Development of tannin-immobilized cellulose fiber extracted from coconut husk and the application as a biosorbent to remove heavy metal ions

Abstract

Cellulose fibers from coconut husk (CH) were modified with tannin and applied as a biosorbent for the removal of heavy metal ions including Cu(II), Cd(II), and Pb(II) in wastewater. To improve the ion adsorption efficiency of the cellulose fiber from CH, epichlorohydrin was used as a crosslinking agent to graft tannin molecules onto cellulose to produce tannin-immobilized cellulose fiber (TCF). Under an optimum condition at pH 5.0 and 30 min of contact time, the adsorption capacity was 38.02 mg/g, 59.52 mg/g, and 72.99 mg/g for Pb(II), Cd(II), and Cu(II) ions, respectively. Adsorption behaviors of the metal ions could be described using the Langmuir isotherm model. The desorbing solution containing 0.1 M EDTA was chosen to regenerate used TCF. Moreover, chemical characterizations of the TCF using Fourier transform infrared spectrometry showed that TCF possessed combined properties of both CH and tannin. The developed TCF is an inexpensive and efficient alternative that could be further developed as a platform for wastewater management. © 2020 Elsevier B.V.