Kinetic studies on removal of phenolic compounds from wastewater using agricultural waste: A review

The release of phenol from wastewater by various industries like petroleum, petrochemical, pulp and paper causes harmful effects on the environment. Adsorption using activated carbon from agricultural waste precursor material has proven to be effective for the removal of phenolic compounds from wastewater. Therefore, it is important to understand the sorption kinetic mechanism in wastewater treatment, since it brings down the problem of large sludge-handling processes. The kinetic analysis also helps in designing large scale treatment plants which have high efficiency and results in high quality treatment of the effluent. In addition, it also assists in proposing the mathematical models, reaction pathways that describe the characteristics of an actual treatment plant. Various theoretical kinetic models are available for determining the mechanism of the adsorption process. In this review, mainly six kinetic models were investigated to study the adsorbate-Adsorbent interactions and to find the rate limiting step. From the recent literature, higher correlation coefficient values were obtained for the pseudo-second-order kinetic model showing that it is the most appropriate one for most of the systems. The pseudo-second order kinetic equation shows that the chemisorption was found to be rate determining step in most of the adsorption process.