Characterization and Performance Evaluation of PVA Nanofiltration Membrane Coupled with TiO2 Nanoparticles

 

Abstract:

A novel PVA/TiO₂ composite polymer membrane was prepared by dip-coating of polysulfone(PS) UF membrane in an aqueous solution. Glutaraldehyde (GA) was used as a cross-linker for the composite polymer membrane in order to enhance the chemical, thermal and mechanical stabilities. The morphological study was investigated by atomic force microscopy (AFM).

 Key words: nanofiltration, PVA, TiO₂ polysulfone

Introduction:

Polysulfone (PS) is one of the most extensively applied ultrafiltration (UF) membrane materials in industry area.But its hydrophobic nature is also well known, which results in the adsorption and deposition of hydrophobic solute on the membrane surface [2,3]. Titanium dioxide (TiO₂) has been the focus of numerous investigations for innocuity , resisting and decomposing bacterias, UV-proof and super hydrophilicity in recent years. Therefore, it has been applied to a variety of problems of environmental interest in addition to water and air purification [4]. In this work, we attempted to disperse the nano-sized TiO₂ particles on the surface of the PVA-coated polysulfone membrane in a reason of enhancing chemical, thermal and mechanical stabilities of the membrane.

2.Experimental:

PVA(1.5 wt%) dissolved in distillated water, was coated on PES barrier layer with dip coating technique. Therefore, GA(5%wt) was crosslinked on the surface of membrane with so called method. TiO₂ nanoparticles were  dispersed in distillated water by sonication  for 1hr and then stirred vigorously for 30 min .finally the result membrane was immersed immediately in TiO2 resultant bath. the composition of prepared membranes is shown in Table.1.

3.Results and Discussion:

Table 1.Compositions of prepared membrane

Fig.1. Three-dimensional AFM surface image of the PVA/TiO2 (0.2% wt) membrane

Since TiO2 has high affinity to water, the membrane performance of solute transport can be improved. The association between PVA and TiO2 also changed the surface potential of PVA. The obtained results clearly reveal that the antifouling property of TiO2-entrapped membrane is significantly improved .TiO2 nanoparticles plug membrane pores at high concentration .thus, the concentration of TiO2 should be optimized. according to flux and salt retention, the membrane containing 0.2%wt  TiO2 nanoparticles had the best performance between so called membranes. In fact, the increment in TiO2 concentration has apparent influence on membrane behavior.but rising to 0.5%wt TiO2, does not significantly affect the membrane yield. Fig. 1 is the three dimensional AFM surface imageof the optimal PVA/TiO2 composite membrane (0.2%wt TiO₂). All roughness parameters of optimal membrane are shown in Table.2.as it can be seen, TiO2 nanoparticles are well-coated on the membrane surface and  

                                                                                                                                                      

Table 2.Surface parameters of the PVA/TiO2 (0.2 %wt) membrane

 

 

Abstract:

A novel PVA/TiO₂ composite polymer membrane was prepared by dip-coating of polysulfone(PS) UF membrane in an aqueous solution. Glutaraldehyde (GA) was used as a cross-linker for the composite polymer membrane in order to enhance the chemical, thermal and mechanical stabilities. The morphological study was investigated by atomic force microscopy (AFM).

 Key words: nanofiltration, PVA, TiO₂ polysulfone

Introduction:

Polysulfone (PS) is one of the most extensively applied ultrafiltration (UF) membrane materials in industry area.But its hydrophobic nature is also well known, which results in the adsorption and deposition of hydrophobic solute on the membrane surface [2,3]. Titanium dioxide (TiO₂) has been the focus of numerous investigations for innocuity , resisting and decomposing bacterias, UV-proof and super hydrophilicity in recent years. Therefore, it has been applied to a variety of problems of environmental interest in addition to water and air purification [4]. In this work, we attempted to disperse the nano-sized TiO₂ particles on the surface of the PVA-coated polysulfone membrane in a reason of enhancing chemical, thermal and mechanical stabilities of the membrane.

2.Experimental:

PVA(1.5 wt%) dissolved in distillated water, was coated on PES barrier layer with dip coating technique. Therefore, GA(5%wt) was crosslinked on the surface of membrane with so called method. TiO₂nanoparticles were  dispersed in distillated water by sonication  for 1hr and then stirred vigorously for 30 min .finally the result membrane was immersed immediately in TiO2 resultant bath. the composition of prepared membranes is shown in Table.1.

3.Results and Discussion:

Table 1.Compositions of prepared membrane

Fig.1. Three-dimensional AFM surface image of the PVA/TiO2 (0.2% wt) membrane

Since TiO2 has high affinity to water, the membrane performance of solute transport can be improved. The association between PVA and TiO2 also changed the surface potential of PVA. The obtained results clearly reveal that the antifouling property of TiO2-entrapped membrane is significantly improved .TiO2 nanoparticles plug membrane pores at high concentration .thus, the concentration of TiO2 should be optimized. according to flux and salt retention, the membrane containing 0.2%wt  TiO2 nanoparticles had the best performance between so called membranes. In fact, the increment in TiO2 concentration has apparent influence on membrane behavior.but rising to 0.5%wt TiO2, does not significantly affect the membrane yield. Fig. 1 is the three dimensional AFM surface imageof the optimal PVA/TiO2 composite membrane (0.2%wt TiO₂). All roughness parameters of optimal membrane are shown in Table.2.as it can be seen, TiO2 nanoparticles are well-coated on the membrane surface and  

 

Table 2.Surface parameters of the PVA/TiO2 (0.2 %wt) membrane