Nanostructured fusiform hydroxyapatite particles precipitated from aquaculture wastewater

Abstract

The present work represents a new approach for the isolation of uniform nano particulate hydroxyapatite (HAp). The chemical characterization of a calcium phosphate product obtained from industrial trout farm aquaculture wastewater by two different routes, washing either with a basic aqueous medium (wash) or followed by a further washing with ethanol (wash), is explored. Characterization of the isolated materials includes morphology studies (SEM and TEM), structural (XRD, electron diffraction), compositional (EDX) and thermogravimetric analysis (TGA). The obtained products are a mixture of different compounds, with hydroxyapatite the predominant phase. The morphology is unusually nanometric size with fusiform shaped particles, such characteristics are ordinarily only obtained by synthetic routes. This process of phosphate precipitation represents a unique self-sufficient process to be compared to conventional chemical or biological practices for precipitating phosphate.

The preparation of hydroxyapatite from unrefined calcite residues and its application for lead removal from aqueous solutions

“…Thus, exploring innovative and simpler approaches, employing inexpensive recycled calcium materials and using reduced energy consumption protocols to synthesise such a benign material presents a worthwhile research challenge. Besides conventional synthetic chemical routes, a plethora of waste materials that attain high calcium content have been successfully utilised as a calcium source in the preparation process of HAP, such as mussel shells, 6-9 eggshells, 10-13 kina shells, 14 sh bones or scale, 15,16 gypsum, [17][18][19][20][21] ash of poultry waste, 20 aquaculture wastewater, 22 biomass ashes, 23 oyster shells, 24 calcium sulte from production of agrichemicals, 25 abalone shells, 26 cattle bones 27 and mystery snail shells. 28 Heavy metals' pollution of aquatic environments as a consequence of anthropogenic activities has drawn international attention due to their persistency, non-biodegradability, bioaccumulation and toxicity.…”