Studies on kinetics and thermodynamics of Cr(VI) adsorption onto sand to check feasibility of its use as tracer in oilfields

Abstract

The present investigation is aimed to evaluate the adsorption kinetics and its thermodynamics of Cr(VI) on sand. Effects of various parameters like pH, adsorbent dosages, adsorbate loading, concentration, contact time, and temperature were studied in detail. Among different kinetic models such as pseudo‐first‐order, pseudo‐second‐order, and intra‐particle diffusion, pseudo‐second‐order kinetics was found to fit best. The Langmuir isotherm adsorption model could describe the adsorption isotherm best compared to the other models. From the results, it was observed that adsorption of Cr(VI) was reduced to a negligible value at temperature > 50 °C and increased salinity, which specifies the feasibility of its application as tracer at reservoir condition. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Characterization of porous media by chemical tracers using time‐of‐flight and residence time distribution concept

“…Our previous study had reported the kinetics and thermodynamics of Cr(VI) adsorption on clean sand at 0% salinity. To test the effects of presence of salts in the formation water on adsorption, the salinity up to 10,000 ppm was varied in the present study.…”

“…Figure indicates the substantial reduction in adsorption of Cr(VI) on sandstone when NaCl salinity is increased from 0 ppm to ~3,000 ppm, and becomes negligible beyond this value. It revealed that the presence of salt inhibited the adsorption of Cr(VI) onto sandstone . Na + ion may compete with Cr 6+ for binding sites on sand surface, thereby reducing its adsorption on sand …”

“…It revealed that the presence of salt inhibited the adsorption of Cr(VI) onto sandstone . Na + ion may compete with Cr 6+ for binding sites on sand surface, thereby reducing its adsorption on sand …”