Recuperation and characterization of calcium carbonate from residual oyster and clamshells and their incorporation into a residential finish

The final disposal of waste generated by human activities has been turned into a great challenge; until now, little attention has been paid to organic waste, particularly from the restaurant sector. This work describes the process of obtaining calcium carbonate contained in oyster and clam shells re-collected in seafood restaurants. The IR absorption spectra of all the samples revealed the presence of characteristic bands of the carbonate group located at 872, 712 and 1414 cm(-1); the peak at 1081 cm(-1) of the clamshells confirms the presence of the aragonite phase. The SEM images allow observing a granular morphology whose agglomerates having a size within the range of 0.5-15 mu m in brown shells, and a lower dispersion prevails in the grey species and oyster shells that go from 0.3 to 5.9 mu m. All of the shells were found to be composed of carbon (C), oxygen (O2) and calcium (Ca) in different concentrations. The calcium carbonate obtained from clamshells has an orthorhombic crystalline structure, while the oyster carbonate has a rhombohedral structure as the calcium carbonate used in the construction industry; the morphology particles also coincide with each other. The material obtained combined with a mixture composed of resin, cellulose, and granules were used to prepare a paste, which was used as a residential finish.

Automated summary

This study focuses on obtaining calcium carbonate from oyster and clam shells collected in seafood restaurants, and using it to prepare a paste for residential finishes. Different types of shells were found to have variations in composition and crystal structures, which could enhance the utilization of organic waste.