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Open AccessArticle

Study of Adsorption Mechanism of Congo Red on Graphene Oxide/PAMAM Nanocomposite

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Department of Chemistry, Faculty of Science, Lorestan University, Khoramabad 68137-17133, Lorestan, Iran
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Department of Chemical Engineering, Ryerson University, Toronto, ON M5B 2K3, Canada
*
Author to whom correspondence should be addressed.
Materials 2018, 11(4), 496; https://doi.org/10.3390/ma11040496
Received: 1 February 2018 / Revised: 12 March 2018 / Accepted: 19 March 2018 / Published: 26 March 2018
Graphene oxide/poly(amidoamine) (GO/PAMAM) nanocomposite adsorbed high quantities of congo red (CR) anionic dye in 0.1 M NaCl solution, with the maximum adsorption capacity of 198 mg·g−1. The kinetics and thermodynamics of adsorption were investigated to elucidate the effects of pH, temperature, shaking rate, ionic strength, and contact time. Kinetic data were analyzed by the KASRA model and the KASRA, ISO, and pore-diffusion equations. Adsorption adsorption isotherms were studied by the ARIAN model and the Henry, Langmuir, and Temkin equations. It was shown that adsorption sites of GO/PAMAM at experimental conditions were phenolic hydroxyl groups of GO sheets and terminal amine groups of PAMAM dendrimer. Analysis of kinetic data indicated that amine sites were located on the surface, and that hydroxyl sites were placed in the pores of adsorbent. CR molecules interacted with the adsorption sites via hydrogen bonds. The molecules were adsorbed firstly on the amine sites, and then on the internal hydroxyl sites. Adsorption kinetic parameters indicated that the interaction of CR to the –NH3+ sites was the rate-controlling step of adsorption of CR on this site and adsorption activation energies calculated for different parts of this step. On the other hand, kinetic parameters showed that the intraparticle diffusion was the rate-controlling step during the interaction of CR molecules to –OH sites and activation energy of this step was not calculable. Finally, the used GO/PAMAM was completely regenerated by using ethylenediamine. View Full-Text
Keywords: graphene oxide/poly(amidoamine); congo red; adsorption; KASRA model; ARIAN model; ISO equation graphene oxide/poly(amidoamine); congo red; adsorption; KASRA model; ARIAN model; ISO equation
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MDPI and ACS Style

Rafi, M.; Samiey, B.; Cheng, C.-H. Study of Adsorption Mechanism of Congo Red on Graphene Oxide/PAMAM Nanocomposite. Materials 2018, 11, 496.

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