Isolation, Characterization and Hydrogen Sulfide H2S Sorption Properties at Room Temperature of Magnetite Sludge from Radiator

Radiator sludge is caused by hydrothermal corrosion of ferrous metals that make up the system, with more than 98 % being magnetite Fe3O4 (e.g., magnetite sludge). When hot circulating water reacts with metals such as the steel inside radiator, the build-up of sludge can be costly, leading to heating inefficiency or system breakdown through pipes blockage. Therefore, the sludge must be removed from radiator on a regular basis, ending up as waste to the environment without any further use. Taking into account the numerous applications of magnetic iron oxides, as well as the vast number of installed radiators existing worldwide, it becomes apparent that magnetite sludge makes a considerable yet cheap waste meriting further attention towards practical applications. In this work, we isolate and characterize magnetite sludge from radiator, providing evidence about the magnetic nature of the iron oxide phase for the first time. Following, we exploit the sludge as sorbent material towards hydrogen sulfide H2S removal. Due to trace amounts of catalytic elements in the sample from the steel body of radiator, this shows a high removal capacity of 2.68 mmol H2S per gram of sorbent at room temperature, thus surpassing literature-reported values of synthetic magnetite Fe3O4 nanoparticles (0.1-1.5 mmol H2S per gram of sorbent in the range 30-120 °C). This finding is important taking into consideration that there is an ever-increasing need towards an efficient removal of hydrogen sulfide H2S at room temperature by low-cost sorbents.