Preparation And Properties Of Nano-magnetic Forward Osmosis Draw Solute

At present,membrane water treatment technology has been widely used in seawater desalination,sewage regeneration and industrial wastewater treatment.Among various membrane processes,forward osmosis technology is considered to be one of the most promising membrane treatment technologies for domestic water and wastewater treatment.However,because it is difficult to recover the forward osmotic solutes,the reuse effect is not satisfactory,and the problems such as membrane fouling result in high cost,which leads to restrictions in their application areas.Therefore,the development of suitable draw solutes is the key to solving the problems of forward osmosis technology.In this experiment,the suitability of core-shell magnetic nanomaterials Fe3O4,Fe3O4@CS,Fe3O4@DHAA,Fe3O4@SiO2 and Fe3O4@SiO2@PEG-(COOH)2 as forward osmosis draw solute was investigated.The influence of the concentration of the raw liquid and the loading of the modifier on the water flux during the separation process of the forward osmosis membrane,and the recovery efficiency and reuse effect of the comparative material,and selecting a suitable forward osmosis solute.The main findings are as follows:1.Transmission electron microscopy and thermogravimetric analysis showed that the hydrophilic group such as silica(SiO2)or hydroxyl group(-OH)supported the dispersion and stability.The material structure is core-shell structure and core shell.The structure is stable and the surface is fully wrapped.After hydrophilicity measurement,the hydrophilicity of Fe3O4@SiO2@PEG-(COOH)2 loaded with 30%TEOs was significant,and the contact angle was increased from 900 to 200 of Fe3O4.It can be known from XRD that the prepared magnetic nanomaterials are all spinel structures.After loading the surface groups,the characteristic diffraction peak of Fe3O4 will be relatively reduced,while SiO2 will have obvious broad diffraction peaks and increase with the load.Its corresponding diffraction peak-to-peak value is relatively increased.The average particle size calculated using the Scherrer formula is reduced as the relative molecular mass and mass of the supported groups increase.Infrared indicates a successful loading of target groups in the magnetic nanomaterial,such as hydroxyl and silicon-oxygen bonds.2.Five kinds of nano-magnetic materials were selected as the forward osmosis-driven solute,which were Fe3O4,Fe3O4@CS,Fe3O4@DHAA,Fe3O4@SiO2 and Fe3O4@SiO2@PEG-(COOH)2,which were obtained by the separation test of forward osmosis membrane.As a result,the maximum water flux of Fe3O4@CS can reach 6.8 LMH,70%higher than Fe3O4;the maximum water flux of Fe3O4@DHAA can reach 7.9 LMH,70%higher than Fe3O4;the maximum water flux of Fe3O4@SiO2 can reach 11.4 LMH,97.5%higher than Fe3O4;while Fe3O4@SiO2@PEG-(COOH)2 The maximum water flux of the new secondary magnetic material with a secondary load can reach 12.22 LMH,205%higher than Fe3O4.3.The results of magnetic nanomaterial modifier loading show that the water flux effect of Fe3O4@SiO2 with 30%TEOs can reach 11.4 LMH,which is better than Fe3O4@SiO2 with 23%TEOs and Fe3O4@SiO2 with 13%TEOs.It shows that the water flux increases as the TEOs load increases.Further modification of Fe3O4@SiO2,Fe3O4@SiO2@PEG-(COOH)2 was obtained by loading PEG-(COOH)2,and it was found that the water flux of Fe3O4@SiO2@PEG-(COOH)2 with 30%TEOs loading can be It reaches 12.22 LMH,and increases with the increase of TEOs loading.It is known that the higher the mass ratio of effective hydrophilic groups in the magnetic nano-material shell,the better the water flux improvement effect.The membrane surface flow rate is optimal at 46 cm/min,and the surface flow rate is too fast,which increases the cost.4.After repeated reuse of various nano-magnetic materials,Fe3O4@SiO2@PEG-(COOH)2 with 30%TEOs has the best recycling effect,and the nano-magnetic material Fe3O4 is also stable several times,but the treatment effect is the lowest.Compared with the recovery rate of nano-magnetic materials,the highest recovery rate of Fe3O4 is 94.2%,and the recovery rate of nano-magnetic material Fe3O4@SiO2@PEG-(COOH)2 with 30%TEOs is 67.4%,and the recovery rate with shell load is obtained.The increase is reduced,so finding efficient and modifiable loadable materials is a key point.