Zinc sorption by permanganate treated pine chips

Abstract

The sorption equilibria and kinetics of zinc from aqueous solution on both untreated and permanganate treated pine chips were investigated. The sorption kinetics were best described by pseudo-second-order equation and the sorption isotherms were well fitted by a Langmuir model for both untreated and treated pine chips. Zinc sorption increased from 1.2mgg−1 in untreated samples to 3.9mgg−1 for the treated pine chips. Analysis shows that the carboxylic content increased after oxidative treatment of wood sorbents. This was responsible for the improved sorption of zinc onto the pine chips. The permanganate-wood reaction rate in batch experiments was biphasic first-order with an initial rate (0–25min) and then a slower rate (25–807min). The initial rates were approximately 3 times greater than the later stage rates. The reaction rates was also particle size dependent with the rate for 4.75mm pine chips, 11–19% less than that of the 1.18mm pine chips. Rate limiting mechanisms included intra-particle mechanism of MnO4− interaction with pine chips is complex and consisting of surface external mass transfer as well as intra-particle diffusion. Rate-limiting reactions in the column caused the shape of the breakthrough curve to exhibit tailing.