ABSTRACT
Objective To optimize conditions for the preparation of amidoximated polyacrylonitrile (PAO) membrane for U (VI) adsorption that can be easily recycled and reused. Methods Using polyacrylonitrile powder as a raw material, the PAO membrane was prepared using the nonsolvent-induced phase separation method under different conditions. The effects of the polyacrylonitrile concentration and temperature and duration of amidoximation in the preparation of casting solution as well as alkali treatment before adsorption on the U (VI) adsorption performance of PAO membrane were investigated. Results Alkali treatment significantly improved the U (VI) adsorption performance of PAO membrane, and the temperature and duration of alkali treatment affected the U (VI) adsorption capacity. The optimal alkali treatment conditions were 0.1 mol/L NaOH, 80 min, and 60℃. The polyacrylonitrile concentration and temperature and duration of amidoximation in the preparation of casting solution influenced the adsorption performance of PAO membrane. The optimal preparation conditions were 10wt% polyacrylonitrile and amidoximation at 65℃ for 18 h. Under the optimal preparation and alkali treatment conditions, the U (VI) adsorption capacity of PAO membrane reached 255 mg/g. Conclusion The PAO membrane has the advantages of simple preparation, high adsorption capacity, and easy recycling and reuse, which can be used as an ideal material for adsorbing U (VI) in wastewater.
ABSTRACT
Objective To find new methods to control the pollution of dye,the law of adsorption and adsorption kinetics of vat blue RSN by amidoxime fiber were studied. Methods The amidoxime-Fe(Ⅲ) adsorption fiber was made from PAN fiber containing amidoxime groups reaction with Fe3+. The adsorption of vat blue in the aqueous solution on the amidoxime-Fe(Ⅲ) adsorption fiber was studied. The reaction order was determined by infinitesimal calculus,based on the relationship between the adsorption time and the concentration of vat blue. The activation energy was obtained by the rate constant of different temperature and the Arrhenius equation. Results The results of adsorption showed the optimal condition:pH was 10.5,the temperature was 45 ℃ and adsorption time was 80 min. The absorption was accorded with the Freundlich isotherm and the character of the first-order reaction. Conclusion The process of vat blue RSN adsorption by amidoxime fiber is simple and the raw materials of amidoxime fiber is very cheap,so it may be expected to apply to the industrial wastewater treatment