Characterization and application of Fe and iso-Ti-pillared bentonite on retention of organic matter contained in wet industrial phosphoric acid (54 %): kinetic study

Abstract

Pillared bentonites were prepared by a simple intercalation method with iron oxide and iso-propoxide titanium to improve its adsorption of organic matter (OM) contained in industrial phosphoric acid 54 % P2O5. The solid structure of raw and modified bentonite were analyzed using X-ray diffraction and transmission electronic microscopy. The effects of contact time, temperature, and the adsorbent dose were investigated. The surface area was measured via the Brunauer–Emmett–Teller isotherm. Experimental results showed that the maximum amounts of OM loaded on raw bentonite, Fe–B, and Ti–B were 55, 83.5, and 73 %, respectively. The adsorption of OM contained in industrial phosphoric acid could reach equilibrium after 90 min. The experimental data were analyzed with Langmuir, Freundlich, and Temkin isotherm models. The experimental adsorption isotherm complies with Langmuir equation model (R 2 = 0.99). The kinetic study showed that the OM adsorption is rapid and it complies with the pseudo second-order kinetic for raw and pillared bentonite, reflecting a relative affinity between pillared bentonite and OM and suggesting the occurrence of chemisorption.