A bentonite sample from the Petreş ti deposit, Cluj County (Romania), was used to remove heavy-metal ions (Cd2+, Pb2+, Cr3+) from wastewaters. A representative sample of bentonite (P) was characterized using the Brunauer-Emmett-Teller (BET) method, wet chemical analyses, X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The bentonite deposit from Petreş ti is present at the contact between Upper Jurassic limestones and basaltic andesites with subordinate basalt bodies. These rocks are composed of clay minerals (mainly smectite), with opal, quartz, feldspar and mica/illite as minor phases. The bentonite sample was used in powdered form (d < 0.2 mm) without any chemical treatment. The influence of the working regime, static and dynamic, on the process efficiency was studied using monocomponent synthetic wastewaters containing Cd, Pb and Cr ions. The bentonite sample proved to be efficient for the removal of these heavy-metal ions; removal efficiencies up to 100% (lead removal) were achieved.
ABSTRACT. Volcanic tuffs out cropping in Măcicaş area (Cluj County) have been investigated and tested for their ammonium removal capacity. The zeolitic volcanic tuffs from Măcicaş are mainly represented by vitric and vitric crystal tuffs. In this region, significant amounts of volcanic glass in the pyroclastic sequence have been replaced by zeolites (between 50-80 %). The main zeolite species identified in volcanic tuffs from Măcicaş is clinoptilolite and subordinately mordenite. The zeolitic tuff samples considered in zeolitic sodium form (labeled M1-Na and M2-Na) are tested in ammonium removal experiments. The ammonium ions were completely removed from 0.0716g/dm 3 NH 4 + solution onto 10g of zeolitic material in static regime. In dynamic regime, the ammonium ions were completely removed after 250 ml and 500 ml solution passed on M1-Na and M2-Na sample respectively. Also the zeolite exhaustion takes place after more than 1500 ml solution is processed in both cases. The ionic exchange properties suggest that the zeolitic tuff of the Măcicaş region can be used as a final stage (following the biological process) in wastewater treatment plants in order to assure compliance with environmental standards.
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. Zn 2+ 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 Zn 2+ 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 Zn 2+ 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.
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