National Research Council of Canada

Other

Ashwani Kumar

Oleh Kutowy

Jamal Kurdi

Deepak Musale

Shi Qiu Zhang

Sandeep K Karode

In order to synthesize semi-interpenetrating polymer networks (semi-IPNs) with molecular sieve characteristics, polyetherimide/bismaleimide (PEI/BMI) chromophore composites were made through sol-gel technique. A tunable and compatible chemical structure with fine morphology was obtained through in situ controlled sol-gel polymerization, crosslinking, chemical modification and membrane fabrication. The novel semi-IPN, synthesized and assembled by using ethanol as polar protic modifier and pore former, had a superior structure and morphology suitable for making gas separation membranes. These semi-IPN membranes gave fifteen times higher gas flux without significant decrease in their gas permselectivity than membranes prepared from pure PEL The chemical structures of these novel semi-IPNs were characterized by using FTIR, XPS and SEM. It was discovered for the first time that in situ simultaneous ethoxylation, anionic polymerization of BMI and imide modifications were responsible for creating the new chemical structure and molecular morphology that was different from traditional BMI resins. In addition to the superior structure, this chemical processes have the advantages of using simple green chemistry, ambient temperature and does not require initiators for polymerization.

Highly microporous thermoplastic/bismaleimide semi-interpenetrating polymer network

The invention disclosed relates to feed spacers used in various filtration membrane modules, such as in spiral wound membranes, used in cross-flow filtration. Such spacers have an influence in promoting the mixing between the bulk of the fluid and the fluid element adjacent to the membrane surface so as to keep the membrane surface relatively clean. To optimize these properties, novel spacer designs are disclosed having a plurality of rows of elongated strands, the strands in each row being arranged substantially in parallel to one another, with adjacent rows being attached and disposed at an angle to one another, the strands of at least one row when viewed in cross-section having a central portion of a width smaller than the width of its extremities. Novel membrane modules incorporating such feed spacers are also disclosed.

Feed spacers for filtration membrane modules

The invention disclosed relates to a nanofiltration composite membrane that is solvent and pH stable and may be used to separate at least one dissolved or suspended component from a liquid phase, including (a) a substrate ultrafiltration membrane formed from an ethylenically unsaturated nitrile, such as acrylonitrile and substituted acrylonitrile polymers, and (b) a coating of a hydrophilic polymer containing reactive functional groups. Preferably, the reactive functional groups described in (b) are subjected to a post-coating cross-linking reaction with a substantially non-cytotoxic cross-linking agent such as bi-functional aldehydes. A method for the preparation of such composite membranes is also disclosed.

Composite solvent resistant nanofiltration membranes

The invention disclosed relates to a process for the extraction of sweet compounds from Stevia rebaudiana Bertoni, by column extraction, followed by purification by filtration. The extraction is at temperatures in the range of 0 to 25.degree. C. Preferably, a pre-treatment step of microfiltration is used to clarify the extract. Purification is by ultrafiltration followed by nanofiltration. The filtration conditions are controlled to optimize the recovery of the sweet compounds.

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Ottawa, Canada

Ashwani Kumar