Equilibrium adsorption of hydrogen sulfide onto CuO and ZnO

Removal of hydrogen sulfide from aqueous solutions has been studied using cupric oxide (CuO) and zinc oxide (ZnO) as adsorbents. The adsorption capacity of both CuO and ZnO for H2S from aqueous solutions was determined under various conditions of temperature and solution pH. Equilibrium data were used to construct adsorption isotherms and to fit various adsorption models. Results show that increasing temperature leads to an increase in the adsorption capacity of both oxides. Studying the effect of pH at 4, 7 and 11 show that the maximum adsorption capacity of CuO is attained at pH 7. However, the Redlich–Peterson isotherm shows a better fit than both the Langmuir and Fruendlich isotherms.

The adsorption capacities of both CuO and ZnO, presented at different operating conditions of temperature and solution pH, show that each of them is a good adsorbent for H2S in aqueous solutions. However, CuO has a better adsorption capacity. The experimental data were fitted using the Langmuir, Freundlich and Redlich–Peterson isotherms.