Preparation And Application Performance Of Cationic And Acylated Collagen

Collagen is a kind of biological macromolecule widely existing in animals and plants.It is environmentally friendly,easy to degrade and easy to be chemically modified,and has broad source.Collagen contains a large amount of free amino groups,which can react with a variety of active compounds,thus varieties of new functional groups and new properties can be introduced into collagen.For instance,modified collagen can be used as flocculants,surfactants or other chemical auxiliaries.Through charge neutralization and bridging mechanism,flocculants can make the pollutant particles which are difficult to be removed in water accumulate and settle.Flocculation process is simple to conduct and relatively cheap.Natural flocculants have prospects for development because of non-toxic and wide source.By introducing positive charge groups into collagen,the charge neutralization ability of collagen can be enhanced,and it can be used as cationic flocculants.Collagen was modified by glycidyl trimethyl ammonium chloride(GTA).The optimum conditions are as follows: reaction time is 3 h,reaction temperature is 50 ?,and molar ratio of NaOH and GTA to amino group is 1:1.Cationic collagen with 60% degree of substitution(DS)was prepared under these conditions.Zeta potential was increased from-13.3 mV to-7.3 mV and isoelectric point was increased from 6.6 to 7.8.5 mg/L cationic collagen was added to 1 g/L acidic kaolin suspension.After stirring for 5 min and settling for 2 h,the turbidity of the supernatant decreased by 68%.Surfactant is a kind of amphiphilic compounds with hydrophilic and hydrophobic groups.Common surfactants come from petrochemical products,while with the energy shortage,a large number of research on biomass surfactant has appeared.Collagen-based surfactants with good biocompatibility and biodegradability can be prepared by adjusting the proportion of hydrophobic groups.Hydrophobic modification of collagen was carried out with lauryl,myristyl and palmityl chloride.The optimum reaction temperature is 20 ? and reaction time is 2 h.Under these conditions,acylated collagen surfactants with different degree of acylation(DA)were prepared by changing the amount and type of acyl chloride.Lauryl collagen can reduce the surface tension of aqueous solution to 36 mN/m and the foaming property enhances with the increase of DA.Foam volume of its 25 mL aqueous solution reaches the maximum value of 31 mL when DA is 48% and concentration is 1 g/L.The foaming properties of myristyl and palmityl collagens decrease with the increase of DA.The maximum foam volumes were 31 mL and 37 mL at the concentration of 2 g/L with 31% DA and 27% DA,respectively.Acylated collagen surfactants can emulsify oleic acid.The emulsifying property increases with the lengthening of hydrophobic carbon chain and the increasing of DA.The emulsion layer can reach 62% of the mixing liquid of 5 g/L palmityl collagen with 52% DA and oleic acid at the same volume.The emulsifying capacity under acidic condition is better than that under neutral and alkaline conditions.