Eggshell Valorization: Membrane Removal, Calcium Oxide Synthesis, and Biochemical Compound Recovery towards Cleaner Productions

As climate change continues to rank high among issues of global concern, industries such as agriculture and construction continue to unearth possible ways to curb carbon dioxide generation and encourage the use or reuse of a variety of by-products and waste materials, fostering the implementation of cleaner technologies. Eggshells form a notable component of this waste, making up more than 7.6 million metric tonnes annually. Research works involving the calcination of eggshells have often been done by burning both shell and its constituent proteins and membrane to produce calcium oxide, CaO. This novel research investigated a cleaner means of CaO synthesis by recovering the shell membrane and some valuable chemical compounds from eggshells before calcination. Atomic absorption (AA), thermogravimetric analysis (TGA), scanning electron microscope (SEM), X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), Ultra-performance-liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS), and RGB color analysis were all employed. Acetic and Nitric acid was used to weaken the shell-membrane bond, thereby aiding membrane separation. Shell membrane was easily separated after 17 minutes of soaking time. Calcium oxide, CaO was synthesized from separated shells after calcination for 3 hours at 900 ℃. 99% CaO with an RGB value of 253 was produced. Collagen, as well as other chemical compounds, were recovered. Eggshell was successfully valorized for CaO production. The shell membrane, collagen, and other recovered compounds, which would have been burnt off and left as an impurity in the CaO, can now the put to more profitable use.

Core/Shell Glycine-Polyvinyl Alcohol/Polycaprolactone Nanofibrous Membrane Intended for Guided Bone Regeneration: Development and Characterization

Glycine (Gly), which is the simplest amino acid, induces the inflammation response and enhances bone mass density, and particularly its β polymorph has superior mechanical and piezoelectric properties. Therefore, electrospinning of Gly with any polymer, including polyvinyl alcohol (PVA), has a great potential in biomedical applications, such as guided bone regeneration (GBR) application. However, their application is limited due to a fast degradation rate and undesirable mechanical and physical properties. Therefore, encapsulation of Gly and PVA fiber within a poly(ε-caprolactone) (PCL) shell provides a slower degradation rate and improves the mechanical, chemical, and physical properties. A membrane intended for GBR application is a barrier membrane used to guide alveolar bone regeneration by preventing fast-proliferating cells from growing into the bone defect site. In the present work, a core/shell nanofibrous membrane, composed of PCL as shell and PVA:Gly as core, was developed utilizing the coaxial electrospinning technique and characterized morphologically, mechanically, physically, chemically, and thermally. Moreover, the characterization results of the core/shell membrane were compared to monolithic electrospun PCL, PVA, and PVA:Gly fibrous membranes. The results showed that the core-shell membrane appears to be a good candidate for GBR application with a nano-scale fiber of 412 ± 82 nm and microscale pore size of 6.803 ± 0.035 μm. Moreover, the wettability of 47.4 ± 2.2° contact angle (C.A) and mechanical properties of 135 ± 3.05 MPa average modulus of elasticity, 4.57 ± 0.04 MPa average ultimate tensile stress (UTS), and 39.43% ± 0.58% average elongation at break are desirable and suitable for GBR application. Furthermore, the X-ray diffraction (XRD) and transmission electron microscopy (TEM) results exhibited the formation of β-Gly.

The eggshell membrane: A potential biomaterial for corneal wound healing

The eggshell membrane (ESM) is an abundant resource with innate complex structure and composition provided by nature. With at least 60 million tonnes of hen eggs produced globally per annum, utilisation of this waste resource is highly attractive in positively impacting sustainability worldwide. Given the morphology and mechanical properties of this membrane, it has great potential as a biomaterials for wound dressing. However, to date, no studies have demonstrated nor reported this application. As such, the objective of this investigation was to identify and optimise a reproducible extraction protocol of the ESM and to assess the physical, chemical, mechanical and biological properties of the substrate with a view to use as a wound dressing. ESM samples were isolated by either manual peeling (ESM-strip) or via extraction using acetic acid [ESM-A0.5] or ethylenediaminetetraacetic acid, EDTA [ESM-E0.9]. Energy dispersive X-ray spectroscopy (EDS) confirmed that there were no traces of calcium residues from the extraction process. Fourier transform infrared (FTIR) spectroscopy revealed that the extraction method (acetic acid and EDTA) did not alter the chemical structures of the ESM and also clarified the composition of the fibrous proteins of the ESM. Scanning electron microscopy (SEM) analyses revealed a three-layer composite structure of the ESM: an inner layer as continuous, dense and non-fibrous (limiting membrane), a middle layer with a network of fibres (inner shell membrane) and the outer layer (outer shell membrane) of larger fibres. Material properties including optical transparency, porosity, fluid absorption/uptake, thermal stability, mechanical profiling of the ESM samples were performed and demonstrated suitable profiles for translational applications. Biological in vitro studies using SV40 immortalised corneal epithelial cells (ihCEC) and corneal mesenchymal stromal cells (C-MSC) demonstrated excellent biocompatibility. Taken together, these results document the development of a novel sustainable biomaterial that may be used for ophthalmic wounds and/or other biomedical therapies.

Eggshell membrane-based water electrolysis cells

Egg shell membrane based novel alkaline water electrolysis cells are constructed. The performance of such membranes are found to be on-par with commercial water electrolysis membranes, exemplifying the potential of such bio-membranes in future energetics.