Macroporous hydroxyapatite ceramic beads for fluoride removal from drinking water

Abstract

Abstract BACKGROUND This study evaluates the capacity of hydroxyapatite ceramics to remove fluoride from drinking water. Porous hydroxyapatite ceramic beads approximately 5 mm in diameter were fabricated using soluble potato starch as well as insoluble rice starch, wheat starch, corn starch, and cellulose as pore‐forming agents. RESULTS Calcination of hydroxyapatite particles, followed by mixing with starches and water, compaction, and sintering at 1200 °C resulted in the formation of macroporous ceramic beads with maximum fluoride adsorption capacities ranging from 7 to 12 mg g −1 , depending on the relative proportions of different pore‐forming agents. Increasing the insoluble starch content from 0 to 25% by volume in ceramics with 50% by volume hydroxyapatite led to a marked improvement in fluoride adsorption by creating interconnected macropores, as evidenced by scanning electron microscopy ( SEM ). Calcination of hydroxyapatite powder at or above 400 °C before ceramic preparation was required to obtain a ceramic material with sufficient structural integrity to withstand operation and handling after sintering. CONCLUSION This study evaluates the potential of using porous hydroxyapatite ceramics to remove fluoride from drinking water. An increase in fluoride adsorption capacity was consistent with the observation of macropores in SEM images as well as an increase in open porosity and specific surface area ( SSA ) measurements as the insoluble starch content was increased from 0 to 25%. © 2016 Society of Chemical Industry