Preparation Of Activated Carbon From Fast-growing Eucalyptus Wood Chips And Its Application In Sugar Refining And Clarification

The clarification process has always been one of the core steps of the sugar manufacturing process.In order to improve product quality and bring economic and social benefits,optimizing the clarification and decolorization process is an urgent problem to be solved by sugar mills and sugar industry workers.Fast-growing eucalyptus,as a plant variety abundant in Guangxi,uses its wood chips to prepare high-efficiency activated carbon as a comprehensive resource utilization measure.This study used fast-growing eucalyptus wood chips as raw materials,studied the pyrolysis characteristics of fast-growing eucalyptus wood chips and analyzed their pyrolysis kinetics,prepared activated carbon by CO₂activation method,explored the main influencing factors of the preparation process to obtain the optimal preparation conditions,and then characterized the most Under the optimal conditions,the activated carbon of eucalyptus wood chips was subjected to the decolorization experiment of sugar juice,the adsorption decolorization isotherm was drawn to understand the adsorption characteristics and analysis of the adsorption kinetics of the eucalyptus wood chips,and finally the application of the eucalyptus wood chips in the refining sugar filling and clarification process In order to explore the effect of adsorbent coupling fast-growing eucalyptus wood activated carbon on the quality of sugar juice.The main research contents are as follows:?1?Experiment with thermogravimetric analyzer on the fast-growing eucalyptus wood chips,analyze its thermal decomposition process,and study its pyrolysis kinetics.The research results show that there are two obvious stages of thermal weightlessness in the thermal decomposition process of fast-growing eucalyptus wood chips.The maximum decomposition rate is between 300?and 400?,and almost complete thermal decomposition at about 450?.Through different thermodynamic methods,the thermodynamic parameters of fast-growing eucalyptus wood chips can be obtained.From the analysis results of Kissinger method,FWO method and KAS method,the activation energy calculated by Kissinger method is obviously small,and the correlation coefficient is also low.The activation energy obtained by FWO method and KAS method is almost the same,and the correlation coefficient is high,so The thermogravimetric analysis data is consistent with the model.Compared with other biomass raw materials,the activation energy of fast-growing eucalyptus wood chips is slightly higher,and relatively high energy is required to complete pyrolysis.?2?Carry out carbonization using fast-growing eucalyptus wood chips as the raw material,and use activated carbon dioxide to prepare activated carbon.Observe the effect of activated carbon adsorption performance by setting process parameters such as carbonization temperature,activation temperature,activation time and CO₂ flow rate.The best process conditions were determined by orthogonal test.The best conditions were carbonization temperature 500?,activation temperature 900?,activation time 50min,CO₂ flow rate 150ml/g.The nitrogen adsorption isotherm,pore size distribution and surface microstructure of the optimized sample were characterized.The results showed that a large number of macropores and mesopores and some micropores were generated on the surface of the activated carbon,with a specific surface area of1085m²/g.The average pore diameter was calculated by the BJH method0.509nm,total pore volume 0.108cm³/g.Activated carbon has rich oxygen-containing functional groups and many organic species.?3?Using the prepared fast-growing eucalyptus activated carbon to decolorize the juice.The results show that the activated carbon has a good decolorization ability,the decolorization rate is close to 75%,especially when a small amount is added,the decolorization rate is close to the commercially available activated carbon.With the increase of the added amount,the decolorization rate of the fast-growing eucalyptus activated carbon is comparable to that of the commercially available activated carbon The gap widens.With the increase of heating temperature,the decolorization efficiency of activated carbon increased significantly from the beginning,and tended to equilibrium after 75?80?;the optimum temperature of adsorption temperature was 75?80?.Under low temperature conditions,when p H=5.5?8.0,as the p H value increases,the decolorization rate of sugar juice decreases significantly.As far as adsorption is concerned,lowering the p H value is conducive to adsorption decolorization.The isotherm adsorption process of eucalyptus activated carbon to sugar juice pigments is in accordance with the Freundlich isotherm adsorption?4?Decolorization experiment of sugar juice using the combination of prepared activated carbon and carbonation.The results of the study indicate that it is feasible to use the coupling process of carbonic acid saturation and activated carbon for the refining and clarification of raw sugar.The best process is to add ash to fill and then add activated carbon to decolor.This process can play the role of carbonated coagulation and activated carbon adsorption of soluble pigments,improve the overall decolorization rate,and increase the filtration rate.At the same time,the decolorization process of coupling carbonic acid filling and activated carbon can be used to combine the two operations into one,shortening the process.In the range of saturated p H value from 7.5 to 8.0,with the increase of p H value,the purity of sugar juice first increased obviously,and then tended to be gentle;the color value of sugar juice first obviously decreased,and then tended to be gentle.The change of the amount of activated carbon has little effect on the purity of sugar juice,but with the increase of the amount of activated carbon,the decolorization rate of sugar juice is significantly improved.After the addition amount reaches 1g/L,the decolorization rate rises slowly.The optimal process parameters are,The saturated p H value is 8.0,and the amount of activated carbon added is 1.5 g/L.