Optimization of H2SO4-modification of ITU bentonitic clay under box Behnken design

Bentonite clay from Itu, Akwa-Ibom State, Nigeria was modified using sulfuric acid (H2SO4). The chemical compositions of the raw (RI) and H2SO4 modified (HI) Itu clay was determined using X-ray fluorescence (XRF) technique. Box Behnken Design (BBD) was used to optimize the H2SO4 and clay modification process using wet acidification method. The process parameters considered for the optimization were H2SO4 concentration (0.1-6.0 M), activation temperature (60-100 oC) and activation time (5-10 minutes). Optimum catalyst yield of 6.12 g was obtained in 7.5 min and at 60 oC when 6 M H2SO4 concentration was used for clay modification. The predicted value of the catalyst yield was found to be in agreement with its observed values (R2 = 0.9681 and Adj R2 = 0.9271). These results revealed that the process parameters had significant influence on the clay modification process. The XRF analysis of the samples also revealed that the RI and HI are calcium montmorillonite with SiO2/Al2O3 ratio values of 3.20 and 5.48 respectively.