Investigation on preparing Mn₃O₄ nanopowder by hydrothermal reaction method

Abstract

A process to prepare Mn3O4 in the mixed solvent of water and ethanol under hydrothermal condition was studied, in which manganese sulphate was used as raw material, manganese hydroxide from precipitation with sodium hydroxide as a precursor, potassium permanganate as oxidant. The influences of the factors on Mn mass percentage (Mn wt-%) in manganese oxide product, including potassium permanganate dosage, solvent composition, temperature and time of the hydrothermal reaction as well as drying temperature, were analysed. Potassium permanganate dosage could be a third of the theoretical amount because of the auxiliary oxidation of existent O2 in the process. The results show that the optimal conditions are hydrothermal temperature 433 K and time 2–4 hours, solvent composition (ethanol/(ethanol + water), in volume) 0·33 and drying temperature 393 K, Mn wt-% in the optimal product exceeds 71% and Na content meets the standard of magnetic material.