Great improvement on tetracycline removal using ZnO rod-activated carbon fiber composite prepared with a facile microwave method

Highlights: • ZnO rod-ACF was prepared by a method involving a microwave within only 3 min. • ZnO rods (average diameter of 0.3–0.5 μm, length of 1.0–1.5 μm) were grown on ACF. • 99% of tetracycline was degraded and 90.7% TOC was removed within 1 h under UV light. • ZnO rod-ACF achieved high performances even after three cycles of uses. - Abstract: New composite materials of activated carbon fiber (ACF) coated with zinc oxide (ZnO) were obtained by applying a green, cost-effective and rapid synthetic route using a commercial microwave oven. ZnO rods with a uniform and stable structure and an average diameter of 0.3–0.5 μm and length of 1.0–1.5 μm were achieved after only 3-min microwave treatment. The properties of ZnO were efficiently transferred to ACF, such that the resulting material, termed ZnO rod-ACF, demonstrated a promising potential as an efficient photocatalyst and simultaneously as an adsorbent. Pharmaceutical tetracycline at a concentration of 40 mg/L was used to evaluate the organic pollutant removal capacity of the synthesized materials. At pH 8, ZnO rod-ACF exhibited excellent removal capacity (over 99%) and mineralization (90.7%) of tetracycline in aqueous solution within 1 h under UV irradiation. The stability of ZnO rod-ACF was maintained and the mineralization of tetracycline was also maintained at 81.35% after multiple usage cycles. The photodegradation pathways of tetracycline were proposed based on the identified reaction intermediates.