Walnut Shell Research Articles

Influence of filler content and surface modification on physical and mechanical properties of epoxy/walnut shell particulate composites

The current study aims to examine the influence of treating micro-sized walnut shell particulates (WSP) with an aqueous solution of sodium hydroxide (NaOH) at the varied concentration on the physical and mechanical properties of a newly developed epoxy composite. Three sets of epoxy/WSP composites are prepared, i.e. Set A is for composites prepared with raw WSP, set B and set C is for composites prepared with treated WSP with 2 and 4 moles NaOH aqueous solution, respectively. For each set, four samples are fabricated for different WSP content (5, 10, 15, and 20 wt. %). It has been observed that the density of the composites reduces as the content WSP increases over the entire range of filler content. Against that, the volume of voids increases with WSP loading. Similarly, the water intake of composites also increases with filler loading. Mechanical properties like compressive strength, hardness, tensile and flexural modulus increase as a linear function of filler content whereas, tensile strength and flexural strength increase up to 10 wt. % of filler and decreases thereafter. Further, it is found that when WSP is modified with a 2-moles NaOH aqueous solution improves all the properties under investigation. Though, WSP treated with a 4-mole NaOH aqueous solution slightly deteriorates the properties of the material due to the excess concentration of NaOH.

Liquefaction and chemical composition of walnut shells

AbstractThe cultivation of walnut (Juglans regiaL.) for the exploitation of the fruit has been increasingly recognized worldwide; therefore, it is important to valorize a large amount of biomass from walnut shells (WS), where liquefaction may play an important role. This work intends to contribute to an improved understanding of the best uses for this material. The assays were made with a binary mixture of ethylene glycol and glycerol (1:1 v/v) as solvents, catalyzed by sulfuric acid. The tested parameters were as follows: particle size >0.420–0.177 mm, temperature 140–200°C, and reaction time between 15 and 60 min. The initial dried material, the liquefied material, and the resulting solid residue were analyzed by FTIR-ATR for polyol characterization. The results showed that WS are mostly composed of lignin with 35.0% and polysaccharides, 30.0% cellulose and 24.9% hemicelluloses. High-lignin content indicated that WS might be used as a bio-fuel or adhesives. Extractives represent 10.2% with almost half (4.6%) of polar extractives. The best conditions to attain the optimal liquefaction yield were 160°C, 30 min, and 0.420–0.250 mm particle size, for the tested parameters. FTIR spectrum of the liquefied material is very different from the original material, and solid residue spectra seem to indicate that there is higher liquefaction of polysaccharides when compared with lignin since there is a higher absorption at 1,600 cm−1and lower absorption at 1,040 cm−1and that liquefied compounds are probably in smaller molecules.

Hard Carbons for Use as Electrodes in Li-S and Li-ion Batteries.

Activated hard carbons, obtained from the pyrolysis of various waste biomasses, were prepared and characterized for use as the active material for the fabrication of battery electrodes. The preparation consisted of a pyrolysis process, followed by an activation with KOH and a further high-temperature thermal process. TG and DTA were used to discriminate the steps of the activation process, while SEM, XRD, and Raman characterization were employed to evaluate the effects of activation. The activated carbons were tested as electrodes in lithium-sulfur and lithium-ion batteries. The carbonaceous materials coming from cherry stones and walnut shells have proved to be particularly suitable as electrode components. When used as anodes in lithium-ion batteries, both carbons exhibited a high first cycle discharge capacity, which was not restored during the next charge. After the first two cycles, in which there was a marked loss of capacity, both electrodes showed good reversibility. When used as cathodes in lithium-sulfur batteries, both carbons exhibited good catalytic activity against the redox reaction involving sulfur species with good cycle stability and satisfactory Coulombic efficiency.

ROENCAPSULACIÓN DE Bacillus thuringiensis (BERLINER) EN MATRICES BIOPOLIMÉRICAS CON SECADO POR ASPERSIÓN PARA EL CONTROL DE Hyphantria cunea (DRURY)

<p><strong>Background.</strong> The formulation of agents of biological origin with insecticidal activity is one of the most effective methods for the control of lepidopteran pests due to their feeding forms. The insecticidal activity of <em>B. thuringensis</em> is widely known, which is why it is believed that native strains of this bacillus could have toxic activity on larvae of the cobweb worm, <em>H. cunea</em>. <strong>Objective.</strong> To prepare by means of the spray drying technique microencapsulated formulations of a native strain of <em>B. thuringensis</em> with toxic activity on <em>H. cunea</em>. <strong>Methodology.</strong> The experimental design was completely randomized and the means were compared with the Tukey test (p ≤ 0.05). The strain selected for the formulation is a key Mexican strain GM-10 belonging to the aizawai variety and presented an LC<sub>50</sub> of 0.007 ng cm<sup>-2</sup> in artificial diet, and a LT<sub>50</sub> of 80.83 h. To prepare the formulations, a phago-stimulant was first selected by means of food preference tests with powdered leaves of walnut, blackberry, ash, loquat and walnut shell powder and a commercial phage-stimulant (Coax<sup>®</sup>), and ash was selected with 61.4% of the larvae attracted. Once the phagostimulant was selected, encapsulated formulations were developed with a mixture of polymers (Capsul<sup>®</sup>-bovine gelatin), as a base. Several formulations were then made to select an adhesion additive, and the ingredients tested were guar gum, core<sup>®</sup> gum and xanthan gum. <strong>Results.</strong> Food preference bioassays to establish the affinity of <em>H. cunea</em> for some of the formulations showed that the larvae had a similar affinity for feeding on all formulations (p ≥ 0.05), while in the trials to select an adherent for the formulation xanthan gum presented the best adherence (p ≤ 0.05). <strong>Implications.</strong> The evaluated formulations preserved their toxic activity after microencapsulation with an LC<sub>50</sub> of less than 0.05 ng cm<sup>-2</sup> of <em>B. thuringensis</em>. <strong>Conclusion. </strong>These results show the feasibility of using the spray drying method to obtain an effective formulation for the treatment of the immature stages of <em>H. cunea</em>.</p>

Treatment on thiodicarb in pesticide wastewater with walnut shells-derived carbon and its improved modification: adsorption behavior.

The health problems caused by water pollution cannot be ignored, and the contribution of pesticides to water pollution has also become increasingly unignorable. The modified semi-coke as an adsorbent for reducing pesticide pollution to water was obtained from activated semi-coke which was modified by nitric acid (HNO3). The semi-coke was obtained by carbonization using 60 mesh walnut shell powder. After acid-base deashing, the semi-coke is dipped into zinc chloride (ZnCl2) solution to obtain activated semi-coke. Through BET analysis, the specific surface areas of semi-coke, activated semi-coke and modified semi-coke were 26.8 m2/g, 243.9 m2/g, and 339.6 m2/g respectively. An extremely high adsorption capacity of the adsorbents which is used to treat wastewater was achieved. The optimum adsorption conditions for modified semi-coke on thiodicarb solution were 30 mg/L of thiodicarb solution, adsorbent dosage of 0.01 g, adsorption temperature of 25 °C and adsorption time of 90 min. The optimum adsorption amount of 29.54 mg/gsor was achieved (sor is the abbreviation for sorbent). Moreover, through kinetics study, the result manifests that the modified semi-coke adsorption process is more fitted to the second-order kinetic model. This study provided a research implication theoretically for the treatment of pesticides in water.

Research on Obtaining Biocomposite Structures with Sound Absorbing Properties

The paper addresses the methodology for obtaining biocomposite structures from waste, with sound-absorbing properties, such as: thuja shells, walnut shells, pistachio shells, beech sawdust, pumpkin seeds shells and sunflower seeds shells. The experimental analysis carried out considers the study of the sound-absorbing properties held by the proposed new biocomposite materials, by determining the value of the sound absorption coefficient, reflection coefficient, impedance ratio, using the Kundt tube. The interpretation of the results obtained from the evaluation of biocomposites shows that they have sound-absorbing properties. Consequently, sound-absorbing panels with soundproofing properties can be made from these materials, which can be used in industry, transportation, construction, etc. as well as for decorative purposes in spaces such as cinemas, malls, spas, etc.

Amine-Modified Biochar for the Efficient Adsorption of Carbon Dioxide in Flue Gas

Biochar-based carbonaceous adsorbents are gaining interest due to their high availability, ease of modification, and low cost; however, they show limited adsorption of CO2 in flue gas due to common textural properties. In this study, TEPA-modified biochar was used to prepare a solid amine adsorbent for the efficient capture of CO2 in flue gas. First, the porous biochar was prepared with FeCl3, Mg(NO3)2, and H2O (g) as activators and walnut shells as carbon sources. Next, the biochar was modified with TEPA to obtain a solid amine adsorbent. Porous texture properties and sample surface functional groups were characterized, and we measured the adsorption CO2 of the amine-modified biochar in a breakthrough adsorption device. Results showed that biochar has a large specific surface area (744.38 m2 g−1), a total pore volume of 1.41 cm3 g−1, and a high mesoporous volume ratio (82.7%). The high pore volume provided a more efficient support space for loading tetraethylenepentamine (TEPA). The adsorbent had an excellent CO2 adsorption capacity, corresponding to 2.82 mmol g−1, which increased to 3.31 mmol g−1 and kept water resistance at 10% H2O (g) simulated flue gas (SFG). The FTIR analysis showed that H2O (g) inhibited urea production after cyclic adsorption. Therefore, solid amine adsorbent created by amine-modified biochar has potential advantages in its application for capturing CO2 in SFG.

Eggshell and Walnut Shell in Unburnt Clay Blocks

Agricultural residues/by-products have become a popular choice for the manufacturing of building materials due to their cost-effectiveness and environmental friendliness, making them a viable option for achieving sustainability in the construction sector. This study addresses the utilisation of two agro-wastes, i.e., eggshell and walnut shell, in the manufacture of unburnt clay blocks. The experiments were carried out on three series of samples in which first eggshell (10–50%) and walnut shell (5–20%) were incorporated individually and then combined (5% walnut, 10–30% eggshell) in the mixture to assess their influences on the physical and mechanical properties of the unburnt clay blocks. This study performed the following tests: Density, capillary water absorption, linear shrinkage, flexural and compressive strength. The results indicated that eggshell enhanced the strength relative to the control sample when the materials were employed individually, but walnut shell lowered it. Moreover, combining the two materials in the mixer reduced the strength of the samples even further. Nevertheless, the inclusion of the waste materials decreased the density, capillary water absorption coefficient and linear shrinkage of the samples. The findings indicate that eggshell has great potential for unburnt clay block manufacture. However, walnut shell integration needs further research.

Development of infusion tea formulations with food wastes: Evaluation of temperature and time effects on quality parameters

The study aimed to investigate the suitability of some food wastes for use in the production of herbal tea and to reveal their properties in terms of bioactive component content, some physical properties and sensory quality. Three new blends consisting of banana, pomegranate, mandarin, eggplant and red onion peels, walnut shell, cherry stalk and corn tassel were infused at different temperatures (70 and 100 °C) and time (3, 4 and 5 min). Corn tassel tea, which has a high phenolic component content (677.7 mg GAE/L), received less sensory acceptance due to its bitter aftertaste. Therefore, walnut shell tea containing moderate phenolic content was the most preferred tea blend. Significant effects of different infusion temperatures and times on the color indices of teas were also demonstrated. The sensory properties of samples infused for 3 min were more acceptable. The highest correlation coefficients were calculated between total phenolic compounds and subjective odor parameters. Utilization of mandarin, pomegranate, banana, eggplant and red onion peels, walnut shell, corn tassel and cherry stalk in formulating a functional and an alternative food product can be attractive to consumers and industrial producers due to their affordability and high bioactivity.

Strategic valorization of bio-oil distillation sludge via gasification: A comparative study for reactivities, kinetics, prediction and ash deposition

Biomass refinery system is gradually maturing as an emerging technology for waste management and carbon neutral, but bio-oil distillation sludge (DS) as an unexpected product significantly hampers the continuous operation of the system and hazards human health. Herein, we conducted a comparative investigation on the gasification characteristics of bio-oil distillation sludge char (DSc) and walnut shell char (WSc) to explore the clean and efficient strategy for disposal of DS. The biochar was prepared on a fixed bed reactor under two different temperatures (900 °C and 1100 °C), followed by being gasified on a thermogravimetric analyzer with the purposes of evaluating the gasification behaviors and kinetic evolution. Meanwhile, machine learning approach (back-propagation neural network as an example) and thermodynamic equilibrium simulations were innovatively adopted to predict the gasification performances and ash deposition characteristics, respectively. The results indicated the gasification reactivities for WSc varied with gasification conditions and preparation temperatures, whereas the DSc reactivity was far lower than that of WSc. Gasifying WSc accompanied with the development of porous structures and thus was kinetically fitted by random pore model well. However, the gasification process for DSc was more representative by volume model and grain model. The back-propagation neural network performed an excellent prediction effect on gasifying DSc and WSc under whatever (non–)isothermal conditions, with the correlation coefficients beyond 0.9983. In addition, mineral compositions and ash deposition prediction indicated the presence of potassium and calcium in WSc induced the decreased melting temperatures of ash, and thus severe ash slagging and fouling, while DSc ash, composed of iron and silicon, exhibited flocculent morphology and was difficult to deposit.

Efficient desalination system for brackish water incorporating biomass-derived porous material

BackgroundCapacitive deionization (CDI) is a recent advancement to monitor massive reverse osmosis (RO) reject concentrate. With the conventional material activated carbon developed from biomass, surface modifications and composite materials have improved surface properties. MethodTherefore, with the green motive to re-use agro-waste, the walnut shell powder was calcined (WSAC), which was modified with potassium hydroxide (K-WSAC), incorporated with iron nanoparticles (Fe@Nanoparticle) and iron-copper nanoparticles (FeCu@Nanoparticle) for fabricating CDI electrodes. FindingsDeveloped electrodes were electrochemically characterized, revealing the specific capacitance of 97.5 F/g and implemented for deionizing the RO concentrate. The FeCu@Nanoparticles electrodes showed the best desalination performance of 89.8% removal with an initial concentration of 1000 ppm at an electro-sorption time of 20 min exhibiting a salt sorption rate of 1.21 mg/g min. The economics of the system was evaluated, revealing the least energy consumed system of 0.5 kWh m−3. FeCu@Nanoparticles electrodes were implemented to treat real samples from commercial and domestic drinking water systems and groundwater samples, resulting in positive outcomes. Therefore, the investigation revealed that WSAC based electrodes resulted in the development of an excellent desalination system.

Utilization of corncob as adsorbent to remove oil and grease from produced water

The hazardous composition of produced water (PW) places it as a dangerous contamination agent, which must be treated to meet environmental and operational requirements before disposal, reuse, or reinjection. The current work evaluated an adsorption treatment using raw and pretreated corncob samples to remove total oil and grease (TOG) from PW. The influence of adsorbent dosage (1.0, 2.5, and 5.0 g), particle size (0.5, 1.0, and 2.0 mm), and contact time (60, 120, and 240 min) were tested in a batch system, showing that the lowest oil concentration was achieved with the smallest particle size (0.5 mm) and highest contact time (240 min) and adsorbent dosage (5.0 g). Using a 20 cm secondary partition in the fixed-bed column system was more efficient for TOG removal than a 10 cm one: the raw corncob removed 85.23% of TOG against 17.41% pretreated biomass. Comparative studies showed that the adsorption performance of untreated corncob was superior to that observed for walnut shells (69%), a widely used commercial absorbent. Results indicated corncob’s environmental and economic potential as a natural and cost-effective adsorbent.

Mineral carbonation of thermally treated and weathered biomass ashes with respect to their CO2 capture and storage

Five long-term stored biomass ashes (BAs) from beech wood chips, corn cobs, sunflower shells, plum pits, and walnut shells produced at 500 °C were thermally treated at 900 °C and subsequently weathered to evaluate their CO2 capture and storage (CCS) potential by mineral carbonation. A combination of different mineralogical, chemical and thermal analyses was used for that purpose. The BAs studied are highly enriched in alkaline-earth and alkaline oxides (52–91%) and they belong to diverse chemical ash types. The minerals responsible for CCS of these BAs include Ca, K, K-Ca and Ca-Mg carbonates and bicarbonates such as calcite, fairchildite, kalicinite, dolomite, and butschliite. The formation of these minerals is a result of interactions between alkaline-earth and alkaline oxyhydroxides in BA and flue CO2 gas during residual char combustion and especially atmospheric CO2 during BA storage and weathering. It was found that the BAs studied show significant CCS capacity, namely about 19–33% (mean 27%). It was emphasized that the renewable and carbon-neutral biomass also has some extra CCS potential due to the sequestration of atmospheric CO2 during BA storage and weathering. Therefore, the future large-scale bioenergy production in a sustainable way can contribute greatly for decreasing CO2 emissions in the atmosphere and can reduce the use of costly CCS technologies.

Study of alkali metals and alkaline earth metals in chlorobutyl rubber-based model truck inner tube compound

This paper describes the effects of various alkali metal and alkaline earth metal compounds, as well as walnut shell ash (WNS ash), on the cure characteristics (ts2, tc90) of a chlorobutyl rubber (CIIR)-based heat resistance truck inner tube compound. We observed that CIIR-F (KOH) has a very high scorch safety and a very slow cure. As it is a strong base with a high pH (13.84), it cures very slowly. Despite having a pH of 10.6, a ts2 of 6.36, and a tc90 of 18.84 min, CIIR-D (CaCO3) cures faster than CIIR-A (blank). The ts2 and tc90 values for CIIR-A (blank) were 6.55 and 18.88 min, respectively. Except for CIIR-D (CaCO3), all of the materials used to have higher scorch safety (ts2) and optimum cure time (tc90) in rheometer than CIIR-A (blank). CIIR-C (BaCO3) performed nearly as well as a blank. This study revealed that the trend of cure characteristics (ts2, tc90) in rheometer and Mooney scorch (t5) in Mooney viscometer not only depends on pH but also depends on ionic radius, ionization enthalpy and oxidation number of alkali metal and alkaline earth metal and the type of compound of alkali metal and alkaline earth metal.

Characterization of the hierarchical architecture and micromechanical properties of walnut shell (Juglans regia L.)

In the present work a comprehensive characterization of the hierarchical architecture of the walnut shell (Juglans regia L.) was carried out using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Furthermore, micromechanical properties (hardness, HIT and elastic modulus, EIT) of plant tissues were evaluated at cell wall level by applying the instrumented indentation technique (IIT). The complex architecture of the material was described in terms of four hierarchical levels (HL): endocarp (H1), plant tissues (H2), plant cells (H3) and cell wall (H4). Our findings revealed that the walnut shell consists of a multilayer structure (sclerenchyma tissue, ST; interface tissue, IT; porous tissue, PT; and flattened parenchyma tissue, FPT), where differences in the microstructure and composition of plant tissues generate parallel gradients along the cross-section. The indentation tests showed a functional gradient with a sandwich-like configuration, i.e., a lightweight and soft layer (PT, HIT = 0.04 GPa) is located between two dense and hard layers (ST, HIT = 0.33 GPa; FPT, HIT = 0.28 GPa); where additionally there is an interface between ST and PT (IT, HIT = 0.16 GPa). This configuration is a successful strategy designed by nature to improve the protection of the kernel by increasing the strength of the shell. Therefore, the walnut shell can be considered as a functionally graded material (FGM), which can be used as bioinspiration for the design of new functional synthetic materials. In addition, we proposed some structure-property-function relationships in the whole walnut shell and in each of the plant tissues.

Porous structure of carbon materials obtained from the shell of walnuts

Samples of porous carbon material (PCM) were obtained by carbonization of the feedstock (walnut shells). Small-angle X-ray scattering (SAXS) was used to study the porous structure of the obtained carbon materials. The fractal dimension of the surface increases and significant changes are observed in the distribution of the pore volume of the PCM samples with an increase in the carbonization temperature of the initial feedstock, which is especially pronounced for the sample obtained at 700 °C. It is shown that PCM obtained at 400-700 °С are macroporous materials, the maximum porous volume corresponds to pores with radius R ≈ 30 nm, and samples obtained at 700-1000 °C are mesoporous with R ≈ 5 nm. The characteristics of the porous structure of the obtained materials were calculated on the basis of isotherms of low-temperature adsorption-desorption of nitrogen and it was shown that the carbonization temperature significantly affects the specific surface area and pore volume of PCM. It was determined that to obtain of PCM with an optimal ratio of micro- and mesopores, the temperature is 800 °C, at which the specific surface area of the carbon material is 238 m2/g with an average pore diameter of 2.2 nm.

Temperature and Moisture Dependent Dielectric and Thermal Properties of Walnut Components Associated with Radio Frequency and Microwave Pasteurization.

To provide necessary information for further pasteurization experiments and computer simulations based on radio frequency (RF) and microwave (MW) energy, dielectric and thermal properties of walnut components were measured at frequencies between 10 and 3000 MHz, temperatures between 20 and 80 °C, and moisture contents of whole walnuts between 8.04% and 20.01% on a dry basis (d.b.). Results demonstrated that dielectric constants and loss factors of walnut kernels and shells decreased dramatically with raised frequency within the RF range from 10 to 300 MHz, but then reduced slightly within the MW range from 300 to 3000 MHz. Dielectric constant, loss factor, specific heat capacity, and thermal conductivity increased with raised temperature and moisture content. Dielectric loss factors of kernels were greater than those of shells, leading to a higher RF or MW heating rate. Penetration depth of electromagnetic waves in walnut components was found to be greater at lower frequencies, temperatures, and moisture contents. The established regression models with experimental results could predict both dielectric and thermal properties with large coefficients of determination (R2 > 0.966). Therefore, this study offered essential data and effective guidance in developing and optimizing RF and MW pasteurization techniques for walnuts using both experiments and mathematical simulations.

Characterization and adsorption capacity of four low-cost adsorbents based on coconut, almond, walnut, and peanut shells for copper removal

Characterization and adsorption capacity of four low-cost adsorbents based on coconut, almond, walnut, and peanut shells for copper removal

Pyrolysis of lignocellulosic and algal biomasses in a fixed‐bed reactor: A comparative study on the composition and application potential of bioproducts

The pyrolysis of six biomass samples consists of Rice husk (RH), Coconut shell (CS), and Walnut shell (WS) as lignocellulosic biomasses and Cladophora glomerata (CG), Gracilaria gracilis (GG), and Azolla filiculoides (AF) as algal biomasses were investigated at a constant operating condition in a fixed-bed reactor. The effect of biomass biochemical structure on the yields and composition of pyrolysis products and their potential for future applications were discussed. CS, AF, and CG showed respectively the highest yield of bio-oil (50.25 wt%), biogas (33.70 wt%), and biochar (40.21 wt%). WS, AF, and RH-derived gas products had a medium level of LHV (10-13 MJ/Nm3), and CG and GG algae samples had a very suitable H2/CO ratio close tow. Characterization of bio-oils showed that CS, WS had a high content of hydrocarbon components (23.5%, 17.6%, and 17%, respectively), and phenols (35.3% and 35.6%, respectively). Furthermore, useful nitrogen-containing components such as pyridine, nitrile, indole, and derivatives were detected in algae bio-oils. Biochar characterization showed the highest surface area and total pore volume for AF. Also, CG's biochar with a high concentration of carboxylic and carbonyl groups in their structure may be suitable for absorbing water and soil contaminants.

Nickel behavior as affected by various physical-chemical modified biochars of cypress cones in a calcareous nickel-spiked soil

ABSTRACT This study aimed to investigate the effects of cypress cone biochar (RB) and its modifications (chitosan-coated biochar (CB), acid-modified biochar (AB), alkali-modified biochar (ALB), humic acid-coated biochar (HB), walnut shell residue extraction-coated biochar (WB), ball-milled biochar (BMB)) on the behavior of nickel (Ni) in Ni-spiked calcareous soil. The biochars were added separately to the soil at the rates of 1.5% and 3%, and the Ni behavior was investigated using methods of desorption kinetics and sequential extraction. The modification process significantly changed the specific area and functional groups of BMB, CB and HB compared to RB. Application of CB (26.3%), HB (28.7%), ALB (28.8%), BMB (30.7%), AB (31.9%) and RB (32.6%) showed the most effects on reduction of Ni mobility factor compared to control soil sample (38.8%). The results of Ni desorption showed high effectiveness of CB, BMB, ALB and HB, in reducing the Ni release compared to the control soil sample. Overall, our findings indicated that among the modified biochars, BMB, CB and HB showed a good performance in Ni stabilization, due to the simple and low-cost process of physical modification. BMB can be suggested as a suitable amendment for soil Ni immobilization.