Analysis of bentonite specific surface area by kinetic model during activation process in presence of sodium carbonate

In this paper activation of a typical bentonite in the presence of sodium carbonate was studied by a modified kinetic model. Activation process was carried out at different concentrations of sodium carbonate, ranging 3.0–4.5 wt.%. The effects of sodium carbonate concentration, particle size distribution of natural bentonite, activation time and temperature on specific surface area were investigated. It was found that the activation rate significantly depends on sodium carbonate concentration and it was maximized in presence of 4.5 wt.% of alkali solution. Also, the specific surface of bentonite was greatly affected by particle size distribution of starting raw material. The kinetic calculation results indicated that the concentration of alkali solution and particle size of starting bentonite negligibly change the activation energy. The mathematical calculations showed that there is an optimum activation time to achieve the maximum specific surface area in each condition. The validity of proposed model to estimate the optimum activation time was substantiated by comparing computational results with experimental data.

The variation of specific surface area of natural bentonite was shown as function of time and temperature during the activation in presence sodium carbonate. The optimum conditions were determined to be 180 min at 96 °C.Figure optionsDownload as PowerPoint slideResearch highlights
► The activation of bentonite in a batch reactor has been investigated in presence sodium carbonate.
► The effects of time, temperature, concentration of alkali agent and particle size of starting material on specific surface area have been studied.
► It was found that the activation rate significantly depends on sodium carbonate concentration and it was maximized in presence 4.5 wt.% of alkali solution.
► The optimum particle size of bentonite for using in activation was determined less than 38 μm.