Development of CuO/Cu₄(OH)₆SO₄ Nanoparticle Mixtures to Optimize the H₂S Adsorption

In this paper, we report the H₂S adsorption behavior of a sorbent composed of mixtures of tenorite (CuO) and brochantite [Cu₄(OH)₆SO₄]. These materials are readily prepared through the addition of NaOH_(aq) to CuSO_4(aq). They can be loaded onto polymer foams to create effective filters that can remove malodorous H₂S gas, as evidenced by breakthrough tests. X-ray diffraction shows that the ratio of the two compounds in the mixture can be finely tuned by varying the amount of NaOH_(aq) that is added to the reaction mixture. X-ray photoelectron spectroscopy shows that brochantite, like tenorite, has the ability to chemically adsorb H₂S. Correlation of the H₂S breakthrough data with scanning transmission electron microscopy measurements shows that the most effective sorbents contain nanoscale needle-like particles. These are likely to be formed largely by the tenorite phase. The samples with the greatest H₂S adsorption efficacy contained less than 20% tenorite in the mixture, where these particles had the greatest abundance. The application of this sorbent onto porous substrates to create effective filters, along with the synthetic ease of its production, could allow this methodology to find use in a number of areas where H₂S poses a problem. This could include areas where protective clothing is required to adsorb the gas from environments where there is a high level of H₂S, for example, in wastewater treatment plants, oil and gas wells, or in the medical sector, where it could be deployed as filter media.