Macadamia Nut Shell Research Articles

Macadamia Nutshell Biochar for Nitrate Removal: Effect of Biochar Preparation and Process Parameters

Agricultural runoff is a major cause of degradation to freshwater sources. Nitrate is of particular interest, due to the abundant use of nitrogen-based fertilizers in agricultural practices globally. This study investigated the nitrate removal of biochar produced from an agricultural waste product, macadamia nutshell (MBC). Kinetic experiments and structural analyses showed that MBC pyrolsed at 900 °C exhibited inferior NO3− removal compared to that pyrolsed at 1000 °C, which was subsequently used in the column experiments. Concentrations of 5, 10 and 15 mg/L, with flowrates of 2, 5 and 10 mL/min, were examined over a 360 min treatment time. Detailed statistical analyses were applied using 23 factorial design. Nitrate removal was significantly affected by flowrate, concentration and their interactions. The highest nitrate removal capacity of 0.11 mg/g MBC was achieved at a NO3− concentration of 15 mg/L and flowrate of 2 mL/min. The more crystalline structure and rough texture of MBC prepared at 1000 °C resulted in higher NO3− removal compared to MBC prepared at 900 °C. The operating parameters with the highest NO3− removal were used to study the removal capacity of the column. Breakthrough and exhaustion times of the column were 25 and 330 min respectively. Approximately 92% of the column bed was saturated after exhaustion.

Ultrahigh-energy-density fluorinated calcinated macadamia nut shell cathodes for lithium/fluorinated carbon batteries

Lithium/fluorinated carbon (Li/CFx) batteries are widely applied in various industries because of the high energy densities of CFx compounds. However, incompatibility between high degrees of fluorination and the electrochemical activity of C–F bonds limits further improvements of the energy densities of CFx cathodes. Here, calcined macadamia nut shell is fluorinated with F2 gas below 300 °C. The products deliver specific capacities exceeding 900 mAh g−1, associated with discharge potentials exceeding 3.0 V (vs. Li/Li+). The product fluorinated at 280 °C achieves an unprecedented maximum energy density of 2585 W h kg−1, surpassing the present maximum theoretical energy density of commercial (CF)n (2185 W h kg−1). Its electrochemical properties presumably originate from the complete destruction of the periodic crystalline lattice in the basal plane, which substantially alters the electron distribution within the C–F bonds. This study presents a new approach for designing exceptionally high-energy-density CFx compounds for lithium primary batteries using an accessible and inexpensive raw material.

Application of mesoporous magnetic nanosorbent developed from macadamia nut shell residues for the removal of recalcitrant melanoidin and its fractions

ABSTRACTA novel mesoporous magnetic nanosorbent developed from macadamia nut shell residues was applied as an adsorbent for the removal of dissolved organic carbon (DOC) associated with melanoidin and its fractions in a batch system. The most favored molecular fraction of the melanoidin for adsorption onto the nanosorbent was 1–5 kDa with adsorption capacity of 10.26 mg DOC g−1 achieving 68.4% removal efficiency. The sorption behaviors were all well fitted to a pseudo-second-order kinetic model and Langmuir isotherm. Optimum operating conditions needed for the maximum uptake of 14.7 mg DOC g−1 were found to be pH of 6.3, temperature of 41.7°C at the dosage of the magnetic nanosorbent of 877.7 ppm.

Hexavalent chromium removal by polyacrylic acid-grafted Macadamia nutshell powder through adsorption–reduction mechanism: Adsorption isotherms, kinetics and thermodynamics

Hydrochloric acid-treated Macadamia nutshell (AMM) powder was grafted with acrylic acid monomers at different doses of 0.5, 1.0 and 2.0 M to incorporate the carboxylic groups on its surface. The grafted materials were labeled 0.5 GAM, 1 GAM and 2 GAM signifying the grafting ratios. The incorporation of acrylic acid was demonstrated by an increase in oxygen content from 0.18% to 1.20% in the elemental analysis. The splitting and shifting of the alcohol intermolecular bonded –OH functional groups at 3330 cm−1 to 3396 and 3321 cm−1 observed after grafting was further proof of the addition of acrylic acid. Scanning electron microscopy (SEM) images revealed that the materials exhibited stacked sheets with spherical halo openings typical of biomaterials. The maximum conditions for chromium(VI) removal were obtained at pH 2, 180 min contact time, 7.5 g/L adsorbent dosage concentration and a temperature of 40 °C. The adsorption mechanism was best described by the monolayer sorption postulated by Langmuir with reported adsorption capacity of 39.21 mg/g. The best fit for the kinetic data was obtained with the pseudo-second-order rate model suggesting a chemisorption nature of interaction. Accordingly, the thermodynamic factors were feasible, spontaneous and endothermic. The acrylic acid-functionalized Macadamia adsorbent showed greater potential compared to other biosorbents in the removal of hexavalent chromium from aqueous solution in the presence of competing anions.

Graphene-Like Carbon Derived from Macadamia Nut Shells for High-Performance Supercapacitor

The graphene-like carbon was obtained from macadamia nut shells by an activated hydrothermal method and applied for high-performance supercapacitors. The morphologies and microstructures are investigated by X-ray diffractometer, Raman spectrometer, scanning electron microscopy and transmission electron microscopy. The experimental results show that the obtained carbon exhibits perfect graphene-like structure filled with more micropores and mesopores. The graphene-like carbon displays high surface areas of 1057 m2 g−1. The graphene-like carbon delivers an impressive specific capacitance of 251 F g−1 and has no capacitance loss at the current density of 1 A g−1 after 1000 cycles, which demonstrates the excellent cycle stability and high specific capacitance. The graphene-like carbon derived from macadamia nut shells can be expected for the widespread application of supercapacitors.

Mechanical behavior of macadamia nutshells

The paper presents the results related to the static mechanical characterization of macadamia nutshells, according to a procedure previously defined on hazelnut shells. Curved specimens were obtained from macadamia nutshells, and they were then subjected to three points bending testing between flat plates of a testing machine. Density, hardness, microhardness, mechanical characterization and microscopic analysis are also presented, related to two macadamia nut varieties. The specimens showed mechanical properties which can be compared with aluminum alloys ones. The behavior of each specimen was also compared with analytical results of equivalent curved beams, monolithic and multilayer.

Mechanical Properties of Polypropylene Composites Reinforced with Macadamia Nutshell Fibers

Mechanical Properties of Polypropylene Composites Reinforced with Macadamia Nutshell Fibers

Biomass carbon materials derived from macadamia nut shells for high-performance supercapacitors

The new biomass carbonaceous materials were obtained from macadamia nut shells (MNS) by immersion method and high-temperature activation (MNSCA) for high-performance supercapacitors. The morphologies and microstructures are investigated by X-ray diffractometer, Raman spectrometer, scanning electron microscopy and transmission electron microscopy. The experimental results show that the obtained activated carbon (MNSCA) exhibits perfect porous structure filled with more micropores and mesopores. MNSCA displays high specific surface area of 1057 $$\hbox {m}^{2}\hbox { g}^{-1}$$ . The porous carbon delivers an impressive specific capacitance of 325.7 F $$\hbox {g}^{-1}$$ and has no capacitance loss at the current density of 2 A $$\hbox {g}^{-1}$$ after 10,000 cycles, which demonstrates the excellent cycle stability and high specific capacitance. The biomass carbonaceous materials derived from MNS can be expected for the widespread application of supercapacitors.

Preparation and properties of hydrochars from macadamia nut shell via hydrothermal carbonization.

Macadamia nut shell (MNS) is a type of waste lignocellulose obtained from macadamia nut production processing. Large MNS wastes caused serious resource waste and environmental pollution. So, preparation of hydrochars from MNS via hydrothermal carbonization (HTC) is of great significance. HTC of MNS was conducted to study the effect of process parameters, including HTC temperature (180–260°C) and residence time (60–180 min) on the properties of hydrochars. Results showed that the increase in HTC temperature and residence time decreased the mass yield of hydrochars and increased the high heating value of hydrochars. Furthermore, the C content of hydrochars increased, whereas the H and O contents decreased. Mass yield of hydrochar is 46.59%, energy yield is 64.55% and the higher heating value is 26.02 MJ kg−1 at a temperature of 260°C and time of 120 min. The surface structure of hydrochars was rougher compared with that of MNS as observed via scanning electron microscopy. The chemical and combustion behaviour of MNS and hydrochars was analysed by Fourier transform infrared spectroscopy, and thermogravimetric analysis indicated that decarboxylation and dehydration reactions were the predominant pathways during the HTC process. Results showed that HTC can facilitate the transformation of MNS into solid fuel.

Mesoporous activated carbon-zeolite composite prepared from waste macadamia nut shell and synthetic faujasite

Abstract Novel activated carbon-zeolite composite adsorbent was prepared from macadamia shell bio-waste and synthetic zeolite X using hydrothermal treatment. Characterisation studies revealed mainly mesoporous structure with 418 m2·g− 1 BET surface area with faujasite clusters on the carbon carrier. Sorption capacity for methylene blue model pollutant increased from 85 to 97 mg·g− 1 with the temperature increase from 25 to 45 °C, and improved with increasing pH. Nonlinear regression analyses found accurate fit to the pseudo-first-order kinetics model and intra-particle diffusion rate controlling mechanism. Excellent fits to the Jovanovic isotherm model indicated monolayer coverage on chiefly homotattic surfaces with variable potential. The thermodynamic analysis confirmed spontaneous and endothermic physisorption process. The spent adsorbent was regenerated with 20% capacity loss over five reuse cycles. Although the adsorbent was developed for ammonia, heavy metal and organic matter removal from water sources, the results also indicate good performance in cationic dye removal from wastewaters.

Biomass-derived carbon composites for enrichment of dilute methane from underground coal mines

Ventilation air methane (VAM), which is the main source of greenhouse gas emissions from coal mines, has been a great challenge to deal with due to its huge flow rates and dilute methane levels (typically 0.3–1.0 vol%) with almost 100% humidity. As part of our continuous endeavor to further improve the methane adsorption capacity of carbon composites, this paper presents new carbon composites derived from macadamia nut shells (MNSs) and incorporated with carbon nanotubes (CNTs). These new carbon composites were fabricated in a honeycomb monolithic structure to tolerate dusty environment and to minimize pressure drop. This paper demonstrates the importance of biomass particle size distributions when formed in a composite and methane adsorption capacities at low pressures relevant to VAM levels. The selectivity of methane over nitrogen was about 10.4 at each relevant partial pressure, which was much greater than that (6.5) obtained conventionally (at very low pressures), suggesting that capturing methane in the presence of pre-adsorbed nitrogen would be a practical option. The equilibrium and dynamic performance of biomass-derived carbon composites were enhanced by 30 and 84%, respectively, compared to those of our previous carbon fiber composites. In addition, the presence of moisture in ventilation air resulted in a negligible effect on the dynamic VAM capture performance of the carbon composites, suggesting that our carbon composites have a great potential for site applications at coal mines because the cost and performance of solid adsorbents are critical factors to consider.

Defective Carbons Derived from Macadamia Nut Shell Biomass for Efficient Oxygen Reduction and Supercapacitors

AbstractEfficient yet cost‐effective electrode materials play deciding roles in the widespread application of fuel cells, as precious metals, such as platinum (Pt), remain the main component of the cathodic oxygen reduction reaction (ORR) electrocatalyst. Herein, a type of biomass, macadamia nut shell (MNS), is utilized for synthesizing ORR catalysts, aiming at enhancing the activity and lowering the production cost of the electrode materials. Benefiting from a defective catalysis mechanism, the resulting defective MNS material (D‐MNS‐A) shows greatly improved ORR performance in alkaline solutions. The onset potential of D‐MNS‐A is only 29 mV more negative than that of the commercial Pt/C. Moreover, the durability of D‐MNS‐A is superior to that of Pt/C, and it presents excellent tolerance to methanol. In addition, D‐MNS‐A is an ideal material for supercapacitors. It exhibits a specific capacitance of 155 F/g under the current density of 1 A/g in 1 M Na2SO4 electrolyte, which was further increased to 231 F/g after coating with MnO2. The defective nature combined with the highly porous structure of D‐MNS‐A render it a potential material for fuel cell and supercapacitor applications.

Mesoporous activated carbon prepared from macadamia nut shell waste by carbon dioxide activation: Comparative characterisation and study of methylene blue removal from aqueous solution

AbstractActivated carbons are the most widely used adsorbents; however, producing high‐performance mesoporous activated carbons with simple technology still remains a challenge. In this research, waste macadamia nut shell (MNS) was explored as precursor for preparing mesoporous activated carbons by carbon dioxide activation. The material characteristics of MNS‐based activated carbon (MAC) were thoroughly examined in comparison with a premium‐grade commercial activated carbon (CAC). MAC and CAC had specific surface areas of 830 and 1,299 m2 g−1, respectively. Although CAC had a predominantly microporous structure, about 74% of the pore volume of MAC is composed of mesopores. Adsorption performances were evaluated in batch experiments using methylene blue model pollutant and demonstrated 135 and 181 mg g−1 saturation capacities for MAC and CAC, respectively. Non‐linear regression found that the fractal‐like pseudo first‐order model accurately described sorption kinetics, and intraparticle diffusion was the rate‐limiting step. Among 6 established isotherm models, the Liu equilibrium model showed the best statistics. Thermodynamic analysis verified that the process was favourable and involved physisorption. These results show that valuable mesoporous activated carbons can be prepared from the biowaste MNS with simple production technology to suit environmental and industrial applications.

Biochar modulates heavy metal toxicity and improves microbial carbon use efficiency in soil

Soil organic carbon is essential to improve soil fertility and ecosystem functioning. Soil microorganisms contribute significantly to the carbon transformation and immobilisation processes. However, microorganisms are sensitive to environmental stresses such as heavy metals. Applying amendments, such as biochar, to contaminated soils can alleviate the metal toxicity and add carbon inputs. In this study, Cd and Pb spiked soils treated with macadamia nutshell biochar (5% w/w) were monitored during a 49days incubation period. Microbial phospholipid fatty acids (PLFAs) were extracted and analysed as biomarkers in order to identify the microbial community composition. Soil properties, metal bioavailability, microbial respiration, and microbial biomass carbon were measured after the incubation period. Microbial carbon use efficiency (CUE) was calculated from the ratio of carbon incorporated into microbial biomass to the carbon mineralised.Total PLFA concentration decreased to a greater extent in metal contaminated soils than uncontaminated soils. Microbial CUE also decreased due to metal toxicity. However, biochar addition alleviated the metal toxicity, and increased total PLFA concentration. Both microbial respiration and biomass carbon increased due to biochar application, and CUE was significantly (p<0.01) higher in biochar treated soils than untreated soils. Heavy metals reduced the microbial carbon sequestration in contaminated soils by negatively influencing the CUE. The improvement of CUE through biochar addition in the contaminated soils could be attributed to the decrease in metal bioavailability, thereby mitigating the biotoxicity to soil microorganisms.

Nutrient changes in potting mix and Eucalyptus nitens leaf tissue under macadamia biochar amendments

The effect of macadamia nut shell biochar on nitrogen, potassium, phosphorus, magnesium, calcium and sodium concentrations in potting mix used to grow Eucalyptus nitens seedlings was investigated in a glasshouse experiment. The treatments combined two fertiliser rates (50 and 100% rate of the commercial mix commonly used in forestry nurseries) with eight biochar rates (0, 2, 5, 10, 20, 50, 80 and 100 t ha-1) arranged in a randomised complete block with three replicates of four sample plants. Nutrients were quantified in the potting mix and seedling leaves at four destructive harvests 135, 177, 219 and 269 days after planting. Biochar significantly increased nitrate-N, Colwell P, Colwell K and exchangeable Na and reduced ammonium-N, Mg and Ca concentrations in the potting mix. Seedling leaf concentrations of P, K and Na were increased by biochar application, while N remained dependent on fertiliser rate only. Mg and Ca leaf concentrations decreased in response to increasing biochar rates. Elevated nitrate-N and decreased ammonium-N concentrations suggest that biochar might have increased nitrification in the potting mix. We presumed that biochar mediated processes that reduced uptake of P and K when high doses of biochar were combined with full fertilisation. Changes in potting mix K, Na, Mg and Ca were consistent with selective adsorption of ions to biochar surfaces.

Convenient preparation of nitrogen-doped activated carbon from Macadamia nutshell and its application in supercapacitor

Nitrogen-doped activated carbon has been successfully prepared via a convenient buried-type chemical activation technology, by using Macadamia nutshell as carbon source, melamine as nitrogen source and KOH as activating agent. The nitrogen-doped activated carbon product is used as electrode material for the application of supercapacitor. The material structures and surface morphologies are studied by XRD, SEM and TEM techniques. The electrochemical properties are investigated by CV, constant current CDC and AC impedance methods. The results showed that after activation procedure the nitrogen-doped activated carbon have a high specific surface area (1615 m2 g−1) and moderate nitrogen content (6.83%). The nitrogen-doped activated carbon electrode exhibits good capacitance performances in 1 mol L−1 KOH aqueous electrolyte. At a current density of 1 A g−1, the specific capacitance of the nitrogen-doped activated carbon electrode is 229.7 F g−1, which is much higher than that (98.4 F g−1) of nitrogen-free activated carbon electrode.

Cleaner production of iron by using waste macadamia biomass as a carbon resource

Macadamia nut shell, an Australian waste biomass, was pyrolyzed to produce biochars at temperatures ranging from 500 °C to 1300 °C, using lab scale horizontal tube furnace. Biochar characterization was carried out to assess their potential usefulness as a carbonaceous material in ironmaking. Thermal decomposition analysis on waste macadamia biomass was performed using thermogravimetry and kinetic studies. The changes in chemical nature and composition of produced biochars were studied using various analytical techniques. Biochar prepared at 1300 °C was found to have around 92% carbon content as well as highly ordered graphitic structure. Biochar was used as a carbon source to reduce iron oxides to metallic iron at different temperatures i.e.1000 °C, 1100 °C, 1200 °C and 1300 °C. X-ray diffraction and scanning electron microscope analysis were performed on the reduced samples to investigate the phases present in the samples and for morphology respectively. The results of the study suggest that the biochar derived from macadamia nut shell biomass waste can be used as a valuable and renewable carbon resource in sustainable and cleaner production of iron.

Use of macadamia nut shell residues as magnetic nanosorbents

Nanosorbents have been increasingly used for targeted contaminant removal; however, handling and separation of spent sorbents from treated water remains a challenge. To address these drawbacks, a hybrid magnetic nanosorbent was prepared from waste macadamia nut shell and magnetite nanoparticles. The novel nanosorbent had primarily meso- and macroporous structure with 70 m2 g−1 specific surface area. Batch sorption tests using methylene blue model pollutant found sorption capacities increasing from 33 to 42 mg g−1 with temperature in the 25–45 °C range. Nonlinear regression analyses found that process kinetics was accurately described by a fractal-like pseudo first order model. The isotherms showed excellent fits to the Langmuir model and implied monolayer adsorption mechanism. The thermodynamic parameters confirmed that the process was spontaneous, endothermic, and involved physisorption. The point of zero charge was 7.4, which is advantageous in the removal of anionic aquatic pollutants. The ferrimagnetic sorbent had 48 emu g−1 saturation and 0.65 emu g−1 remanence that allowed easy handling and rapid separation by magnetic field. Spent sorbents were effectively regenerated by acidic wash for subsequent reuse over four cycles. The intrinsic characteristics of the magnetite/carbon nanosorbent befit tailored water and wastewater treatment applications.

Microwave-assisted one-step preparation of macadamia nut shell-based activated carbon for efficient adsorption of Reactive Blue

In this work, macadamia nut shell-based activated carbon (MNSAC) was prepared using macadamia nut shells (MNS) through KOH activation under microwave radiation.

Exploration and optimization for methylene blue dye removal with modified macadamia nut shell

Exploration and optimization for methylene blue dye removal with modified macadamia nut shell