Current advances in liquid–liquid mixing in static mixers: A review

•Static mixers are a promising alternative to stirred vessels for emulsification.•Robust numerical codes have enabled the optimization and innovation of new mixers.•Most available performance predictive models are limited and cannot be generalized.•Further enquiry into fundamental concepts is required (e.g. surfactant-laden flows). This review article revisits the role of static mixers in the process industry nowadays and summarizes the most relevant developments and literature available on this type of mixers handling liquid-phase systems. In particular, this review seeks to discuss in depth the progress that has been made on the hydrodynamic understanding of immiscible liquid–liquid dispersions and emulsion formation using motionless types of mixers, both through experimental and computational approaches. Models and correlations on key process parameters, such as mean droplet size and pressure drop, proposed over the last couple of decades, are compiled and discussed. The latest progress on computational modelling through numerous frameworks is also thoroughly covered. In addition, this paper includes a brief review of the fundamental concepts in liquid static mixing and emulsion formation to further enrich the discussion on the innovations made on this field.