Bimetallic Bi/Cu0-catalyzed persulfate-based advanced oxidation processes towards clofibric acid degradation in wastewater

Clofibric acid (CFA), an important blood-lipid regulatory drug is an emerging organic pollutant and widely reported in water resources. A novel bimetallic, bismuth/zero valent cupper (Bi/Cu⁰) catalyst was prepared which showed better physiological, structural, and catalytic properties than Cu⁰. The Bi/Cu⁰ effectively catalyzed persulfate (S₂O₈²⁻) and caused 85% degradation of CFA. The Bi coupling improved reusability and stability of Cu⁰. The use of alcoholic and anionic radical scavengers and analyzing change in [S₂O₈²⁻]₀ proved that Bi/Cu⁰/S₂O₈²⁻ yield hydroxyl radicals (^●OH) and sulfate radicals (SO₄^●–). The ^●OH and SO₄^●– showed faster reaction with CFA, i.e., 4.65 $\times$ 10⁹ and 3.82 $\times$ 10⁹ M⁻¹ s⁻¹ and degraded CFA into four degradation products. Under optimal conditions of [Bi/Cu⁰]₀ = 1.0 g/L and [S₂O₈²⁻]₀ = 40 mg/L, 99.5% degradation of the 10 mg/L of CFA was achieved at 65 min. Temperature showed promising effects on the removal of CFA by Bi/Cu⁰/S₂O₈²⁻ and caused 98% removal at 323 K than 75% at 298 K at 32 min. The temperature effects were used to calculate activation energy, enthalpy, and rate constant of CFA degradation. The Bi/Cu⁰/S₂O₈²⁻ showed effective removal of CFA in real water samples also. The ecotoxicity study confirmed non-toxic product formation which suggests high capability of the proposed technology in the treatment of CFA.