Methods and systems for the separation of isotopes from an aqueous stream are described as can be utilized in one embodiment to remove and recover tritium from contaminated water. Methods include counter-current flow of an aqueous stream on either side of a separation membrane. The separation membrane includes an isotope selective layer (e.g., graphene) and an ion conductive supporting layer (e.g., Nafion). An electronic driving force encourages passage of isotopes selectively across the membrane to enrich the flow in the isotopes.

The present disclosure relates to, inter alia, a modified surface comprising an optically active monomer, a polymeric material having a surface onto which the optically active monomer is covalently bound. In one aspect, a membrane comprising an optically active monomer, a poly(aryl sulfone) membrane having a surface onto which the optically active monomer is covalently bound. The present disclosure also relates to a method of modifying a surface, the method comprising applying sufficient energy to a surface to induce covalent bonding with an optically active monomer, and contacting the optically active monomer with the surface. In one aspect, a method of modifying a surface of a poly(aryl sulfone) membrane is disclosed. In another aspect, a method of synthesizing an optically active monomer is disclosed. In one aspect, a method of filtration of chiral compounds is disclosed.

Improved systems and processes for forward osmosis water purification or desalination are herein disclosed. According to one embodiment a process for purifying contaminated water is provided wherein a contaminated feed solution stream comprising water and with a first osmotic pressure is passed through a semipermeable membrane to a draw side having a draw solution stream with a second osmotic pressure on a draw side of the semipermeable membrane. The diluted draw solution stream is heated, agglomerated and cooled to produce a cooled single phase water rich stream that is purified to produce a water product stream.

Asymmetric membrane structures are provided that are suitable for various types of separations, such as separations by reverse osmosis. Methods for making an asymmetric membrane structure are also provided. The membrane structure can include at least one polymer layer. Pyrolysis can be used to convert the polymer layer to a porous carbon structure with a higher ratio of carbon to hydrogen.

Asymmetric membrane structures are provided that are suitable for various types of separations, such as separations by reverse osmosis. Methods for making an asymmetric membrane structure are also provided. The membrane structure can include at least one polymer layer. Pyrolysis can be used to convert the polymer layer to a porous carbon structure with a higher ratio of carbon to hydrogen.

Asymmetric membrane structures are provided that are suitable for hydrocarbon reverse osmosis of small hydrocarbons. Separation of para-xylene from ortho- and meta-xylene is an example of a separation that can be performed using hydrocarbon reverse osmosis. Hydrocarbon reverse osmosis separations can be incorporated into a para-xylene isomerization and recovery system in a variety of manners.

This disclosure presents a new device for the removal and separation of isotopes of Helium in Compressed Natural Gas, based on a system with two cascades operating together to increase, in the first cascade, the concentration of Helium in the cascade head, and at the tail of the same cascade, Helium-depleted Compressed Natural Gas is discharged, while the second cascade, fed from the head of the first cascade, allows separation of the isotopes of Helium-3 and Helium-4, discharging Helium-3 through the head of the second cascade, while Helium-4 is discharged through the tail of the second cascade, with a configuration that is efficient from the energy consumption standpoint, while using a small number of rotating parts.

Selective removal of non-aromatic hydrocarbons from a xylene isomerization process for para-xylene production is accomplished using a membrane unit positioned within a xylene recovery loop. The membrane unit may include a one-stage or multi-stage (e.g., two-stage) membrane system and may be configured to separate a membrane unit product stream from a non-aromatics rich stream, which can be removed from the xylene recovery loop. The membrane unit may have a xylene permeance of about 60 gm/m2/hr/psi and a xylene to non-aromatic permeance ratio of about 15.