Browsing by Author "Eslami, Naser"

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Electroosmotic permeability in kaolinite and CaCO3 poultice mixtures
    (Journal of Cultural Heritage, 2024) Eslami, Naser; Feijoo, Jorge; Paz-García, Juan M.; Franzoni, Elisa; Ottosen, Lisbeth M.
    Electrokinetic treatment of masonry for desalination or electroosmotic dewatering depends on a poultice, in which the electrodes are placed, which fulfills several purposes. Poultice composed of kaolinite and CaCO3 have been shown to have good workability and high pH buffering capacity. In this work, the elec- troosmotic (EO) permeability is studied in different kaolinite - CaCO3 mixtures. In addition, the effect on EO of using NaCl as a mixing solution is investigated. A special cell is used to test the EO in the speci- mens. A phenomenological approach, based on the potential gradient and the flux of solution, was used to calculate the EO flow rate and EO permeability coefficient. Results showed that by increasing the con- centration of CaCO3 in the poultice mixture, the EO flow rate decreased and the poultice with 80 % CaCO3 and more did not have any EO flow. Furthermore, the ionic strength in the mixing solution decreases the EO flow rate.
  • No Thumbnail Available
    Item
    Evaluation of the Suitability of Electrokinetic Treatment to Desalinate the Limestone of the Tomb of Cyrus, a UNESCO World Heritage Site in Iran
    (Heritage, 2023) Eslami, Naser; Feijoo, Jorge; Aly, Nevin
    The tomb of Cyrus the Great, founder of the Persian Empire, is considered one of the most important monuments of Iran. Its advanced state of deterioration motivated the need to carry out a study focused on analyzing the possible damage caused by the presence of soluble salts, and to assess the suitability of an electrokinetic treatment for their extraction. Preliminary diagnostics carried out on stone samples taken from the tomb confirmed that it is affected by the action of soluble salts, and especially by the presence of nitrates and sulfates. The effectiveness and possible harmful effects caused by electrokinetic treatment were evaluated, under laboratory conditions, using the same limestone that makes up the tomb. The obtained results show that this treatment, in a short period of time, reduces the ionic content, reaching high percentages of anion extraction, without causing any damage, which indicates that it is suitable for this type of stone.
  • No Thumbnail Available
    Item
    Experimental study of electroosmosis and (Cl-) diffusion in fired-clay bricks
    (Construction and building materials, 2024) Eslami, Naser; Ottosen, Lisbeth M.; Feijoo, Jorge; Franzoni, Elisa; Paz-García, Juan M.
    Electroosmosis (EO) is considered as a base for methods in drying moist masonry. EO and the other transport mechanisms, namely electromigration and diffusion, that can influence EO in the bricks, were studied in four Danish bricks with different manufacturing years and locations. Brick cubes were cut from each brick type and then saturated in NaCl 0.1 M solution. A cell with four electrodes was used to measure the electroosmotic permeability coefficient using a phenomenological approach based on non-equilibrium thermodynamics. The effective diffusion coefficient for chloride and electromigration coefficient were calculated. Results showed that the EO flux obtained in the bricks did not follow either the magnitude of zeta potential or ionic content present in the bricks. It was observed that there was a correlation between the EO coefficient and the porous structure of the brick, especially with the pore connectivity, since the bricks with higher pore connectivity and, therefore, with higher effective diffusion coefficient had a higher electroosmotic coefficient.
  • No Thumbnail Available
    Item
    Influence of Activated Carbon Granulometry on H2 Purification in Glycerol Reforming Syngas: Adsorption and Kinetic Analysis
    (Energies, 2024-11-29) Maceiras, Rocío; Feijoo, Jorge; Pérez-Rial, Leticia; Álvarez-Feijoo, Miguel A.; Eslami, Naser
    This study investigates the adsorption performance of granular activated carbon (GAC) and pelletized activated carbon (PAC) for the purification of syngas produced from glycerol reforming, focusing on the removal of CO2, CO, and CH4. The adsorption process was studied at two different flow rates (0.5 L/min and 1 L/min) to assess the impact of particle size and gas flow rate on adsorption capacity. The results indicate that GAC exhibits superior multi-gas adsorption, particularly at lower flow rates, effectively capturing CO2, CO, and CH4, while PAC exhibits lower adsorption performance. Kinetic analysis revealed that the pseudo-second-order and Avrami models fit well with both adsorbents, though GAC aligns more closely with the Avrami model, reflecting its multi-step adsorption mechanism and greater pore diffusion efficiency. These findings highlight the importance of adsorbent size and flow rate in optimizing hydrogen purification processes, with GAC emerging as a highly efficient adsorbent for industrial-scale syngas treatment.
  • No Thumbnail Available
    Item
    Measuring the Electro-osmotic Permeability Coefficient in Single Bricks
    (Journals of materials in civil engineering, 2024) Eslami, Naser; Feijoo, Jorge; Paz García, Juan M.; Franzoni, Elisa; Ottosen, Lisbeth M.
    The transport process electroosmosis (EO) has been suggested to be used for dewatering damp brick masonry for decades. Still, it is debated whether EO can be obtained in bricks. By use of an advanced EO laboratory cell, this paper reports that an EO flow can be generated in two types of Danish bricks. The electroosmotic permeability coefficient was shown to be dependent on both intrinsic properties of bricks, such as pore size distribution, and extrinsic properties, such as zeta potential. Results showed that the brick with a higher pore volume but with a lower surface charge the EO permeability coefficient is lower.