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.

The composition of Fusarium species in wheat husks and grains in south-eastern Poland

Fusarium populations were investigated on 53 samples of wheat grains and husks collected approximately three weeks before harvest in 53 wheat fields in south-eastern Poland. A limited area of sample collection was chosen intentionally to avoid the effect of climate and weather variability. The study was conducted to assess the occurrence of 13 Fusarium species using species-specific PCR assays separately on grains and husks of winter wheat. The obtained data suggest that husks could take a protective role of wheat grain against Fusarium spp. The incidence of Fusarium species decreased in grains vs. husks from 29 to 100%. While Fusarium species were present in husks at 11.32% and less, they were absent in the grain. The presence of Fusarium species on husks is inversely proportional to the percentage reduction of Fusarium spp. in grain. There was a correlation of the presence of certain species of Fusarium in husks and in grains. The number of Fusarium species found on husks was about three times higher in comparison to wheat grain. In conclusion, the presented data indicate the importance of Fusarium populations analysis on wheat husk in seeds pathological studies.

Adsorption of Malachite Green from Aqueous Solutions onto Rice Husks: Kinetic and Equilibrium Studies

A study was done to evaluate the removal of a cationic dye from simulated waste water onto rice husks (RH). Spectroscopic methods such as FTIR and SEM/EDX were used for adsorbent characterization. Experimental dependency on solution pH, initial dye concentration, agitation speed, adsorbentparticle size, temperature of the solution and contact time was evaluated. The adsorption data was tested using both Langmuir and Freundlich isotherms. The data fitted well into Langmuir isotherm model with a monolayer adsorption capacity of 6.5 mg/g. Further, the separation factor (RL) value was less than unity indicating a favorable adsorption process. Adsorption kinetics was determined using pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The results showed that the adsorption of malachite green onto rice husks followed pseudo-second-order model with a determination coefficient of 0.986. This work has revealed that rice husks have a great potential to sequester cationic dyes from aqueous solutions and therefore it can be utilized to clean contaminated effluents.

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.

Syngas Production and Losses Encountered in Gasification of Rice Husks

This paper addresses the syngas production and evaluation losses in high temperature gasification process using coffee husks. A fast and inexpensive way to evaluate the losses in gasification processes is by the application mathematical models which allow to predict the values needed in full scale. Hence, the quantification of gasifier’s losses at temperatures ranges of 800 K - 1400 K at an equivalence ratios of 0.3, 0.35 and 0.4 at 1 bar are revealed by using exergy model incorporating a chemical equilibrium model. The model evaluated the product syngas compositions, syngas heating values and degree of irreversibility values (losses). The results from the model showed that the production of H2 increased from 9.9% to 18.9% and the formation of CO2 ranges from 7.2% to 12.3%. CO production is from 21.8% to 17.2%. The irreversibility values obtained were less than 27%. Hence, reduction of losses protracts biomass resources to be used in energy generation.

Pryloysis of Coffee Husks for Biochar Production

Effective utilization of coffee wastes has been a great challenge in Uganda despite their wider use to replenish soil organic matter. This study explored the possibility of producing biochar from coffee husks that could be used as a soil amendment for replenishing soil nutrients and also for enhancement of soil water holding capacity. Pyrolysis of coffee husks was done in a batch bio-reactor under slow pyrolysis conditions of temperatures 350°C - 550°C and residence times 30 - 60 min. For easy characterization, biochar was grinded, sieved through a 1 mm sieve and then analyzed using a computerized Thermo Graphic Analyzer with an inbuilt and integrated ELTRA 84 GmbH Precision Digital weighing scale. Proximate analysis (wet basis) of biochar gave a moisture content of 5.2%, ash content of 14.7%, volatile matter of 13.2% and fixed carbon of 66.9%. Biochar was applied to soil at different rates (0%, 5%, 10% and 20% w/w) and its effect on water holding capacity was investigated. Results show that bio-char amended soils had higher water holding capacity (p ≤ 0.05) compared to biochar free soils. The water holding capacity also increased with increase in biochar amendment with a 1.5% increase in soil water holding capacity for each 1% increase in biochar application rate. Biochar was also rich in soil nutrient elements with 0.96% N, 0.39% P and 1.97% K;this increased the availability of soil nutrients for crop growth. The results suggest that biochar could be a better tool to improve soil conditions thus enhancing the sustainability of agriculture.

Mechanical, Microstructural and Mineralogical Analyses of Porous Clay Pots Elaborated with Rice Husks

This paper deals with the elaboration of porous ceramic pots with raw clay materials and rice husks for water filtration. The basic raw clays have been mixed with rice husks at different ratio 10% and 15% weight (wt) and sintering at 1200&degC, 1300&degC and 1400&degC for 30 minutes. The elaborated pots have been tested for their densification properties and filtration flow. The mineralogy and microstructure of pot have been also studied to explain the different results. The pot with 10% wt rice husks and sintering at 1300&degC during 30 minutes presents a sufficient porosity and mechanical strength to be used for water filtration.

Evaluation of Sawdust and Rice Husks as Fillers for Phenolic Resin Based Wood-Polymer Composites

We produced Wood-Polymer Composites (WPCs) with phenolic resin (PR) filled with saw dust (SD) and rice husks (RH) in a PR:fillerratio of 60:40 wt.%. RH and SD were grinded and sieved into particles μm. The aim of this research work was to evaluate sawdust and rice husks as fillers for sustainable phenolic resin based WPCs. Therefore, we investigated the thermal stability of PR/RH and PR/SD WPCs then we studied and compared the tensile, flexural properties of PR/SD and PR/RH WPCs samples, as well as their dimensional stability after water absorption test. Furthermore, through ultraviolet light exposure, we evaluated the effects of photo-oxidation on the water stability and mechanical properties of PR/RH and PR/SD WPCs samples compared to unexposed ones. PR filled with SD presented better mechanical properties compared to PR/RH WPCs samples. However, PR/RH WPCs showed good mechanical properties, and better thermal resistance and better water repulsion capabilities compared to PR/SD WPCs samples. Although, long time UV exposure ended up lowering considerably the mechanical properties and water resistance of PR/SD and PR/RH WPCs, both RH and SD offer great added value as fillers for PR based WPCs;SD having better interactions with PR matrix compared to RH.

Biosorption of Crude Oil Spill Using Groundnut Husks and Plantain Peels as Adsorbents

Adsorption techniques using meshed groundnut husks and plantain peels have provided cheap alternative to the conventional methods of crude oil spillage control and also for good waste management approach. The biodegradable nature of these adsorbents makes it a better alternative to the non biodegradable synthetic polymers. Dry unripe plantain peels and groundnut husks were used to prepare the adsorbents. The adsorption and percentage removal of crude oil from effluent produce water was dependent on adsorbent dosage, contact time,temperature and particle size. The particle size of the adsorbents should not be less than 150 μm to avoid making the particles so loosed thus posing difficulty in recovery. The two adsorbents exhibit high affinity for oil adsorption with time especially at 75 μm, groundnut husk has a better performance because of its larger surface area and the presence of residual oil in the plantain peels. Agitation at 150 r.min-1 and contact time between 15 - 75 min are recommended. The optimum adsorption temperature ranged between 25°C - 45°C and 15°C - 45°C for groundnut husks and plantain peels respectively. The adsorption data indicated that a pseudo-second- order equation could be used to study the adsorption kinetics of both adsorbents.

Effects of Treatment of Cocoa Pod Husks with Aqueous Ash Extract of Bean Haulms on Growth Performance and Haemato-Biochemical Parameters of Rabbits

Sustainability of animal production system depends mostly on feed used. Therefore, the utilization of agricultural by product is one of the safe ways to attempt this goal. For this end, a study on the level of incorporation of cocoa pod husk on growth performance, haematological and biochemical parameters were carried out. A total of 80 young rabbits composed of 40 males and 40 females with an average weight of 824.30 ± 53.8 g and 826.09 ± 40.61g respectively. There were randomly assigned to 5 experimental rations in a complete randomized designed with 8 rabbits per treatment and each rabbit served as experimental unit. From the control ration R (0-);0% cocoa pod husks and R (0+);20% of untreated hulls, 3 other rations of which three (R1, R2, R3) were formulated with respectively 20%, 25%, and 30% husks treated with ash from bean haulms at concentrations of 12.5 kg/100 litters of water. The results revealed that the initial weight, feed consumption, feed conversion ratio, were not significantly affected (p > 0.05) by the different treatments. However, total weight gain, daily weight gains and final body weight of rabbit fed R1 ration were significantly (p < 0.05) higher (1973.77;23.49;2794.60 g respectively) as compare to other treatment irrespective of sex. Analysis of variance generally revealed a significant effect (p < 0.05) on fasting body weight (2447.43;2476.22;2687.99;2512.52;2425.89 g respectively for rations R0-, R0+, R1, R2 and R3), carcass weight (1270.84 g) and carcass yield (52.37%) was lower for animals feed R3 ration regardless of sex. On the other hand, no significant difference (P > 0.05) was observed in the relative weights of some parts, organs and those of the abdominal fat of the rabbits. Similarly, no significant difference (P > 0.05) was observed for haematological and biochemical parameters studied. Cocoa pod husks treated at 12.5% with bean haulm ash extracts can be incorporated up to 20% - 25% to improve growth performance of rabbits without any negative effect on their health.

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.

Strategies for Fermentable Sugar Production by Using Pressurized Acid Hydrolysis for Rice Husks

This study investigated the use of leftover biomass(rice husks)as the raw material for the biotechnological production of platform chemicals and biopolymers.Following the biorefinery concept,different acid hydrolysates were studied and resulted into a wide range of treatment strategies.Chemometrics were applied throughout the procedures in multivariate experimental conditions.By using the best hydrolytic conditions of 6.0%H3PO4,135oC(45 MPa)and reaction time of 62 min,21.0 g/L sugar hydrolysates were produced;by using the best hydrolytic condition of 4.5%HNO3,135oC/35 min,16.1 g/L sugar hydrolysates were produced;and with the hydrolysates use of 1.5%H2SO4 and 1.5%HCl,135oC/62 min,18.2 and 17.8 g/L sugar hydrolysates were produced,respectively.The highest productivity,in terms of fermentable sugars,reached 68%of integral cellulose/hemicellulose fraction and surpassed those found in the literature,with regard to the processing of rice husks,by considering just one step process.Sulfuric hydrolysate,detoxified with active carbon,was used to prove this proposal viability,resulting in a fermentation substrate for A.terreus(ATCC10020)and R.radiobacter(LMG196)strains(natural producers of bioproducts),which certified the feasibility of the proposal.The production of fermentable sugars from leftover biomass should encourage a search for new bioconversion routes,which can result in economic and environmental benefits and a spread of knowledge.

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.

Waste Shell Husks Concrete: Durability, Permeability and Mechanical Properties

Shell husk is annually produced as a byproduct of shell production in Japan. According to Japanese Ministry of Forestry, Fisheries and Agriculture, the amount of the abandoned shell husk is about 151,000 tons per year. This huge amount of abandoned shell husk is not only thrown away without any commercial return but also causing pollution and environmental problems. To mitigate the pollution and environmental problems, possible utilization of abandoned shell husk is thoroughly observed in concrete construction. Overall response of the mechanical properties of concrete specimens containing different percentage of abandoned shell husk aggregates such as 0, 10%, 0, 30%, 40% and 50% in the ratio of mass is demonstrated. Results of engineering properties such as compressive strength,Young’s modulus, tensile strength, unit weight, water absorption capacity and coefficient of hydraulic conductivity are depicted. It is observed that the use of shell husk in concrete improves strength and durability performance of concrete treated in aggressive sea environments.

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.

Novel Activated Carbon Monoliths for Methane Adsorption Obtained from Coffee Husks

Methane adsorption by different forms of activated carbon obtained from coffee husks, including monolith honeycomb and disc types, was studied by activation with zinc salts and potassium hydroxide at 298.15 K and 303.15 K and pressures up to 30.00 atm in a volumetric adsorption apparatus. We observed increased methane adsorption capacity on a mass basis in the different activated carbon monoliths with increasing surface area, total pore volume and micropore volume, with the honeycomb type displaying the highest methane absorption capacity. The maximum volumetric methane uptake by the synthesised carbon monoliths was observed to be 130 V/V at 298.15 K and 30.00 atm for honeycomb monoliths synthesised with zinc chloride (ZnCl2) and Polyvinyl alcohol (PVA) as the binder. Adsorption calorimetry results were used to describe the interaction between guest molecules and the adsorbent at low surface coverage and the energetic heterogeneous surface nature of the adsorbent.