Fig. 3From: Novel pre-treatment of zeolite materials for the removal of sodium ions: potential materials for coal seam gas co-produced wastewaterIntra-particle diffusion model of Na+ ions and experimental data for natural and treated zeolite materials. Initial Na+ concentration 0.1 M at pH 7, shaking speed of 300 rpm at 25 °C and solid–liquid ratio 50 g/L. The symbols are as follows: (circles) Natural zeolite form, (triangle) Ca2+ form, (square) H+ form, (cross) K+ form, (diamond) NH4 + formBack to article page