Regeneration of porous electrospun membranes embedding alumina nanoparticles saturated with minocycline by UV radiation

A regeneration method for porous electrospun membranes embedding alumina nanoparticles saturated with minocycline was investigated by UV-LED system. The percentage of adsorption capacities before and after regeneration were used to evaluate regeneration efficiency. The PVDF and PVDF-Al 2 O 3 fiber mats were prepared by electrospinning technique. Scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS) analyses directly confirmed that Al 2 O 3 nanoparticles were generally exposed to the surface of PVDF-Al 2 O 3 fiber mats. Among them, PVDF-Al 2 O 3 10% fiber mats can effectively adsorb minocycline (remove efficiency >97% in 18 h) with first-order rate constant k  = 2.253 ± 0.331 h −1 . The sorption capacity can still keep 81% after five sorption/UV-regeneration circulations. Two successional stages may exist during regeneration: (i) transfer of minocycline from the surface of PVDF-Al 2 O 3 fibers to the DI water , followed by the (ii) decomposition of this compound in aqueous solution by direct and indirect photolysis to yield the intermediate species. The desorption capacity and desorption percentage were 4.39 mg g −1 and 23.30% respectively. The regeneration yields were further enhanced to 94.20% by UV radiation. Minocycline was effectively degraded to intermediate products by direct and indirect photolysis, further degraded into CO 2 , H 2 O, and NO x by UV-generated ozone during regeneration. The results indicated that UV radiation was an effective method of regenerating PVDF-Al 2 O 3 fiber mats with low energy requirements. The photochemical byproducts and the reaction sites during regeneration were also determined and recognized.