Modification of Vermiculite for the Preparation of Floating Adsorbent for Phosphate in Wastewater.

Floating adsorbents made from exfoliated vermiculite (EV) were tested for their ability to remove phosphate in aqueous solution. The modified vermiculites (MEV) were prepared with EV/ glycerol ratio of 1/4 where glycerol contained 4 mol% H₂SO₄ and heated until designated temperatures. The highest specific surface area of 58.6 m²/g and carbon content of 62.2% were obtained for MEV heated at 580 °C and 380 °C, respectively. The dry density of MEV was decreased from 1.78 g/cm³ (EV) to 0.25 g/cm³, indicating these adsorbent floating characteristic. The MEV heated at 380 °C showed the highest Freundlich partition coefficient of 45.7 L/kg and the highest Langmuir sorption capacity of 714.3 mg/kg among other MEVs (476.2 mg/kg for MEV-580 and 181.8 mg/kg for MEV-780). Removal of phosphate using MEV heated at 380 °C was well explained by pseudo-second-order model and model parameters were comparable to other phosphate adsorption tests. [ABSTRACT FROM AUTHOR]