Study On Synthesis And Properties Of Protein-based Surfactants With Different Chain Length

About 1 million of leather wastes are produced in China,leather scrap is the major part of leather wastes,the main of which is collagen.Therefore the recycling use of leather scraps has enormous environmental and economic value.In this thesis different peptide chain length protein-based surfactants with excellent properties were synthesized by using chrome shavings as raw material.The three aspects of work were as follows:Firstly,by using chrome-shavings as raw material the effects of alkali dosage,temperature,time and liquid ratio in CaO and NaOH hydrolysis system were studied.And the hydrolysis yield,hydrolysis degree,intrinsic viscosity and chromium content were characterized to study the law and difference in the hydrolysis of chrome shavings.The experimental results showed that the process of calcium oxide hydrolysis of chrome shavings was similar to that of sodium hydroxide.The order of the experimental conditions on the hydrolysis yield was as follows: alkali dosage> temperature> time> liquid ratio.The highest hydrolysis yield of the calcium oxide hydrolysis process conditions is: CaO 8%,hydrolytic temperature 90?,hydrolytic time 5 h,liquid ratio 10,and the highest hydrolysis yield is 73%.The highest hydrolysis yield of the sodium hydroxide hydrolysis process conditions is: NaOH 10%,hydrolytic temperature 80?,hydrolytic time 3 h,liquid ratio 6,and the highest hydrolysis yield is 86%.Compared with the calcium oxide hydrolysis,the hydrolyzate of sodium hydroxide has higher hydrolysis yield,lower molecular weight and low chrome removal rate.Secondly,according to the law of alkali hydrolysis chrome shavings,Five series of shavings hydrolysates with different chain length were produced by alternating using calcium oxide and sodium hydroxide hydrolysis chrome shavings.Then the five kinds of hydrolysates were condensed with oleyl chloride.The effects of pH,solvent dosage,temperature and time on the condensation yield were investigated by single factor test to obtain the optimal condensation conditions.The research showed that with the decrease of length of the peptide chain,the conversion rate of the condensation reaction increased gradually.Under the condition of the same nucleophile,with the decrease of length of the peptide chain,the space steric hindrance reduced gradually.Therefore,the conversion rate of condensation increased gradually.Finally,the performance of five kinds of surfactants was studied,including viscosity analysis,infrared spectroscopy,hydrophilic-lipophilic balance(HLB)value,surface tension,critical micelle concentration(CMC)value,emulsifying ability,wetting ability and foaming ability.Viscosity and infrared spectroscopy showed that the protein-based surfactants had been successfully synthesized.The HLB values of the products are about 7.The surfactants have good emulsifying property and emulsifying stability,which increase first and then decrease with the decrease of the length of the peptide chain.Synthetic surfactants are able to reduce the surface tension of water which reduces with the increase of hydrophilic peptide.The foaming ability of the five surfactants reduces with the increase of the length of the peptide chain,but the foam stability increases with the increase of the length of the peptide chain.The wetting performance of the five surfactants is better than that of sodium oleate,and the ability gets better with the decrease of length of the peptide chain of the surfactant.The five kinds of surfactants are suitable to be used as emulsifier,wetting agent;surfactant 1 and surfactant 2 are also suitable to be used as foam stabilizer;surfactant 3,surfactant 4 and surfactant 5 are also suitable to be used as detergent and foaming agent.