Carpathian Journal of Earth and Environmental Sciences

Zeolitic tuff (from the region of Barsana, Maramures, Romania) was used in the experimental determinations for retaining the Pb and Zn ions from industrial wastewater. The determination was performed in static regime using 10 g zeolitic tuff/100 cm³ wastewater (from the slag granulation basin of the metallurgical factory S.C. Romplumb S.A. Baia Mare, Romania). The initial concentration of the metal ions in the wastewater was 3.806 mg Pb²⁺/l, respectively 129.20 mg Zn²⁺/l. We followed the evolution of the ion exchange process upon retaining the heavy metal ions in three types of particle size range from the zeolitic tuff sample, i.e. 0.4 – 0.2 mm (G04); 0.2 – 0.12 mm (G02); <0.012-mm (G012). The clinoptilolite was predominant in the zeolitic material used in this experiment and was identified by qualitative analysis with the electronic microscope (SEM) and quantitative analyses by spectral analyses (EDS). For the G012 set of samples, particle surface were analysed by the scanning electronic microscope (SEM) and local X-ray energy dyspersive spectrometry (EDS). The zeolitic tuff which was in contact with the wastewater was separated by filtration, and the samples for determining the Pb and Zn ions were prelevated after 12 hours. The concentration of the Pb and Zn ions was determined by atomic absorption spectroscopy at a pH of 5.90. The determined ion exchange efficiency values for Pb were above 96%, with the maximum 99.17% for the G012 set of samples. For Zn, where the Zn ions had high concentrations in the initial sample, the maximum ion exchange efficiency was 52.95%.