Oil–Water Emulsion Flocculation through Chitosan Desolubilization Driven by pH Variation

[Image: see text] Water pollution is a major concern in our modern age. The contamination of water, as a valuable and often limited resource, affects both the environment and human health. Industrial processes such as food, cosmetics, and pharmaceutical production also contribute to this problem. Vegetable oil production, for example, generates a stable oil/water emulsion containing 0.5–5% oil, which presents a difficult waste disposal issue. Conventional treatment methods based on aluminum salts generate hazardous waste, highlighting the need for green and biodegradable coagulant agents. In this study, the efficacy of commercial chitosan, a natural polysaccharide derived from chitin deacetylation, has been evaluated as a coagulation agent for vegetable oil emulsions. The effect of commercial chitosan was assessed in relation to different surfactants (anionic, cationic, and nonpolar) and pH levels. The results demonstrate that chitosan is effective at concentrations as low as 300 ppm and can be reused, providing a cost-effective and sustainable solution for oil removal. The flocculation mechanism relies on the desolubilization of the polymer, which acts as a net to entrap the emulsion, rather than solely relying on electrostatic interactions with the particles. This study highlights the potential of chitosan as a natural and ecofriendly alternative to conventional coagulants for the remediation of oil-contaminated water.