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

•Hydroxyapatite was prepared using mussel shells as calcium source by pH control.•Ag/hydroxyapatite behaved 100 % conversion of ethyl acetate at 260 °C.•Small Ag particles and Ag2O species were formed by more skeletal OH groups on HAP.•The lower ratio of Ag0/Ag+ was crucial for lower-temperature conversion of VOCs. Volatile organic compounds (VOCs) triggered serious air pollution and mussel shell caused the marine environmental issues. Herein, hydroxyapatite (HAP) using mussel shells as calcium source was prepared by hydrothermal 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 effectively, 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 °C and 300 °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.