APPLICATIONS OF PHOTOTHERMAL DISPLACEMENT SPECTROSCOPY TO THE STUDY OF ASPHALTENES ADSORPTION

We have developed an application of photothermal surface deformation ( PTD) to study asphaltenes adsorption on inorganic surfaces. Using an a ppropriate ratio of the probe and excitation beam spot size at the sam ple surface we have been able to measure the magnitude of the PTD usin g a single photodiode detector, The magnitude of the PTD signal is sho wn 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 asph altenes from two Venezuelan extra-heavy oil (Jobo and Hamaca) were mea sured using a glass thin plate as adsorbent. The results obtained are in good agreement with those reported using conventional indirect tech niques but better precision is achieved. (C) 1998 Elsevier Science B.V .