On the Thermal Dependence of the Colloidal Behavior of Water-Based Magnetic Colloids: Studying the Key Parameters

The present talk focuses on the investigation of the effect of temperature on the colloidal behavior of aqueous ferrofluids, as a basis for possible technological applications in thermoelectric devices. Magnetic fluids samples based on core@shell nanoparticles (CoFe2O4@g-Fe2O3) were studied using light scattering techniques (DLS and ELS) to determine the hydrodynamic size and zeta potential, in the temperature range of 25-60 °C, evaluating the effects of ionic strength, nature of the co-ions (Na+ and TMA+) and pH. Also, simultaneous potentiometric and conductometric titrations were applied to determine the temperature dependence of the point of zero charge as a method for the evaluation of thermodynamic data of the surface charging process. The whole of the results is discussed in terms of the key parameters that affect the electrostatic and electrophoretic properties of the colloidal system.