Chemosynthesis, characterization and application of lignin-based flocculants with tunable performance prepared by short-wavelength ultraviolet initiation

•LBFs with tunable performances were prepared by short-wave UV initiation.•The effect of preparation conditions on flocculation performance was explored.•The decolorization, turbidity removal and bacterial removal of LBF were investigated.•Sterilization performance of LBF was revealed for the first time.•The flocculation efficiency and mechanism of LBF were investigated.