Cationic flocculants derived from native cellulose: Preparation, biodegradability, and removal of dyes in aqueous solution

Water-soluble quaternized celluloses with various substitution degrees were prepared. The polymers showed excellent flocculation ability
against anionic dyes; this ability was strongly dependent on the substituent degree and not affected by the temperature and pH of the dye solution.
The flocculation ability was accurately fitted by a pseudo-second order kinetic model, which enabled reliable predictions of the flocculation
behavior. In addition, the flocculation behavior of the anionic dyes followed the Langmuir adsorption isotherm model, whose analysis revealed the
maximum anionic dye coagulation/flocculation capacity. The quaternized celluloses could be regenerated by washing in NaOH solution and
precipitation in acetone. The quaternized celluloses exhibited good biodegradability, with a maximum degradation of 48% within 48 h using
cellulase. These encouraging results indicate that the cationic celluloses could be applicable for use as reusable flocculants for wastewater
treatment, leading to an environmentally friendly method to the removal of dyes from aqueous solutions.