Zinc oxide nanoparticles: Biosynthesis, characterization, biological activity and photocatalytic degradation for tartrazine yellow dye

•E. grandis extract was used for ZnO-NPs.•CCDR 23 showed the optimal condition for TY photodegradation with 76.1%.•ZnO-NPs reuse showed photocatalytic stability (k = 0.0077–0.0067 min−1).•MIC of 0.625 mg mL−1 against S. Aureus, E. Coli, K. Pneumoniae, and P. Auruginosa.•ZnO-NPs showed biocompatibility against 293T, tumor activity A549, and U87MG. The present study aims to synthesize/characterize zinc oxide nanoparticles (ZnO-NPs) to evaluate the application of tartrazine yellow (TY) dye removal. ZnO-NPs were synthesized by the biosynthesis method from Eucalyptus grandis extract. X-ray diffraction (XRD), zeta potential (ZP), N2 porosimetry, Field Emission Gun Scanning Electron Microscope (FEG-SEM), zero charge point (pHZCP) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) were used to the ZnO-NPs characterization. The antimicrobial activity was performed by the MIC (Minimum Inhibitory Concentration) method against gram-positive (S. aureus) and gram-negative (E. coli, K. pneumoniae and P. aeruginosa) strains. For cellular activity assays, MTT (3-(4,5-Dimethylthiazol-2-yl) and DCFH-DA (2′7′ dichlorofluorescein diacetate) tests were performed with cell lines of the 293T, A549 and U87MG. FEG-SEM micrography indicated a heterogeneous and porous morphology with rod-shaped zinc oxide nanoparticles (particle size ranged from 40 to 50 nm). ZnO-NPs showed a negative charge surface (−11.6 ± 0.2 mV), pHZCP ≈ 7.16 with type III and H1 hysteresis (SBET = 3.9 m2/g, and Dp = 16.2 nm) indicating a mesoporous material with pores open at both ends. The optimal condition was [ZnO-NPs] = 0.6 g/L, [TY] = 20 mg/L and pH ≈ 6.0 with 76.1 % (k = 0.0077 min−1) for the TY photodegradation under visible radiation, and after VI cycles of ZnO-NPs recycling, there was a decrease of only 6 %. ZnO-NPs showed antimicrobial activity of 0.625 mg mL−1, as well as a decrease in cell viability in the three tested lines in 100 and 300 µg mL−1. Therefore, ZnO-NPs showed potential application for TY photodegradation to be used in wastewater treatment and nanomedicine.