Calcined Mytella falcata shells as a source for CaAl/LDH production: Synthesis and characterization

Abstract

A huge environmental problem in the world is related to the volume of waste produced by bivalve mollusks culture, which generates great impact and high costs for proper treatment and disposal. Faced with this problem, for the first time, the feasibility of introducing bivalve mollusks culture shells to produce layered double hydroxides (LDH) was studied. Produced LDH was characterized by TG/DTG, SEM/EDS, N2 adsorption/desorption, FTIR, XRD, EDX, and pHPZC. The composition of Mytella falcata shells constituted mainly of calcium carbonate with aragonite and calcite polymorphs, low surface area, irregular and rough morphology composed of a conglomerate of overlapping plates. CaCO3 is converted to CaO after calcination. Calcium oxide obtained from the mollusk shells showed morphology, particle size distribution, decomposition intervals, crystallinity, and other characteristics similar to the commercial material, indicating that it is a possible substitute for LDH synthesis. The material CaAl/LDH produced presented high crystallinity and surface area, 65.62% greater than the similar material produced with commercial reagents. These results confirmed that it is possible to use Mytella falcata Residue (MFR) to produce CaO with high quality that can be used for CaAl/LDH synthesis.