<p>The use of waste from the food industry can help growing concerns about the environmental impact of chemical synthesis methods. This paper described a bioinspired design strategy for the highly efficient preparation of magnesium aluminate (MgAl₂O₄) nanoparticles using an aqueous extract of apple peel. The impact of calcination temperature on the characteristics of the obtained samples and their photocatalytic capability were discussed. The prepared MgAl₂O₄ samples were characterized using various techniques: X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Fourier transform infrared (FT-IR), Raman, Ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy, and nitrogen adsorption–desorption analysis. The XRD results conformed the obtaining of MgAl₂O₄ with a spinel structure and an average crystallite size of 5–8&#xa0;nm. The morphological analysis by SEM revealed aggregates composed of fine nanoparticles. Raman spectroscopy detected only the bands characteristic of spinel-type MgAl₂O₄ with a high degree of inversion in the cation lattice. The UV–Vis spectra and Tauc’s plot analysis of the magnesium aluminate samples obtained after different thermal treatments revealed band&#xa0;gap values of 3.28 and 3.75&#xa0;eV, respectively. Under visible light irradiation, the photocatalytic efficiency reached ~ 93% against a methyl orange solution. This paper provides new insights into the use of apple peel waste as a bio-renewable and sustainable resource, serving as both a raw material and a platform for the production of useful nanoparticles for environmental remediation.</p> Graphical abstract <p>Ovidiu Oprea, Dana Gingasu, Daniela C. Culita, Jose Maria Calderon Moreno, Gabriela Marinescu, Silviu Preda</p> <p></p>