The dynamic adsorption and in situ rheological behaviour of xanthan biopolymer flowing through porous media have been investigated. Results are related to the depleted layer effect, where polymer/pore wall interaction due to steric hindrance leads to a lower Newtonian apparent viscosity than bulk Newtonian viscosity. Previous work on the depleted layer phenomenon has been presented considering the effects of polymer concentration over the very dilute regime, pH and salinity on xanthan rheological and transport behaviour in porous media. Experimentally, the apparent viscosities of xanthan solution flowing in the ballotini glass bead packed columns were measured under various conditions and compared with the corresponding bulk viscosities. The experimental data were analysed using simple analytical models (two-fluid model and linear layer model) in- order to estimate the apparent depleted layer thickness. The results presented in this paper extend some of our earlier findings on the effect of both polymer concentration and salinity on the apparent depleted layer thickness. The main new results presented in this work concern the effect of xanthan dynamic adsorption on the in situ polymer rheology and depleted layer thickness. The depleted layer effect is measurable both before and after dynamic adsorption has reached equilibrium. However, the additional effect of the adsorbed layer close to the pore wall is small indicating that xanthan molecules are adsorbed very flat against the pore wall.

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