Water adsorption isotherms and thermodynamic properties of cassava bagasse

• Adsorption isotherms and composition of cassava bagasse were determined.
• GAB equation was the best-fitted model to sorption data of type II isotherm.
• Isosteric heat of sorption was calculated in a range of equilibrium moisture content.
• Differential enthalpy and entropy confirmed the isokinetic compensation theory.
• Water adsorption by cassava bagasse is considered an enthalpy driven process.

Losses of food industry are generally wet products that must be dried to posterior use and storage. In order to optimize drying processes, the study of isotherms and thermodynamic properties become essential to understand the water sorption mechanisms of cassava bagasse. For this, cassava bagasse was chemically analyzed and had its adsorption isotherms determined in the range of 293.15–353.15 K through the static gravimetric method. The models of GAB, Halsey, Henderson, Oswin and Peleg were fitted, and best adjustments were found for GAB model with R2 > 0.998 and no pattern distribution of residual plots. Isosteric heat of adsorption and thermodynamic parameters could be determined as a function of moisture content. Compensation theory was confirmed, with linear relationship between enthalpy and entropy and higher values of isokinetic temperature (TB = 395.62 K) than harmonic temperature. Water adsorption was considered driven by enthalpy, clarifying the mechanisms of water vapor sorption in cassava bagasse.