Preparation of a polyvinylidene fluoride membrane material probe and its application in membrane fouling research

• The use of a self-assembly device allowed the preparation of colloidal probes.
• PVDF membrane material and foulant-coated colloidal probes were prepared.
• The membrane–foulant and foulant–foulant interaction forces were measured.
• The PVDF membrane fouling behavior was predicted using the force measurements.

To improve the understanding and elucidate the fouling behavior of a polyvinylidene fluoride (PVDF) membrane, a PVDF membrane material probe was fabricated by sintering PVDF microspheres onto the free end of a cantilever with the aid of self-assembly devices. Foulant-coated colloidal probes were prepared by adsorbing foulants onto the surface of the PVDF microspheres that had been sintered onto the cantilever. Mixtures of the most widespread foulants of SA, HA and HA/SA were used as model organic foulants. The intermolecular forces between the membrane and the foulant and among the foulants themselves were investigated by atomic force microscopy (AFM) in conjunction with the PVDF probe and foulant-coated probe, respectively. Corresponding membrane fouling experiments were also performed to confirm the applicability of the probes made by the methods described above. The results indicate that there is a close relationship between the intermolecular adhesion forces (foulant–membrane and foulant–foulant) and the flux reduction rate and extent in the fouling filtration stage. The PVDF–foulant and foulant–foulant interaction forces measured by AFM in conjunction with the PVDF probe and the foulant-coated probe, respectively, are an effective means to provide useful information for the technology choice of membrane modification, feed water pretreatment and membrane cleaning.

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