Preparation And Performance Optimization Of Collagen Fiber Separation Membrane

The application of environmental protection and low-cost biomaterials to prepare the membrane has incomparable advantages over the traditional synthetic polymer membrane.Collagen,the main biopolymer in the extracellular matrix of vertebrates and invertebrates,is a complex protein with repeating sequence of charged amino acids such as glycine,proline,and hydroxyproline.Due to their good biocompatibility,collagen has been widely used in the pharmaceutical,cosmetic,leather and food industries as well as biotechnology.Fibrotic collagen has a highly ordered triple helix structure,which provide mechanical support and load-bearing functions in tissues.It has been proved that collagen could form thin films under certain conditions.In addition,collagen fibers（CFs）with high water content can promote proton transport and diffusion.Their excellent film forming and mass transfer properties make them a good candidate material for membrane preparation.In this paper,commercial polyacrylonitrile（PAN）ultrafiltration membrane was used as the supporting layer,and collagen fiber membrane and modified collagen fiber membrane were prepared by vacuum filtration.The research work and conclusions are as follows:（1）CFs were extracted from cow skin and prepared into dispersion solution.The dispersion solution was filtered directly to the surface of PAN,and then crosslinked with 1,3,5-benzoyl chloride（TMC）to form a dense polyamide（PA）composite（TFC）membrane.The thickness,surface morphology and hydrophilicity of TFC membrane were adjusted by changing the concentration of CFs dispersion.The experimental results showed that the pure water permeability of the optimal membrane TFC-0.5reached 84.7 L m^-2 h^-1 bar^-1 under an operating pressure of 6 bar.The cut-off rates of three negatively charged dyes,namely,Congo red（CR,Mw=696.68）,reactive blue-19（RB-19,Mw=626.54）and coomasite bright blue G250（CB G250,Mw=854.02）,were99.6%,99.8%and 99.6%,respectively.Meantime,the CF membrane also retain a high permeability for sodium chloride（Na Cl）and sodium sulfate（Na₂SO₄）to achieve the purpose of selective separation.（2）Casein（CA）and chitosan（CS）were introduced to blend with CF to enhance the stability of CF-based NF membrane.Under acidic conditions,the CFs/CA/CS mixed solution was obtained by simple physical mixing,which was uniformly loaded on the surface of PAN-based membrane by vacuum filtration.Then,the enhanced CF/CA/CS NF membrane was obtained by crosslinking with glutaraldehyde（GTA）for acid recovery from acid/metal mixed wastewater.The experimental results revealed that the optimal membrane M-0.15 possessed a functional layer with a thickness about628.4 nm,a good acid permeability(U_H⁺=0.034 M h^-1)and a high H⁺/Fe²⁺separation coefficient（S=33.8）.