Bio-char derived from sewage sludge by liquefaction: Characterization and application for dye adsorption

Bio-chars produced by liquefaction of sewage sludge with methanol, ethanol, or acetone as the solvent at 260-380 degrees C were characterized in terms of their elemental composition, thermogravimetric characteristics, surface area and pore size distribution, and oxygen-containing functional groups composition. The surface area and total volume of the bio-chars were low, but the contents of oxygen-containing functional groups were high. The bio-chars were effective on Malachite green (MG) and Methylene blue (MB) removal from aqueous solution. The MG adsorption equilibrium data showed excellent fit to the Langmuir model and the kinetic data fitted well to the Pseudo-second-order model. Thermodynamic investigations indicated that MG adsorption on bio-char was spontaneous and endothermic. The MG adsorption mechanism appears to be associated with cation release and functional group participation. Additionally, liquefaction of SS with acetone as the solvent at low temperature (280 degrees C) would favor the production of bio-char adsorbent in terms of bio-char yield and MG and MB adsorption capacity. (C) 2015 Elsevier B.V. All rights reserved.