Simultaneous mercury removal from wastewater and hydrogen sulfide scavenging from sour natural gas using a single unit operation

The sustainable development of the world civilization requires a proper waste handling and management. Mercury is one of the most hazardous water pollutants. Additionally, hydrogen sulfide is a life-threatening natural gas contaminant. In this work, a one-pot process for the concurrent removal of mercury (Hg(II)) from mercury-polluted wastewaters and hydrogen sulfide (H₂S) scavenging from sour natural gas has been developed. In this process, the sour natural gas is fed into a bubble column reactor filled with synthetic wastewater containing different levels of Hg(II). The contact of H₂S in the inlet gas with the dissolved Hg(II) in the wastewater samples promotes the reaction of H₂S with Hg(II), forming a water-insoluble HgS precipitant. This leads to the purification of both, the water sample and the gas stream without the need for adding any external material. Almost a complete Hg(II) removal (≥97.6%) from the synthetic wastewater samples is attainable irrespective of the initial Hg(II) concentration. Additionally, each kilogram of Hg(II) could scavenge up to 147.3 and 169.3 g H₂S from the entering sour natural gas at the breakthrough and the saturation time, respectively. These findings reveal the efficacy of the proposed process for the simultaneous removal of Hg(II) from mercury-contaminated waters and H₂S from sour gases using a single unit operation. Thus, the proposed process herein is novel and very appealing from economic, operational, environmental, and safety/occupational health perspectives.