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BIOCERAMIC COMPOSITE: HEN’S EGGSHELL CHARACTERIZATION
AND MAIN APPLICATIONS
Jenniffer Syreetta de Oliveira Spelta^1 * André Gustavo de Sousa Galdino^2 ABSTRACT The chicken eggshell is a bioceramic composite which constitutes a solid waste material whose final disposal is complex and expensive. Brazil generates significant amounts of eggshell residue. This work aimed to characterize the eggshells of white, red and backyard hens and indicate their technological potential as raw material for ceramic products manufacturing. The eggshells were crushed, ground, sifted in a ABNT number 80 sieve and subsequently analyzed by X-rays fluorescence (XRF), X-ray diffraction (XRD) and thermal analyses (DTA and TGA). Through XRF it was observed that the main constituent of eggshell is calcium oxide (CaO), with different percentages between the eggshell types. XRD analysis indicated that the chicken eggshells used in this work are mainly composed of CaCO 3. DTA and TGA demonstrated that the thermal decomposition of the chicken eggshells occurs in three events: water removal; decomposition of organic matter; and decomposition of CaCO 3 in CaO and CO 2. By reviewing the literature, it was verified that chicken eggshells have important applications since they can be used in biomedicine, civil construction, food industries and as soil nutrients. As a result, it is possible to conclude that the chicken eggshell is rich in CaCO 3 and can be easily calcined to obtain CaO. Key words: Hen’s eggshell. characterization and applications. bioceramic composite. (^1) Federal Institute of Education, Science and Technology of Espírito Santo, Road BR- 259, km 70, Zona Rural, Post box 256, Colatina, ES, 29709- 910. (^2) Federal Institute of Education, Science and Technology of Espírito Santo, Av. Vitória, 1729, Jucutuquara, Vitória, ES, 29040-780.
- Corresponding author: jenniffer.spelta@ifes.edu.br.
INTRODUCTION
Everyday, millions of tons of eggshell waste are produced worldwide as a result of the large egg production. In Brazil, according to the Brazilian Institute of Geography and Statistics (IBGE, 2017), the production of chicken eggs is increasing and in the first quarter of 2017 it reached the 788.26 million dozens, representing an increase of 4.1% in comparison with the first quarter of 2016, which was considered a production record year since records started by the government agency in 1987. Chicken eggshell is a bioceramic composite rich in calcium carbonate (CaCO 3 ) and its use is suggested as an alternative to produce other substances of social and industrial interest, contributing to the valuation of the discarded residue (RODRIGUES and ÁVILA, 2017). Re-use of egg shells can reduce the risk of microbiological contamination in the environment and its respective disposal costs, it can also provide raw materials to replace CaCO 3 extracted from non-renewable sources, such as limestone, and the production of other by-products from the CaO obtained by the calcination process (OLIVEIRA et al., 2013). Limestone, the main source of CaCO 3 , has become scarce, and for this reason companies have sought new sources of this compound for its replacement as a raw material for CaCO 3 (RODRIGUES and ÁVILA, 2017). Currently, most commercially available eggs come from laying hens raised in the intensive farming system (confined in cages), with the most noticeable variation of these being the coloring of the eggshells (classified in white and red). Whilst the eggs designated as backyard are of high value and come from laying hens raised in freedom in an extensive or semi-extensive system (MILBRADT et al., 2015). At present, there is an increasing need for environmental sustainability in the world and, therefore, this study aims at chemically characterizing eggshells from farm chicken, white and red color, as well as backyard and determining through review of the literature, possible applications of this residue with the purpose of stimulating its reuse and consequently, its value.
The objective of the tests was to characterize the chemical constituents of the eggshells and to evaluate the constitution of the three different types of chicken eggshell analyzed in this study. The X-ray diffraction analysis allowed the mineral identification of a powder through the characterization of its crystalline structure. This experiment was carried out in the characterization laboratory of the IFES Vitória campus using a Bruker X-ray diffractometer model D8 Advance with Cu (k) incident radiation operating at 40kV/20mA current. The samples were measured in a 2 range: 20-50° in continuous scan mode at a speed of 1o/min with step size of 0.02° at room temperature (23°C). Software with an auxiliary PDF 4 database was used to analyze the results. X-ray Fluorescence spectrometry is an analytical method for determining the chemical composition of the studied material. This stage was performed by means of a SHIMADZU equipment model EDX- 720 belonging to the Laboratory of Characterization of the Academic Unit of Materials Engineering (UAEMa) of the Federal University of Campina Grande (UFCG). The study of the relationship between a sample property and its temperature, while the sample is heated or cooled in a controlled manner, is known as thermal analysis, which was performed in this work by the Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) techniques. The differential thermal analyses were performed on the BP Engenharia equipment, model RB 3000 at a heating rate of 10°C/min. Calcined alumina was the standard used, at a temperature of 1000°C. The results were obtained by measurements of temperature differences between the sample and the standard material through the continuous process, via endothermic and/or exothermic reactions that occurred during heating. The same parameters used for DTA were used to perform the thermogravimetric analysis of the samples, where the mass of the samples was measured and the variations were recorded as a function of the process temperature. These changes occur due to loss of water or CO2`, oxygen gain, burning of organic matter, etc. Finally, a search of scientific articles was carried out with the term "chicken eggshell" as keyword in the main database of the Periódico CAPES portal. A table containing some applications for the reuse of chicken eggshells was made from the selected articles.
RESULTS AND DISCUSSION
The X-ray diffraction patterns for the three types of chicken eggshell analyzed are shown in Figure 2. The analysis indicated that the types of chicken eggshells studied (white, red and backyard) consist mainly of calcium carbonate, which is demonstrated by the correspondence of the sample peaks with those of the calcite standard (CaCO 3 , whose crystallographic data sheet used was ICDD-PDF nº 01- 085 - 1108), results similar to those found in the literature (CÔRREA et al., 2015; TOMASELLI, 2014). The chemical compositions of the three types of chicken eggshells were obtained by X- ray Fluorescence and are shown in Table 1.
CaCO 3
% (Red)
Intensity (counts)
% (Backyard)
Angle 2 (°)
% (White)
Figure 2 - White, red, and backyard egg shell diffractograms consistent with the calcite pattern (CaCO 3 ).
In the COC powder (Figure 4 (c)), water removal occurred between 27 and 345°C, with an approximate mass loss of 4%, while the organic matter decomposition occurred between 346 and 547°C, with around 18% of mass loss (22% of mass loss from the beginning of the process). The CaCO 3 decomposition into CaO and CO 2 generated 35% of mass loss between 548 and 814°C, for a total loss of 57% in this process. The difference between COV, COB and COC mass loss is due to the eggshells chemical composition.
Figure 3 - DTA and TGA curves of chicken eggshell samples: (a) red (COV); (b) white (COB); and (c) backyard (COC).
D. A. Oliveira, P. Benelli, E. R. Amante (2013) Valorization of Solid Residues: Eggshells as Raw Material in the Development of New Products. Calcium for human consumption; Eggshell powder as fertilizer, animal feed and/or heavy metal removal; Calcium carbonate as fertilizer, animal feed and/or removal of heavy metals with separation of the shell membrane; Purified calcium carbonate; Hydroxyapatite production; Protein hydrolyzate from the shell membrane; Protein concentrate from the shell membrane. L.C. Gomes, B. C. Di Lello, J. B. Campos, M. Sampaio (2012) Synthesis and characterization of calcium phosphates from chicken eggshell. Use of the chicken eggshell as the initial precursor for the synthesis of calcium phosphates. T. H. A. Côrrea, R. S. T. Manhães, J. N. F. Holanda (2015) Conversion of gallinaceous eggshell residue into calcium phosphate-based biocement. Conversion of gallinaceous eggshell residue into ceramic biomaterial. R.A. Oliveira, P. A. B. Freitas, M. J. B. Cardoso, R. C. Barbosa, M. R. O. Pinto, M. V. L. Fook (2012) Synthesis and characterization of chitosan composite with calcium carbonate extracted from eggshell for possible wound healing applications. Composite made from eggshell and chitosan for wound healing applications. M. M. V. Naves, D. C. Fernandes, C. M. M. Prado, L. S. M. Teixeira (2007) Food fortification with egg shell powder as a calcium source Food fortification
B. G. Milbradt, A. L. H. Muller, J. S. Silva, J. R. Lunardi, L. I. G. Milani, E. M. M. Flores, M. G. K. Callegaro (2015) Eggshell as source of calcium for humans: mineral composition and microbiological analysis. Eggshell as a source of calcium for humans. M.C. Magalhães, A. Ribeiro, M. Quina, C. Cameira (2011) Treatment and agricultural valorization of eggshell. Use of eggshell as alkalizing agent for soil. CONCLUSIONS The DRX results led to the conclusion that regardless of the type, CaCO 3 is the main constituent in chicken eggshells, and that the percentages of the different constituents vary for each type (via FRX). Using thermal analysis (DTA and TGA) it was verified that it is possible to obtain CaO from the CaCO 3 decomposition when subject to temperatures above 820°C. The bibliographical research demonstrated that chicken eggshells have important applications from the industrial and social point of view, since they can be used in several industries such as biomedical, civil construction, food and agriculture. With the possibility of obtaining CaO from chicken eggshells and using it as a precursor in chemical reactions in several areas, this residue becomes a valued byproduct with high economic potential and of sustainable characteristics, since the CaO obtained from the decomposition of limestone is removed from nature and considered a finite good. ACKNOWLEDGEMENTS The authors thank INCT-Biofabris for the technical support, the Academic Unit of Materials Engineering of the Federal University of Campina Grande, for conducting the thermogravimetric and X-ray fluorescence analyzes and the Federal Institute of Education, Science and Technology of Espírito Santo for the financial support. REFERENCES CÔRREA, T.H.A.; MANHÃES, R.S.T.; HOLANDA, J.N.F. Conversão de resíduo de casca de ovo galináceo em biomaterial cerâmico. In: I ENCONTRO DE
