Enhanced adsorptive removal of hydrogen sulfide from gas stream with zinc-iron hydroxide at room temperature

Bimetallic (zinc-iron) hydroxides adsorbent (Zn-Fe hydroxide) was effectively synthesized through co-precipitation of bivalent zinc and trivalent iron at room temperature. The influences of Zn/Fe molar ratio, pH of a mixing solution of precipitating reagents, and aging temperature on adsorption capacity were investigated to find the optimum condition of the synthesized adsorbent, of which experiment was designed by the one-factor-at-a-time method. Powdered activated carbon (PAC) was employed as the support material to provide an active site on the synthesized composites. An optimized Zn-Fe hydroxide with 10 wt% of PAC had a breakthrough adsorption capacity of 0.143 gH₂S/g, which was much higher than that of either a pure Fe hydroxide or Zn hydroxide. The synergistic interaction between Zn and Fe affected the morphology and the surface structure of the synthesized adsorbent. After hydrogen sulfide adsorption, ZnS and FeS were observed by the Scanning electron microscope-Energy dispersive spectroscopy and X-ray photoelectron spectroscopy.