Esterification of lignin with long chain fatty acids for the stabilization of oil-in-water Pickering emulsions

Pickering emulsions offer numerous advantages over conventional surfactant-stabilized emulsion systems, including lower loading levels and enhanced long-term stability. Through both organic and inorganic Pickering emulsifying particles exist, more efforts are being invested in devising renewable, biodegradable, and non-toxic alternatives to conventional Pickering emulsifiers. In this study, the use of lignin (unmodified and esterified) specimens as an effective alternative to conventional Pickering emulsifiers was investigated. Hexanoyl chloride, decanoyl chloride, and palmitoyl chloride esterified lignin specimens were produced and their employability as Pickering emulsifiers was studied. The effects of varying the concentrations of lignin (unmodified and esterified specimens) and pH of the dispersion medium on the stability of the produced Pickering emulsions were explored. Comprehensive characterization of the esterified lignin stabilized Pickering emulsions exhibited enhanced stability, and smaller average oil droplet size, resulting in stable Pickering emulsions with high zeta potential and better flow properties. Overall, the studied esterified lignin specimens can have appealing applications in various Pickering emulsion systems, as a nontoxic and sustainable alternative to conventional emulsifiers.