Efficient Photodegradation of Dyes from Single and Binary Aqueous Solutions Using Copper(II) Coordination Polymers

The present study reports the application of three copper(II) coordination polymers, namely ¹_∞[Cu₃L₂(N₃)] CH₃COO (<b>CP1</b>), ¹_∞[Cu₃L₂(NO₃)]NO₃·2CH₃OH·2H₂O (<b>CP2</b>), and ¹_∞[Cu₃L₂(H₂O)](ClO₄)₂ (<b>CP3</b>), where <b>H₂L</b> stands for N,N'-bis[(2-hydroxybenzilideneamino)propyl]-piperazine) as catalysts for photocatalytic degradation of Acid Orange 7 and Methyl Orange dyes from single and binary aqueous solutions. The influence of the photocatalyst nature, hydrogen peroxide presence, reaction time, dye concentration, and catalyst dose on the photodegradation efficiency was studied. Under visible light irradiation, complex <b>CP1</b> demonstrated the highest photodegradation efficiency of 92.40% and 80.50% towards Acid Orange 7 and Methyl Orange, respectively. The kinetic studies indicated that the photodegradation process followed a pseudo-first-order kinetics. The highest rate of the degradation process was obtained when <b>CP1</b> is used, and the necessary time for the degradation of the dyes increases with increasing concentration of the dye solutions. The degradation efficiency of more than 75% after five recycling/reuse cycles of <b>CP1</b> and the yields higher than 72% obtained for the degradation of dyes from the binary system demonstrate the photocatalytic capacity of <b>CP1</b>. A photocatalytic oxidation mechanism was proposed and the stability of the <b>CP1</b> complex before and after the photodegradation process of dyes, both from simple and binary solutions, was investigated and confirmed.