Preparation Of Magnetic Litsea Cubeba Slag Activated Carbon And Its Adsorption Properties For Dyes

With the rapid development of the textile industry,a large amount of printing and dyeing wastewater has been generated and discharged by factories,causing serious pollution to the environment.This kind of wastewater has the characteristics of complex components,high pollutant concentration,deep color,large changes in water quality and strong toxicity,and has caused serious impact on the society and even threatened the survival of human beings to a certain extent.Therefore,the treatment of printing and dyeing wastewater has drawn great attention.Biomass carbon has developed pore structure and a large specific surface area,and has been widely used in the treatment of printing and dyeing wastewater for its good adsorption performance to remove pollutants.However,due to the features of activated carbon solid-liquid separation is always difficult in the treatment of pollutants.After magnetizing the activated carbon,the difficulty of separation has been overcome,and the process and time of the separation has been greatly reduced under the influence of external magnetic field.This thesis studies,and combines the advantages of magnetic and biomass carbon materials,the residue after extracting essential oil from Litsea Cubeba is peeled to obtain nuclear residue as raw material,ZnCl₂as the activator,Fe₃O₄as the magnetizing agent,to make magnetic Litsea cubeba slag activated carbon（MLCSAC）by the help of technologies including SEM,XRD,BET,and FT-IR.The common organic dyes congo red,neutral red and methyl green were selected as the adsorption targets.The effect of MLCSAC on the adsorption and removal of three organic dyes was studied,and its adsorption kinetics and thermodynamics were discussed.The main research results of this thesis are as follows:（1）Residues of Litsea cubeba slag from essential oil is extracted by steam method as raw material,ZnCl₂used as activator and Fe₃O₄as magnetizing agent.By adjusting the ratio of raw materials(ZnCl₂to Fe₃O₄),the preparation temperature and time have been studied to optimize the preparation process.Studies show that:when carbonization temperature is 300℃,carbonization time is 2 h,obtained carbonized sample（C）,the mass ratio of C,ZnCl₂,Fe₃O₄is 10:40:0.5 activation temperature is 800℃,the activation time is1.5 h.Its iodine value and methylene blue value is 690.03 mg/g and 298.89 mg/g,respectively.（2）By characterizing MLCSAC,the results show that the prepared MLCSAC has a honeycomb porous structure,with specific surface area of 631.76 m²/g,average pore diameter of 2.234 nm,and total pore volume of 0.3518 cm³/g.After magnetizing agent,the characteristic absorption peak of Fe-O is added on the surface,magnetic separation can be achieved under the condition of external magnetic field.（3）The pH of the two dyes of congo red and methyl green are in the range of 3.0-9.0,which has a great influence on the removal rate.The pseudo-first-order kinetic model can fit the kinetic data of MLCSAC to congo red and methyl green;the Langmuir model can better describe the adsorption process of MLCSAC to congo red and methyl green.Its maximum saturated adsorption capacity of single layer is 431.58 mg/g and 149.61 mg/g at40℃.The pH of the neutral red dye is in the range of 3.0-9.0,which has little effect on the adsorption effect of MLCSAC.The pseudo-second-order kinetic model can fit the kinetic data of MLCSAC to neutral red very well;the Langmuir model can describe the adsorption process of MLCSAC to neutral red very well.Its maximum saturated adsorption capacity of single layer is 235.79 mg/g at 40℃.（4）Isothermal thermodynamic studies have shown that△G<0,MLCSAC adsorption of the three dyes is spontaneous behavior..Therefore,MLCSAC may become an effective magnetic adsorbent.