Adsorption of crystal violet onto epichlorohydrin modified corncob

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, temperature, 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 q(max) of 71.43 mg g(-1) at 318 K. A new method derived from the Langmuir equilibrium constant K-L was first put forward to estimate the thermodynamics. The obtained negative values of Delta 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.