Synthesis of zeolite and gamma-alumina nanoparticles as ceramic membranes for desalination applications

Abstract

Development of ceramic membrane for desalination is gaining interest in order to provide fresh water for human's life. In this work, a ceramic membrane was developed by coating of porous geopolymer with nanoparticles of gamma alumina (γ-Al 2 O 3 ) (Al membrane), zeolite (Z membrane), and its combination (Al-Z membrane) which were synthesized through a sol-gel method. Nanoparticles of γ-Al 2 O 3 exhibit rod structures with 10-20 nm in diameter and 40-70 nm in length, a surface area of 326.26 m 2 /g, total pore volume of 0.10 cm 3 /g, and an average pore diameter of 2.10 nm. Zeolite nanoparticles were obtained from a composition of 6Na 2 O: 0.55Al 2 O 3 : SiO 2 : 150H 2 O having particle sizes in the range from 100 to 400 nm, a surface area of 97.32 m 2 /g, total pore volume of 0.80 cm 3 /g, and an average pore diameter of 11.19 nm. The performance of membranes was evaluated by measuring the salt rejection and the flux of NaCl 1% (w/v) solution that was passed through the membrane. The Z membrane demonstrated the highest salt rejection, up to 87.88%, whereas the Al-Z membrane reached 68%. The Al membrane exhibited the lowest salt rejection rate, amounted to 57.14%. The highest flux was obtained using Al membrane, which was to 3.43 × 10 3 L/m 2 h on the 54.29% rejection value; whereas the Z membrane reached 3.28 × 10 3 L/m 2 h on the 87.88% salt rejection value, and the lowest flux of 2.91 × 10 3 L/m 2 h showed by the Al-Z membrane at the 62% salt rejection value. It is promising to use the synthesized γ-Al 2 O 3 and zeolite nanoparticles as alternative ceramic membrane materials to be applied in the desalination.