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Open AccessArticle

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

Facultad de Ingeniería, Universidad Autónoma del Carmen, C.P. 24180 Ciudad del Carmen, Campeche, Mexico
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
Departamento de Química, Instituto Nacional de Investigaciones Nucleares, Carretera México.Toluca s/n. La Marqueza, Ocoyoacac, C.P. 52750 Estado de México, Mexico
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
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
Facultad de Ingeniería, Universidad Autónoma de Yucatán, Av. Industrias no Contaminantes por Periférico Norte, Cordemex, C.P. 97310 Mérida, YUC, Mexico
Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(12), 2415;
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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