The effects of pH and salinity on kinetics of paraquat sorption onto activated clay

In the present study, activated clay was used as adsorbent for the kinetics of paraquat adsorption from aqueous solution at 25 °C in a batch adsorber. The rate of adsorption has been investigated under the controlled process parameters like initial pH and salinity. A pseudo-second order model has been tested to predict the rate constant of adsorption, equilibrium adsorption capacity, and distribution coefficient by the fittings of the experimental data. The results showed that the adsorption process could be well described with the reaction model. Also, the results were reasonable to be explained by competitive adsorption in the ion exchange process. Further, the process kinetics was reasonably described by the proposed mechanism, which was based on the concepts of completely mixed batch reactor, mass conservation, and homogeneous elementary reaction.