Abstract
The conditions for the homogeneous coating of hydroxyapatite (Ca10(PO4)6(OH)2; HAp) on the multi-wall carbon nanotubes (MWCNTs) were examined via the processes of (i) the acid treatment of conc. nitric and sulfuric acids at 50°C for 24 h or the citric acid at 300 and 350°C for 0.5 h in Ar atmosphere in order to form carboxyl group, and (ii) the microwave heating (100°C, 5 min) of acid-treated MWCNTs in the “apatite-dissolved solution” prepared by bubbling CO2 gas into the commercial HAp-dispersed water. The microwave heating of surface-modified MWCNTs (the citric acid treatment at 300°C for 0.5 h) in the apatite-dissolved solution was effective in the homogeneous coating of calcium-deficient HAp (Ca/P ratio =1.57), compared to the case of surface modification by conc. nitric and sulfuric acids.
