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    STUDIA GEOLOGIA - Issue no. 1 / 2010  
         
  Article:   INVESTIGATIONS ON SOME ZEOLITIC VOLCANIC TUFFS FROM CLUJ COUNTY (ROMANIA), USED FOR ZINC IONS REMOVAL FROM AQUEOUS SOLUTION.

Authors:  HOREA BEDELEAN, ANDRADA MĂICĂNEANU, SILVIA BURCĂ, MARIA STANCA. 		 
       
         
  Abstract:  Representative samples of zeolitic tuffs from Măcicaş, Aluniş, and Apahida occurrences (Cluj County, Romania) were investigated using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and wet chemical analyses. The studied tuff samples are represented mainly by vitric and vitric crystal varieties. The mineral assemblage suggests a rhyodacitic volcanic tuff. Diagenetic alteration led to the formation of zeolites, mainly clinoptilolite. Zn2+ removal was performed on some bulk samples: Aluniş (labelled A1), Apahida (Ap), and Măcicaş (M2) grain size of 0.2-0.4 mm. Each sample was chemically modified with HCl 1M (Z-H form) and NaCl + NaOH 1M pH = 10 (Z-Na form). The ionic exchange experiments were performed in a batch reactor (immobile phases) and in a fixed bed column. Ionic exchange efficiencies for the samples considered are presented for static and dynamic regimes. Removal efficiencies higher than 53.97% and exchanged Zn2+ quantities higher than 1.05 mg/g were obtained. Therefore, the zeolitic tuffs under investigation are considered to be active in the ionic exchange process and can be used in wastewaters treatment to remove Zn2+ ions. The results for all the samples considered in batch and fixed bed experiments are presented by means of cation exchange capacity (CEC) and removal efficiency.

Key words: natural zeolites, clinoptilolite, volcanic tuffs, Cluj County, zinc, ionic exchange.
  
         
     
         
         
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