Dynamic Adsorption Studies Research Articles

Adsorption IV. An evaluation of polyethylene glycol as a sacrificial adsorbate towards ethoxylated sulfonates in chemical flooding

The feasibility of using polyethylene oxide (PEG) as a sacrificial adsorbate in surfactant flooding applying ethoxylated sulfonates in mixture with some of the corresponding ethoxylated alcohol, has been tested in different ways. Static adsorption of the surfactants has been performed using both quartz and kaolinite as adsorbents. Equilibrium times of 24 h showed decreased adsorption of the surfactants for both of the adsorbents. The sacrificial effect of PEG was greater for quartz than for kaolinite. PEG with an average molecular weight of 4000 was found to be most favorable. pH changes between 3.5 and 7.6 have small effects on the sacrificial behavior of PEG towards both of the adsorbents. Long-term dynamic adsorption studies in Berea cores were conducted by circulating the flooding solution through the cores. The addition of 0.3 wt% PEG, after the adsorption equilibrium of the surfactants had established, resulted in a fast desorption of the surfactant, about 30%. The desorption was only temporary, and a slow readsorption of the surfactant to the initial level occurred. A pressure build-up was also registered. PEG added to the surfactant solution from the beginning showed a very slow surfactant adsorption. Also in this case a pressure build-up over the core was observed. For a oil-containing reservoir core the sacrificial effect of PEG was negligible. The concentration of each of the adsorbates, i.e., the ethoxylated sulfonate and the ethoxylated alcohol, and the PEG was quantified, and the adsorption behavior of each of them is discussed. All the adsorption experiments were conducted using synthetic seawater at 80°C.

Dynamic adsorption studies on Ni-based methanation catalysts using the continuous flow method

To elucidate the correlation between the adsorptive and reactive properties of Ni-based composite catalysts, the dynamic adsorption characteristics of gaseous reactants on the catalysts in both the methanation of carbon oxides and the hydrogenation of carbon were investigated by the continuous flow method.The combining of La2O3 with Ni increased the adsorptions of both hydrogen and carbon oxides, especially in carbon dioxide, while the combining of Ru with Ni or Ni + La2O3 markedly increased the H2 adsorption at a given hydrogen partial pressure. The former can be interpreted as an increase of the Ni dispersion by La2O3 and its basicity and the latter supports the hydrogen spillover mechanism. Fast and irreversible adsorption decreased when the temperatures for both catalysts of the silica support and active carbon support were raised, but above 200°C slow and irreversible adsorption increased for the catalyst with the active carbon support. It is suggested that the former corresponds to adsorption on a metallic surface and the latter is attributed to activated adsorption on an active carbon through metallic parts as the transport agents.A linear relationship, in logarithmic coordinates, was found between the relative reaction rates and the products of the relative uptakes of reactants; the significance of this linear relationship is discussed.

Intraparticle mass transport in slurries by dynamic adsorption studies

AbstractRates were measured at 25°C for the adsorption of benzaldehyde from an aqueous solution into particles of Amberlite, or activated carbon, suspended in the solution. The data for monodisperse, Amberlite particles (mean pore radius = 50Å) showed significant intraparticle diffusion resistance over the entire particle size range 200 to 900 microns (diameter). Intraparticle diffusivities were larger (tortuosity factor ∼ 0.35) than expected from pore‐volume diffusion in the liquid‐filled pores.For the activated carbon particles (of the same size) which have a bidisperse pore‐volume distribution (pore diameter range 15 to 104Å), the effect of intraparticle diffusion was much less important and separation of the external diffusion resistance to obtain a precise value of the intraparticle diffusivity was not possible. However, De values are larger than for Amberlite and much greater than the molecular diffusivity of benzaldehyde in liquid‐filled pores. The unusually high intraparticle diffusivity seems most likely to be due to interpreting dynamic adsorption data for a bidisperse porous particle with a theory involving but one diffusivity.