Superior photocatalytic degradation of water pollutant dyes and strong antimicrobial activity in Coelastrella terrestris algal-mediated biosynthesized stable copper hydroxide nanoparticles

Given the detrimental impact of excessive and improper usage of dangerous chemical compounds on environmental pollution, it is imperative to explore facile and eco-friendly methods for the synthesis of nanoparticles (NPs). In this regard, a novel green synthetic protocol was adopted for the synthesis of copper hydroxide nanoparticles (Cu(OH) 2 NPs), using Coelastrella terrestris algal extract. The biosynthesized and chemically synthesized Cu(OH) 2 NPs were systematically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible (UV-Vis), and field emission scanning electron microscopy (FE-SEM) coupled with energy-dispersive spectroscopy (EDS). The XRD confirmed the formation of an orthorhombic phase of Cu(OH) 2 NPs and revealed that the crystallite size of biosynthesized Cu(OH) 2 NPs (Bio-Cu(OH) 2 NPs) and chemically synthesized Cu(OH) 2 NPs (Chem-Cu(OH) 2 NPs) were 29.32 nm and 24.69 nm, respectively, corresponding to the major crystallographic plane (021). The synthesized Cu(OH) 2 NPs were utilized efficiently for important applications, such as photocatalytic and antimicrobial activities. Bio-Cu(OH) 2 NPs demonstrated exceptional photocatalytic activity, achieving degradation efficiencies of 85.67% for Amido black 10B (AB10B) and 98.87% for Fast green (FG) dyes, respectively. They also exhibited potent antibacterial activity against a multidrug-resistant Pseudomonas aeruginosa bacterial strain with a 50 μg/mL MIC value and superior antifungal activity against Candida albicans fungal strain with a 250 μg/mL MIC value. These findings highlight the potential of algal-mediated Cu(OH) 2 NPs as versatile agents for wastewater treatment and antimicrobial applications. Our work underscores the importance of green synthesis methods and the promising future of these nanoparticles in addressing environmental and health challenges. Graphical abstract