Phthalate esters received a considerable attention owing to its various applications and the harmful health effects resulting from phthalate exposure; thus, finding an alternative to phthalate derivatives became a necessity. Phthalate esters are commonly used as plasticizer in polymer formulation; in particular for poly(vinyl chloride) (PVC) formulation. According to the researches in the last 18 years, epoxidized vegetable oils are one of the alternatives that are strongly encouraged to substitute phthalate esters since they were proven to be valid in various applications, eco-friendly and sustainable resource. However, most of the production practices for epoxidized vegetable oil are via conventional epoxidation that concentrates on a catalyst that is homogeneous and non-reusable. This type of catalyst, however, causes several problems later in the process. Therefore, the selective epoxidation of vegetable oils process requires new catalytic systems that are more aligned with the green chemistry principles. This article reviews the harmful health effects associated with the exposure to phthalate esters products, explains the usage of oleochemicals resources as a substitute to phthalate esters and describes different approaches for the epoxidation of vegetable oils. Finally, it draws attention to the usage of epoxy and bio-based compounds as plasticizers in PVC manufacturing.
The aim of this work was to investigate the technical as well as the economic feasibility of producing 2-ethyl hexyl oleate (2-EHO), a non-phthalate plasticizer in a solvent free medium. The esterification reaction between oleic acid and 2-ethyl hexyl alcohol was carried out in a packed bed reactor (PBR) using Candida antarctica lipase B (Novozym 435; Novozymes; Copenhagen-Denmark) as biocatalyst. RSM was employed to optimize the esterification reaction conditions. The optimum reaction conditions were found to be flow rate of 1.5 mL/min, No. of cycles of 12 and molar ratio of 4:1 2-ethyl hexanol to oleic acid. The maximum experimental and predicated conversions were found to be 95.8% and 95.61% respectively. Formation of 2-EHO was approved by FTIR, 1 HNMR and 13 CNMR. From the economic prospective, PBR was capable of producing 2-EHO with a purity of more than 94% over 480 h without remarkable reduction of enzyme activity. This revealed an economic production of 2-EHO at a yield of 2 tons kg-1 lipase. The manufacturing cost was found to be $ 1.88 /kg 2-EHO, this contributed to a profit of about 30% compared to the commercial price of 2-EHO. Such results approve the technical and economic feasibility for this sustainable method in esters production.
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