Performance Optimization Of Magnetically Responsive Glucose Oxidase And In-situ Bleaching

Glucose oxidase?GOD?can catalyze the oxidation decomposition of glucose to produce hydrogen peroxide and gluconic acid,which not only can be used for bleaching directly,but also needn't add other chemical reagents.However,the poor stability,expensive price,and difficult recovery lead to the difficulty in actual production.The immobilization of glucose oxidase can overcome the above defects by using the stability of immobilized enzyme and the characteristics of recycling and reuse.Amylase can be used to hydrolyze starch to produce dextrin,maltose,and small molecular glucose.After that,the immobilized glucose oxidase is used to react with glucose in the desizing solution.This process which is defined as in situ bleaching has the advantages of reusing the desizing liquor and free enzyme,reducing cost and the environmental pollution.In the meanwhile,the damage to the fabric could be decreased due to gentle enzyme treatment.Firstly,the surface of Fe₃O₄ was modified by poly diallyl dimethyl ammonium chloride?PDDA?in different stages of forming Fe₃O₄ crystal through electrostatic self-assembly technology.The influence of this method on the quality of the final product was studied by using the characterization and test results of particle size analyzer,X-ray diffraction,transmission electron microscopy,and vibrating sample magnetometer.Meanwhile,the thickness and ratio of the coating were compared and discussed.The result shows that the modification carried out immediately after formation of crystal iron oxide is optimal.The coating ratio was about 2.01%,the coating thickness was 2.1nm,and the particle was uniformly dispersed.The magnetic property of composite particles reaches 67.060emu/g.Then,the GOD was immobilized on Fe₃O₄/PDDA magnetic composite particles,and the effects of hemoglobin and trace metal ions on the immobilized glucose oxidase activity were also discussed.The results show that metal ion activator Zn2+ has the greatest influence on the enzyme activity,and the relative activity of the obtained immobilized enzyme was 128.09%.The relative enzyme activity of the immobilized enzyme after the introduction of hemoglobin is 185.4%.In comparison with the former,hemoglobin has the largest increase in immobilized enzyme activity.The optimal condition of immobilization is pH=7,temperature 26?,and hemoglobin 2.5mg.On this basis,using response surface methodology to optimize the immobilization parameters of immobilized enzyme after the introduction of hemoglobin,then establish the mathematical model and conduct experiments and verification.The results show that the best fitting model was quadratic,when the relative enzyme activity is maximum.The relative immobilization conditions were as followed.pH=8,temperature is 14.11?,hemoglobin is 3mg.The temperature has the greatest effect on the enzyme activity.Finally,the influencing factors of glucose production in desizing solution were studied,and then in situ bleaching was done with immobilized enzymes.The results show that when the amylase mass concentration is 4g/L,glucoamylase mass concentration is 1g/L,pH=6,and the temperature is 70? the desizing effect is the best,and the glucose concentration is the largest.The immobilized enzyme is reacted with the desizing solution to produce hydrogen peroxide.The optimum reaction conditions were temperature 37?,pH=8,and the amount of immobilized enzyme is 0.25g.The results show that the highest whiteness of fabric obtained in situ bleaching is 81.76,which is increased by 10.61%compared with the original sample,and it meets the demand of bleached fabric with low whiteness.Compared with hydrogen peroxide bleaching,the damage on the fabric strength is small.Desizing liquid composition is more complex,showing inhibition of enzyme activity.The immobilized enzyme can be reused for 3 times,and the whiteness of the fabric does not decline.