Mohammad Mahdi A Shirazi - Department of Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Dariush Bastani - Department of Chemical and Petroleum Engineering, Sharif University of Technology,Tehran, Iran.
Ali Kargari - Membrane Processes Research Laboratory (MPRL), Department of Petrochemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Mahshahr Campus, Mahshahr, Iran

Membrane distillation process (MDP) is an emerging and versatile membrane separation which is currently considered and used for various application i.e., desalination, foodprocessing, water and wastewater treatment, and removal of volatile organic compounds. It is an non-isothermal separationbased on the transport of volatile compound(s) (mostly water) in vapour phase through a microporous hydrophobic membrane, from the hot side (i.e. feed side) towards the coldside (i.e. permeate side) [1]. As most of applied membranes in MDP are those that commercially fabricated for microfiltration purposes,characterization of such membranes could provide the knowledge for better understanding their behaviour andperformance [2]. In this manner, atomic force microscopy (AFM) is a powerful tool for characterization of MDP membranes, which provide good knowledge of surfacemorphology and 3-D view of membranes’ topography without any further sample preparation which is necessary in othermicroscopic method i.e. scanning electron microscopy. Moreover, AFM provides a series of roughness parameters in nano-metric scale [3].In this work, three commercial hydrophobic membranes were characterized by use of AFM and used for MDP experiments via sweeping gas (SGMDP) configuration.