Sustainable Bio-Inspired Limestone Eggshell Powder for Potential Industrialized Applications

Abstract

Biowaste chicken eggshells contain high amounts of calcium carbonate or calcite. Waste eggshells generated by processing industries have the potential to be used as limestone or lime in a variety of applications. Studies have shown removal of membrane from eggshells can be separated at the laboratory level, but mass production has not been industrialized. The aim of this study was to optimize two membrane removable techniques; heat treatment and bleach treatment. The as-received eggshell samples were first water ball milled into a 63 μm powder. In the first method, fine eggshell powders were submitted to elevated temperatures from 105 to 800 °C in air. The second method involved submitting the powder to a chemical treatment of 10% to 100% bleach concentrations and holding in the solutions for different soak times. The powdered samples were characterized for chemical composition and microstructural analysis. The results indicated pure calcite can be produced by heating to a temperature of 300 °C for a period of 2 h or a 10% bleach treatment for 48 h or a 50% bleach for 10 min. In addition, calcite from eggshells could be transformed into lime by heating to 750 °C for 1 h. The heat treatment method can easily be scaled up to mass production. This study signified eggshells can be used as a total or partial alternative replacement to mined limestone.

Biomimetic Calcium Phosphates Derived from Marine and Land Bioresources

“…A continuous effort aims to reduce the impact of unsustainable use of limited resources by developing environment-friendly processing methods and applications [9]. The use of marine and land materials resulted after industrial processing of different animal species for producing performant biomaterials is a sustainable solution for reducing waste generation.…”

“…Conversion of CaCO 3 in biocompatible calcium phosphates can be achieved by direct synthesis with phosphate-based reagents [9,20].…”

“…Further, the obtained powder was repeatedly washed with the same solution and then dried in conventional oven at 100°C for 24 hours [9,20].…”

“…Currently, this trend is expressed by improving a relatively new concept, which combines advanced fabrication of bioceramics with the sustainable use of natural resources, namely functionalization of marine and land resources for preparing biogenic calcium phosphates [2,9,10]. Dedicated studies offer extensive information regarding [1] marine resources such as vertebrates bones-fish bones [5,6,11,12] and calcified structures of invertebrates-coral, snail, seashell, cuttlefish, sea urchin, etc.…”

“…Dedicated studies offer extensive information regarding [1] marine resources such as vertebrates bones-fish bones [5,6,11,12] and calcified structures of invertebrates-coral, snail, seashell, cuttlefish, sea urchin, etc. [12][13][14][15][16][17], and [2] land resources such as animal bone tissue-preponderantly bovine bone [2,4,18,19] or other calcified structures such as eggshells [9,20], which could be used as cost-effective raw materials. Most of these resources are naturally available as various polymorphs of calcium carbonate (CaCO 3 ); by exception, vertebrate bones contain calcium phosphate closely related to the mineral component of human bones.…”