Improving Drying Efficiency And Dye Adsorption Performance Of Sugar Beet Pulp Through Iron(?)-crosslinking Modification

To improve the performance of sugar beet pulp(SBP)in wastewater purification treatment,the structure of the original SBP produced in Xinjiang was modified by iron(?)-crossing and esterification.Due to the large water content and strong water absorption of SBP,the drying energy consumption of SBP is relatively high.The structure modification method is also expected to reduce the water absorption performance and improve the drying rate of SBP,reduce the drying energy consumption cost.The structural modification methods of SBP adopted in this study mainly include iron cross-linking and citric acid esterification.The main research results and abstract are concluded as follows:(1)Proper concentration of iron ion,solution p H,water bath temperature and water bath time were used to treat SBP,the dry base moisture content and the drying time of SBP could be significantly reduced.The optimal modification conditions were as follows: after SBP was crosslinked with iron ions at a concentration of 500 mg/L(the solidliquid ratio was 1:20),it was treated in a 50 ? water bath at p H 4.0 for 60 min.The dry basis moisture content of the iron-crosslinked SBP was 5.76 g/g,and the drying equilibrium time was shortened from the original 195 min to 150 min.(2)The iron-crosslinked SBP(FSBP)after iron cross-linking treatment had good adsorption performance for rhodamine B,and the adsorption could be completed within 30 minutes.Rhodamine B with a high concentration was conducive to providing a greater driving force to move dye molecules towards the active adsorption site,overcoming the resistance of mass transfer in two-phase adsorption and enhancing the adsorption performance of the adsorbent.The adsorption kinetics and isothermal adsorption model fitting results of iron-crosslinked SBP on rhodamine B were more in line with the pseudo-second-order kinetic model and Freundlich isothermal adsorption model,indicating that the adsorption of iron-crosslinked SBP on rhodamine B was a chemical adsorption process and non-uniform multi-molecular layer adsorption behavior.The adsorption thermodynamics results showed that the appropriate increase of temperature was beneficial to the adsorption reaction.(3)After three different treatments of iron-crosslinked SBP,iron-crosslinked SBP activated carbon and activated iron-crosslinked SBP activated carbon,the adsorption performance of beet base adsorbent on methylene blue was the best with ironcrosslinked SBP.The adsorption of methylene blue on iron-crosslinked SBP could be completed within 30 min.It had a strong dependence on temperature and p H of solution.The fitting results of the kinetics and isothermal adsorption model of iron-crosslinked SBP on methylene blue adsorption process were more in line with the pseudo-secondorder kinetic model and Freundlich isothermal adsorption model,indicating that the adsorption of iron-crosslinked SBP on methylene blue was a chemical adsorption process and non-uniform multi-molecular layer adsorption behavior.The results of adsorption thermodynamics showed that the adsorption process was endothermic and advantageous spontaneous reaction.(4)After the structure modification of SBP,such as acid depectin,saponification,citric acid esterification,iron loaded and alkali hydrolysis,the adsorption performance of methylene blue was greatly improved.The p H of the solution system and the dye concentration had a great influence on methylene blue of the iron modified esterified SBP.The adsorption capacity increased significantly with the increase of p H in the range of 3.0~8.0.When the concentration of methylene blue increased from 50 mg/L to 350 mg/L,the adsorption capacity of methylene blue on iron modified esterified SBP increased from 95.78 mg/g to 619.66 mg/g.The adsorption of methylene blue on iron modified beet pulp could be completed within 40 min,which has the advantages of high efficiency and strong adsorption capacity.The adsorption kinetics and isothermal adsorption model fitting results of the adsorption process were more in line with the pseudo-second-order kinetic model and Langmuir isothermal adsorption model,indicating that the adsorption of methylene blue by iron modified esterified SBP was a chemical adsorption process and a uniform adsorption behavior of single molecular layer.The results of adsorption thermodynamics showed that the adsorption process was endothermic and advantageous spontaneous reaction.