Adsorption Behavior of Acid-Treated Brazilian Palygorskite for Cationic and Anionic Dyes Removal from the Water

Vanderlane C. Silva, Maria Eduarda B. Araújo, Alisson M. Rodrigues, Juliana M. Cartaxo, Romualdo R. Menezes and Gelmires A. Neves
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Vanderlane C. Silva: Graduate Program in Materials Science and Engineering (PPG-CEMat), Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil
Maria Eduarda B. Araújo: Academic Unit of Materials Engineering, Science and Technology Center, Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil
Alisson M. Rodrigues: Graduate Program in Materials Science and Engineering (PPG-CEMat), Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil
Juliana M. Cartaxo: Academic Unit of Materials Engineering, Science and Technology Center, Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil
Romualdo R. Menezes: Graduate Program in Materials Science and Engineering (PPG-CEMat), Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil
Gelmires A. Neves: Graduate Program in Materials Science and Engineering (PPG-CEMat), Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil

Sustainability, 2021, vol. 13, issue 7, 1-22

Abstract: The effect of acid treatment on the adsorptive capacity of a Brazilian palygorskite to remove the crystal violet (CV) and congo red (CR) dyes was investigated. The raw palygorskite was acid-treated by different HCl solutions (2, 4, and 6 mol/L). The modifications on the palygorskite structure were investigated using X-ray diffraction, X-ray fluorescence, Fourier-transform infrared spectroscopy, N 2 adsorption/desorption, and thermogravimetric and differential thermal analysis. The efficiency of CV and CR adsorption was investigated, and the effect of the initial concentration, contact time, pH, and adsorbent amount was analyzed. The results revealed that CV adsorption in the acid-treated palygorskite was higher than that of the raw material. A Langmuir isotherm model was observed for the adsorption behavior of CV, while a Freundlich isotherm model was verified for the CR adsorption. A pseudo-second-order model was observed for the adsorption kinetics of both dyes. The higher CV adsorption capacity was observed at basic pH, higher than 97%, and the higher CR removal was observed at acidic pH, higher than 50%. The adsorption parameters of enthalpy (ΔH), entropy (ΔS), and Gibbs energy (ΔG) were evaluated. The adsorption process of the CV and CR dyes on the raw and acid-treated Brazilian palygorskite was predominantly endothermic and occurred spontaneously. The studied raw palygorskite has a mild-adsorption capacity to remove anionic dyes, while acid-treated samples effectively remove cationic dyes.

Keywords: palygorskite; adsorption; anionic dye; cationic dye; water treatment (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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