Composite mixed matrix membranes for membrane distillation and related methods of manufacture

A membrane distillation system comprising:

• a composite mixed matrix membrane which is a flat-sheet composite mixed matrix hydrophilic/hydrophobic membrane having at least a hydrophilic layer and a hydrophobic layer, wherein
• the composite mixed matrix membrane comprises pores that extend entirely through the hydrophobic layer,
• the composite mixed matrix membrane is configured so that vapor transport through the pores takes place predominantly via Knudsen type of flow,
• the hydrophobic layer being configured permeability to water vapor and impermeability to liquid water,
• the hydrophilic layer comprises a hydrophilic polymer and inorganic nano-particles of high thermal conductivity selected from the group consisting of copper oxide, boron nitride, aluminum nitride, aluminum, iron, and silicon carbide,
• the hydrophobic layer comprises a fluorinated surface-modifying macromolecule (SMM),
• the composite mixed matrix membrane is obtained by a phase inversion process that includes (i) dispersing the inorganic nano-particles in a solution comprising the hydrophilic polymer, a non-solvent additive, the SMM, and a solvent to form a polymer-inorganic dispersion, (ii) casting the polymer-inorganic dispersion in a form of a flat sheet having a first main surface and a second main surface, and (iii) allowing or causing the SMM to migrate toward the first main surface and the inorganic nano-particles to migrate toward the second main surface,
• a content of the inorganic nano-particles in the polymer-inorganic dispersion is from 1 wt % to 5 wt % when a total weight of the polymer-inorganic dispersion is considered to be 100 wt %,
• the hydrophilic polymer is selected from the group consisting of polysulfone, polyethersulfone, polyetherimide, and cellulose acetate,
• the composite mixed matrix membrane is configured to have a vapor permeate flux of at least 0.35×10−6 m/s for distilled water solution at a mean temperature of 25° C. when copper oxide is the inorganic nanoparticle,
• the composite mixed matrix membrane is configured to have a vapor permeate flux of at least 0.35×10−6 m/s for distilled water solution at a mean temperature of 25° C. when boron nitride is the inorganic nanoparticle,
• the composite mixed membrane is configured to have a vapor permeate flux of at least 0.35×10−6 m/s for distilled water solution at a bulk solution feed temperature of 40° C. when iron is the inorganic nanoparticle,
• the composite mixed matrix membrane is configured to have a vapor permeate flux of at least 0.35×10−6 m/s for distilled water solution at a bulk solution feed temperature of 40° C. when Aluminum is the inorganic nanoparticle, and
• the composite mixed matrix membrane is configured to have a vapor permeate flux of at least 0.35×10−6 m/s for distilled water solution at a bulk solution feed temperature of 40° C. when silicon carbide is the inorganic nanoparticle.