Loading...

Experimental study on the influence of initial pH, ionic strength, and temperature on the selective adsorption of dyes onto nanodiamonds

Molavi, H ; Sharif University of Technology | 2019

717 Viewed
  1. Type of Document: Article
  2. DOI: 10.1021/acs.jced.8b01091
  3. Publisher: American Chemical Society , 2019
  4. Abstract:
  5. In the current work, the performance of untreated nanodiamonds (UNDs) and thermally oxidized nanodiamonds (ONDs), as adsorbents for selective adsorption of methylene blue (MB) and methyl orange (MO) from aqueous media, was examined. The adsorption isotherm, initial pH, ionic strength, and thermodynamic study were investigated in batch experiments. The equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherm models, which indicated that the isotherms were well fitted with the Langmuir model for both dyes. Thermodynamic parameters indicated that the adsorption operation was a feasible, spontaneous, and physisorption process in experimental conditions. Meanwhile, the adsorption of MO onto the UND was exothermic and determined by enthalpy change, while the adsorption of MB onto the OND was endothermic and an entropy-controlling process. The adsorption selectivity study exhibited that OND can rapidly and selectively separate cationic MB dye from the MO and MB mixture. On the basis of the negatively charged surface of the OND with highly negative zeta potential, the fact that the OND opted to adsorb MB over MO was firmly dependent on the initial pH value and ionic strength, which suggested that the possible mechanism of adsorption such as electrostatic interaction, hydrogen bonding, and π-π stacking might be important. Finally, based on the mentioned considerations, thermally OND was an attractive candidate for rapid adsorption and separation of cationic dyes from aqueous solution. © 2019 American Chemical Society
  6. Keywords:
  7. Aromatic compounds ; Azo dyes ; Dyes ; Hydrogen bonds ; Nanodiamonds ; Physisorption ; Adsorption selectivity ; Equilibrium adsorption ; Experimental conditions ; Langmuir and Freundlich isotherm models ; Negative zeta potentials ; Negatively charged surfaces ; Thermodynamic parameter ; Thermodynamic studies ; Ionic strength
  8. Source: Journal of Chemical and Engineering Data ; Volume 64, Issue 4 , 2019 , Pages 1508-1514 ; 00219568 (ISSN) ; https://pubs.acs.org/doi/abs/10.1021/acs.jced.8b01091
  9. URL: https://pubs.acs.org/doi/abs/10.1021/acs.jced.8b01091