Cross flow ultrafiltration of Cr (VI) using MCM-41, MCM-48 and Faujasite (FAU) zeolite-ceramic composite membranes

• MCM-41, MCM-48 and FAU zeolite membranes prepared by hydrothermal method.
• In cross flow, permeate flux decline trend is not seen for three zeolite membranes.
• 82, 77 and 75% rejection observed with FAU, MCM-48 and MCM-41 zeolite membranes.
• FAU zeolite displayed better performance and cost effective than other membranes.

This work describes the removal of Cr (VI) from aqueous solution in cross flow mode using MCM-41, MCM-48 and FAU zeolite membranes prepared on circular shaped porous ceramic support. Ceramic support was manufactured using locally available clay materials via a facile uni-axial compaction method followed by sintering process. A hydrothermal technique was employed for the deposition of zeolites on the ceramic support. The porosity of ceramic support (47%) is reduced by the formation of MCM-41 (23%), MCM-48 (22%) and FAU (33%) zeolite layers. The pore size of the MCM-41, MCM-48 and FAU membrane is found to be 0.173, 0.142, and 0.153 μm, respectively, which is lower than that of the support (1.0 μm). Cross flow ultrafiltration experiments of Cr (VI) were conducted at five different applied pressures (69–345 kPa) and three cross flow rates (1.11 × 10−7 – 2.22 × 10−7 m3/s). The filtration studies inferred that the performance of the fabricated zeolite composite membranes is optimum at the maximum applied pressure (345 kPa) and the highest rejection is obtained with the lowest cross flow rate (1.11 × 10−7 m3/s) for all three zeolite membrane. The permeate flux of MCM-41, MCM-48 and FAU zeolite composite membranes are almost remained constant in the entire duration of the separation process. The highest removal of 82% is shown by FAU membrane, while MCM-41 and MCM-48 display 75% and 77% of Cr (VI) removal, respectively for the initial feed concentration of 1000 ppm with natural pH of the solution at an applied pressure of 345 kPa.

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