Boosting Fenton-like catalytic performance and environmental stability of nano zero-valent copper (nCu(0)) catalyst by inhibiting the formation of oxide layer: Catalytic performance and mechanistic study

Abstract

Nano zero-valent copper (nCu(0)) as Fenton-like catalyst has shown great potential in the treatment of organic wastewater. However, nCu(0) is prone to be agglomerated and oxidated, causing to the reduction in catalytic ability. Herein, biochar supported highly dispersed nCu(0) (Cu/C) was synthesized by the carbonization method. And acid-modified strategy was proposed to inhibit the oxidation of nCu(0). Physicochemical properties of Cu/C catalysts modified by different acid (HCl, H₂SO₄ and HNO₃) were analyzed by various characterizations. The results showed that only the introduction of HCl could obviously inhibit the formation of oxide layer on Cu(0), while HNO₃ and H₂SO₄ couldn’t. Furthermore, the content of oxide layers decreased with the increase in HCl addition. Correspondingly, the catalytic performance enhanced gradually. Cu(0) was proved to be the active centers. And the presence of oxide layers was adverse to the catalytic reaction. When the adding amount of HCl reached to 1 mL, the Cu/C-HCl-1.0 catalyst showed the optimal catalytic performance. 97.1 % of p-nitrophenol (PNP) was degraded within 60 min. The reaction rate was 7.6 times that of unmodified Cu/C catalyst. Furthermore, Cu/C-HCl-1.0 catalyst possessed excellent environmental stability. After being directly exposed to air for 4 months, catalytic performance had no obvious decrease. In addition, the catalyst showed efficient degradation ability to phenols, dyes and antibiotics. And it was not sensitive to the initial pH of the organic solution (3.7 ∼ 11.2). OH was confirmed to be the main reactive species for the degradation of organic pollutants, which was formed by the decomposition of PMS by obtaining electrons from Cu(0). This work proposed a novel and efficient method to enhance the catalytic ability and environmental stability of Cu(0) by inhibiting the formation of oxide layer.