Experimental study of hygroscopic equilibrium and thermodynamic properties of sewage sludge

Thermodynamic properties of sewage sludge were determined by using the hygroscopic equilibrium data at different temperatures, the net isosteric heat of sorption and entropy of sorption decreased considerably with the increase in equilibrium moisture content. The enthalpy-entropy compensation suggested that the sorption mechanism involved was enthalpy given. Gibbs free energy for adsorption and desorption are respectively 58.87 kJ/mol, and -445.21 kJ/mol, indicating two different processes.