A novel process was developed for the preparation of highly dispersed precipitated nanosilica in a membrane dispersion reactor with H2SO4 and Na2SiO3 as the reactants. The particle size and extent of aggregation were significantly reduced by improving mixing performance and controlling the reaction environment. The effects of the surfactant and the final pH on the properties of the precipitated silica were investigated. By adding the surfactants sodium carboxymethylcellulose (CMC) and polyethyleneglycol (PEG) to the reaction system, silica precipitates with a surface area of 126.2 m(2)/g and primary particle size of approximately 20 nm were obtained. The dispersion index D-I at 1.12 and the coordination number between 1 and 2 indicate an effective dispersion performance of the obtained SiO2. This study provides a controllable, economical and easily scaled up method for the production of this important additive for the tire, paint and toothpaste industry. (C) 2014 Elsevier B.V. All rights reserved.