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 max… Show more
“…Regarding environmental applications, only a few studies have been developed for water treatment so far. Nijhawan et al [25,26] fabricated porous HdA ceramic beads (4.0-5.0 mm) by mixing the p-HdA and solute starch and sintering at 1200 • C for 2 h to adsorb the fluoride. Le et al [27] mixed the p-HdA and polyvinyl alcohol (PVA) and calcinated at 600 • C for 4 h to obtain HdA pellets (2.0 × 10.0 mm) with a maximum lead adsorption capacity of 7.99 mg/g.…”
Although a powdered form of hydroxyapatite (p-HdA) has been studied for the adsorption of heavy metals that contaminate the restoration sites of decommissioned nuclear power plants, most of the studies are limited in the laboratory due to the head loss and post-separation in practical applications. Herein, we fabricated a porous bead form of HdA (b-HdA) as a novel adsorbent for removing radionuclides from aqueous environments via a facile synthesis by mixing the p-HdA precursor and polyvinyl butyral (PVB) as a binder and added a sintering process for the final production of a porous structure. The spherical b-HdA with an approximate diameter of 2.0 mm was successfully fabricated. The effectiveness of the b-HdA at removing Co(II) was investigated via the adsorption equilibrium at various experimental temperatures. The b-HdA exhibited the adsorption capacity for Co(II) ions with a maximum of 7.73 and 11.35 mg/g at 293 K and 313 K, respectively. The experimental kinetic data were well described using a pseudo-second-order kinetic model, and the adsorption mechanisms of Co(II) onto the b-HdA were revealed to be a chemisorption process with intraparticle diffusion being the rate-limiting step. In addition, the competitive adsorption onto the b-HdA with the order of U(VI) > Co(II) > Ni(II) > Sr(II) > Cs(I) was also observed in the multi-radionuclides system. Considering the advantages of the size, applicability to the continuous-flow column, and the easy separation from treated water, the b-HdA can be an excellent absorbent with high potential for practical applications for removing radionuclides.
“…Regarding environmental applications, only a few studies have been developed for water treatment so far. Nijhawan et al [25,26] fabricated porous HdA ceramic beads (4.0-5.0 mm) by mixing the p-HdA and solute starch and sintering at 1200 • C for 2 h to adsorb the fluoride. Le et al [27] mixed the p-HdA and polyvinyl alcohol (PVA) and calcinated at 600 • C for 4 h to obtain HdA pellets (2.0 × 10.0 mm) with a maximum lead adsorption capacity of 7.99 mg/g.…”
Although a powdered form of hydroxyapatite (p-HdA) has been studied for the adsorption of heavy metals that contaminate the restoration sites of decommissioned nuclear power plants, most of the studies are limited in the laboratory due to the head loss and post-separation in practical applications. Herein, we fabricated a porous bead form of HdA (b-HdA) as a novel adsorbent for removing radionuclides from aqueous environments via a facile synthesis by mixing the p-HdA precursor and polyvinyl butyral (PVB) as a binder and added a sintering process for the final production of a porous structure. The spherical b-HdA with an approximate diameter of 2.0 mm was successfully fabricated. The effectiveness of the b-HdA at removing Co(II) was investigated via the adsorption equilibrium at various experimental temperatures. The b-HdA exhibited the adsorption capacity for Co(II) ions with a maximum of 7.73 and 11.35 mg/g at 293 K and 313 K, respectively. The experimental kinetic data were well described using a pseudo-second-order kinetic model, and the adsorption mechanisms of Co(II) onto the b-HdA were revealed to be a chemisorption process with intraparticle diffusion being the rate-limiting step. In addition, the competitive adsorption onto the b-HdA with the order of U(VI) > Co(II) > Ni(II) > Sr(II) > Cs(I) was also observed in the multi-radionuclides system. Considering the advantages of the size, applicability to the continuous-flow column, and the easy separation from treated water, the b-HdA can be an excellent absorbent with high potential for practical applications for removing radionuclides.
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