a solvent to create a binder, which is then mixed with sorghum husk and cold-pressed into composite boards. The study explores the impact of two particle sizes (fine and coarse) and two different concentrations of the recycled EPS binder. Results demonstrate significant variations in the boards’ mechanical properties, displaying a range of Modulus of Rupture (MOR) from 0.84 MPa to 3.85 MPa, and Modulus of Elasticity (MOE) spanning from 658.13 MPa to 1313.25 MPa, influenced by the binder concentration and particle size. These characteristics suggest that the boards can be effectively used in various construction applications, including interior decoration, false ceilings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only exemplifies the valorization of plastic and agricultural wastes but also offers a practical, localized solution to global climate change challenges by promoting sustainable construction materials.

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.

On the “Onion Husk” Algorithm for Approximate Solution of the Traveling Salesman Problem

The paper describes some implementation aspects of an algorithm for approximate solution of the traveling salesman problem based on the construction of convex closed contours on the initial set of points (“cities”) and their subsequent combination into a closed path (the so-called contour algorithm or “onion husk” algorithm). A number of heuristics related to the different stages of the algorithm are considered, and various variants of the algorithm based on these heuristics are analyzed. Sets of randomly generated points of different sizes (from 4 to 90 and from 500 to 10,000) were used to test the algorithms. The numerical results obtained are compared with the results of two well-known combinatorial optimization algorithms, namely the algorithm based on the branch and bound method and the simulated annealing algorithm. .

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.

高粱壳多酚的提取、结构表征及其抗氧化活性研究

采用酶辅助法提取高粱壳多酚。以多酚含量为指标,采用单因素试验和正交试验先确定最佳酶用量,然后进一步优化酶解条件,并对高粱壳多酚进行结构表征和抗氧化活性分析。结果表明:最佳酶用量(以高粱壳粉质量计)为木瓜蛋白酶2.1 mg/g、纤维素酶3.3 mg/g、半纤维素酶3.3 mg/g、木质素酶1.9 mg/g;最佳酶解条件为酶解pH 5.5、酶解温度50℃、酶解时间70 min,在此条件下,多酚含量达9.21 mg/g。结构分析表明,高粱壳多酚具有多个苯环和酚羟基。抗氧化试验结果表明,高粱壳多酚具有较好的抗氧化活性。

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.

水稻整株移除提高镉污染稻田安全利用效果

为探索中轻度Cd污染稻田的安全利用路径,本研究对比利用不同水稻品种专性移除作物有效态Cd,提取修复后对土壤进行调碱补硅,以明确“清洁减量-调理降活”的协同策略对降低稻米Cd积累的作用.2021年大田试验,采取湿润水分管理方式(土壤表面无明显水)分别种植杂交稻(桃优香占)和常规稻(玉针香)两个高Cd积累水稻品种进行土壤有效Cd专性提取并进行整株移除;在次年大田试验,采取常规水分管理种植当地食用杂交稻(Y两优9918),通过单施石灰(CaO)和石灰复配稻壳灰(CaO+RHA)调碱土壤pH和增加土壤有效Si含量,强化水稻安全生产效果.结果表明:(1)采用湿润水分管理模式,种植桃优香占和玉针香对土壤Cd赋存形态表现出显著差异,玉针香使作物易利用态Cd含量(可交换态+碳酸盐结合态)与相对稳定态Cd含量(铁锰氧化物结合态+有机结合态+残渣态)分别降低11%和14%;桃优香占则使其分别降低2%和29%.(2)整株移除玉针香和桃优香植株后,与未进行提取处理的田块相比,Y两优9918稻米Cd由1.02 mg·kg^(-1)降至0.85~0.92 mg·kg^(-1),降幅为10%~18%.提取修复后,单施CaO使稻米Cd含量降低73%~82%;CaO+RHA处理下稻米Cd含量进一步降低26%~71%,其中,经桃优香占提取修复后的田块,施用CaO或CaO+RHA均使稻米Cd达到国家食品安全标准.因此,该地区可在湿润水分模式下种植桃优香占并整株移除减少土壤Cd存量,针对提取修复后的土壤,可结合土壤调碱补硅等必要措施强化控制水稻Cd积累,保障水稻安全生产.

Toxicity and Antifeedant Activity of Extracts from Walnut Green Husk against Wheat Aphid

[Objective] The research aimed to study the toxicity and antifeedant activity of walnut green husk extract on wheat aphid. [Method] Using ultrasonic extraction, 5 kinds of different polarity solvents were used to prepare the extracts from walnut green husk. The toxicity and antifeedant activity on wheat aphid were determined, [ Result ] Walnut green husk extracts in the solvent of ethanol, acetone, ethyl acetate had higher toxicity and antifeedant activity on wheat aphid. When the concentration was 100 mg/ml, after 24 h, the toxicity and antifeedant activity of three kinds extracts on wheat aphid were greater than 84.35% and 66.98%, respectively. After 48 h, the toxicity and antifeedant activity were greater than 85.91% and 79.34%, respectively. Among 5 kinds extracts,ethanol extracts had the highest toxicity and antifeedant activity on wheat aphid. After 24 h, the corrected mortality rate was 93.64% and the antifeedant rate was 83.61%. After 48 h,the corrected mortality rate was 94.95% and antifeedant rate was 92.21%. Petroleum ether extract had the smallest toxicity and antifeedant activity on wheat aphid. After 24 h,the corrected mortality rate and antifeedant rate were 19.54% and 34.65%, respectively. After 48 h,the corrected mortality rate and antifeedant rate were 20.13% and 39. 03%, respectively. [ Conclsion] The extracts from walnut green husk with larger polarity solvent had better toxicity and higher antifeedant activity on wheat aphid.

稻壳生物炭对甲基橙和罗丹明B的吸附研究

文中以稻壳生物炭为吸附剂,系统研究其对甲基橙和罗丹明B的吸附作用及机制。结果表明,生物炭对两种染料的吸附过程均符合准二级动力学方程,表明以化学吸附为主。Langmuir模型和Freundlich模型分别能较好地描述生物炭对甲基橙和罗丹明B的吸附行为。pH值为3.0时生物炭对罗丹明B的吸附量最大。增加溶液的离子强度,促进生物炭对两种染料的吸附,而腐殖酸的存在则抑制染料的吸附。生物炭对两种染料的吸附均包含多种机制,氢键和π-π相互作用是甲基橙吸附的主要机理,而罗丹明B的吸附主要通过离子交换、氢键和π-π相互作用;同时孔隙填充和疏水作用对两种染料的吸附起一定作用。

添加核桃青皮对苜蓿青贮品质及CNCPS蛋白组分的影响

本文旨在研究核桃(Juglans regia L.)青皮对苜蓿青贮品质及蛋白组分的影响。试验以紫花苜蓿‘龙威6010’(Medicago sativa‘Longwei 6010’)和阿克苏‘新温185’纸皮核桃青皮为原料,分别设置CK(苜蓿单独青贮)、A_(1)(添加80 g·kg^(-1)核桃青皮)、A_(2)(添加120 g·kg^(-1)核桃青皮)、A_(3)(添加160 g·kg^(-1)核桃青皮)4个处理,在青贮60 d后取样分析。结果表明:添加核桃青皮后感官评价等级下降,但干物质、粗蛋白及可溶性碳水化合物含量升高(P<0.05),降低乙酸、丙酸和氨态氮含量,并提高了V-Score评分;随着核桃青皮比例的提高非蛋白氮、慢速降解蛋白及结合蛋白含量降低(P<0.05),而快速降解蛋白和中速降解蛋白提高(P<0.05),同时提升了有氧稳定性。利用灰色关联度进行分析并排序,青贮品质由高到低依次为A_(2)>A_(3)>A_(1)>CK。综上所述,添加核桃青皮可以改善苜蓿青贮品质,其中添加120 g·kg^(-1)的核桃青皮较为合适。

稻壳灰在建筑材料中的应用研究现状

作为农业大国,我国每年会产生大量的农业废弃物——稻壳灰(RHA)。RHA含有大量的非晶态二氧化硅,具有较强的火山灰活性,可作为辅助胶凝材料替代部分水泥,不仅能有效减少二氧化碳排放,还能实现RHA的资源化再生利用。大量研究表明,RHA能够显著改善水泥基材料的强度和微观结构,其多孔结构在水化反应体系中具有内养护效应,能够持续释放水分,促进水泥等材料的不断水化,从而表现出与硅灰等其他辅助胶凝材料不同的特性。综述了RHA的理化性质、活性影响因素及其在胶凝材料反应体系中的水化作用机理,并归纳了RHA在水泥混凝土、地质聚合物及土壤固化材料领域的应用研究现状,讨论了RHA对这些材料主要性能的影响,期望能推动RHA在建筑材料领域中的应用。

Kinetics and isotherms of Neutral Red adsorption on peanut husk

Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K. Experiments were carried out as function of pH, adsorbent dosage, contact time, and initial concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Toth isotherm models. The results indicated that the Toth and Langmuir models provided the best correlation of the experimental data. The adsorption capacity of peanut husk for the removal of NR was deter...

Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries

Here,we report the synthesis of hard carbon materials(RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion batteries.The studies show that the electrochemical properties of RHs are affected by the treatment temperatures,which determine the materials morphology,in particular,their degree of graphitization and extent of continuous channels(nanovoids).The latter are accessible to sodium ions and significantly contribute to charge storage capacity of the produced anodes.The RHs obtained at 1600 °C deliver the highest reversible capacity of276 mAh g^(-1) mainly due to insertion of sodium ions into the nanovoids.This work deepens the basic understanding of the influence of the carbonization temperature on the sodium storage mechanism.

Effect of grinding on chemical and physical properties of rice husk ash

The effect of grinding on the chemical and physical properties of rice husk ash was studied. Four rice husk ashes with different finenesses, i.e. coarse original rice husk ash （RHA0）, RHA1, RHA2, and RHA3 were used for the study. Ordinary Portland cement （OPC） was partially replaced with rice husk ash at 20% by weight of binder. The water to binder ratio （W/B） of the mortar was maintained at 110%±5% with flow table test. Specific gravity, fineness, chemical properties, compressive strength, and porosity test of mortars were determined. The differences in chemical composition of the rice husk ashes with different finenesses from the same batch are small. The use of RHA3 produces the mortars with good strength and low porosity. The strength of the mortar improves with partial replacement of RHA3 in comparison with normal coarse rice husk ash. The use of RHA3 results in a strong and dense mortar, which is due to the better dispersion and filling effect, as well as an increase in the pozzolanic reaction.

Pyrolysis of rice husk and sawdust for liquid fuel

The paper is focused on studying how to convert rice husk and sawdust into liquid fuel. Rice husk, sawdust and their mixture were pyrolyzed at the temperature between 420℃ and 540℃, and the main product of liquid fuel was obtained. The experimental result showed that the yield of liquid fuel heavily depended on the kind of feedstock and pyrolysis temperature. In the experiments, the maximum liquid yields for rice husk, sawdust and their mixture were 56% at 465 ℃, 61% at 490℃ and 60% at 475℃ respectively. Analysis with GC-MS and other apparatus indicated that the liquid fuel is a complicated organic compound with low caloric value and can be directly used as fuel oil without any up-grading. As a crude oil, the liquid fuel can be refined to be vehicle oil.

Preparation of fly ash and rice husk ash geopolymer

The geopolymer of fly ash （FA） and rice husk ash （RHA） was prepared. The burning temperature of rice husk, the RHA fineness and the ratio of FA to RHA were studied. The density and strength of the geopolymer mortars with RHA/FA mass ratios of 0/100, 20/80, 40/60, and 60/40 were tested. The geopolymers were activated with sodium hydroxide （NaOH）, sodium silicate, and heat. It is revealed that the optimum burning temperature of RHA for making FA-RHA geopolymer is 690oC. The as-received FA and the ground RHA with 1%-5% retained on No.325 sieve are suitable source materials for making geopolymer, and the obtained compressive strengths are between 12.5-56.0 MPa and are dependent on the ratio of FA/RHA, the RHA fineness, and the ratio of sodium silicate to NaOH. Relatively high strength FA-RHA geopolymer mortars are obtained using a sodium silicate/NaOH mass ratio of 4.0, delay time before subjecting the samples to heat for 1 h, and heat curing at 60oC for 48 h.