Preparation of pearlescent flakes from green mussel shells

Abstract

Pearlescent color is dynamic multiple colors, which change with viewing angles. Green mussel shells show clear pearlescent phenomena and can be transformed into shiny lustrous flakes. Wasted green mussel shells from seafood industries are plenty and causing severe environmental pollution. This research reduces the amount of waste and adds value to wasted shells. The structure of this shell is a brick-and-mortar like structure consisting of aragonite calcium carbonate and protein. The preparation of pearlescent flakes from the green mussel shell is achieved via protein removal process using chemical and thermal treatments. Molecular/structural characteristics of green mussel shells and pearlescent flakes are studied using optical microscopy, scanning electron microscopy, infrared spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. The sizes of pearlescent flakes are in the range of 5 – 200 µm with the aspect ratio of 10. The aragonite calcium carbonate in each layer is 5 µm in width and 200 – 500 nm in thickness. There is also a slight amount of protein (~2.2 wt%) inside the aragonite tiles that cannot be removed. The pearlescent color of the prepared pearlescent flakes is dull unless the flakes are treated with hydrochloric acid in order to remove the residual calcium carbonate dust on their surface. Clean pearlescent flakes are beautiful glittering and suitable for uses in cosmetics, automotive paints, and decorative items.