Preparation of Efficient, Stable, and Reusable Laccase–Cu₃(PO₄)₂ Hybrid Microspheres Based on Copper Foil for Decoloration of Congo Red

Abstract

Issues with separation and recycling of suspension powder samples in wastewater hinder the practical application of hybrid enzyme materials for environmental pollution control. In this work, for the first time, laccase–Cu3(PO4)2 hybrid microspheres with hierarchical structure were successfully prepared and loaded on a treated copper foil surface. First, Cu8(PO3OH)2(PO4)4·7H2O nanoflowers (CPN) were synthesized on the copper foil surface by a solution-growth method. Then the laccase–Cu3(PO4)2 hybrid microspheres were loaded on the CPN surface via an immersion reaction method using a laccase-containing phosphate buffer solution (PBS) solution. The formation mechanisms of CPN and La–CPN (laccase–Cu3(PO4)2 hybrid microspheres on the CPN surface) are discussed in detail and mainly contain the following processes: crystal growth, coordination effect, in situ growth, and self-assembly. Compared with free laccase, the as-obtained La–CPN has a higher decoloration efficiency (more than 95%) and decoloration rate (nearly 3.6 times higher than that of free laccase) on Congo red dye (CR) solution in the short time of 3 h. Cyclic voltammetry results demonstrated that the oxidizability of immobilized laccase could be enhanced as a result of the presence of Cu2+. Meanwhile, the utilization of the CPN carrier and the unique nanostructure gave the laccase–Cu3(PO4)2 hybrid microspheres high and stable decoloration efficiency and improved the tolerance toward pH and temperature changes. La–CPN still maintained about 85% relative activity after storage for 10 days. The concept presented herein can be further expanded to the preparation of other hybrid enzyme materials for environmental control, medical treatment, and more applications.