Adsorption of 1,1-dimethylhydrazine (UDMH) from aqueous solution using magnetic carbon nanocomposite: kinetic and thermodynamic study

Abstract

In this work, removal of UDMH as a pollutant with considerable toxicity is studied using activated carbon magnetic nanocomposite with fast and easy separation. To optimize the process, effective parameters, such as pH, adsorbent dosage, contact time, and temperature, have been investigated. More than 90% UDMH removal efficiency obtained within 30 min of contact time, 20 mg of adsorbent at pH 6 and room temperature. The adsorption behavior was evaluated based on equilibrium data, using both the Langmuir and Freundlich isotherm models. It was found that adsorption data were interpreted by Freundlich model better than Langmuir model with regression coefficient of 0.9971. Besides, the adsorption data were well described by the pseudo-second-order kinetic model. The adsorption thermodynamic parameters showed that the adsorption process is endothermic and spontaneous with positive standard enthalpy of 2.74 J mol⁻¹ and negative standard free energy of 29.08 kJ mol⁻¹, respectively. Also standard entropy changes of 97.56 J mol⁻¹ k⁻¹ was calculated.

Keywords:

• 1,1-Dimethylhydrazine
• Magnetic carbon nanocomposite
• Adsorption isotherms
• Kinetics
• Thermodynamics