Omniphobic surface modification of silica sand ceramic hollow fiber membrane for desalination via direct contact membrane distillation

Comparison of hollow fiber membranes in direct contact and air gap membrane distillation (MD)

Porous hydrophobic ceramic membranes have been increasingly applied in advanced membrane-based separation processes such as Direct Contact Membrane Distillation (DCMD) due to their higher chemical and mechanical resistances. The development of novel ceramic membranes enhanced with porosity is based on conventional techniques such as extrusion and tape casting, and unique processing such as dry–wet spinning and vacuum filtration. The relationships between shaping and surface hydrophobization related to the membrane structure, properties and performance of the ceramic membrane applied to DCMD are explained in this work. The manufacturing technique influences the membrane characteristics, and consequently the permeability in DCMD. Recent research is focused on manufacturing high porous hollow fibre ceramic membranes by dry–wet spinning. In contrast to the grafting of alkylsilanes, the chemical vapour deposition process has been applied as an effective surface modifying technique to enhance membrane hydrophobicity. Ceramic membranes are mostly applied to desalination in DCMD and have been little researched concerning the unique properties they can offer, such as superhydrophobicity and use in a harsh environment. In addition to the review of manufacturing techniques, polymer-derived ceramic (PDC) is proposed as a one-step ceramic membrane processing route for DCMD. Although only a handful of works addressed the use of PDC membranes applied to DCMD, the great potential of these materials is forecast.

Hydrophobic silica sand ceramic hollow fiber membrane for desalination via direct contact membrane distillation

Superhydrophobic modification of TiO2 nanocomposite PVDF membranes for applications in membrane distillation

Surface modification of glass fiber membranes by fluorographite coating for desalination of concentrated saline water with humic acid in direct-contact membrane distillation

Surface modification of nanostructured ceramic membranes for direct contact membrane distillation

A luminescent thermosensitive coating for a non-invasive and in-situ study of thermal polarization in hollow fiber membranes

Optimization of membrane modification using SiO2 for robust anti-fouling performance with calcium-humic acid feed in membrane distillation

Effect of applied pressure on performance of PTFE membrane in DCMD

Hybrid organic-inorganic functionalized polyethersulfone membrane for hyper-saline feed with humic acid in direct contact membrane distillation

Preparation and characterization of PPO/PS porous membrane for desalination via direct contact membrane distillation (DCMD)

Arsenite [As(iii)] and arsenate [As(v)] removal by direct contact membrane distillation (DCMD) using novel hydrophobic green, silica-based ceramic hollow fibre membranes derived from agricultural rice husk was investigated in this work. The green ceramic hollow fibre membranes were prepared from amorphous (ASHFM) and crystalline (CSHFM) silica-based rice husk ash and modified to be hydrophobic via immersion fluoroalkylsilane (FAS) grafting of 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Superhydrophobic contact angle values up to 157° and 161° were obtained for ASHFM and CSHFM, respectively. Remarkably, the membrane surface morphology mimicked a look-alike lotus-leaf structure with decrement in pore size after grafting via the silane agent for both membranes. The effect of arsenic pH (3–11), arsenic concentration (1–1000 ppm) and feed temperature (50–80 °C) were studied and it was found that feed temperature had a significant effect on the permeate flux. The hydrophobic CSHFM, with a flux of 50.4 kg m−2 h−1 for As(iii) and 51.3 kg m−2 h−1 for As(v), was found to be the best of the tested membranes. In fact, this membrane can reject arsenic to the maximum contaminant level (MCL) limit of 10 ppb under any conditions, and no swelling mechanism of the membranes was observed after testing for 4 hours.

Robust surface modified polyetherimide hollow fiber membrane for long-term desalination by membrane distillation

Direct contact membrane distillation (DCMD) has been conducted to treat hydraulic fracturing-produced water using polyvinylidenedifluoride (PVDF) membranes. Tailoring the surface properties of the membrane is critical in order to reduce the rate of adsorption of dissolved organic species as well as mineral salts. The PVDF membranes have been modified by grafting zwitterion and polyionic liquid-based polymer chains. In addition, surface oxidation of the PVDF membrane has been conducted using KMnO4 and NaOH. Surface modification conditions were chosen in order to minimize the decrease in contact angle. Thus, the membranes remain hydrophobic, essential for suppression of wetting. DCMD was conducted using the base PVDF membrane as well as modified membranes. In addition, DCMD was conducted on the base membrane using produced water (PW) that was pretreated by electrocoagulation to remove dissolved organic compounds. After DCMD all membranes were analyzed by scanning electron microscopy imaging as well as Energy-Dispersive X-Ray spectroscopy. Surface modification led to a greater volume of PW being treated by the membrane prior to drastic flux decline. The results indicate that tailoring the surface properties of the membrane enhances fouling resistance and could reduce pretreatment requirements.

β-Sialon ceramic hollow fiber membranes with high strength and low thermal conductivity for membrane distillation