Development of low-cost adsorbents derived from sludge of groundwater treatment for gaseous hydrogen sulfide removal

The goal of this research is to create adsorbents from groundwater treatment sludge that have the functional property of H2S adsorption in air. The prepared adsorbent samples were characterized to have a main phase component of crystalline CaCO3 (the average crystallite size of 25-36 nm), finely dispersed on the surface by an amorphous oxide phase of silicon and iron metals. The raw sludge when drying at 105 degrees C for 24 h (SL-105) was shown to be effective for the adsorption, with H2S removal efficiency (x(H2S)) decreasing from 100% to 74% in adsorption time 70 min (conditions: adsorption temperature of 25 degrees C; inlet H2S concentration of 4000 ppm; inlet gas-air flow rate of 2.0 L/min; adsorbent mass of 10.0 g). The SL-105 sample, when calcinated at 300 degrees C, showed a higher x(H2S) of similar to 75% in 100 min; the adsorption capacity (a(H2S)) of the latter could be increased to similar to 75% (a(H2S) approximate to 507.5 mg/g) in 600 min when it was impregnated with copper oxide. The H2S adsorption process was found to be chemisorption and monolayer, following the Langmuir adsorption isotherm. Thus, it is obvious that economically and technically efficient adsorbents derived from sludge precursors can be effectively used for H2S purification in air.