Chlorination of polyvinyl pyrrolidone–polysulfone membranes: Organic compound release, byproduct formation, and changes in membrane properties

• Organic compound released from PVP–PSF membranes after chlorine contact.
• Some membrane properties changed after chlorine treatment even at low dosages.
• Some toxic byproducts formed during chlorination of PVP–PSF membranes.
• Sources of the precursors of the toxic byproducts were determined.

In this work, the release of organic compounds, the variations of membrane properties and the formation of toxic byproducts during chlorine treatment of polyvinyl pyrrolidone–polysulfone (PVP–PSF) membranes were investigated. Chlorine treatment decreased bovine serum albumin rejection, permeability and hydrophilicity of PVP–PSF membranes and resulted in the release of organic compounds as measured by total organic carbon (TOC). More organic compounds were released from the membranes at higher chlorine concentrations and higher initial values of chlorine contact pH. The presence of bromide that can be oxidized to bromine by chlorine also increased the release of organic matter from the membranes and contributed to the formation of high toxic brominated byproducts. Five toxic volatile chlorinated byproducts, chloroform, chloral hydrate, 1,1-dichloro-2-propanone, 1,1,1-trichloro-2-propanone and trichloronitromethane, were formed during chlorination of the organic compounds from the PVP–PSF membranes. Three brominated byproducts including bromodichloromethane, dibromochloromethane and bromoform were determined in the presence of bromide. The PVP appears to be more susceptible than PSF to chlorine destruction in the PVP–PSF membranes as analysis of the chlorinated byproducts derived from PVP precursors.

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