The effect of ethoxylate nonionic surfactants on phase inversion temperature and salinity: an alternative approach for vegetable oil recovery from spent bleaching earth

Abstract

Abstract. An accurate determination of the hydrophilic-lipophilic nature of surfactants plays an important role in guiding microemulsion formation. The objective of this study is to determine the effect of ethoxylate numbers (EONs) (3, 5, and 7 moles) of nonionic surfactants on a phase inversion temperature (PIT) and optimum salinity based on the equivalent alkane carbon numbers (ACNs) of vegetable oils. Three vegetable oils, soybean oil, crude rice bran oil and crude palm oil, were selected for use as a surrogate oil to represent the residual oils found in spent bleaching earth. In this study, the hydrophilic-lipophilic deviation (HLD) was used to predict the optimum salinity (0-20 %wt.) at various temperatures (25-55°C). The results showed that the ACNs of crude rice bran oil, crude palm oil, and soybean oil were 15.41±0.35, 13.71±0.41, and 17.60±0.28, respectively. In comparison, these predictions with the experimental results, the data showed slight deviations in the optimum salinity with the specific temperature. Finally, the ACN and the surfactant characteristics obtained in this study were combined with the HLD equation and used to validate its practically and utility for guiding the optimum microemulsion formulation.

Application of Hydrophilic–Lipophilic Deviation Equations to the Formulation of a Mixed‐Surfactant Washing Agent for Crude Rice Bran Oil Removal from Spent Bleaching Earth

“…In this study, the β and k values of all the surfactants and the ACN of the CRBO (15.41) were used to predict the optimum salinity (theory‐based, S* the ) of the microemulsion‐based washing agent using HLD equations () and (). The β and k values for nonionic surfactants were obtained from the previous works (Panumonwatee et al, 2018; Salager et al, 2013) and are summarized in Table 1. For the LE surfactant, β and k were determined from the plot of S* exp versus the ACN of the alkane oil (slope = k; y‐intercept = − β‐ a T (ΔT)) (data not shown).…”

“…CRBO was used as a representative residual oil in SBE. The ACN of CRBO is 15.41 (Panumonwatee et al, 2018). The main fatty acids in CRBO are oleic acid (18:1, 41.79%), linoleic acid (18:2, 32.05%), and palmitic acid (16:0, 20.81%).…”