Biosynthesis of zinc oxide nanoparticles (ZnO NPs) using fungal extract for tetracycline removal from prawn farm wastewater

Antibiotics are frequently found in the environment, particularly in wastewater. They can cause acute and chronic toxicity, disrupt indigenous microbial populations, and have adverse effects on photosynthetic aquatic organisms. Tetracycline (TC), a widely used antibiotic, has been extensively employed in aquaculture in Malaysia, leading to water pollution and health issues. This paper investigates the formation of zinc oxide nanoparticles (ZnO NPs) utilizing fungus extract from Aspergillus arenarioides EAN603 for removing TC from prawn farm wastewater (PFWW). ZnO NPs were characterized, and the adsorption performance was optimised using a central composite design (CCD) of response surface methodology (RSM). The adsorption parameters, including adsorbent dosage (1–2 g/L, A), TC concentration (500–2000 mg/L, B), pH (4–6, C), and contact time (60–70 min, D), were determined. Adsorption kinetics, isotherms, and the effect of adsorption on the structure of ZnO NPs were also investigated. ZnO NPs contained a hexagonal wurtzite phase and were porous and homogeneous. The optimization data fitted significantly well to the quadratic model, with a non-significant lack of fit, suggesting that 95% of the data fit the quadratic model well. The TC concentration showed the highest, whereas the interaction of contact time and pH showed the lowest impact on the adsorption of TC. Factor effects were in the order B > C > A > D, while interaction effects were in the order BD > AB > BC > AC > AD > CD. The best TC removal effectiveness of 93% was achieved at the parameters of 500 mg/L, pH 5, 1.5 g/L, and 65 min. TC was adsorbed onto ZnO NPs via chemisorption, resulting in a TC monolayer with the best adsorption capacity of 10.86 mg/g. The biosynthesized ZnO NPs demonstrated good performance in removing TC from PFWW, making it a viable alternative adsorbent for wastewater treatment.