Extraction of pectin from sour orange and its application as the adsorbent for removal of nickel from aqueous solution: Kinetic and equilibrium study

The present study investigates the potential applicability of the extracted pectin from sour orange pomace as adsorbent for Ni (II) removal from aqueous solution. Pectin extraction from the pomace was carried out using HCl and the highest pectin extraction yield of 26.75% was obtained. The Fourier transform infrared (FTIR) spectroscopy analysis confirmed that the structure of the extracted pectin was similar to the commercial one. The morphology and chemical characteristics of pectin beads were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) techniques. The influence of several parameters including pH, initial metal concentration, adsorption temperature and time was studied to optimize nickel removal. The maximum Ni (II) removal of 85.1% was obtained at initial concentration of 20 mg/L and the highest adsorption capacity of 19.76 mg/g was achieved at nickel concentration of 100 mg/L. Kinetic and equilibrium studies were done to evaluate Ni (II) sorption from aqueous solution by the synthesized beads. Results showed that the sorption process follows a pseudo- second- order kinetic model. The equilibrium data were well correlated with Langmuir and Redlich-Peterson models by high regression coefficients.