Oyster shell reuse: A particle engineering perspective for the use as emulsion stabilizers

Abstract

Oyster shells are an important bioresource that causes serious environmental problems and is currently only partially repurposed. Its versatile nature is reflected in the manifold studies already proposed for the material. In this study, we add to this effort by first grinding the material with a hammer mill, beater disc mill, pin mill and wet media mill, treating part of it in a muffle furnace, noting the shift in its properties such as particle size, morphology, surface free energy, specific surface area and choosing a fraction to incorporate in a particle stabilized emulsion. The particle stabilized emulsions were prepared with oyster shells grinded by the agitated wet media mill at 2000 rpm for 30 min, with a media at x 50 = 0.79 μm, a SSA at 17.16 m 2 /g, a SFE at 32.53 mN/m and with particles resembling a spherical shape. The emulsion was studied in terms of particle concentration, ranging from 2 to 10 wt% with the 8 wt% showing the best stability. The 8 wt% oyster shell formulation was tested and compared with a formulation using 2 wt% Aerosil particles and a surfactant store-bought product. The oyster shell particle formulation exhibited minor viscosity changes in the studied period of 8 weeks, a constant LVE range and promising behaviour in the proposed application. • Description of applications suggested for waste oyster shells in different sectors. • Grinding experiments for oyster shells performed with four different types of mills. • Characterization of the physicochemical properties of the grinded fractions including size, shape and surface interactions. • Proposition of an innovative application for oyster shells as emulsion stabilizers. • Rheological analysis to support suitability of the particles as stabilizers.