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

Copper(II) hydroxide sulfate was synthesized by a microwave-assisted hydrothermal method from a mixed solution of CuSO4 and urea. Needle-like crystals of ca. 20–30 μm in length precipitated by irradiating microwave for 1 min were characterized as Cu3(OH)4SO4 corresponding to mineral antlerite. The reaction pathway and kinetics of the thermal decomposition of the synthetic antlerite Cu3(OH)4SO4 were investigated by means of thermoanalytical techniques complemented by powder X-ray diffractometry and microscopic observations. The thermal decomposition of Cu3(OH)4SO4 proceeded via two separated reaction steps of dehydroxylation and desulfation to produce CuO, where crystalline phases of Cu2OSO4 and CuO appeared as the intermediate products. The kinetic characteristics of the respective steps were discussed in comparison with those of the synthetic brochantite Cu4(OH)6SO4 reported previously.