Obtention of agricultural gypsum traced on 34 S (Ca34 SO4.2H2O), by chemical reaction between H234 SO4 and Ca(OH)2

The gypsum (CaSO4.2H2O) has double function in the soil: as source of calcium and sulfur and reducing agent of aluminum saturation. The sulfur for the plants has acting in the vital functions and it is proven fact increase of the S deficiency in Brazilian soils. The isotope tracer 34 S can elucidate important aspects in the sulfur cycle. The Ca34 SO4.2H2O was obtained by chemical reaction between Ca(OH)2 and H234 SO4 solution. The acid was obtained by chromatography ionic change, using cationic resin Dowex 50WX8 and Na234 SO4 solution. The reaction was realized under slow agitation. After the reaction, the precipitate was separated and dried in ventilated stove at 60 deg C temperature. The Mass of the Ca34 SO4.2H2O produced was determined by method gravimetric. This way, a system contends resin 426 cm3, considering volume of 2.2 liters can be obtained a solution contends 44.2 g of H234 SO4, theoretically could be produced 78.0 g of Ca34 SO4.2H2O approximately. With results of the tests were verified that there was not total precipitation of the Ca34SO4.2H2O. Were produced 73.7± 0.6 g of Ca34 SO4.2H2O representing average income 94.6±0.8 %. The purity of the produced CaSO4.2H2O was 98%. (author)