Adsorption of carbamazepine on sludge/fish waste derived adsorbents: Effect of surface chemistry and texture

•Adsorbents were produced from sewage sludge/fish waste by carbonization at 650/950 °C.•Adsorption capacity for carbamazepine was measured.•Surface chemistry (complexation and/or acid–base mechanisms) governed performance.•Adsorption mechanisms includes dispersive and specific interactions.

Sewage sludge, fish waste and their homogenized mixtures (90:10, 75:25, or 50:50) were carbonized at two temperatures (650 and 950 °C). The obtained materials were extensively characterized in terms of their chemistry and porosity, and tested as adsorbents of carbamazepine from an aqueous phase. The content of a carbon phase was between 26% and 45% and the main components of an inorganic phase were oxides and salts of such metals as Si, Ca, Al, and Fe. The materials were predominantly mesoporous, with pore sizes larger than 30 Å. The high carbonization temperature led to better performing materials. Moreover, for the composites a synergistic effect of the component mixture was observed. An addition of a small amount of the fish waste increased the content of the carbon phase. A high carbonization temperature improved the level of carbonization and thus resulted in the favorable dispersion of the polar inorganic phase. While the former increased the adsorption of carbamazepine in the small pores via dispersive interactions, the latter contributed to the specific adsorption in mesopores via complexation and/or acid–base interactions.

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