Effect of pH on mussel shells-originated HAP supported Ag catalysts for catalytic combustion of VOCs

Volatile organic compounds (VOCs) triggered serious air pollution and mussel shell caused the marine envi-ronmental issues. Herein, hydroxyapatite (HAP) using mussel shells as calcium source was prepared by hydro -thermal method with different pH (pH = 6, 8, 10, 11) controls to support Ag catalyst for removal of VOCs. It was found that the amount of skeletal hydroxyl species and textual properties of HAP were controlled by pH effec-tively, and the increase of hydroxyl groups in the framework resulted in forming smaller-sized Ag2O particles. When pH was 8, the Ag/HAP-BpH=8 catalyst exhibited 100 % conversion of ethyl acetate and toluene at 260 degrees C and 300 degrees C, respectively. Silver species were more likely existed on the surface of HAP-BpH=8 to form large-size Ag particles (6.4 nm) and more Ag2O species. The lower ratio of Ag0/Ag+ were crucial for improving the VOCs oxidation activity at lower temperatures. This work applied waste mussel shells to prepare high value-added Ag/ hydroxyapatite catalysts and to promote VOCs catalytic oxidation.