Uptake of Zn2+ ions by a fully iron-exchanged clinoptilolite. Case study of heavily contaminated drinking water samples.
Clinoptilolite, a natural zeolite, was used for the synthesis of a high surface area clinoptilolite (Clin)-iron (Fe) oxide system, in order to be used for the removal of Zn(2+) ions from drinking water samples. The new system was obtained by adding natural Clin in an iron nitrate solution under strongly basic conditions. The Clin-Fe system has specific surface area equal to 151 m(2)/g and is fully iron exchanged (Fe/Al=1.23). Batch adsorption experiments were carried out to determine the effectiveness of the Clin and the Clin-Fe system in removal of Zn from drinking water. Adsorption experiments were conducted by mixing 1.00 g of each of the substrates with certain volume of water samples contaminated with ten different Zn concentrations (from 7.65x10(-5) to 3.82x10(-2)M or from 5.00 to 2500 ppm Zn). For our experimental conditions, the maximum adsorbed Zn amount by Clin was 71.3mg/g, whereas by the Clin-Fe system 94.8 mg/g. The main factors that contribute to different adsorbed Zn amounts by the two solids are due to new surface species and negative charge of the Clin-Fe system. In addition, the release of counterbalanced ions (i.e. Ca(2+), Mg(2+), Na(+) and K(+)) was examined, as well as the dissolution of framework Si and Al. It was found that for most of the samples the Clin-Fe system releases lower concentrations of Ca, Mg and Na and higher concentrations of K than Clin, while the dissolution of Si/Al was limited. Changes in the composition of water samples, as well as in their pH and conductivities values were reported and explained.
Dimirkou
Anthoula
A
Department of Agriculture, Crop Production and Agricultural Environment, University of Thessaly, Soil Science Laboratory, N. Ionia 38446 Magnesias, Greece. adimirkou@uth.gr
D000327:Adsorption; D006115:Greece; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods; D014881:Water Supply; D017641:Zeolites / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D014874:Water Pollutants, Chemical; C083175:clinoptilolite; D017641:Zeolites; D008345:Manganese; D007501:Iron; D015032:Zinc