Hydrogen sulphide removal on carbonaceous adsorbents prepared from coffee industry waste materials

• The alternative method of utilisation of coffee industry waste materials is proposed.
• Very effective H2S adsorbents were prepared from coffee industry waste materials.
• The adsorbents prepared show greater efficiency of H2S removal than commercial ones.
• Sorption capacity depends mainly on mineral matter content and adsorption conditions.

The sorption properties of chars and activated carbons obtained from coffee industry waste materials toward hydrogen sulphide are characterised. The effects of pyrolysis temperature and method of activation as well as porous structure, acid–base character of the surface and mineral matter content on the efficiency of H2S removal are checked. Moreover, four different variants of adsorption test are applied, in order to estimate the optimal conditions of hydrogen sulphide capture. Depending on the method of activation, the adsorbents prepared are characterised by diverse textural parameters, strong basic or medium-acidic character of the surface and various mineral matter content, varying from 1.2 to 58.4 wt.%. The results obtained in our study have proved that through an appropriate choice of pyrolysis conditions and activation procedure for coffee industry waste materials it is possible to obtain adsorbents with high capacity of hydrogen sulphide, reaching to 281.5 mg H2S/gads. The results of our study have also shown that the adsorption ability of activated carbons prepared depends first of all on the conditions of adsorption test, mineral matter content and basicity of the surface and only to a small degree on porous structure development.