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H2S removal: Correlation between performance and loading species of Zn-Fe/attapulgite



Three kinds of sorbents, Zn/attapulgite (ATP), Fe/attapulgite, and Zn-Fe/attapulgite with different amounts of Fe and Zn were prepared and used for H2S removal at room temperature. The stirring time and final pH were selected. According to the breakthrough time, desulfurization efficiency and sulfur capacity, the order of desulfurization performance was Zn-Fe/ATP > Zn/ATP > Fe/ATP. The results of X-ray diffraction (XRD), Ultraviolet–visible diffuse reflectance spectroscopy (UV–vis-DRS), ammonia-dissolving tests and transmission electron microscope (TEM) indicated that for the Fe sorbents, a stronger interaction between the loadings and supports (ILS) led to a poorer desulfurizing capability, even with increasing loading amounts. The oligomeric Fe species which were the main active substance for H2S removal among the three kinds of Fe species in the sorbents, affected the desulfurization performance. The performance of Zn sorbents depended on the loading amount and ILS rather than dispersity. Due to the interaction between Zn and Fe, Zn-Fe/ATP has the best ILS and the greatest amount of oligomeric Fe species, and hence has the best performance. However, an increase in loading amount leads to a decline in the proportion of the oligomeric Fe species and an increase in large particle Fe species, and hence the reaction rate of loading was reduced. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 378–384, 2014