Dissolution System And Recycling Process Of Metal Salt-Reducing Agent Blend For Extracting Waste Wool

As a kind of natural fiber raw material with good wearability,wool has been widely favored in the textile industry at home and abroad since ancient times.As one of the major wool producing countries and wool consuming countries in the world,China often has a large amount of waste wool and waste wool products in industrial production and daily life,which can not be adequately and properly treated,resulting in certain environmental pollution.Extracting keratin from wool in an appropriate way can not only reduce the environmental pressure caused by improper disposal of waste wool but also improve its added value through recycling keratin,which has good economic benefits.At present,most of the common keratin extraction methods have toxic and harmful by-products in the extraction process or the dissolution system itself has a certain toxicity,resulting in the extraction of wool keratin while increasing the environmental burden,or there are problems with extraction cost.Based on the above problems,this project adopts the dissolution system of non-toxic and low toxic substances,which effectively reduces the environmental pollution caused by the keratin extraction process.At the same time,the recovery and reuse of the dissolved system can not only greatly reduce the raw material cost required to extract keratin,but also effectively relieve the economic pressure and environmental burden caused by the disposal of waste liquid and waste.In this study,the wool was first dissolved by lithium bromide(Li Br)-sodium bisulfite(Na HSO3)system,and keratin was extracted by dialysis purification,isoelectric drip,and freeze-drying.The effects of reaction time,reaction temperature,Li Br concentration,and Na HSO3 dosage on keratin yield were investigated,and the optimization process for the extraction of regenerated keratin was obtained.Besides,the molecular structure of keratin and insoluble matter was analyzed by Fourier transform infrared spectroscopy(FTIR).The surface morphology of undissolved matter was observed by scanning electron microscope(SEM)to analyze the effect of the dissolved system on wool under different process conditions.The test results were as follows:The optimal dissolution conditions for wool in the LiBr-NaHSO₃ solution dissolution system were 12 h reaction time,reaction temperature of 90 °C,Li Br concentration of 7 mol/L,and wool mass of 100 % Na HSO3 dosage.Under these conditions,the wool dissolution rate could reach66.05±4.25 %,the keratin extraction rate reached 81.6±0.74 % and the keratin yield reached53.91±2.99 %.The results of keratin production and SEM images of undissolved substances under different reaction conditions showed that Li Br had a good swelling effect only in the concentration range of about 7 mol/L.Na HSO3 could be used as a reducing agent only when the dosage of wool was more than 100 %.FTIR image analysis showed that the extracted keratin had obvious protein structure characteristics,with amide I,amide II,and amide III structures similar to the original wool,and the secondary structure ?-helix and ?-sheet structure were preserved to a high degree.It was also proved that Na HSO3 can effectively reduce cystine in wool,which is difficult to be hydrolyzed.Additionally,an aqueous solution of dialysis at high ion concentration obtained by dialysis during keratin purification is collected and concentrated,and reapplied for keratin extraction.Compare the effects of collected recovered solutions on wool by comparing keratin yields,SEM image analysis.The test results were as follows:The dissolution system was directly recycled and reused.With the increase in recycling times,the dissolution effect of the solution on wool decreased sharply,and the extraction rate of keratin did not change.The final keratin yield decreased dramatically,and the yield of keratin was reduced to20.2 % after recycling twice.Finally,the BaCl₂ solution was used to titrate the recovered solution to remove SO42-,SO32-and other ions in the solution that had a greater impact on the solubility of Li Br,to improve the solubility of Li Br in the recovered solution and reconcentrate the solution.The recovery process was optimized by comparing the effects of the reprocessing solution concentrated to different densities on wool dissolution and keratin yield,and the recovery rate of the solution was calculated.The test results were as follows:BaCl₂ titration and reconcentration of the recovered solution could improve the solution's dissolution effect on wool.For the solution obtained from the first recovery,when the solution was concentrated to a density of 1.47 g/ml,the dissolution effect of the solution system based on it on the wool could reach the level of the original solution.For the second recovery,when the solution was concentrated to a density of 1.51 g/ ml,the dissolution effect of the solution system based on the solution could reach the level of the original solution.The effective recovery rate of the two solutions both could reach more than 80 %.Based on the above research results,the LiBr-NaHSO₃ solution can be used to extract keratin efficiently from wool,and the recycling of its solution system can also achieve high recovery and utilization rate.The research is of positive significance to waste wool recycling and utilization,in line with the needs of green development and sustainable development,and has good environmental protection and economic benefits.