BIOMIMETIC PROTECTION FOR REVERSE OSMOSIS MEMBRANES AGAINST FREE CHLORINE

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Author:
Koninckx, Elsa J
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Manish Kumar, Thesis Supervisor
  • Andrew Zydney, Honors Advisor
Keywords:
  • Reverse osmosis
  • membranes
  • free chlorine
  • biomimetic
  • RO membrane
  • mrpx
  • methionine
  • surface modifications
Abstract:
Water availability is being threatened with growing demand and shrinking resources. Desalination using reverse osmosis (RO) membranes is one of the most promising ways of obtaining clean drinking water. However, a major challenge to the widespread use of reverse osmosis membranes is the growth and accumulation of organisms, known as biofoulants, on polyamide RO membranes. Biofouling grows to cover the surface of the membrane and is detrimental to the membrane’s water flux and lifetime. The easiest conventional way of removing these microorganisms is through the use of free chlorine (sodium hypochlorite, commonly known as bleach); however, this causes the polyamide membrane to degrade during chlorine exposure. This work demonstrates a bioinspired coating for RO membranes that protects against free chlorine. Two methods were investigated to protect the membrane: polyelectrolyte coatings containing methionine and methionine nanocrystals. The development of the procedure required successful attachment of the amino acid to the RO membrane surface, a reaction to sequester chlorine, and the regeneration of methionine at the surface. Ultimately, we show that the developed coatings protect the polyamide structure from degradation and are regenerable with a reducing agent. This work provides a potentially impactful solution to keep membrane desalination efficient by preventing biofilm growth.