Stability and characteristics of kerosene-in-water emulsions with xanthate surfactants: Influence of hydrophilic-lipophilic balance and molecular weight

The understanding of emulsion stability is important for several industrial applications including foods, pharmaceuticals, petroleum, personal care products, and in our case mineral processing. Xanthate functional surfactants may be useful to improve mineral recovery through froth flotation by delivering oil to valuable mineral surfaces as they may be used to stabilize kerosene-in-water emulsions. The eco-friendly nature of naturally derived reagents such as vitamin E-based xanthates would be beneficial to the mineral processing industry. In this study, conventional (potassium amyl xanthate (PAX)) and novel xanthate functional surfactants such as α-tocopherol polyethylene glycol 400 succinate (TPGS) xanthates which we synthesized from Vitamin E were investigated as emulsifiers. The creaming and oil phase separation of the kerosene-in-water emulsions produced with the xanthate surfactants were studied. The influence of hydrophilic-lipophilic balances (HLBs) and molecular weights (MWs) of the water-soluble xanthates and other commercial surfactants including polyoxyethylene fatty acid esters (Tweens), sorbitan fatty acid esters (Spans), and polyoxyethylene fatty ethers (Brijs) on the characteristics of the kerosene-in-water emulsions was examined. The experimental results showed that the TPGS xanthate formed the most stable emulsion among the xanthate surfactants considered. The results indicated that HLB is not the only factor influencing the emulsifying properties of surfactants. The chemical structure, particularly the molecular weight of the surfactant has a significant impact on its emulsifying properties. Thus, an emulsion stability chart incorporating the HLB and molecular weight of surfactants is proposed. This stability chart can be used for a better classification of the emulsifying properties of commercially available surfactants and novel reagents.