ADSORPTIVE REMOVAL OF SULFUR FROM CANOLA OIL

The presence of sulfur compounds in canola oil is mainly responsible for nickel catalyst poisoning during hydrogenation. In this study, different adsorbents (alumina, alumina-silicate, diatomaceous silica and silica gel) were used in conjunction with different bleaching earths (AOCS official natural bleaching earth, G 160 from Harshaw-Filtrol and montmorillonite K 10 from Aldrich Chemical Co.) to remove the three types of sulfur compounds [total sulfur (TS), Raney nickel sulfur (RS) and volatile sulfur (VS)] from canola oil. The TS content of the oil was not affected during bleaching. The AOCS bleaching earth removed 28.6-36.4% RS and 57.8-78.9 % VS in the bleaching temperature range of 120-150-degrees-C. The some bleaching earth, in combination with 6 % TriSyl (micronized silicon dioxide adsorbent) 45.7-81.4 % RS and 73.3-95.6 % VS were successfully removed. TriSyl also improved the chlorophyll content and color of the oil bleached at 120-degrees-C. Bleaching at 120-degrees-C with G 160 and K 10 removed 44 and 81 % RS and 69 and 61 % VS respectively. These two bleaching earths, in combination with alumina, alumina-silicate, diatomaceous silica or silica gel did not further improve the removal of all the three types of sulfur present in the oil.