Preparation Of Nano-carbon-alginate Calcium Composite Hydrogel Filter Membrane And Dye Desalination Research

The self-supporting calcium alginate hydrogel filter membrane(CaAlg)prepared from natural polymer sodium alginate has good dye-rejection property,a simple preparation method and mild membrane-forming conditions.However,the filter membrane has poor mechanical properties,and it's easily dissolved in salt solution and other defects.In this paper,in order to improve these shortcomings of pure CaAlg hydrogel filtration membrane,I prepared composite hydrogel filtration membrane,which takes sodium alginate as membrane-forming substrate and adds carboxylated multi-walled carbon nanotubes and graphene oxide in casting solution,and I applied it to research on dye desalination.The research work is divided into the following two aspects:(1)The preparation of carboxylated multi-walled carbon nanotubes/calcium alginate(CMWCNT/CaAlg)composite hydrogel filtration membrane without pore-forming agent was used CaCl2 solution as a crosslinking agent and natural polymer sodium as membrane-forming substrate,and it was applied to dye desalination research.The chemical structure,surface morphology and thermal properties of the composite membranes were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FTIR)and thermogravimetric analysis(TG).The mechanical properties,swelling properties and anti-fouling properties of the composite membranes were investigated.The effects of dye concentration,temperature,operating pressure,pH,dye type and salt concentration on the dye interception performance of CMWCNT/CaAlg compound dye were also studied.The results showed that the composite membrane had good mechanical properties and anti-pollution properties.When the content of CMWCNT was 1%of the mass of sodium alginate,the rejection rate of the compound membrane was close to 100%for the brilliant blue G250 and the NaCl was almost no interception.However,it's found that the stability of the composite membrane was not good when the salt solution was treated at a higher temperature.Therefore,in the following sections,composite hydrogel filtration membranes prepared with graphene oxide(GO)and sodium alginate were discussed.(2)Graphene oxide(GO)was added to a casting solution containing sodium alginate as a membrane-forming substrate to prepare a graphene oxide/calcium alginate(GO/CaAlg)composite hydrogel filter.The composite membranes were characterized by SEM,TEM,FTIR and TG.The mechanical stability,swelling property and anti-fouling property of the composite membranes were investigated.The effects of dye concentration,temperature,operating pressure,pH,dye type,salt concentration on dye rejection in desalination of GO/CaAlg composite membrane.The results showed that the optimum composition ratio of the prepared composite membrane was GO/NaAlg:1?2 wt%,NaAlg:2.5wt%.The composite membrane not only showed excellent anti-pollution,mechanical properties and dye rejection,but also showed good thermal stability and dye desalination performance.The composite membrane has a good application prospects in the field of dye deep desalination.