Synthesis and characterization of MCM-41-ceramic composite membrane for the separation of chromic acid from aqueous solution

• MCM-41-ceramic composite membrane was prepared by hydrothermal method.
• Porosity and pore size of the membrane reduced with repeated cycle of coating.
• Solvent permeation through the membrane was governed by chemical nature of liquids.
• Membrane displayed 80% rejection of Cr (VI) with permeate flux of 1.1007×10−5 m/s.

This work addresses the fabrication and characterization of MCM-41-ceramic composite membrane on a porous circular shaped support by hydrothermal synthesis method. A facile uni-axial compaction method was employed for the preparation of ceramic support and sintered at 950 °C. The properties of MCM-41-ceramic composite membrane and MCM-41 powder were characterized by X-ray diffraction (XRD), porosity, thermogravimetric analysis (TGA), nitrogen adsorption–desorption isotherm (BET), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and zeta potential measurement. The average pore size of support and MCM-41-ceramic composite membrane are estimated to be 1.0 and 0.173 µm, respectively. The porosity of the ceramic support decreases from 47% to 23% by repeated cycle of coating (three times) with MCM-41 on the support. The obtained MCM-41 powder possesses high surface area (1305 m2/g) and pore volume (0.7472 cm3/g). Solvent permeation studies through the MCM-41-ceramic composite membrane reveals that non polar solvents are more permeable in comparison with polar solvents and the chemical nature of liquids are the main controlling factor for the transport of solvents. Further, the fabricated MCM-41-ceramic composite membrane was subjected to investigate the potential for the separation of Cr (VI) from aqueous solution. The influence of various parameters such as applied pressure, feed concentration and pH of the solution on the rejection of Cr (VI) was examined. The rejection and the flux behavior of Cr (VI) are found to be mainly dependent on the electrostatic interaction with charged molecules and the MCM-41-ceramic composite membrane. The permeate flux increases with an increase of applied pressure and follows Darcy׳s law. The highest rejection of 80% is observed at acidic pH (pH=2) for the feed concentration of 1000 ppm with an applied pressure of 207 kPa.