Using recycled cooking oil to manufacture laundry soap

Abstract

During frying, temperatures rise up to around 170oC to 190oC. At these temperatures, complex, multistage reactions of hydrolysis, oxidation and polymerization occur within the oil producing polar molecules like proteins, free fatty acids and others which together degrade both physical and chemical properties of the oil like colour, smoke point etc. Among other products formed with in the oil are the free radicals which when ingested into the body attach themselves to the heathy cells forming carcinogenic cells. Several works have been done to expose the danger of repeated heating and use of vegetable oils but very little work or even none has been done to provide an alternative use for the oil apart from using it and that’s why this project becomes relevant. Cooking oil heated for 7 hours was collected from hotel, treated with activated carbon, filtered using filter paper and funnel and free fatty acid test was done to check the efficiency of the treatment process which was found to be 70%. 3 soap samples were prepared where sample 1 and 2 were prepared using treated oil but sample 1 was recovered 3 times whereas sample 2 was recovered once with NaCl. Sample 3 was a blend of 50% treated oil and 50% fresh oil. The samples were than tested for moisture content, total alkali, free caustic alkali and total fatty matter (TFM). It was found that the TFM in sample 2 is high enough in that a considering a blend would be irrational. The 81.67% TFM in sample one would be high enough in that addition of builders would just reduce this value to a required minimum of 62% for laundry soap. Therefore recycled cooking oil can be used to make laundry soap.