Thermal decomposition of synthetic antlerite prepared by microwave-assisted hydrothermal method

Abstract

Copper(II) hydroxide sulfate was synthesized by a microwave-assisted hydrothermal method from a mixed solution of CuSO 4 and urea. Needle-like crystals of ca. 20–30 μm in length precipitated by irradiating microwave for 1 min were characterized as Cu 3(OH) 4SO 4 corresponding to mineral antlerite. The reaction pathway and kinetics of the thermal decomposition of the synthetic antlerite Cu 3(OH) 4SO 4 were investigated by means of thermoanalytical techniques complemented by powder X-ray diffractometry and microscopic observations. The thermal decomposition of Cu 3(OH) 4SO 4 proceeded via two separated reaction steps of dehydroxylation and desulfation to produce CuO, where crystalline phases of Cu 2OSO 4 and CuO appeared as the intermediate products. The kinetic characteristics of the respective steps were discussed in comparison with those of the synthetic brochantite Cu 4(OH) 6SO 4 reported previously.