Abstract:

A novel, high-yielding synthesis of micro/nano ZnO pompons using glutamic acid fluoborate (GluBF₄) ionic liquid is reported. The precursor was prepared with zinc acetatedihydrate [Zn(Ac)₂·2H₂O] and sodium hydroxide (molar ratio = 1:6) as starting materials in an aqueous solution of the GluBF₄ ionic liquid at room temperature, which was then heated by microwave to form nano-ZnO powder. The ZnO pompons were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), specific Brunauer-Emmett-Teller (BET) surface area method, and energy dispersive spectrometry (EDS). The product displayed a hexagonal wurtzite structure. The pompon diameter was determined to be 20.4 nm, with a pompon specific surface area of 28.3 m²·g^-1. A possible mechanism for the formation of the nano-ZnO pompons is discussed. The ZnO pompons displayed high photocatalytic reactivity and photostability under sunlight. Aqueous solutions of methyl orange (MO) and methyl violet (MV) containing the ZnO pompons were exposed to sunlight and the decolorization rates were determined by monitoring the drop in color intensity. After 5 h, the solutions reached 74.3% and 96.9% degradation, respectively. The total organic carbon (TOC) content decreased as the photodegradation process occurred. The morphology, color, and weight of the ZnO pompons remained unchanged even after being reused five times.

Key words: Amino acid ionic liquid, Microwave heating, Micro/nano ZnO, Organic contaminant, Photocatalytic degradation