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

Abstract

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.