Preparation method of lasting hydrophilization modified polyvinylidene fluoride (PVDF) ultrafiltration membrane

Abstract

The invention discloses a preparation method of a lasting hydrophilization modified polyvinylidene fluoride (PVDF) ultrafiltration membrane. The preparation method of the lasting hydrophilization modified PVDF ultrafiltration membrane comprises the following steps: 1) preparing a film casting solution; 2) preparing a crosslinked blend membrane. After liquid phase blending modification is carried out on PVDF and an organic hydrophilic macromolecule PVA (polyvinyl alcohol), further anhydrous ferric chloride is added into the film casting solution, and PVA is fixed through a complexing reaction carried out on a hydroxyl on a molecular chain of the PVA and Fe<3+>, so that lasting hydrophilic modification of a membrane is realized, and water permeability stability is improved while a membrane structure is optimized; after modification, performances of the membrane are shown as follows: a contact angle is reduced by 30-40 degrees, flux is increased by 1-3 times compared with the flux before modification, and strength is increased by 1-1.5MPa; the anti-pollution capacity of the membrane is shown as follows: after filtering is carried out for 2 hours, the recovery rate of the flux of the membrane is increased by 10-20%, and the attenuation rate of the flux of the membrane is reduced by 5-10%.

Description

technical field [0001] The invention relates to a preparation method, in particular to a preparation method of a persistently hydrophilized modified polyvinylidene fluoride ultrafiltration membrane. Background technique [0002] China's per capita fresh water resources are only 2300m 3 , is one of the 13 countries with the poorest per capita water resources in the world. Under the severe situation of increasing depletion of water resources and environmental pollution, the recycling of urban sewage will become a very important link to promote the sustainable development and utilization of urban water resources. [0003] Polyvinylidene fluoride (PVDF) ultrafiltration membranes are widely used in urban sewage treatment due to their excellent mechanical properties, chemical stability and thermal stability. However, membrane fouling caused by strong hydrophobicity limits its promotion. Studies have reported that regardless of the nature of the organic matter, the adsorption rat...

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Problems solved by technology

[0004] 2. Research status of existing technologies at home and abroad

However, many studies have shown that in PVDF / PVA blended composite membranes, since PVA is a polymer with a large number of strong hydrophilic hydroxyl groups, the stability of the formed membrane is poor, and it is easy to swell or even dissolve, destroying the structure of the membrane. , reducing the selective separation of the membrane, resulting in rapid attenuation of the flux when the membrane is used to filter secondary water treatment, and the anti-pollution effect is not ideal, so it is necessary to modify the PVDF / PVA blend membrane

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