Many cleaning and remediation methodologies exist to treat contaminated water sources in the environment. One of such methods uses carbonaceous materials as adsorbents of dissolved target pollutants. After the treatment, the adsorbents must be removed from the water medium. One approach involves the addition of magnetite nanoparticles to the carbonaceous material to allow its removal via magnetic separation. Modeling empirical data is essential for the understanding and predictability of the mechanism, the kinetics, and the thermodynamic parameters of the adsorption process. The work presented here focuses on a multi-week laboratory learning experience where students synthesize a magnetite-charcoal composite and study its adsorption capacity for anthropogenic chemicals commonly found in the water supply. In the experiment, food dye blue #1, yellow#4, and red #40 were used as the targets for removal from aqueous solutions. Students also investigate the kinetics and thermodynamic parameters of the adsorption process. Three adsorption isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich, were used to correlate the experimental data. The kinetics study was done using UV-visible spectroscopy, and the obtained data were modeled to determine the order of the process. Finally, the adsorption process was performed at different temperatures to study the thermodynamic parameters via the van’t Hoff isochore equation. To further immerse students into data modeling, linearized and non-linearized models were compared and discussed by evaluating the model’s correlation coefficients (r<sup>2</sup>) and standard errors. A discussion of the laboratory procedures, data, and results will be presented in light of their design and implementation for the General Chemistry laboratory program at Sam Houston State University.

Adsorption isotherms, kinetic, and thermodynamic studies of magnetite-charcoal: linearized and non-linearized modeling of experimental data in general chemistry

ACS Spring 2022

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