Displaying all 2 publications

  1. Mohd Ramli MR, Ahmad AL, Leo CP
    ACS Omega, 2021 Feb 23;6(7):4609-4618.
    PMID: 33644568 DOI: 10.1021/acsomega.0c05107
    Membrane distillation (MD) is an attractive technology for the separation of highly saline water used with a polytetrafluoroethylene (PTFE) hollow fiber (HF) membrane. A hydrophobic coating of low-density polyethylene (LDPE) coats the outer surface of the PTFE membrane to resolve membrane wetting as well as increase membrane permeability flux and salt rejection, a critical problem regarding the MD process. LDPE concentrations in coating solution have been studied and optimized. Consequently, the LDPE layer altered membrane morphology by forming a fine nanostructure on the membrane surface that created a hydrophobic layer, a high roughness of membrane, and a uniform LDPE network. The membrane coated with different concentrations of LDPE exhibited high water contact angles of 135.14 ± 0.24 and 138.08 ± 0.01° for membranes M-3 and M-4, respectively, compared to the pristine membrane. In addition, the liquid entry pressure values of LDPE-incorporated PTFE HF membranes (M-1 to M-5) were higher than that of the uncoated membrane (M-0) with a small decrease in the percentage of porosity. The M-3 and M-4 membranes demonstrated higher flux values of 4.12 and 3.3 L m-2 h-1 at 70 °C, respectively. On the other hand, the water permeation flux of 1.95 L m-2 h-1 for M-5 further decreased when LDPE concentration is increased.
  2. Mohd Ramli MR, Ahmad AL, Oluwasola EI, Leo CP
    ACS Omega, 2021 Oct 05;6(39):25201-25210.
    PMID: 34632179 DOI: 10.1021/acsomega.1c02887
    Membrane distillation (MD) is a thermal technology for the desalination process that requires a hydrophobic microporous membrane to ensure that the membrane can maintain the liquid-vapor interface. This work aims to enhance the water permeation flux of the previously coated membrane by modifying the surface of the polytetrafluoroethylene hollow fiber (PTFE HF) membrane with a selected non-solvent such as acetone, cyclohexanone, and ethanol in low-density polyethylene as a polymeric coating solution. However, the modification using acetone and cyclohexanone solvents was unsuccessful because a reduction in membrane hydrophobicity was observed. The modified PTFE HF membrane with ethanol content exhibits high wetting resistance with a high water contact angle, which can withstand pore wetting during the direct contact MD process. Since MD operates under a lower operating temperature range (50-90 °C) compared to the conventional distillation, we herein demonstrated that higher flux could be obtained at 7.26 L m-2 h-1. Thus, the process is economically feasible because of lower energy consumption. Performance evaluation of the modified PTFE HF membrane showed a high rejection of 99.69% for sodium chloride (NaCl), indicating that the coated membrane preferentially allowed only water vapor to pass through.
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