Insights into Mn loaded carbon-silica-membrane based catalytic ozonation process for efficient wastewater treatment: Performance and mechanism

Heterogeneous catalytic ozonation (HCO) is a promising technology for advanced wastewater treatment, and developing catalysts with both high catalytic activity and easy recycling capability is challenging but essential. In this work, easily separable Mn loaded carbon-silica-membrane (Mn-CSM) was synthesized by electrospinning and Mn-CSM based packed bed reactor was constructed for catalytic ozonation, achieving excellent catalytic performance for refractory organic degradation. Mn-CSM exhibited a lamellar structure with a thickness of several hundred micrometers and was centimeter-sized in the other two dimensions, which make it easy to be separated in wastewater treatment. At the microscopic scale, Mn-CSM was composed of highly connected nanofibers, which provided large specific surface area for the exposure of active sites. In oxalic acid (OA) degradation and coal gasification wastewater advanced treatment, Mn-CSM demonstrated superior catalytic ozonation performance. After 60 min, 93% of OA was degraded in Mn-CSM based HCO process, and the effluent COD of coal gasification wastewater decreased from 105 mg L-1 to 42 mg L-1. Reactive oxygen species in aqueous solution and on catalyst surface contributed to the organic degradation. The introduction of SiO2 nanoparticles in Mn-CSM can not only enhance its catalytic stability, but also improve fluid flow field distribution. Furthermore, the presence of SiO2 increased the hydrophilicity of Mn-CSM and a better removal of hydrophilic substances (HIS) was achieved in Mn-CSM based HCO. This study highlights a Mn-CSM ozone catalyst with high catalytic activity and easy recycling capability and a Mn-CSM based catalytic ozonation process, which is promising for the degradation of refractory organics in wastewater.