Adsorption of crystal violet onto epichlorohydrin modified corncob

Abstract

A novel low-cost biosorbent, corncob modified with epichlorohydrin, was used to remove crystal violet (CV) from its aqueous solution. The influences of process parameters, such as initial pH, tem-perature, contact time and initial CV concentration on its adsorption capacity were investigated in a batch system. The equilibrium data were evaluated using the Langmuir and the Freundlich isotherms, and the former could provide a better fit with the qmax of 71.43 mg g—1 at 318 K. A new method derived from the Langmuir equilibrium constant KL was first put forward to estimate the thermodynamics. The obtained negative values of G demonstrated a spontaneous process of CV onto corncob. The adsorption kinetics could be well described by the pseudo-second-order model. It was concluded that the intra-particle diffusion was one of the rate-controlling steps in this process. The corncob modified with epichlorohydrin was proved to be a promising adsorbent to treat dye wastewater.