Arsenic contamination of groundwaters in the Tisza River Basin and treatment of well water with Al nanoclusters

Arsenic is one of the most toxic, naturally occurring elements with carcinogenic effects on chronically exposed human populations. Geogenic arsenic concentrations in the groundwater of the Tisza river basin (part of the east Pannonian Basin, at the border area of Hungary and Romania) range between < 0.5 µg/L and 210 µg/L. The majority of the groundwaters can be classified as sodium-bicarbonate type. The dominant inorganic arsenic species is arsenite and the iron content is generally low. In many regions of the studied area, the publicly accessible artesian wells play an important role in the water supply due to the preference for the well water by the local population, and in a few villages also because distributing water pipes are not installed yet. The arsenic contamination of this water therefore represents a potential risk factor for the health of the affected population. This study investigates arsenate and arsenite adsorption on aluminium nanoclusters for the average groundwater composition of the Hungarian-Romanian border area. Batch experiments are conducted with synthetic water based on the composition of the groundwater of the studied area. The effect of pH and phosphate concentrations on arsenic adsorption is studied from pH 6.5-9.0 and 0-0.1 mM dissolved phosphate. The arsenic adsorption onto aluminium nanoclusters is tested for both arsenate and arsenite, at five different concentrations: 20 µg/L, 50 µg/L, 100 µg/L, 180 µg/L and 260 µg/L. Resulting concentrations of aqueous arsenic species remaining in the water are measured by HG-AFS. The aqueous speciation and kinetic reactions for the batch experiments are modeled consecutively. In the present contribution, first results of an arsenic treatment method with aluminum nanoclusters for groundwater compositions representative for the Romanian and Hungarian border area are shown and discussed.

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