| Corn straw is a renewable biomass energy, but the development and utilization is not enough.Most of the corn straw burned by in situ, and caused serious resource waste and environmental pollution.Preparing of modified corn stalk into adsorption materials, sewage processing to the environment, with a strong research value and profound realistic significance. Dye wastewater pollution is due to the stability and toxic of dye,after entering water environment difficult to natural degradation, destroy the balance of waters original.The adsorbent of modified corn straw treat sewage with a strong research value and profound realistic significance.This experiment used microwave zinc chloride,NaOH and cellulose enzyme prepared modified corn straw,and orthogonal to its preparation conditions.The influence of dosing quantity and pH on the adsorption of methylene blue as dye wastewater performance.The adsorption thermodynamics of methylene blue by three kinds of modified corn straw and fitted adsorption isotherm and dynamic models to determine the asorption performance; They were characterized by SEM, FI-RT and XRD. The main findings are as follows:The microwave zinc chloride modified corn straw absorbed 20 mL,20mg·L-1 methylene blue, when the corn straw-zinc chloride was ratio 1:1, microwave power was 700 W, 40% ZnCl2, 2 min, the adsorption rate reached 84.67%; the NaOH modified corn straw of the adsorption rate was 98.76% when 1% NaOH, the corn straw-NaOH ratio was 1:30,40℃,8 h; the modified corn straw of cellulose enzyme under the conditions of 45℃, 6 h,the enzyme activity ratio was 100U/g, the adsorption rate was 99.63%. When the dosing was 0.04 g of the microwave zinc chloride modified corn straw, the cellulose enzyme modified corn straw and the NaOH modified corn straw dosing quantity was 0.02 g,they have the maximum adsorption.The microwave zinc chloride and NaOH modified corn straw absorbed methylene blue the best condition were pH≥4,and the cellulose enzyme modified corn straw the best condition was pH≥6.Langmuir model can be a very good description of the three kinds of modified corn straw of isothermal adsorption of methylene blue, the three adsorb reaction were monolayer adsorption.The three kinds of modified corn straw maximum adsorption theory were 75.70mg·g-1,144.93mg·g-1,94.07mg·g-1. The three kinds of adsorption reaction were easy by the Freundlich model parameters. D- R equation showed that modified corn straw of NaOH and the modified corn straw of microwave zinc chloride were ion exchange adsorption reaction,the cellulose enzyme modified corn straw was a chemical reaction. Adsorption reaction of the three kinds of modified corn straw conformed to pseudo second dynamics model. Chemical adsorption mechanism control the reaction rate. The three kinds of modified corn straw to methylene blue adsorption reaction were ΔS < 0,ΔG < 0,ΔH< 0, improved that the three adsorption reaction reduced freedom, cloud occur spontaneously, were the exothermic reaction.Adsorption modified corn straw of microwave zinc chloride when 50℃, 0.01 mol · L-1 HCl, 50 min, the desorption rate was 96.82%; the adsorption modified corn straw of NaOH and the modified corn straw of cellulose enzyme when60℃, HCl 0.01 mol · L-1, 50 min, the desorption rate were 95.67% and 96.82%.Three kinds of modified corn straw particles were smaller than unmodified corn straw, surface structure became rough shaggy,exposed the internal structure, hydrolyzed a part of cellulose and more conducive to the adsorption. |
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