STUDIA UBB CHEMIA, LXVII, 2, 2022 (p. 7-21) (RECOMMENDED CITATION) DOI:10.24193/subbchem.2022.2.01 MEASUREMENTS AND CORRELATIONS OF THE VISCOSITY OF ISOPROPANOL MIXTURES WITH DIESEL FUEL AND BIODIESEL IRINA NIŢĂ a,* , OLGA IULIAN b , SIBEL OSMAN a , TIMUR CHIŞ a ABSTRACT. Isopropanol could be an additive or substitute for diesel fuel due to some of its key properties. Viscosity influences the atomization and spray formation, affecting the combustion process and the emission of diesel engine. Experimental data of viscosity of diesel fuel + isopropanol and biodiesel + isopropanol mixtures over the entire composition range at five temperatures (288.15, 293.15, 303.15, 313.15 and 323.15 K) are presented. Based on experimental data, the ability of predictive and correlative models to estimate the viscosity of the studied systems was tested. The best accuracy in viscosity estimation at a desired temperature is given by a polynomial equation, followed by Grunberg-Nissan equation. The value of Grunberg-Nissan interaction parameter G12 increases with temperature increasing, following a trend described by a polynomial equation. Negative values for deviation in viscosity were obtained for diesel fuel + isopropanol mixtures and positive values for biodiesel + isopropanol mixtures. The best fit with viscosity experimental data for viscosity dependence on temperature was provided by Vogel model. Keywords: viscosity, biodiesel, isopropanol, diesel, viscosity models INTRODUCTION The search for sustainable and alternative fuels is a major topic of today research, taking into account that the use of fossil fuels is an important source for environmental pollution. It was proved that oxygenated fuels improve the combustion process, reducing harmful emissions like greenhouse gas and particulate matter [1]. The effect of biodiesel and alcohols such as a Ovidius University, of Constanta, Faculty of Applied Sciences and Engineering, 124 Mamaia Blvd, RO-900521 Constanta, Romania. b Polytechnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, 132 Calea Grivitei, RO-010737, Bucharest, Romania. * Corresponding author: irinan9090@yahoo.com.