Morphology-dependent activation of hydrogen peroxide with Cu_(2)O for tetracycline hydrochloride degradation in bicarbonate aqueous solution

The design of efficient heterogeneous catalysts in bicarbonate-activated hydrogen peroxide systems(BAP)is a hot topic in wastewater treatment.In this work,Cu_(2)O nanoparticles with different morphologies including cubic shape(c-Cu_(2)O),octahedron shape(o-Cu_(2)O)and spherical shape(s-Cu_(2)O),were applied in BAP for the first time to degrade tetracycline hydrochloride(TC).Compared with Cu^(2+)ions and CuO,TC degradation was boosted in the presence of Cu_(2)O in the BAP system,with the degradation rate following the order c-Cu_(2)O>o-Cu_(2)O>s-Cu_(2)O.The morphology-dependent effects could be linearly correlated with the ratio of surface oxygen species(O_S),but not with the surface area or Cu(Ⅰ)ratio.The c-Cu_(2)O catalyst with exposure of(100)facets contained 76.6%O_Sas the active site for H_(2)O_(2)adsorption and activation,while the value was much lower for o-Cu_(2)O and s-Cu_(2)O with dominant(111)facets.The presence of HCO_(3)-enhanced the interactions among Cu_(2)O,H_(2)O_(2)and TC,leading to facile oxidation of Cu(Ⅰ)to Cu(Ⅱ)by H_(2)O_(2),and the formation of various reactive species such as hydroxyl radicals and Cu(Ⅲ)contributed to TC degradation.This work provides a new method for enhancing H_(2)O_(2)activation with heterogeneous catalysts by crystal facet engineering.