Removal of Hydrogen Sulfide on Composite Sewage Sludge-Industrial Sludge-Based Adsorbents

Abstract

The sludge-based adsorbents were obtained either from mixtures of sewage sludge, waste oil sludge, and metal sludge or single components by carbonization at 650 °C in an inert atmosphere. The materials were used as media to remove hydrogen sulfide at room temperature in the presence of moisture. The initial and exhausted adsorbents after the breakthrough tests were characterized using sorption of nitrogen, thermal analysis, XRD, ICP, and surface pH measurements. Although on all materials hydrogen sulfide is oxidized to elemental sulfur, exceptionally good performance is obtained on the waste oil sludge-based adsorbent. This is attributed to the combined effects of surface chemistry and porosity. High pore volume of the waste oil sludge-based adsorbent provides space to store 30 wt % elemental sulfur formed when hydrogen sulfide undergoes oxidation on the surface. Mixing sludges and carbonization of their mixtures result in adsorbents whose capacity, although smaller than that for the single-component waste oil sludge-based adsorbent, is high compared to that of conventional activated carbons. Moreover, when additional chemical heterogeneity is provided, the structural and chemical features of the mixed waste oil sludge/sewage sludge-based adsorbents are enhanced as a result of synergy between the individual components, which occurs during solid-state reactions.

Removal of copper on composite sewage sludge/industrial sludge-based adsorbents: The role of surface chemistry

“…The difference in the performance is likely related to differences in the surface chemistry of sludge-derived adsorbents. As indicated elsewhere, the samples pyrolyzed at 650 • C do not have a high degree of mineralization and the predominant crystalline phase found there is aluminosilicates with exchangeable cations, mainly calcium, magnesium, and sodium [24,25]. This can affect the mechanism of adsorption, which is discussed further in this paper.…”

“…The initial materials are very basic, with pH between 9 and 11 (Table 3), owing to the presence of alkali earth metal oxides, which in spite of their limited solubility shift the pH of the materials to the basic range [24,25]. After copper ion adsorption, the pH values either of the filtrates or of the samples (measured again after adsorption and drying, as described in Section 2) decreased, which indicates the removal of basic species (cations) via cation-exchange reactions.…”

“…The efficient method of their industrial "recycling" and thus waste minimization is via pyrolysis, in which adsorbents are produced. It was recently demonstrated that such adsorbents can effectively remove dyes [13,19,20], heavy metals [13][14][15], phenols [13], or hydrogen sulfide [21][22][23][24][25][26][27]. Their high removal capacity is a result of complexity of surface chemistry, specific porosity, and high volume of mesopores.…”

“…That surface chemistry includes basic pH and presence of catalytic centers based on iron and other transition metals. These entities are formed as a result of solid state reactions during pyrolysis of complex inorganic/organic matrices [24,25,27]. Moreover, there is an indication that the pyrolysis conditions can be adjusted toward obtaining the most effective adsorbents for a desired application [28,29].…”

Uso de adsorvente à base de lodo biológico na remoção de sulfeto de hidrogênio de corrente gasosa

“…Outro tipo de material recentemente utilizado em trabalhos científicos como adsorvente ou material precursor na remoção de gases odorantes é o lodo de reatores de digestão (SEREDYCH et al, 2008;BANDOSZ, BLOCK, 2006), justificado seu uso pela fácil aquisição em estações de tratamento de efluentes, menor custo em relação a outros adsorventes e como forma de utilização da crescente quantidade de lodo que se acumula nessas estações (KANTE et al, 2008).…”