Polymer deposition and modification of membranes for fouling resistance

Abstract

The present invention describes methods and compositions for the reduction, prevention and elimination of biofilm formation on a surface. The present invention provides a method of depositing a coating material to reduce or prevent biofilm formation on a surface by adding a dopamine coating material to a liquid solvent to form a solution mixture, adjusting a pH of the solution mixture to 8, 9, or 10 and dissolving the dopamine coating material in the liquid solvent. The solution mixture is then placed into contact with one or more surfaces to form a dopamine coating on the surface to reduce biofilm formation.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is related to U.S. Provisional Application Ser. No. 61 / 079,608, filed Jul. 10, 2008, the contents of each of which are incorporated by reference herein in their entireties.STATEMENT OF FEDERALLY FUNDED RESEARCH[0002]This invention was made with U.S. Government support under National Science Foundation Agreement numbers DMR-0423914 and 0650277. The government has certain rights in this invention.TECHNICAL FIELD OF THE INVENTION[0003]The present invention relates in general to the field of membranes for water purification, and more particularly to the deposition of polymers and modification of membrane surfaces to reduce biofilm formation on membranes.INCORPORATION-BY-REFERENCE OF MATERIALS FILED ON COMPACT DISC[0004]None.BACKGROUND OF THE INVENTION[0005]Without limiting the scope of the invention, its background is described in connection with the use of hydrophilic polymers to coat and modify membrane surfaces to reduce m...

AI Technical Summary

Benefits of technology

[0012]The present invention provides methods and compositions to alleviate fouling, scaling, and / or biofilm formation (i.e., biofouling) of conventional polymeric membranes using a novel polymer deposition. The present invention provides a highly hydrophilic polymer, polydopamine, which can be deposited with strong adhesion onto virtually any surface. In addition, the present invention provides a substrate for the attachment (covalently and / or non-covalently) of molecules to provide specific membrane surface chemistries and properties. The present invention also provides a highly hydrophilic polymer that can further react with metal ions to form metallic particles on the membrane surface via an electroless metallization mechanism.

[0013]The present invention provides methods and compositions to alleviate biofilm formation on membranes using hydrophilic molecule attachment (such as poly(ethylene glycol)); attachment of metal ions (e.g., silver / copper) to polydopamine; and attachment of other molecules to the membrane surface (e.g., furanones can reduce bacterial proliferation on surfaces). The present invention also provides methods and compositions to alleviate fouling and / or scaling by tuning pertinent membrane surface properties through the attachment of long chain polymers (e.g., poly(ethylene glycol) (PEG) and other hydrophilic or hydrophobic polymers) to the polydopamine deposition layer.

[0014]The polydopamine of the present invention increases the membrane resistance to biofilm formation, fouling and / or scaling, which, in turn, results in higher membrane fluxes. Furthermore, the present invention may be tailored to specific properties through the addition of compositions from a library of possible compounds available to covalently attach to the polydopamine layer, making it an extremely versatile modification.

[0015]The present invention also provides a method for treating and / or coating existing surfaces or membrane support through non-specific adhesion of polydopamine to any surface, therefore allowing modification of all wetted parts of a membrane module or membrane treatment system. Another advantage of the polydopamine deposition of the present invention is its ease of applicability to membrane modules and other wetted parts of membrane treatment systems, even in large-scale applications. In addition, all the wetted module parts that are susceptible to fouling can be modified by the present invention. Furthermore, polydopamine is applicable to practically any membrane, regardless of membrane material, whereas most surface modification techniques have only been accomplished using one specific membrane. Polydopamine can also react with many different conjugated molecules, which allows membrane surface properties to be further tuned to specific applications.

[0018]The present invention provides a method of depositing a coating material to reduce or prevent fouling, scaling, and / or biofilm formation on a surface by adding a dopamine coating material to a liquid solvent to form a solution mixture, adjusting the pH of the solution mixture to an alkaline pH (e.g., 8, 9, or 10) and dissolving the dopamine coating material in the liquid solvent. The solution mixture is then placed into contact with one or more surfaces to form a dopamine coating on the surface to reduce fouling, scaling, or biofilm formation.

[0020]The present invention includes a liquid separation apparatus having reduced fouling, scaling, and / or biofilm formation including a purification membrane and a polydopamine layer deposited on the purification membrane to form a polydopamine coated membrane to reduce fouling, scaling, and / or biofilm formation, wherein the polydopamine layer increases the hydrophilicity of the purification membrane and the polydopamine coated membrane has high water flux. One or more containers are positioned on different sides of the polydopamine coated membrane to contain the separated liquid.

Problems solved by technology

One of the major problems with membrane water purification is fouling of the membrane.

Generally, fouling occurs when impurities in water deposit on the surface of the membrane and is also seen when the internal pore structure of the membrane is obstructed.

Biofilms are remarkably difficult to treat with antimicrobials.

The growth conditions are quite different, particularly in the depths of biofilms, where nutrients and oxygen are usually limited, and waste products from neighbors can be toxic.

Another major problem with membrane water purification is scaling of the membrane.

The deposition of these contaminants can lead to a dramatic reduction in water flux, which increases operating costs and decreases membrane lifetime.

Many of these techniques are not applicable to multiple types of water purification membranes and many require commercially unviable treatment steps, such as plasma treatment.

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