| Nowadays,with the continuous development of China's leather industry,tannery sludge,as an industrial solid waste produced by tannery wastewater treatment,produces about 50 million tons per year,and continues to increase at a rate of 10% per year.Landfill,incineration and other tannery sludge disposal methods have been unable to meet people's environmental requirements,so the harmless treatment and resource utilization of tannery sludge has become the focus of research.At present,the resource utilization of tannery sludge mainly focuses on the recovery of heavy metal chromium,but there are few studies on the extraction and utilization of protein in tannery sludge.Different from municipal sludge protein,tannery sludge protein contains heavy metal chromium,which limits its application.Therefore,how to reduce the content of heavy metal chromium in tannery sludge protein becomes the difficulty of extraction and utilization.In this thesis,proteins were extracted from tanning sludge by thermoalkali method and applied to the flame-retardant finishing of cotton fabric.The specific research contents are as follows:(1)Tannery sludge protein was extracted by thermo-alkali method.The influence of each factor on the protein extraction rate of tannery sludge was clarified by single factor experiment and response surface experiment,and the protein extraction process was optimized.Finally,the properties of tannery sludge protein were characterized.The results showed that the optimal extraction conditions were as follows: extraction temperature was 148.3 ?,extraction time was60.3 min and Na OH dosage was 9.1 g/L,under which the extraction rate of tannering sludge protein was up to 72.6%.The protein purity of tanning sludge was 83.1%,the total chromium content was 1.5 mg/kg,and No Cr6+ was detected.The isoelectric point of tannery sludge protein was 4.5,the molecular weight distribution was 5-35 k Da,and the denaturation temperature was 132.5 ?,which contained 14 kinds of common amino acids.(2)Tannery sludge protein was hydrolyzed to prepare amino acid hydrolysate under acidic conditions,and then fr-P was synthesized by Mannich and ammonium reaction successively,which was used for finishing cotton fabric.The thermal stability and flame retardancy of flameretardant finishing cotton fabric were studied,and the flame retardancy mechanism of FR-P was revealed.The results showed that the weight gain rate of 30% FR-P/ cotton fabric was17.1%,the limiting oxygen index was 32.9%,and the PHRR and THR values were reduced by51.9% and 19.1%,respectively,showing excellent thermal stability and flame retardancy.Fr-p was covalently grafted onto the surface of the cotton fabric,and the flame-retardant finished cotton fabric still had good flame resistance after 30 times of washing.Free formaldehyde was not detected in flame-retardant finishing cotton fabric.(3)Chitosan-phytic acid-tanning sludge protein biomass flame retardant coating was self-assembled on the surface of cotton fabric to study its influence on the thermal stability,flame retardant performance and breaking strength of cotton fabric,and reveal the flame retardant mechanism of biomass flame retardant coating.The results showed that the weight gain rate,limiting oxygen index,PHRR and THR of 15TL/ cotton fabric were 22.9%,29.3%,33.1% and 38.9%,respectively.The FGI of cotton fabric was reduced from 11.3 to 9.9k W/(m2·s),which improved the fire safety of cotton fabric.The biomass flame retardant coating is adsorbed on the surface of cotton fabric by electrostatic attraction,and the flame retardant finish cotton fabric can only withstand 20 times of washing test.The biomass flame retardant coating can effectively improve the breaking strength of cotton fabric. |
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