Functional chitosan scaffold with surface charge tunability as filtering medium
AssigneeNano and Advanced Materials Institute Limited
InventorsKa Wai WONG, Ching Yee Novem LAM, Mui Kimmy CHAN
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Abstract
The present invention discloses a method of preparing a functional chitosan scaffold and said functional chitosan scaffold for use as a filtering medium. Said method involves freeze-drying chitosan in the presence of appropriate cross-linkers and additives. The present chitosan scaffold is associated with an increased mechanical strength and elasticity and an adjustable surface polarity, porosity and morphology which enable its use in a wide range of devices, equipments and appliances in need of a filtering medium such as air or water purification system.
Claims19
A method of preparing a functional chitosan scaffold for a filtering medium comprises
- dissolving chitosan or derivatives thereof in a solution of one or more carboxylic acids to form a chitosan solution, wherein said one or more carboxylic acids act as a solvent and a cross-linking agent to dissolve and cross-link said chitosan or derivatives thereof;
- freeze-drying said chitosan solution, wherein said freeze-drying comprises freezing said chitosan solution at a first temperature under a first pressure and drying said solution under a second temperature and pressure, said second temperature is higher than said first temperature and said second pressure is lower than said first pressure such that the solution of one or more carboxylic acids directly sublime from solid phase into gas phase, and
- wherein surface charge and charge density of the functional chitosan scaffold is selectively adjusted according to a selected ratio of different carboxylic acids in said solution of one or more carboxylic acids such that the resulting surface charge is positive, negative or neutral.
A filtering medium suitable for filtering matter in a gaseous or a liquid state comprising a functional chitosan scaffold that has been freeze-dried in a solution of one or more carboxylic acids that act as a solvent and a cross-linking agent to dissolve and cross-link chitosan or derivatives thereof into said functional chitosan scaffold, wherein surface charge and charge density of said functional chitosan scaffold is selectively adjusted according to a ratio of different carboxylic acids in said solution of one or more carboxylic acids such that the resulting surface charge is neutral, positive or negative.
Dependencies are inferred from the claim text.