پوشش‌دهي نانوذره‌هاي كلسيم‌كربنات بيوژنيك به‌دست‌آمده از پوسته‌ي تخم‌مرغ با رنگدانه‌هاي آلي و طبيعي و بررسي كاربرد آن‌ها به‌عنوان نانوپركننده و نانورنگدانه در آميزه‌هاي پلي‌وينيل كلريد

Calcium carbonate (CaCO3) is one of the most abundant mineral fillers used in the plastics industry to meet the needs of polymer resins. In nature, calcium carbonate occurs as a mineral in sedimentary rocks such as limestone, gypsum, an‎d metamorphosed marble, which are often mined. An alternative method for obtaining calcium carbonate is to use biogenic wastes such as eggshells an‎d oysters, which contain high amounts of calcium carbonate. In this study, biogenic calcium carbonate nanoparticles were synthesized from waste eggshells an‎d subsequently coated with organic an‎d natural pigments for application as nanofiller an‎d nanopigment in poly vinyl chloride (PVC) composites. The eggshell-derived calcium carbonate was prepared by mechanical milling an‎d characterized using x-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), an‎d energy dispersive X-ray spectroscopy (EDX) analyses. The results confirmed the formation of crystalline calcite with suitable chemical an‎d morphological properties. Subsequently, the calcium carbonate nanoparticles were coated with quinacridone, indigo, auramine O, an‎d Persian pomegranate flower extract through hydrothermal an‎d wet milling processes. Characterization of137 the coated particles using XRD, FT-IR, TGA, diffuse reflectance spectroscopy (DRS), FE-SEM, transmission electron microscopy (TEM), an‎d determination of specific surface area using the BET method an‎d adsorptiondesorption isotherms confirmed the successful immobilization of pigments on the particle surface, while preserving the crystalline structure an‎d thermal stability of calcium carbonate . To investigate the applicability of the prepared nanofillers in polymer industries, PVC nanocomposites were fabricated by two different approaches, electrospinning an‎d wet milling. In the first approach, electrospinning parameters, including polymer concentration, solvent ratio, applied voltage, flow rate, an‎d tipto-collector distance, were optimized to obtain uniform PVC nanofibers. Subsequently, colored calcium carbonate nanofillers were incorporated into the PVC solution. The results indicated that the type of pigment an‎d nanofiller content significantly influenced the electrospinning behavior an‎d fiber formation. In the second approach, the synthesized nanofillers were incorporated into PVC by melt compounding using an internal mixer, followed by hot pressing to prepare composite sheets for further investigations. The successful preparation of PVC samples containing colored biogenic calcium carbonate nanofillers demonstrated the feasibility of employing waste eggshell-derived calcium carbonate as a sustainable functional filler in polymeric materials. This study provides an environmentally friendly strategy for valorization of eggshell waste an‎d the development of colored biogenic nanofillers with potential applications in PVC-based compounds. Key words: Biogenic calcium carbonate, Eggshell waste, Organic pigments, Natural pigments, Quinacridone, Indigo, Auramine O, Persian pomegranate flower, Poly vinyl chloride (PVC), Nanofiller, Nanopigment, Electrospinning, Hot press.

حسن حداد زاده

پرستو كشتي‌آرا

محمد ديناري , كاظم كرمي