title: Use of natural mordenite to remove chromium (III) and to neutralize pH of alkaline waste waters.
abstract: The natural mordenite from Palmarito de Cauto deposit (PZ), Cuba, was studied in this work as an ion exchanger to remove Cr(3+) cations from alkaline aqueous solutions at different pH and chromium concentrations. The mordenite stability under cyclic treatment processes with alkaline solutions and its capacity to decrease the pH of the solutions was also analyzed. It was shown that PZ removes Cr(3+) ions from alkaline solutions, and it happens independently of the starting chromium concentration and the pH of the exchange solution used. This material has an important neutralizing effect on alkaline solutions, expressed in a significant pH decrease from the early stages of the treatments. For solutions with initial pH equal to 11, it decreases to a value of around seven. The stability of this material is not affected significantly after continuous cyclic treatment with NaOH solution, which shows that mordenite, in particular from Palmarito de Cauto deposit, has high stability in alkaline solutions. The results are important as they suggest that natural zeolites may be of interest in treatments of alkaline industrial waste effluents.
authors.affiliation: a Department of Chemical and Biological Foundations , Faculty of Chemical Engineering, University of Oriente , Santiago de Cuba, Cuba.
authors.forename: Valduvina
authors.initials: V
authors.lastname: Córdova-Rodríguez
authors.affiliation: b Institute of Science and Technology of Materials (IMRE), University of Havana , Havana , Cuba.
authors.forename: Inocente
authors.initials: I
authors.lastname: Rodríguez-Iznaga
authors.affiliation: c Chemical Department , Faculty of Natural Sciences, University of Oriente , Santiago de Cuba, Cuba.
authors.forename: Raquel María
authors.initials: RM
authors.lastname: Acosta-Chávez
authors.affiliation: d Physics Department , ESFM-IPN , Mexico.
authors.forename: Fernando
authors.initials: F
authors.lastname: Chávez-Rivas
authors.affiliation: e Nanocatalysis Department , Center of Nanosciences and Nanotechnology (CNyN) - UNAM , Ensenada, B.C, Mexico.|f Department of Zeolite Research , Science Institute, BUAP , Puebla , Mexico.
authors.forename: Vitalii
authors.initials: V
authors.lastname: Petranovskii
authors.affiliation: g Tomsk Polytechnic University , Tomsk , Russia.
authors.forename: Alexey
authors.initials: A
authors.lastname: Pestryakov
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D002857:Chromium / Q000032:analysis / Q000737:chemistry*; D003462:Cuba; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007474:Ion Exchange; D062065:Wastewater / Q000032:analysis / Q000737:chemistry*; D017641:Zeolites / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D002412:Cations; D002857:Chromium; D007220:Industrial Waste; D062065:Wastewater; D017641:Zeolites; C048397:mordenite
keywords: Cr(III) removal; natural zeolites; pH neutralization; waste effluents