Hydrogen peroxide exfoliation of vermiculite and phlogopite

The exfoliation characteristics of Karakoç phlogopite (KP), Phalaborwa phlogopite (PP) and Phalaborwa vermiculite (PV) with hydrogen peroxide were investigated. A series of swelling tests were done to obtain comparative data in order to determine the effects of hydrogen peroxide concentration (1–50 wt.%) and reaction time (1–30 h) that were determined to be the main parameters with solid/liquid ratio being of minor importance. Experimental results show that Karakoç sample has higher exfoliation rate and Phalaborwa samples show a steep increase in exfoliation rate when hydrogen peroxide concentration exceeds 30%. Maximum swelling values of 103-, 90- and 118-fold were reached at 50% H2O2 concentration in 30 h for KP, PP and PV samples, respectively. Exfoliation mechanism was explained in terms of crystal water contents, released cations and change of pH values of solutions.