Highly selective removal of cationic dyes from water by acid-base regulated anionic functionalized polyacrylonitrile fiber: Fast adsorption, low detection limit, reusability

摘要

A series of anionic functionalized polyacrylonitrile fibers were prepared and used to remove cationic dyes from water. The phenolate immobilized fiber (PAN(P(-))F) exhibited excellent adsorption capacities for cationic dyes, among which the best results was obtained for Brilliant cresyl blue (BCB) with color changing of the solution from sapphire to light yellow. Additionally, PAN(P(-))F can selectively remove cationic dyes from dye mixtures containing both anionic and cationic dyes. After acid-base regulating, the highest adsorption capacity of PAN(P(-))F was obtained at pH 10. Moreover, adsorption kinetic illustrated that PAN(P(-))F can achieve half adsorption capacity within 10 mins and follow pseudo-second-order model. The maximum adsorption capacity calculated from isotherms experiments reached 2.306 mmol/g (890.1 mg/g) at 25 degrees C. The activation energy of the adsorption process was 30.74 kJ/mol indicating that the BCB adsorption process occurs via chemical adsorption. Furthermore, the PAN(P(-))F can be readily separated from solution and reused 10 cycles. Under a continuous flow condition, the BCB concentration can be reduced to 20 ppb at first and remained below 1.69 ppm during the 825 mins adsorption process. At the same time, the removal ratio kept above 98.31%. In general, this novel PAN(P(-))F adsorbent is eco-friendly, highly efficient, selective, reusable, and has great potential for the removal of dyes from industrial wastewaters.