Removal Of Phosphorus From Vegetable Oil By Acid-activated Sepiolite

摘要

The adsorption of phosphorus (P) from rapeseed oil on acid-activated sepiolite (AAS) was investigated for different AAS dosages and bleaching temperatures. The P concentration in the oil was reduced from 29.7 to 1.11 mg/kg at the optimal conditions: bleaching temperature -100℃, AAS dosage -1.5%. The adsorption capacity of AAS in relation to P and mean adsorption energy were calculated according to Langmuir and Freundlich models and the former was found to be better. The negative values of free energy of adsorption (ΔG_(ads)~o) show that the adsorption is spontaneous, whereas the positive value of the entropy of adsorption [ΔS_(ads)~o) probably results from the reorganisation in the internal structure of the adsorbent appearing during adsorption of P on AAS. The low value of adsorption enthalpy (ΔH_(ads)~o) indicates a relatively weak adsorbate-adsorbent affinity probably due to hydrogen bond formation. The division of phos-pholipids and phosphates between external surface and micropores of the sepiolite is suggested.