Eggshell biomaterial: Characterization of nanophase and polymorphs after mechanical activation

Eggshell Membrane as a Biomaterial for Bone Regeneration

The physicochemical features of the avian eggshell membrane play an essential role in the process of calcium carbonate deposition during shell mineralization, giving rise to a porous mineralized tissue with remarkable mechanical properties and biological functions. The membrane could be useful by itself or as a bi-dimensional scaffold to build future bone-regenerative materials. This review focuses on the biological, physical, and mechanical properties of the eggshell membrane that could be useful for that purpose. Due to its low cost and wide availability as a waste byproduct of the egg processing industry, repurposing the eggshell membrane for bone bio-material manufacturing fulfills the principles of a circular economy. In addition, eggshell membrane particles have has the potential to be used as bio-ink for 3D printing of tailored implantable scaffolds. Herein, a literature review was conducted to ascertain the degree to which the properties of the eggshell membrane satisfy the requirements for the development of bone scaffolds. In principle, it is biocompatible and non-cytotoxic, and induces proliferation and differentiation of different cell types. Moreover, when implanted in animal models, it elicits a mild inflammatory response and displays characteristics of stability and biodegradability. Furthermore, the eggshell membrane possesses a mechanical viscoelastic behavior comparable to other collagen-based systems. Overall, the biological, physical, and mechanical features of the eggshell membrane, which can be further tuned and improved, make this natural polymer suitable as a basic component for developing new bone graft materials.

Structural and luminescence characterization of β-Ga2O3 nanopowders obtained via high-energy ball milling

β-Ga2O3 nanocrystals have been successfully obtained by the high-energy ball milling method. The obtained nanocrystalline powders have been characterized using X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and luminescent spectroscopy. X-ray diffraction patterns show a single gallium oxide structure formed in the milling process with a small amount of α-Ga2O3 phase. The grains of irregular shape were identified with the TEM technique. HRTEM images confirmed the formation of the β-Ga2O3 nanocrystals with a size distribution of 50–80 nm. Three luminescence bands peaked at about 2.52, 2.91, and 3.26 eV were observed in photoluminescence spectra. The gradual blue shift of the emission maxima at the excitation in the fundamental absorption edge under the different milling conditions was detected.

Fabrication, Characterization, and Evaluation of Eggshells as a Carrier for Sustainable Slow-Release Multi-Nutrient Fertilizers

Development of environment-friendly fertilizers to adhere to the sustainability in agronomic practices and to overcome the limitations posed by the conventional fertilizers has been an important challenge. In this study, a cost-effective biowaste eggshell (ES) material was utilized as a sustainable support for eco-friendly slow-release multi-nutrient fertilizers (SMFs) by simple impregnation of micro- and macronutrients. The synthesized multi-nutrient composite was characterized by various characterization techniques. The leaching tests were conducted using simulated soil solutions and tap water, which showed slow and steady release patterns of the impregnated nutrients. Also, the water holding and water retention capacity of soil were improved upon addition of ES-SMF. Further, the results of pot experiments showed enhanced plant growth of cucumber (Cucumis sativus) and tomato (Solanum lycopersicum) seedlings that proved the efficiency of ES-SMF to serve as an environment-friendly fertilizer in agriculture to attain sustainability.

Comparative Study of Fire Resistance and Char Formation of Intumescent Fire-Retardant Coatings Reinforced with Three Types of Shell Bio-Fillers

Three types of shell bio-fillers, including eggshell (CES), conch shell (CHS) and clamshell (CMS), were prepared by cleaning, ultrasonication and pulverizing processes of biowastes, and then applied to intumescent fire-retardant coatings. The effects of shell bio-fillers with different polymorphs on the fire resistance and char-forming of intumescent fire-retardant coatings were investigated by cone calorimeter test, fire protection tests, smoke density test, thermogravimetric analysis (TG), and the fire resistance and char-forming mechanism of bio-fillers in intumescent fire-retardant coatings were proposed. The results show that three kinds of bio-fillers exert an excellent synergistic effect on enhancing the fire resistance and char-forming properties of the intumescent fire-retardant coatings, while clamshell has the best synergistic efficiency among the bio-fillers. Especially, IFRC-CMS coating containing 3 wt% clamshell shows the best fire protection performance and lowest smoke production and heat release, which offers an equilibrium backside temperature of 134.6 °C at 900 s, a flame-spread rating of 14.4, and a smoke density rating value of 22.8%. The synergistic efficiency of bio-fillers in the intumescent coatings depends on the polymorphs of CaCO₃ in bio-fillers, and aragonite CaCO₃ shows a higher synergistic efficiency compared to calcite CaCO₃ and the mixture of aragonite and calcite CaCO₃. The CMS composed of aragonite shows the best synergistic effect, CHS composed of aragonite and calcite comes second, and CES composed of calcite has the weakest synergistic effect.

Evaluating the buffering and acid-resistant properties of eggshell-titanium dioxide composite against erosive acids

OBJECTIVE:

This paper reports on the buffering and acid-resistant properties of a modified eggshell-titanium composite against citric acid attack.

MATERIALS AND METHODS:

Eggshell-titanium EB-TiO₂ was prepared by ball-milling eggshell powder and titanium dioxide. Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) were used to characterize EB-TiO₂. The buffering property against citric acid at pH values of 2, 4, and 5 was measured using a pH meter. Five brands of toothpaste (Colgate, Colgate Sensitive, Aquafresh, Oralwise, and Sensodyne) were used to assess the acid-resistant properties of EB-TiO₂. Enamel models were simulated by dissolving each brand of toothpaste with eggshell (control) and EB-TiO₂. The samples were exposed to citric acid of pH 2. The average slope (kPa/s) was measured using a pressure sensor. An analysis of variance was used to analyze the kPa/s values (α =.05).

RESULTS:

The FTIR and XRD analyses suggest the surface modification of EB-TiO₂. The TEM image revealed spherical-shaped particles in EB-TiO₂. The pH test results showed that the buffering properties of eggshell and EB-TiO₂ were comparable. Significant differences were observed in the acid resistance properties of the samples exposed to citric acids ( P < .05). The Colgate toothpaste infused with eggshell powder had the highest mean kPa/s values, whereas Sensodyne infused with EB-TiO₂ had the lowest kPa/s values.

CONCLUSION:

The salient features of this study indicate that modification of eggshell with titanium dioxide does not affect its carbonate buffering properties. Connecting the kPa/s values to acid-resistant properties, EB-TiO₂ effectively reduces erosive attacks when added to toothpaste.

Bio-waste chicken eggshells to store energy

Bio-waste in the form of chicken eggshells, which contain high amounts of calcium carbonate (CaCO3), is used to store energy. The fine eggshell powders are used as an electrode against a metallic lithium anode in a non-aqueous electrolyte. The initial discharge capacitance of the eggshell system was found to be 232 F g-1, while the reversible capacitance was 120 F g-1. Thereon, the cell maintained an excellent capacitance retention of 92% over 1000 cycles. The electrochemical performance obtained is comparable to that of commercially available classical activated carbon (AC) material. CaCO3 showed a non-faradaic behaviour and the shape of the electrochemical curves resembles that of the AC electrode. The preliminary findings suggest that CaCO3 from eggshells can be used as the electrode in Li-ion capacitors to store and release charges effectively over a wide electrochemical stability window of 4 V. Using chicken eggshells in this manner not only reduces the amount of bio-waste, but also adds considerable value. A detailed understanding of the electrochemical and physical behaviour of the material is needed in order to improve its performance and to enable its widespread use.

Simultaneous valorization of polyvinyl chloride and eggshell wastes by a semi-industrial mechanochemical approach

A semi-industrial approach for simultaneous treatment of eggshell and industrial polyvinyl chloride waste utilizing tools of ball milling is reported therein. On a hundred-gram scale, it is possible to transfer more than 55% of chlorine present in the polyvinyl chloride representing an environmental burden, into harmless soluble form. On a laboratory scale, a complete dechlorination was achieved. The ratio of eggshell-to-polyvinyl chloride plays a significant role for the effective dechlorination and the kinetics of semi-industrial process follows zero-order kinetics with the rate constant 1.23 × 10^-5 s^-1. Chlorine is mainly in the form of calcium chloride. This study is an example of efficient simultaneous valorization of two waste materials on a semi-industrial scale, as the products can be utilized again.

Mechanochemical synthesis of hydroxyapatite using cuttlefish bone and chicken eggshell as calcium precursors

This work explores the possibility of synthesising hydroxyapatite via mechanochemical route using biogenic calcium carbonate sources, namely calcite in chicken eggshell and aragonite in cuttlebone. The calcium source and orthophosphoric acid in ratio complying with Ca/P = 1.67 were submitted to high-energy ball milling with transferred energy values in the 1.6 to 123.0 kWh/g range, in the presence of 6.4 wt% water. Results show that increasing transferred energy results in CaCO₃ → DCPD → HA reaction sequence when the used calcium source is cuttlebone, and in CaCO₃ → DCPD → DCPA → HA when eggshell is used. The produced calcium orthophosphates exist in delimited energy transfer ranges; HA forms monophasic regions at the highest transferred energy ranges tested. 52.5 kWh/g is the minimum energy value for hydroxyapatite formation starting from eggshell, while only 6.2 kWh/g is required starting from cuttlebone. Calcium orthophosphate dimensionality depends on the supplied energy and on the starting CaCO₃ polymorph, and includes nanospheres and nanoplates, and more complex flower-like geometries built from individual nanoparticles. Milling maps were built to systematise the effect of initial CaCO₃ polymorph and transferred milling energy on the conditions for hydroxyapatite mechanochemical formation. Obtained results demonstrate the potential of chicken eggshell and cuttlefish bone as natural precursors to produce hydroxyapatite, and the ability of high-energy milling as the corresponding processing route. This indicates an opportunity window for the development of reliable, scalable, fast and cost-effective HA production method.

Ball milling of eggshell waste as a green and sustainable approach: A review

Eggshell waste belongs to the most abundant natural waste in nature and is created in huge amounts by everyday consumption of eggs. The majority of this material is being discarded, despite the fact that it has multidisciplinary applications. In this review, the possibility of utilizing the method of ball milling to further broaden the application potential of this material is discussed. The particular application fields include the formation of nanophases, bioceramics synthesis, formation of composites and preparation of material with increased sorption ability. In addition, some other specific applications, like the utilization of ball-milled eggshell as a drug delivery agent, or for the formation of antibacterially active species, are also mentioned. The review provides a critical mechanochemical insight into this topic and aims to emphasize the green and sustainable way of utilizing eggshell waste by environmentally friendly method.

Physicochemical characterization of a dental eggshell powder abrasive material

BACKGROUND

This study aimed to determine the physicochemical characteristics of an eggshell-based dental abrasive material.

METHODS

The eggshell powder abrasive material (EPAM) was synthesized by ball milling eggshell powder and surfactants. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and a laser diffraction particle size analyzer (PSA) were used to characterize EPAM. In addition, the abrasive characteristics of EPAM were evaluated by comparison using poly(methyl methacrylate) (PMMA) resins. Surface roughness (Ra) was measured using a profilometer.

RESULTS

The FTIR spectroscopy and XRD analysis confirmed that the carbonate product was primarily calcite (97.3%) with traces of graphite 2H (1.3%) and thenardite (1.4%). The TEM imagery revealed irregular particles in EPAM. The PSA analysis of the particle size distribution showed EPAM to be a superfine powder (0.3 µm to 50 nm). In addition, the 50-nm EPAM (Ra = 0.04 µm) measured the lowest Ra value when compared with pumice (Ra = 0.08 µm).

CONCLUSIONS

The salient features of this study indicate that EPAM can naturally replace calcite, which is generally mined and used as a dental abrasive material. In addition, and regarding the abrasive characteristics of EPAM in reducing the surface roughness of PMMA resin specimens, this study conclusively showed that EPAM effectively reduces the surface roughness below the threshold limit value of 0.2 µm. Potentially, EPAM could reduce waste disposal problems while enabling an economic benefit from using eggshell waste material.

Phosphorus removal from aqueous solution in parent and aluminum-modified eggshells: thermodynamics and kinetics, adsorption mechanism, and diffusion process

Parent and aluminum-modified eggshells were prepared and characterized with X-ray diffraction, specific surface area measurements, infrared spectroscopy, zeta potential, and scanning electron microscope, respectively. Besides, phosphorus adsorptions in these two eggshells at different temperatures and solution pH were carried out to study adsorption thermodynamics and kinetics as well as the mechanisms of phosphorus adsorption and diffusion. The results indicated that high temperature was favorable for phosphorus adsorption in parent and aluminum-modified eggshells. Alkaline solution prompted phosphorus adsorption in parent eggshell, while the maximum adsorption amount was achievable at pH 4 in aluminum-modified eggshell. Adsorption isotherms of phosphorus in these eggshells could be well described by Langmuir and Freundlich models. Phosphorus adsorption amounts in aluminum-modified eggshell were markedly higher compared to those in parent eggshell. Adsorption heat indicated that phosphorus adsorption in parent eggshell was a typically physical adsorption process, while chemical adsorption mechanism of ion exchange between phosphorus and hydroxyl groups on the surface of eggshells was dominated in aluminum-modified eggshell. The time-resolved uptake curves showed phosphorus adsorption in aluminum-modified eggshell was significantly faster than that in parent eggshell. Moreover, there existed two clear steps in time-resolved uptake curves of phosphorus in parent eggshell. Based on pseudo-second order kinetic model and intraparticle diffusion model, we inferred more than one process affected phosphorus adsorption. The first process was the diffusion of phosphorus through water to external surface and the opening of pore channel in the eggshells, and the second process was mainly related to intraparticle diffusion.

Influence of milling on the adsorption ability of eggshell waste

Eggshell waste was successfully used for the removal of heavy metal ions from model solutions. The effect of ball milling on the structure and adsorption ability of eggshell (ES) and its membrane (ESM) was investigated, with the conclusion that milling is benefitial only for the ES. The adsorption experiments showed that the ESM is a selective adsorbent, as the adsorption ability toward different ions decreased in the following order: Ag(I) > Cd(II) > Zn(II). The obtained Qm values for Ag(I) adsorption on the ESM and ES were 52.9 and 55.7 mg g(-1), respectively. The potential industrial application of ES was also demonstrated by successful removal of Ag(I) from the technological waste.