Study On Adsorption Of Modified Magnetic Chitosan Microspheres For Wastewater Treatment In Food Industry

In this paper,magnetic chitosan（Fe₃O₄/CTS）was prepared from chitosan（CTS）and nano-Fe₃O₄by inverse suspension cross-linking method,and modified magnetic chitosan（triethylamine,diethylamine,dimethylamine）was prepared by amination.Due to the different target adsorbents,triethylamine modified magnetic chitosan（TEA-Fe₃O₄/CTS）has better adsorption effect through the selection of adsorbents.The effects of the amount of epichlorohydrin,activation time,modifier dosage and reaction temperature on the preparation of modified magnetic chitosan were studied.TEA-Fe₃O₄/CTS was used to adsorb azo containing synthetic pigments（sunset yellow,carmine）,chromium containing ions and potato protein containing simulated wastewater.The effects of p H,adsorption time,adsorbent dosage and adsorption temperature on the adsorption of azo synthetic pigments（sunset yellow,carmine）,chromium ion and potato protein by TEA-Fe₃O₄/CTS were investigated.The regeneration experiment of TEA-Fe₃O₄/CTS was carried out.The adsorption process was analyzed by kinetics and thermodynamics,and the adsorption mechanism was discussed.（1）The optimum conditions for the preparation of TEA-Fe₃O₄/CTS are as follows:the amount of epichlorohydrin is 5 m L,the reaction time is 2 h,the amount of triethylamine is 2m L,the reaction temperature is 50℃,and the highest content of amino group is 4.31 mmol/g.The absorption peak of N-H bond was found at 3436.81 cm^-1,1559.02 cm^-1and 1377.52 cm^-1by FT-IR.The absorption peak was enhanced and the amino content was increased.At588.02cm^-1,the Fe-O stretching vibration peak of Fe₃O₄was found.Fe₃O₄was successfully embedded in chitosan.Through SEM analysis,it was found that the size of the adsorbent ranged from 0.1μm to 10μm,the shape of the adsorbent was spherical,and the nano-Fe₃O₄crosslinked well with chitosan.（2）The adsorption conditions of TEA-Fe₃O₄/CTS dual nitrogen synthetic pigments（sunset yellow and carmine）were as follows:the concentration of sunset yellow was 50 mg/L,the concentration of carmine was 100 mg/L,p H=3,adsorption temperature was 40℃,adsorbent dosage was 0.01 g,the theoretical maximum adsorption capacity of adsorbent for sunset yellow and carmine was 243.90 mg/g and 526.32 mg/g respectively;The adsorption process is better in accordance with the pseudo-second-order kinetic model and Langmuir model.After three desorption adsorption regeneration experiments,the adsorption rates of sunset yellow were 92.1%,72.3%and 61.5%respectively,and the adsorption rates of carmine were 95.56%,65.84%and 52.23%respectively.（3）The adsorption conditions of TEA-Fe₃O₄/CTS for chromium ion are as follows:when the concentration is 80 mg/L,p H=3,adsorption temperature is 40℃,adsorbent dosage is0.10 g,equilibrium time is 150 min,theoretical maximum adsorption capacity of TEA-Fe₃O₄/CTS for chromium ion is 86.97 mg/g;The adsorption process is in good agreement with the pseudo-second-order kinetic model and Langmuir model.After three desorption adsorption regeneration experiments,the adsorption rates can reach 64.81%.（4）The adsorption conditions of TEA-Fe₃O₄/CTS for potato protein were p H=5,adsorption temperature 45℃,adsorbent dosage 0.01 g,equilibrium time 70min,theoretical maximum adsorption capacity of TEA-Fe₃O₄/CTS for potato protein 105.263 mg/g;The adsorption process is better in accordance with the pseudo-second-order kinetic model and Langmuir model.The best desorption solution is 1 mol/L Na OH solution,and the desorption rate is 78.8%.After three cycles of experiments,the adsorbent still showed a good adsorption effect,the adsorption rate was 57.4%.When the p H is more than 4.5,the solubility,water holding capacity,emulsification and emulsification stability of potato protein are better.