Utilizing Ulva linza as eco-friendly biogenic synthesis approach of gold nanoparticles for reduction of 4-nitrophenol and degradation of dyes in wastewater

Abstract

Untreated printing and dyeing wastewater can significantly harm the environment and the ecosystem upon which humans rely for survival. Ulva linza (U. linza) is a green alga, one of the species of green tides that has been growing in recent years and can cause environmental problems. In this research, a straightforward one-pot biogenic synthesis method was used to mediate the production of gold nanoparticles (Au NPs) with U. linza for wastewater treatment. The resulting Au NPs, referred to as Au@UL NPs, were characterized using various methods, including Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), inductively coupled plasma (ICP) analysis, and transmission electron microscopy (TEM). The size of Au@UL NPs ranged primarily from 6 to 12 nm, showcasing a refined morphology in the TEM images. The impressive catalytic performance of Au@UL NPs was demonstrated in the conversion of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP), with an activation energy of 12.3 kJ mol⁻¹. Furthermore, Au@UL NPs displayed exceptional abilities to remove methylene blue (MB) dye and actual printing and dyeing wastewater through processes of adsorption and photocatalysis. The study also proposed mechanisms by which Au@UL NPs catalyze the reduction of 4-NP and the decolorization of dyes. This research offers an economical and environmentally friendly solution for pollutant removal and addresses the detrimental effects of algal blooms on the environment, providing new insights into the use of harmful organisms for wastewater treatment.