Industrial wastewaters, particularly those associated with mining and mineral processing, can contain high concentrations of sulphate. There are various methods of sulphate removal e.g. reverse osmosis, ion exchange, precipitation by lime, cements, and salts of barium and the biological removal process. The soluble salts of barium are most commonly used for precipitation of sulphate from aquatic acidic solutions to the insoluble product barium sulphate BaSO₄. Benefits of precipitation are high sulphate removal efficiency but limitations are toxicity of barium compounds and high economical costs. For this reason the recycling of BaSO₄ to barium sulphide BaS (the precipitating reagent) is very important.

The paper deals with study of BaSO₄ reduction by activated carbon to BaS by thermal analysis and infrared spectrometry. DCS analysis indicated that conversion of BaSO₄ to BaS in the range of temperature 800-1,000 °C was performed. Thermal analysis and infrared spectra of the products confirmed the change in its composition, but process of reduction by carbon was incomplete and in sample was still present a part of BaSO₄. Presence of BaS was confirmed by colorimetric method.

DOI: https://doi.org/10.3846/enviro.2017.004