Effective Removal of Cr(VI) from Aqueous Solution Using Modified Orange Peel Powder: Equilibrium and Kinetic Study

A new adsorbent modified from orange peel (OP) was successfully synthesized by ethylenediamine crosslinking method to remove Cr(VI) from wastewater. The modified orange peel powder (MOPP) was investigated in a batch adsorption system, including both equilibrium adsorption isotherms and kinetics. Effects of several factors, including adsorbent dose, initial pH and Cr(VI) concentration were studied. The data indicated that the pH was not an essential factor that affected the adsorption process, it has a wide pH range from 4 to 10, and high adsorbent dose and lower Cr(VI) concentration could increase the Cr(VI) removal efficiency. Equilibrium data were analysed using the Langmuir, Freundlich and Temkin isotherm models and found to be well represented by the Langmuir isotherm model. The maximum capacity (qmax) obtained from Langmuir model was 52.08 mg/g at pH 6.0. The kinetics of adsorption followed the pseudo-second-order kinetic equation. The results suggest that MOPP is an inexpensive and efficient adsorbent for removing Cr(VI) from aqueous solution.