Lead sorption by a Mexican, clinoptilolite-rich tuff

• Published in: Environmental science and pollution research international Vol. 14; no. 6; pp. 397 - 403
• Main Authors: Olguin, M, Llanes-Monter, M, Solache-Rios, M
• Format: Journal Article
• Language: English
• Published: Germany Springer Nature B.V 01.09.2007
• Subjects: Absorption; Aqueous solutions; Atomic absorption spectroscopy; Chemical composition; Chemical speciation; Electron microscopy; Hazardous Substances; Heavy metals; Hydrogen-Ion Concentration; Ion exchange; Isotherms; Lead; Lead - chemistry; Metal ions; Mexico; Mexico, Oaxaca; Microscopy; Nitrates; Nitrates - chemistry; pH effects; Q1; Q3; Sodium; Soil - analysis; Sorption; Speciation; Spectral analysis; Spectrometry; Waste treatment; Wastewater; Wastewater pollution; Wastewater treatment; Water pollution; Water treatment; Zeolites; Zeolites - chemistry; Mexico; Mexico, Oaxaca
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1065/espr2006.10.357

The retention of lead by a Mexican, clinoptilolite-rich tuff from Oaxaca (Mexico) at different pH values was evaluated and the lead sorption mechanisms on the zeolitic material in this work were discussed. Isotherms were determined using lead nitrate solutions (initial pH values between 2 and 5) at 303 K. After the equilibrium was reached, the content of lead in the liquid phases was determined by atomic absorption spectrometry. The elemental composition of the clinoptilolite-rich tuff before and after the lead sorption process was evaluated by electron microscopy. The maximum ion exchange capacity of the Mexican, clinoptilolite-rich tuff for lead was 1.4 meq/g at pH 3, considering an ion exchange mechanism in the absence of any precipitated or hydrolyzed lead species in the sorption process or any change in the zeolite network. Langmuir and Freundlich isotherms were also considered in this work for comparison purposes. It is important to consider the nature of the sorption processes before choosing a model to describe the interaction between the metal ions and the sorbent. The chemical lead speciation, the pH, as well as the characteristics of the clinoptilolite-rich tuff are important factors to be considered on the lead sorption process by natural zeolites. The chemical species involved in that process are Na, from the zeolite and Pb2+ from the aqueous solution at pH 2 and 3, so that the ion exchange mechanism explains the lead sorption processes by the clinoptilolite-rich tuff through the ion exchange isotherms. The sodium, Mexican, clinoptilolite-rich tuff is a potential adsorbent for lead from aqueous solutions. The natural zeolite-rich tuffs are very important as ion exchangers for the treatment of polluted water due to their sorption properties and low cost. The sorption behavior of each natural material depends on their composition. Mexican, clinoptilolite-rich tuff from Oaxaca (Mexico) could be used for the treatment of waste water contaminated with lead. It would be important to propose this material as an alternative as waste water treatment, because it shows good selectivity for the removal of heavy metals from water.