Calculating adsorption efficiencies and reusability cycles by retrieving the concept of operating lines

ABSTRACT

Adsorption is one of the most promising separation processes for removing heavy metals, dyes, and emerging pollutants from wastewater. Research has focused on developing adsorbents with enhanced performance, conducting many experiments to characterize the process by isotherms, kinetics, thermodynamics, reusability cycles, the effect of co-existing ions, and fixed-bed operation. The adsorption efficiency is a critical parameter that determines how much adsorbate is removed depending on the adsorbent dose and the initial concentration. Retrieving the concept of operating lines would save time and resources by focusing only on the equilibrium without increasing the amount of experimental work. This study demonstrates how adsorption efficiencies can be calculated from the operating lines and the equilibrium given by Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. Herein, predicted efficiencies were in agreement with experimental values (0.961 < r² < 0.999) for different adsorbent doses since all experiments led to the same Langmuir isotherm (r² = 0.994). Moreover, the operating lines could also predict reusability cycles (r² = 0.997) since the mass balance principle applies to these conditions as well, helping to elucidate the long-term behavior of the adsorbent after regeneration cycles.

KEYWORDS:

• Adsorption
• operating line
• modeling
• isotherm
• water treatment

Acknowledgements

Two authors (C.M. Laureano-Anzaldo and M.E González-López) acknowledge the financial support of the Mexican National Council for Science and Technology (CONACYT #701030 and #481448) for their scholarships.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Mexican National Council for Science and Technology[701030, 481448].