Micro-interfacial mechanisms on sludge dewaterability enhancement using cerium chloride for preparation of carbon-based functional material

In this work, sludge conditioning efficiency of cerium chloride (CeCl3) in combination with organic polymers was evaluated, the floc microstructure and extracellular polymeric substances (EPS) properties under flocculation conditioning were analyzed. The interaction mechanisms between EPS and Ce(III) were systematically investigated through two-dimension correlation spectroscopy, X-ray photoelectron spectroscopy, and confocal laser scanning microscopy. In addition, the adsorption and catalytic abilities of Ce-sludge based carbon (SBC) in tetracycline (TC) removal were evaluated. The results showed that CeCl3 conditioning performed well in improving sludge dewaterability, and CeCl3 and cationic polyacrylamide showed a synergistic effect in sludge conditioning. Contents of EPS decreased as the dosage of CeCl3 increased because of charge neutralization and complexation reactions. 2D-UV-FTIR heterospectral correlation spectroscopy analysis suggested the reaction activity of EPS to Ce(III) followed the order of Mimic acid > protein > polysaccharide. The decrease of alpha-helix content improved the hydrophobicity of proteins in EPS, which was responsible for sludge dewaterability improvement in CeCl3 conditioning. Besides, the SBC was prepared with CeCl3 conditioned sludge for treating water containing TC. Ce-SBC had a dual function of adsorption and Fenton-like activity. This work provides a sludge recycling process that coupled chemical conditioning to pyrolysis carbonization to prepare functional carbon-based materials.