Modified phoenix tree leaves and their adsorption removal of Ca2+ from wastewater

Abstract

Too much Ca 2+ in the water would have a bad effect on the papermaking process. Phoenix tree leaves were modified by NaOH or H 3 PO 4 treatment for Ca 2+ adsorption and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The effects of adsorption time, particle size, and adsorbent dosage on Ca 2+ adsorption from wastewater were studied. Moreover, the adsorption kinetics and thermodynamics of Ca 2+ adsorption before and after modification were analyzed. Results showed that the surface of natural phoenix tree leaves is relatively smooth without obvious porosities prior to modification. After modification, the surface of the leaves became loose and rough; and concave pores were also found. After NaOH-modification, functional groups on the surface of the phoenix tree leaves increased, which is conducive to adsorption. The removal effect of Ca 2+ by NaOH-modified leaf adsorbent was better than that by H 3 PO 4 . Under optimal conditions, the NaOHmodified phoenix tree leaves had a removal efficiency of 74.18% for Ca 2+ in the wastewater. The adsorption process was consistent with the pseudo-second-order kinetic reaction and Langmuir isotherm equations.