Apatite inducing ability on silk fabric and its ammonium gas adsorptivity

Abstract

Silk fabric contains silk fibroin protein which consists of an amino group. This amino group can act as a nucleation site of hydroxyapatite by inducing the Ca2+ ions from surrounding solution at an appropriate pH. To increase the initial Ca2+ ions on the surface of silk fabric, the commercial grade silk fabric was drenched in CaCl2 solution for 12 h, Na2HPO4 solution for 20 min, and CaCl2 for 20 min, respectively. Finally, the fabric was rinsed by deionized water and the drenching processes were repeated for 7 times in order to increase the inducing ability of hydroxyapatite. XRD patterns showed the phases of hydroxyapatite coexisted with monetite. The sample drenched in CaCl2 over 12 h gave more apatite peak intensity which was a result of increased Ca2+ ions over the surface and dot mapping technique with SEM showed the well distribution of both calcium (Ca) and phosphorus (P) on silk fabric. It is worth noting that hydroxyapatite induced on the surface of silk fabric can enhance the selectivity in ammonia gas adsorption. An ammonia gas adsorption resulted in better performance of silk with hydroxyapatite over raw silk fabric were displayed. These results are promising for development of Thai silk in term of superior ammonia gas adsorption characteristic.