A membrane is the intermediate phase that separates two phases,and a membrane that has a separation effect is called a separation membrane,also commonly referred to as a membrane.The selective separation of membranes can achieve the separation,concentration,and purification of different liquids or gases.Due to the absence of morphological changes,membrane separation technology has been widely applied in fields such as medicine,biology,food,energy,and water treatment.Common water treatment membranes include microfiltration membranes,ultrafiltration membranes,reverse osmosis membranes,and nanofiltration membranes.

Hollow fiber nanofiltration membrane is a type of nanofiltration membrane,abbreviated as NF,with a molecular weight between ultrafiltration and reverse osmosis.The size of solute particles removed is in the range of nanometers(nm),hence it is called"nanofiltration".The nanofiltration membrane separation process has no chemical reactions,requires no heating,no phase transition,does not damage biological activity,does not change flavor and aroma,and is widely used in the fields of food,medicine,and water treatment.Nanofiltration membranes are divided into hollow fiber nanofiltration membranes,roll type nanofiltration membranes,tubular nanofiltration membranes,and plate type nanofiltration membranes.

Hollow fiber nanofiltration membrane combines the advantages of nanofiltration membrane and hollow fiber membrane.It has a self-supporting structure-a hollow capillary tube shape,with many micropores densely distributed on the tube wall.It is composed of inner and outer layers and a middle finger shaped support layer,and has the functions of cell like membrane biological transport,selective permeability,and adsorption.Hollow nanofiltration membrane with a pore size range of 1-10nm is selected,which can remove bacteria,viruses,drug residues,environmental hormones,and other pollutants from water Toxic and harmful substances such as heavy metal hydrated ions retain beneficial minerals in water,and have excellent properties such as resistance to biological corrosion,acid and alkali corrosion,chlorine and pressure resistance,as well as excellent anti pollution performance and large water flux.

Separation principle of hollow fiber nanofiltration membrane

The nanofiltration process can usually be understood as a screening process related to the pore size of the membrane,driven by the pressure difference on both sides of the membrane and using the nanofiltration membrane as the filtering medium.Under a certain pressure,when the original solution flows through the membrane surface,many small micropores densely distributed on the surface of the nanofiltration membrane only allow water and small molecular substances to pass through the membrane and become the permeate.Large molecular substances with a volume larger than the micropores on the membrane surface are intercepted in the original solution,becoming a concentrated solution,thereby achieving the purpose of purifying,separating,and concentrating the original solution.

The characteristics of hollow fiber nanofiltration membranes

The most direct manifestation is high effluent flux,low total organic carbon,low turbidity,high total desalination rate,and certain discrimination in the removal of high and low valence ions.Under low pressure,it has a high flux,a high degree of selective separation for monovalent and multivalent ions,and a low wastewater rate,fully responding to the national call for water conservation.At the same time,the actual energy consumption and cost during operation are much lower than those of reverse osmosis membranes and roll up nanofiltration membranes.