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Open AccessArticle

Sorption of Pb(II) from Aqueous Solutions by Acid-Modified Clinoptilolite-Rich Tuffs with Different Si/Al Ratios

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Facultad de Ingeniería, Universidad Autónoma del Carmen, C.P. 24180 Ciudad del Carmen, Campeche, Mexico
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Facultad de Química, Universidad Autónoma del Carmen, Calle 56 No. 4 Esq. Av. Concordia, Col. Benito Juárez, C.P. 24180 Ciudad del Carmen, Campeche, Mexico
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Departamento de Química, Instituto Nacional de Investigaciones Nucleares, Carretera México.Toluca s/n. La Marqueza, Ocoyoacac, C.P. 52750 Estado de México, Mexico
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Instituto de Ciencias Aplicadas y Tecnología, UNAM, Circuito Exterior, S/N, Ciudad Universitaria, A.P. 70-186, Delegación Coyoacán, C.P. 04510 Ciudad de México, Mexico
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Instituto de Investigaciones en Materiales, Unidad Morelia, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex Hacienda de San José de la Huerta, C.P. 58190 Morelia, Michoacán, Mexico
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Facultad de Ingeniería, Universidad Autónoma de Yucatán, Av. Industrias no Contaminantes por Periférico Norte, Cordemex, C.P. 97310 Mérida, YUC, Mexico
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Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(12), 2415; https://doi.org/10.3390/app9122415
Received: 15 April 2019 / Revised: 9 June 2019 / Accepted: 9 June 2019 / Published: 13 June 2019
(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)
The removal of Pb(II) from aqueous solutions by acid-modified clinoptilolite-rich tuff was investigated in this work. Clinoptilolite-rich tuff samples were treated using H2SO4 at different concentrations. Prior to and following acid treatment, the samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). The pH of the point of zero charge (pHPZC) was also determined as part of this characterization. Batch studies were studied to investigate Pb(II) removal as a function of contact time, initial Pb(II) concentration, adsorbent dosage, and solution pH. The results of the XRD and SEM techniques showed that clinoptilolite is the main mineral of the non- and acid-treated natural zeolite samples. However, EDS analysis indicated that the Si/Al ratio increases as the exchangeable ions decrease with increasing acid concentrations. The optimum conditions for Pb(II) removal for samples with 4.37 ≤ Si/Al ≤ 7.9 were found to be as follows: Contact time of 60–360 min, pH: 6–8, and adsorbent dose of 6 mg g−1; whereas for acid-modified clinoptilolite-rich tuffs with 9.01 ≤ Si/Al ≤ 9.52, these conditions were as follows: Contact time of 1440 min, pH: 8–10, and adsorbent dose of 10 mg g−1. The experimental data were analyzed by kinetic and isotherms models. The results showed that the sorption of Pb(II) on samples with Si/Al ratios of 4.37, 5.31, and 7.91 were in agreement with the pseudo-second order and Langmuir isotherm with qm = 48.54, 37.04, and 14.99 mg g−1, respectively, while the kinetic data and isotherm for samples with 9.01 ≤ Si/Al ≤ 9.52 were found to fit the pseudo-first order and Freundlich model. View Full-Text
Keywords: lead; sorption; natural zeolite; clinoptilolite; sulfuric acid lead; sorption; natural zeolite; clinoptilolite; sulfuric acid
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Abatal, M.; Córdova Quiroz, A.V.; Olguín, M.T.; Vázquez-Olmos, A.R.; Vargas, J.; Anguebes-Franseschi, F.; Giácoman-Vallejos, G. Sorption of Pb(II) from Aqueous Solutions by Acid-Modified Clinoptilolite-Rich Tuffs with Different Si/Al Ratios. Appl. Sci. 2019, 9, 2415.

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