Adsorption of organic amines from wastewater by carboxyl group‐modified polyacrylonitrile fibers

Abstract

AbstractIn this study, hexamethylenediamine (HMD) and hexamethyleneimine (HMI) were removed from a real wastewater by carboxyl group‐modified polyacrylonitrile (RPFC‐I) fibers. Adsorption of organic amines by fibrous absorbents is a new technique. Adsorption by fibers has advantages of fast kinetic, high adsorption capacity, and efficiency. Moreover, the fibers could be repeatedly used after regeneration. Batch adsorption tests were conducted to investigate adsorption comparison of the three fibers, adsorption kinetic, adsorption isotherms, regeneration, and readsorption stability. The experiments showed that RPFC‐I fibers had excellent adsorption capacity for HMI and HMD. The adsorption equilibrium was achieved very fast within about 5 min, and the removal rate of total nitrogen (TN) was above 99%. The adsorption kinetic could be well fitted by the pseudo‐second‐order equation. And the adsorption isotherm could be well fitted by the Langmuir model. The estimated maximum adsorption capacity was 105.2 mg g−1, nearly similar with cation exchange capacity (CEC) of RPFC‐I fibers. Results from adsorption stability tests demonstrated that the RPFC‐I fibers could be fully regenerated by HCl and the regenerated fibers could be repeatedly used even after 12 adsorption–desorption cycles. Analyses from Fourier transform infrared and the adsorption tests suggested that chemical reaction between carboxyl groups and organic amines was the main mechanism for removal of HMI and HMD from the wastewater. The RPFC‐I fibers prepared in the current study have a wide application in wastewater treatment and useful substance recovery. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013