Economical sorbents for the remotion of Cr (III) and Mn (II) from water

C. ADAMO; F. ESPINOZA; E. M. FARFÁN TORRES

Puerto Iguazú

Workshop; Solar Safe Water, Tecnologias Emergentes para estudiar problemas de tratamiento de agua en Países en Desarrollo; 2005

Unión Europea - CNEA - Ministerio de Educación y Ciencia de España ?Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas ? Fundación Balseiro ? Plataforma Solar Almeria ? Universidad Nacional de San Martín

Many toxic heavy metals are discharged to the environment as industrial wastes, causing serious soil and water pollution. Variousphysicochemicaland biological methods were studied for metal removal. Some naturally occurring clay minerals may serve as cost-effective sorbents for the removal of heavy metals. While their sorption capacity is usually less than those of synthetic sorbents, these materials could provide an inexpensive substitute for the treatment of heavy metal waste waters. Clays are materials widely used in many fields due to their-high specifie surfaee area, high chemieal and mechanical stability and a variety of surface and structural properties. Various research studies have been earried out on montmorillonite polluted water systems and their eapacity as eation exchangers for heavy metals removal. The primary aim of this work is ta investigate the sorptive characteristics of several heavy metals onto modified locally available clay mineral. Here we present the results of experiments performed to describes the interaction between two argentinian montmorillonites and Cr{III) and Mn.{II)aqueous solutions. Sorption experiments were carried out by batch mode. In each experiement 0,50 9 of dried natural or sodium homoionie montmorillonites: PJ, PESP, PJ-Na .and PESPNa, were stirred with 1000 mmollL of Cr3+and/ or Mn2+aqueous solutions during variables times ranging from 30 to 12 hours. The solid were separated by filtering and the metal ion eoneentration determined by Atomie Absorption Analysis. In this way the necessary time to reach the exchange equilibrium was determined to be 2 hours for chromium and 4 hours for manganese. Sorption isotherms were determined using 1000 mL of solution with various metal concentrations and 0,50 mg of sorbents. The initial metal concentrations ranged from 500 and 2000 mmo/L. The solution was shaken for 2 and four hours for Cr (III) and Mn respectively. After separating the solutions from  the clay the reminded eoneentration of Cr1+and Mn2+were determined. The uptake eapacities of the sorbents were determined from Langmuir Isotherms: Pesp-Cr = 10,98 mg Cr/g; Pesp-Na-Cr = 14,56 mg Cr/g y PJ -Mn = 2,27 mg Mn /g de arcilla; Pj-Na~Mn=8,10 mg Mn./g.These values are quite higherthan those reported in the literature for chromium and are the first reported for manganese.