Solar light induced tetracycline hydrochloride elimination over La2S3-CoIn2S4/NH2-functionalized polyacrylonitrile nanofibers

Abstract

La₂S₃ and CoIn₂S₄ were in-situ grown on the surface of NH₂-functionalized polyacrylonitrile (PAN) nanofibers to form Z-scheme La₂S₃-CoIn₂S₄/NH₂-PAN heterojunction for boosting solar light driven photodegradation of tetracycline hydrochloride (TCH). Z-scheme junction between La₂S₃ and CoIn₂S₄ was favorable for facilitating the separation and migration of e^-/h⁺ pairs, meanwhile S defects and -NH₂ groups served as the vacant sites of TCH adsorption and photon capture. In addition, ·O₂^- was the vital radical for the conversion of TCH to the harmless species and small molecules. The adsorption-photocatalytic capacity of La₂S₃-CoIn₂S₄/NH₂-PAN was greatly affected by La₂S₃ content, pH, and inorganic salts. La₂S₃-CoIn₂S₄/NH₂-PAN nanofibers exhibited the better adsorption-photocatalytic activity than La₂S₃-CoIn₂S₄/PAN, La₂S₃/NH₂-PAN, and CoIn₂S₄/NH₂-PAN for TCH elimination. The removal efficiency of TCH over optimal 3-La₂S₃-CoIn₂S₄/PAN with a nominal La₂S₃ content of 16 wt% was 98.32 % within 120 min, while declined to 89.01 % after five cycles due to the change in the valance states of surface components and metal leaching under the long-time irradiation.