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

The high value utilization of lignin is facing sheer challenge, and the use of lignin as a raw material to prepare flocculants is of tremendous significance for wastewater treatment. In this study, lignin-based flocculants (LBFs) with tunable performances were prepared by mild copolymerization of lignosulfonate and [2-(Methacryloyloxy) ethyl] trimethylammonium chloride solution (METAC) under short-wavelength ultraviolet light. The effect of preparation conditions on the product performances was investigated, and two classes of LBFs were obtained in the same system by adjusting the preparation conditions. As compared with the preparation of LBFs suitable for simulated dye wastewater, higher monomer dose and lower pH were required for the preparation of LBFs suitable for kaolin and E. coli suspensions. Among them, LBF-1 could remove more than 95 % dye, and LBF-2 had 99.2 % and 97.5 % turbidity and bacterial removal rates, respectively. Moreover, the effects of external factors such as the LBF-1 dose, initial concentration of dye and wastewater pH on the decolorization efficiency were also explored. In addition, the sterilization function of LBF was studied, and LBF-2 experienced a process of first flocculation followed by sterilization. Furthermore, the flocculation mechanisms of LBFs in treating three kinds of wastewaters were discussed in detail.