| Summary: | Providing pretreatment prior RO filtration is essential to avoid biofouling and
subsequent loss of membrane performances. Chlorine is known to degrade polymeric
membrane, improving or reducing membrane efficiency depending on oxidation
conditions. This study aimed to assess the impact of alternative disinfectant, NH2Cl,
as well as secondary oxidants formed during chloramination of seawater, e.g. HOBr,
HOI, or used in water treatment e.g. ClO2, O3, on membrane structure and
performances. Permeability, total and specific rejection (Cl-, SO4
2-, Br-, Boron), FTIR
profile, elemental composition were analyzed. Results showed that each oxidant
seems to react differently with the membrane. HOCl, HOBr, ClO2 and O3 improved
membrane permeability but decreased rejection in different extent. In comparison,
chloramines resulted in identical trends but oxidized membrane very slowly. On the
contrary, iodine improved membrane rejection e.g. boron, but decreased permeability.
Reaction conducted with chlorine, bromine, iodine and chloramines resulted in the
incorporation of halogen in the membrane structure. All oxidant except iodine were
able to break amide bonds of the membrane structure in our condition. In addition,
chloramine seemed to react with membrane differently, involving a potential addition
of nitrogen. Chloramination of seawater amplified membrane performances evolutions
due to generation of bromochloramine. Moreover, chloramines reacted both with
NOM and membrane during oxidation in natural seawater, leading to additional
rejection drop.
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