To investigate the aging characteristics of the ultrafiltration membrane used in water treatment

the polyvinylidenefluoride (PVDF) ultrafiltration membrane was aged with sodium hydroxide (NaOH)

sodium carbonate(Na2CO3)

sodium hypochlorite (NaClO)

hydrochloric acid (HCl) and citric acid (H3Cit)

respectively. The effect of low-concentration cleaning agents on the aging of the PVDF membrane was investigated

with the analyzing of the parameters of pure water flux

total organic carbon (TOC) rejection

tensile strength

field emission scanning electron microscopy (FESEM)

contact angle and fourier transform infrared (FTIR). Experimental result shows that acid

alkali and oxidant

especially NaOH and NaClO

changed the structure and performance of the PVDF ultrafiltration membrane. After exposed to NaOH

Na2CO3 and NaClO for 75 days

the total organic carbon (TOC) rejection efficiencies decrease from 36% to 15%

27% and 17%

respectively. Compared to the virgin membrane

the tensile strength and ultimate elongation of the membrane which aged 15 days with NaOH declines by 11% and 20%

respectively. The negative effect of alkali and oxidant on mechanical performance and TOC rejection was higher than that of HCl and H3Cit

and the decreasing of hydrophilicity of the membrane exposed to NaClO is more significant than that of the other cleaning agents. The dehydrofluorination

which can generate of C＝C and C＝O bond

is one of the most important reasons that caused the ageing of PVDF membrane.