Ground Walnut Shell Research Articles

One-step synthesis of magnetic biochar via co-pyrolysis of walnut shells and Fe-rich mine tails for adsorption capacity improvement of polystyrene sulfonate microplastics: Role of microplastic size

Microplastics made of polystyrene sulfonate microplastics (PSMPs) are highly mobile in aquatic ecosystems and can consequently lead to undesirable health effects in humans. Herein, the adsorption capacity of PSMPs was comprehensively analyzed using untreated biochar made from ground walnut shells (WSB) and iron (Fe) engineered WSB acquired from Fe-mining waste (Fe-WSB), to explore the changes in the adsorption potential and mechanisms by the co-pyrolysis of walnut shells and Fe-rich mine tailings. The adsorption of PSMPs for Fe-WSB (adsorption capacity (Qe) = 0.77–6.75 mg/g) was greater than that for WSB (Qe = 0.27–0.79 mg/g), particularly at lower pH levels, indicating that Fe integration and electrostatic interaction between Fe-WSB and PSMPs significantly affected the adsorption of PSMPs. The R2 values for adsorption kinetics and isotherms highlighted that chemisorption plays a fundamental role in PSMP adsorption using WSB and Fe-WSB in liquid solutions. Further, thermodynamic assessments indicated that PSMP210 (210 Da), PSMP10 K (10,000 Da), and PSMP32 K (32,000 Da) were adsorbed exothermically, with the adsorption efficiency decreasing as van der Waals forces became weaker at high temperatures. The results of X-ray photoelectron spectroscopy, which was conducted on WSB and Fe-WSB both before and after the adsorption of PSMPs, supported the notion that an enhancement in the primary adsorption mechanism (electrostatic interactions, pore-filling effects, π-π and H-bond interactions), following the integration of Fe-oxides onto the WSB surfaces, improved the adsorption of PSMPs in aqueous environments.

Physico-mechanical and energy properties of pellets made from ground walnut shells, coniferous tree cones and their mixtures

The aim of this study was to verify the possibility of obtaining good-quality pellets from mixtures of materials with different particle structures and shapes. The paper describes the pressure agglomeration of ground walnut shells and coniferous tree cones as well as their three mixtures. The process involved the production of pellets with a diameter of 6 and 8 mm at the temperatures of 95 and 120°C by applying the force of 5 and 6 kN. The fraction distribution of the particles from which the pellets were made was assessed. It was found that the pellets made only of cones, as opposed to those made only of nutshells, have a fairly even distribution, i.e. the particles were of similar size. The size parameters of the pellets (length and diameter) were measured, on the basis of which the density of individual pellets was calculated. Compressive stresses of the pellets were tested on an endurance testing machine. It was found that the pellets with a greater share of nut shells were less durable than those made with the addition of ground cones. The pellets with a diameter of 6 mm and formed at a temperature of 120°C also showed a higher strength than those with a diameter of 8 mm and compacted at a temperature of 95°C. Increasing the force did not statistically significantly improve the compressive strength of the pellets. Tests of the elemental composition and the amount of ash allowed for concluding that pellets are a good energy material, as evidenced by their average calorific value of about 19 MJ kg−1. Due to exceeding the permissible limit of nitrogen content (ISO 17225), the pellets made solely of cones were classified as quality class B, while the addition of ground walnut shells shifted them to class A2.

The Potential Application of Starch and Walnut Shells as Biofillers for Natural Rubber (NR) Composites.

The goal of this study was application of corn starch and ground walnut shells in various amounts by weight as biofillers of natural rubber (NR) biocomposites. Additionally, ionic liquid 1-butyl-3-methylimidazolium chloride (BmiCl) and (3-aminopropyl)-triethoxysilane (APTES) were used to increase the activity of biofillers and to improve the curing characteristics of NR composites. The effect of biofillers used and their modification with aminosilane or ionic liquid on the curing characteristics of NR composites and their functional properties, including crosslink density, mechanical properties in static and dynamic conditions, hardness, thermal stability and resistance to thermo-oxidative aging were investigated. Starch and ground walnut shells were classified as inactive fillers, which can be used alternatively to commercial inactive fillers, e.g., chalk. BmiCl and APTES were successfully used to support the vulcanization and to improve the dispersion of biofillers in NR elastomer matrix. Vulcanizates with starch, especially those containing APTES and BmiCl, exhibited improved tensile properties due to the higher crosslink density and homogenous dispersion of starch, which resulted from BmiCl addition. NR filled with ground walnut shells demonstrated improved resistance to thermo-oxidative aging. It resulted from lignin present in walnut shells, the components of which belong to polyphenols, that have an antioxidant activity.

An Investigation of the Ground Walnut Shells’ Addition Effect on the Properties of the Fly Ash-Based Geopolymer

The development of geopolymers is in line with the requirements of sustainable development. Creating a new type of material from various industrial and bio-based wastes and by-products can lead to reduced energy consumption, reduced waste generation, reduced global CO2 emissions, as well as reduced resource extraction of natural resources. In this study, geopolymer composites based on class F fly ash with the addition of fine quartz sand and ground walnut shells used as a substitute for sand were examined. The study focused on investigating the effects of different weight percentages of ground walnut shells and quartz sand on the density and strength properties, including compressive and flexural strength, thermal conductivity, efflorescence formation, and water absorption of the fly ash-based geopolymer composites. The microstructure of the studied geopolymers was also analyzed using a scanning electron microscope (SEM). It was observed that the addition of ground walnut shells contributes to the decrease in density and mechanical properties, increase in absorption properties, and decrease in porosity of fly ash-based geopolymers. Furthermore, the addition of ground walnut shells allows for a significant reduction in efflorescence on the surface of the tested geopolymer composites. Moreover, partial or complete replacement of sand by ground walnut shells in geopolymer composites based on fly ash allows for a significant reduction in their thermal conductivity, which makes it possible to use these composites as insulation materials.

Synthesis of Fe/Mg-Biochar Nanocomposites for Phosphate Removal.

Magnetic biochar derived from agricultural biomass has been recognized as a cost-effective biochar sorbent for phosphate removal. This study evaluated the use of novel Fe/Mg-biochar nanocomposites (WBC1x), prepared by impregnating ground walnut shell in a solution with a different molar ratio of Fe2+ to Mg2+, then pyrolyzing slowly, at a temperature of 600 °C, to remove phosphate. The results showed that MgO and Fe3O4 were loaded onto the biochar successfully through the impregnation-pyrolysis method and the composites were able to be separated easily by magnetic field. Meanwhile, a higher surface area and point of zero charge on WBC1x were observed compared to the non-magnetic biochar (WBC). Moreover, the isothermal adsorption and kinetics data further suggested the that phosphate adsorption onto WBC1x resulted from chemisorption. Additionally, the maximum phosphate adsorption capacity of WBC1x was 6.9 mg.g−1, obtained though the Langmuir–Freundlich model, which was threefold higher than WBC, where MgO addition could enhance the adsorption capacity of WBC1x markedly by improving the surface charge.

Investigation of filtration properties and microbiological characteristics of sewage sludge after physical conditioning with the use of ground walnut shells

In this research, ground walnut shells were used in order to improve the sewage sludge treatment. The influence of walnut shells on capillary suction time (CST); the sludge moisture content (MC), bound water (BW), the specific resistance to filtration (SRF) as well as the total bacteria number was investigated. The results have shown that the addition of ground walnut shells into sewage sludge affected the reduction of total bacteria count and the improvement of sewage sludge dewaterability. The addition of ground walnut shells in the amount of approximately 200% of sewage sludge dry mass (DS) decreased the MC by 66%, CST by 68% and SRF by 64%. The total bacteria number was reduced by approximately 88% after physical conditioning with the use of walnut shells in a dosage of 200% DS. It was proved that walnut shells might be considered as a material assisting the sewage sludge treatment.

Chemical modification of cellulose for boron sorption from water solutions

Abstract It is shown that natural cellulose obtained from the walnut shell (Juglans regia) can be used for chemical modification of the selective boron sorbent. The modification was carried out by the coupling technique of chlorine derivatives of the polyhydric alcohols or polyols (mannitol, xylitol, sorbitol or glycerol). In this case new hybrid substances (sorbents) were obtained and they are represented by the formula: R-O-(CHOH)n-CH3, where R is a residue of the cellulose backbone, n is the number of functional (OH) groups of the polyhydric alcohols. The pulp mercerization was carried out by processing the ground walnut shell (WS) with hot solution of sodium hydroxide. Chlorination of polyhydric alcohols was carried out by gaseous hydrochloric acid sparging through the polyhydric alcohol aqueous solution. The coupling process proceeds according to the mechanism of substitution of the cellulose hydroxyl groups with chlorine atoms.

Evaluation of highly filled epoxy composites modified with walnut shell waste filler

Epoxy composites modified with ground walnut shell used as organic waste fillers were prepared and examined. Post-agricultural waste materials after grinding were characterized by evaluation of grain size distribution and structure observations realized using scanning electron microscope (SEM). The influence of filler addition on the mechanical properties of epoxy-based composites was determined by: static tensile test, Charpy impact test, and ball indentation hardness measurements. Composite samples containing 20, 30, 40, and 50 wt% of walnut shell were characterized by increased stiffness and hardness in comparison to the unmodified resins. Moreover, the incorporation of the filler resulted in a decrease of composite material tensile strength and impact resistance. Thermo-mechanical properties of the composites were investigated by dynamic mechanical thermal analysis (DMTA). Results obtained from DMTA tests showed a growth in the composites’ stiffness at elevated temperatures as a function of the increasing natural filler content. The material characterization was supplemented by thermal stability evaluation realized by thermogravimetric analysis (TGA). It was found that the incorporation of ground walnut shell led to an improved thermal stability of composite materials. The analysis of the change in composite material properties, caused by natural filler incorporation, was complemented by material microstructure observations.

Biobased polyurethane foams modified with natural fillers

Two biopolyols have been synthesized from rapeseed oil and applied to obtain rigid and flexible polyurethane foams. Biopolyols were prepared using a two-step method of epoxidation and opening of the oxirane rings. It was found that, regardless of the type of prepared foams, the addition of biopolyols to the polyurethane composition reduces its reactivity, which was confirmed by changes of the dielectric polarization, as well as the reduction of the maximum temperature in the foam core during the foaming process. In the case of the rigid polyurethane polyol, biomodification caused a decrease of the apparent density of the foams, but the foam involving biopolyol had a higher compressive strength. An increase of added ground walnut shells in rigid polyurethane foams also improved their mechanical properties. The introduction of a biopolyol based on rapeseed oil and ultra-fine cellulose to the polyurethane formulation resulted in high resilience flexible foams with improved comfort factor.

Acoustic fluidized bed hydrodynamics characterization using X-ray computed tomography

Acoustic vibration in a fluidized bed can be used to enhance the fluidization quality of particulate matter; this particular noninvasive method provides no internal changes to the bed material structure. However, due to the complexity of this multiphase flow system, characterizing the hydrodynamics of a fluidized bed has become critical in understanding this system behavior. The local void fraction behavior in a cold flow 3D fluidized bed with and without acoustic intervention is investigated in this research. Several noninvasive techniques like gamma-ray computed tomography (GRT), X-ray computed tomography (XCT), or electrical capacitance tomography (ECT), can be used to study the void fraction distribution in multiphase flow systems. In this study, XCT imaging is used to determine the time-average local void fraction or gas holdup. Experiments are implemented in a 10.2cm ID fluidized bed filled with glass beads or ground walnut shell, having a material density of 2500kg/m3 and 1440kg/m3, respectively, and particle size ranges between 212 and 600μm. In this study, three different bed height-to-diameter ratios are examined: H/D=0.5, 1 and 1.5. The loudspeaker’s frequency, used as the acoustic source, is fixed at 150Hz with a sound pressure level of 120dB for glass beads, and 200Hz and 110dB for ground walnut shell. Local time-average gas holdup results show that the fluidized bed under the presence of an acoustic field provides a more uniform fluidization, the bed exhibits less channeling, and the jetting phenomena produced by the distributor plate is less prominent when compared to no acoustic field. Thus, acoustic intervention affects the local hydrodynamic behavior of the fluidized bed.

Comparisons of Annular Hydrodynamic Structures in 3D Fluidized Beds Using X-Ray Computed Tomography Imaging

Fluidized beds are common equipment in many process industries. Knowledge of the hydrodynamics within a fluidized bed on the local scale is important for the improvement of scale-up and process efficiencies. This knowledge is lacking due to limited observational technologies at the local scale. This paper uses X-ray computed tomography (CT) imaging to describe the local time-average gas holdup differences of annular hydrodynamic structures that arise through axisymmetric annular flow in a 10.2 cm and 15.2 cm diameter cold flow fluidized bed. The aeration scheme used is similar to that provided by a porous plate and hydrodynamic results can be directly compared. Geldart type B glass bead, ground walnut shell, and crushed corncob particles were studied at various superficial gas velocities. Assuming axisymmetry, the local 3D time-average gas holdup data acquired through X-ray CT imaging was averaged over concentric annuli, resulting in a 2D annular and time-average gas holdup map. These gas holdup maps show that four different types of annular hydrodynamic structures occur in the fluidized beds of this study: zones of (1) aeration jetting, (2) bubble coalescence, (3) bubble rise, and (4) particle shear. Changes in the superficial gas velocities, bed diameters, and bed material densities display changes in these zones. The 2D gas holdup maps provide a benchmark that can be used by computational fluid dynamic (CFD) users for the direct comparisons of 2D models, assuming axisymmetric annular flow.

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Fluidized beds are being used in practice to gasify biomass to create producer gas, a flammable gas that can be used for process heating. However, recent literature has identified the need to better understand and characterize biomass fluidization hydrodynamics, and has motivated the combined experimental-numerical effort in this work. A cylindrical reactor is considered and a side port is introduced to inject air and promote mixing within the bed. Comparisons between the computational fluid dynamics (CFD) simulations with experiments indicate that three-dimensional simulations are necessary to capture the fluidization behavior of the more complex geometry. This paper considers the effects of increasing side port air flow on the homogeneity of the bed material in a 10.2 cm diameter fluidized bed filled with 500-600 μm ground walnut shell particles. The use of two air injection ports diametrically opposed to each other is also modeled using CFD to determine their effects on fluidization hydrodynamics. Whenever possible, the simulations are compared to experimental data of time-average local gas holdup obtained using X-ray computed tomography. This study will show that increasing the fluidization and side port air flows contribute to a more homogeneous bed. Furthermore, the introduction of two side ports results in a more symmetric gas-solid distribution.

Bed height and material density effects on fluidized bed hydrodynamics

Characterizing the hydrodynamics of a fluidized bed is of vital importance to understanding the behavior of this multiphase flow system. Minimum fluidization velocity and gas holdup are two of these key characteristics. Experimental studies addressing the effects of bed height and material density on the minimum fluidization velocity and gas holdup were carried out in this study using a 10.2 cm diameter cylindrical fluidized bed. Three different Geldart type-B particles were tested: glass beads, ground walnut shell, and ground corncob, with material densities of 2600, 1300, and 1000 kg/m 3, respectively. The particle size range was selected to be the same for all three materials and corresponded to 500–600 μm. In this study, five different bed height-to-diameter ratios were investigated: H/ D=0.5, 1, 1.5, 2, and 3. Minimum fluidization velocity was determined for each H/ D ratio using pressure drop measurements. Local time-average gas holdup was determined using non-invasive X-ray computed tomography imaging. Results show that minimum fluidization velocity is not affected by the change in bed height. However, as the material density increased, the minimum fluidization velocity increased. Finally, local time-average gas holdup values revealed that bed hydrodynamics were similar for all bed heights, but differed when the material density was changed.

Local time-averaged gas holdup in a fluidized bed with side air injection using X-ray computed tomography

Local time-averaged gas holdup in a 10.2 cm diameter fluidized bed is determined using X-ray computed tomography (CT) over a range of superficial gas velocities ( U g), side air injection flow rates ( Q side), and fluidized bed material. Without side air injection, only small variations in the local time-averaged gas holdup are observed for beds composed of glass beads, ground walnut shell, or ground corncob. With the introduction of side air injection, which simulates the immediate volatilization of biomass in a fluidized bed gasifier, a distinctive plume is observed along the reactor wall above the side injection port. The plume gradually expands toward the center of the bed as height increases; the expansion is found to increase with increasing Q side. As U g increases, fluidization becomes more uniform and the effect of the side air injection on the fluidization hydrodynamics is less pronounced. Additionally, increasing U g increases overall gas holdup and bed expansion. Of the three bed materials examined, ground corncob fluidization is the least affected by side air injection and shows the highest overall gas holdup while glass bead fluidization is much more affected by side air injection and has the lowest overall gas holdup. This study demonstrates the usefulness of X-ray CT in noninvasively visualizing detailed internal features of fluidized beds. These results will be used in future studies to validate computational fluid dynamics (CFD) models of fluidized beds.

Preparation of activated charcoal from walnut shells

The proximate, group, and ultimate analysis of walnut shells was performed from the standpoint of their applicability as a raw material for the production of activated charcoal. It was found that the composition of walnut shells was close to that of birch wood, which is used for the manufacture of BAU and OU activated charcoals. Dried and ground walnut shells can be used as a raw material for the production of activated charcoal by carbonization followed by the steam-gas activation of the carbonization products. It was found that the adsorption activity of activated charcoal increased with the combustion loss of the carbonization products.

Two-phase measurements of saltating turbulent boundary layer flow

Mean wind and particle speed measurements as functions of heigh were made for a saltating turbulent boundary layer flow. An exponential dependence of particle flux with height above the surface was found independent of windspeed and particle size. Particle-speed distributions as functions of height above the surface were measured for experiments conducted at two ambient pressures: atmospheric pressure and approximately 1% atmospheric pressure. The wind was shown to be a more efficient mover of particles at atmospheric pressure. High-speed motion pictures of saltating ground walnut shells (of diameter 500–1500 μm and density 1.1 g/cm 3) were taken in an environmental wind tunnel to simulate the planetary boundary layer. These experiments verify the existence and magnitude of particle spin rates proposed by White & Schulz (1977). There was remarkable agreement between numerical trajectory solutions, including the spin effect, and the filmed trajectories. An observation was made that not all particles spin exclusively in the vertical longitudinal plane (in the direction of flow). At low pressures (0.6 kPa) the effect of spin forces on the particle's trajectory was shown to have little influence and was verified by a theoretical force ration balance of spin to drag force.

Electroless Nickel Sand Consolidation: Laboratory Studies of Cementation and Calculated Effect on Well Productivity

Abstract The electroless consolidation of formation sand with the catalytic plating of nickel from aqueous solution provides a flexible alternative to "plastic" or resin sand consolidation in certain cases. A shut-in period (required for resin curing) is not needed, stronger bonding is achieved, and the consolidation is suitable for exposure to temperatures far beyond the range of plastic sand consolidations. The character of laboratory-consolidated cores is described, with emphasis on the permeability, porosity, and compressive strength attained. A model of the influence of nickel sand consolidations on well productivity is presented to show that very little productivity is presented to show that very little impairment is to be expected. Introduction Electroless nickel plating for sand consolidation was perfected in the latter half of the 1960's. A general description of the plating process and deposit properties is available in Ref. 1. Design procedures properties is available in Ref. 1. Design procedures for consolidation, along with a description of system chemistry, is provided in Ref. 2, a companion to this paper. The process involves injecting a catalyst that paper. The process involves injecting a catalyst that activates the sand and then injecting various aqueous solutions of nickel salts containing a chemical reducing agent. The metal layer deposits spontaneously on the sand grains, binding them into a consolidated mass. Although originally developed for higher-temperature applications up to about 550 degrees, far beyond the useful range of plastic sand-consolidation treatments, electroless nickel sand consolidations are available for the full range of reservoir temperatures. Nickel-consolidated sands exhibit compressive strengths much higher than organic cementing materials, with the strength highest near the wellbore, and require no curing time. Furthermore, since consolidation permeabilities depend strongly on nickel content, the placement tends to be self-regulating. Zones of initially higher permeability tend to be brought to the same level as permeability tend to be brought to the same level as the bulk of the formation to be treated; consequently, placement becomes more uniform. placement becomes more uniform.Electroless nickel plating has successfully consolidated a wide variety of materials, ranging from 700-micron ground walnut shells, to glass beads of all sizes, through fine, high-clay-content sands, as well as the typical Gulf Coast formation sands. Job design primarily depends on the specific surface area of the material to be plated and on the plating temperature. A variety of chemical systems plating temperature. A variety of chemical systems are available, depending on the application in question. Yet, even with significant uncertainty in the design parameters, successful consolidations can be expected. parameters, successful consolidations can be expected.Presented here are the results of core flow consolidations illustrating how the nickel content, porosity, permeability, and compressive strength is porosity, permeability, and compressive strength is likely to vary according to plating conditions. A model of the plating process that assumes uniform coatings around the sand grains leads to a simple permeability-porosity relationship that is in good permeability-porosity relationship that is in good agreement with experimental measurements, at least for porosity reductions of less than 50 percent. The influence of the consolidation on well productivity is examined, assuming a linear porosity profile, to show only minor "impairment." EXPERIMENTAL PROCEDURES AND RESULTS The standard test material was Clemtex No. 5 sand, a clean, rounded, 80-120 mesh sand often used in formation simulation. Although results presented here are only for this material, other materials already cited exhibit the same general behavior. Design conditions were chosen to achieve 100-cc consolidations. The design specification involves choosing flow rate and solution composition for a given sand specific surface area and plating temperature. Design details are available in Ref 2. The sand was packed into steel pipe sections, with appropriate packed into steel pipe sections, with appropriate retaining screens, flow distributors and compression springs at each end. The packed pipe sections were then connected to the flow system, preceded by a constant-rate Whitey pump and followed by a backpressure regulator and gas-liquid separator. The pipe section was set into a constant temperature bath, and injected solutions were heated to the desired bath temperature before reaching the sand. The volume of plating solution was about 75 PV. SPEJ P. 203

EQUILIBRIUM PROFILES OF MODEL BEACHES

The investigation reported herein covers two aspects of equilibrium beach profiles, namely, (a) the criterion governing their type and (b) their reflection characteristics The problems are first analysed from dimensional considerations and then studied experimentally in laboratory wave flumes using different sizes of quartz, ground walnut shell and ground plastic as movable bed material. Empirical relations between pertinent parameters governing the beach process are given.

Movable Bed Model for River Structures Design

Laboratory tests using a movable bed hydraulic model were conducted to develop optimum design criteria for a new type river control structure called an L-head dike. The large size of the prototype, the Missouri River, made it necessary to distort the model, thus requiring careful consideration of the various scale factors. Rates of sediment transport strongly influence bed roughness, therefore it was important that the movable bed material be light to permit transport at low velocities. Ground walnut shells were found to satisy not only the sediment transport requirements but also simulated bank caving that occurs in the prototype. Verification tests as well as constant checks on scale factors were performed through the investigation period. The most surprising benefit was the ability of the engineer to observe sediment transport, dune patterns, bed waves, current boils, eddy currents, accretion buildup, and bank erosion.

High Strength Granular Sealing Material Increases Efficiency of Primary Cementing and Squeeze Cementing

Abstract The use of high strength granular materials in cement slurries has proved beneficial for cementing casing and squeeze cementing operations in Permian in Basin oil and gas wells. The addition of 1 to 4 lb of ground walnut shells to each sack of cement made possible successful high column cementing jobs in fields where high fill-ups normally cannot be obtained because of lost circulation. In squeeze cementing operations the number of cementing stages required for shutting off water was reduced by the addition of walnut shells to the last 50 per cent of the volume of cement slurry. Introduction The high hydrostatic head, created in the annulus when cementing casing, frequently is the cause of loss of slurry into weak formations or formations containing fractures or vugs. Common precautions taken to reduce this loss are reducing the density of the slurry adding effective sealing agents to the slurry, or both. One phase of this paper concerns the use of high strength granular sealing materials in cement slurry to seal openings into formations so that the slurry may be pumped to the desired level behind the casing. In squeeze cementing operations neat cement often fails to effect a complete seal because of the tendency of the slurry to enter only the weakest zones. This is indicated by the number of stages frequently required to stop the flow of water or gas. The intrusion of cement slurry into each perforation in a water or gas producing zone is probably necessary to eliminate flow completely, and a high final squeeze pressure may be a means of assuring entry of cement into each perforation or zone of weakness. The second phase of this paper concerns the use of high strength granular materials in cement slurries to obtain a high final squeeze pressure.