Studies On Preparation And Properties Of Nano-Lignocellulosic/Montmorillonite Composite

With the increasing emphasis on environmental protection,it is necessary to research and develop low-cost,environment-friendly new types of bio-adsorption materials for adsorption of heavy metals contaminating the water quality.In this paper,nano-LNC and montmorillonite(MMT,silicate)were synthesized under different conditions using lignocellulose as raw material and nanometer-sized by ultrasonic cell pulverizer.According to the different properties of the adsorbed heavy metal zinc ion and manganese ion,the heavy metal ion solution with different conditions was selected respectively,and the adsorption performance of zinc ion manganese ion was studied using Nano-LNC/MMT composite adsorbent material.In the study,the maximum adsorption capacity of zinc ions and manganese ions for the novel nanocomposites was determined and analyzed.The structure of nanocomposites was characterized by means of XRD,TEM,SEM,EDS,BET and FT-IR,and the changes of their structure and surface properties were analyzed to explore the various adsorption influencing factors of nanocomposites for different heavy metal ions.The adsorption performance of nano-lignocellulose/montmorillonite composite adsorbent and the practical application of adsorption range were discussed,which provided valuable laboratory reference data for the treatment of social industrial wastewater.Research content and results:Preparation of Nano-Lignocellulose: The nano-lignocellulose with the best effect of reaction with montmorillonite is fed back through the adsorption of zinc ions and manganese ions.The nano-lignocellulose under the optimal preparation conditions was characterized by its morphology.Through experiments,it was found that the nano-wood fiber had a ultrasonic power of 1080 W;the ultrasonic time was 150 min;the ultrasonic medium Na OH mass concentration was 20%;and the ultrasonic nano-fibrin was composited with montmorillonite when the ultrasonic temperature was below 30° C.The post-product adsorption of zinc ions and manganese ions compared to the product under other conditions.Preparation of Nano-Lignocellulosic/Montmorillonite Intercalation Layer Exfoliation Composites: The optimal conditions for the preparation of the composites were investigated by the adsorption capacity of nano-lignocellulose/montmorillonite composites for manganese and zinc ions.The resulting material was characterized by SEM,TEM,BET,XRD and FTIR.The experimental results show that when the montmorillonite and nano-lignocellulose intercalation reaction ratio is close to 1:1;Na OH mass concentration is 12.5%;the intercalation compound reaction temperature is 50°C;and the intercalation reaction time is 4h,the composite material is Mn-Zn.The adsorption of double ions tends to be at the limit of the current preparation conditions.The adsorption conditions of manganese ion and zinc ion in nano-lignocellulosic/montmorillonite intercalated and exfoliated composites were screened,and the kinetics and isothermal model analysis of the above two ions were performed to explore the adsorption mechanism:1)Search for the optimum adsorption conditions of manganese ion and zinc ion by changing the adsorption conditions.The experimental results show that the optimum adsorption conditions of manganese ion: initial concentration of manganese ion 900mg/L;adsorption temperature 55 ° C;adsorption time 120min;manganese ion solution p H The value of 5.8;optimum adsorption conditions of zinc ions: initial concentration of zinc ion 800 mg / L;adsorption temperature 60 °C;adsorption time 160min;zinc ion solution p H value of 4.7.2)Kinetic and isotherm model correlation tests for the adsorption of zinc ions and manganese ions,respectively.Kinetic model: Quasi-first-order kinetic equation;quasi-second-order kinetic equation;inward diffusion dynamics;Elovich dynamics.Isotherm model: Langmuir isotherm model;Freundlich isotherm model;Temkin isothermal model;Dubinin-Radushkecich isothermal model.In the kinetic model isotherm model experiments,the maximum adsorption capacity of nano-lignocellulose/montmorillonite composites for manganese ions can reach 513.48 mg/g,and the maximum adsorption capacity of nano-lignocellulose/montmorillonite composites for manganese ions can be achieved.628.05 mg/g was reached.3)Using different media for desorption of manganese and zinc ion-absorbing materials.Finally,hydrochloric acid is used as the desorption medium for both ions.Although the effect of nitric acid on desorption of ions is strong,the cyclic adsorption value of the materials after the desorption of nitric acid drops sharply.This is due to nitrification of nitric acid with lignocellulose,which reduces the ability of the material to adsorb ions.The experimental results show that the optimum desorption conditions of manganese ions: 0.06mol/L HCl solution;desorption time: 60min;desorption temperature 55°C.The optimum desorption conditions of zinc ion: 0.08 mol/L HCl solution;desorption time 60 min;desorption temperature 65°C.Under the optimal analytical conditions,the two ions were almost completely desorbed,and the cycle adsorption effect was little different from the initial adsorption.Scanning electron microscopy,EDS,and FT-IR were used to characterize the adsorbed and desorbed materials,respectively,and their structural changes were compared.