Applications of photothermal displacement spectroscopy to the study of asphaltenes adsorption

Abstract

We have developed an application of photothermal surface deformation (PTD) to study asphaltenes adsorption o inorganic surfaces. Using an appropriate ratio of the probe and excitation beam spot size at the sample surface we have been able to measure the magnitude of the PTD using a single photodiode detector. The magnitude of the PTD signal is shown to be related to the amount of adsorbed asphaltene. This technique offers a direct non-perturbing and completely contactless detection of adsorbed asphaltenes. Solute-solid adsorption isotherms (SSA) of asphaltenes from two Venezuelan extra-heavy oil (Jobo and Hamaca) were measured using a glass thin plate as adsorbent. The results obtained are in good agreement with those reported using conventional indirect techniques but better precision is achieved. 1998 Elsevier Science B.V.