Study On Preparation Of Activated Carbon From Rice Husk And Co-production Of Zeolite X

In recent years,with the rapid development of science and technology,rice husk activated carbon has been widely used in pharmaceutical,environmental,adsorption,energy and other fields.However,in the process of producing rice husk activated carbon,a large amount of waste liquid is inevitably generated.These waste liquids are directly discharged,which will pollute the water and then affect people’s living environment.Therefore,it has become a new direction of rice husk activated carbon industrialization research to establish a green and environmentally friendly preparation process,reduce production cost,improve product income and reduce environmental pollution.In order to develop the environmentally friendly production process of rice husk activated carbon,this paper prepared rice husk activated carbon with high specific capacitance.At the same time,zeolite X was synthesized by using the waste liquid containing silicon in the preparation process to reduce the waste liquid discharge and waste of the silicon resources.This green production process solved the environmental pollution caused during the preparation process and realized the recycling of waste liquid.In this paper,rice husk activated carbon was prepared by the steps of carbonization,alkali boiling,and activation.The effects of activation temperature,activation time,and activated alkali/carbon ratio on the pore structure and specific capacitance of rice husk activated carbon were investigated.Zeolite X were synthesized from waste liquid in the alkali boiling process.The effects of crystallization temperature,crystallization time and material ratio on Ca²⁺exchange performance of zeolite X were studied.The main research results were as follows:（1）The results showed that different activation temperatures,activation times,and activation alkali/carbon ratios affected the pore structure and specific capacitance of rice husk activated carbon.The impact of the activation alkali-carbon ratio was the most pronounced of these.The greatest specific surface area of the rice husk activated carbon-3（RHAC-3）was 2447m² g^-1when the mass ratio of the activator to the template carbon was 3:1.All rice husk activated carbon was tested electrochemically in 6 mol L^-1 of KOH electrolyte,RHAC-3 exhibited the best electrochemical performance.The specific capacitance of RHAC-3 is 246.27 F g^-1 at a scan rate of 5 m V s^-1.Even at a high scan rate of 200 m V s^-1,RHAC-3 achieves a specific capacitance of110.59 F g^-1.This demonstrates the good electrochemical performance of RHAC-3.A constant current charge/discharge test was performed on RHAC-3 in a two-electrode system.With a current density of 0.2 A g^-1,it has a specific capacitance of 253 F g^-1.When the current density is up to 5 A g^-1,the capacitance retention rate is remained at 82.4%,showing good rate performance.（2）Preparation of silica with 98.97%purity from the wastewater in the preparation of rice husk activated carbon,using this as the basic material,zeolite X was successfully prepared by hydrothermal synthesis.The optimal conditions were obtained by single factor analysis methods,the crystallization temperature was 90℃,the crystallization time was 18 h,the ratio of Si O₂/Al₂O₃ was 3.6,the ratio of Na₂O/Si O₂ was 1.0,and the ratio of H₂O/Na₂O was 30.（3）An environmentally friendly preparation process from rice husk to the rice husk activated carbon cooperative produce zeolite was proposed,as well as the economic analysis of the manufacturing process was performed.During the preparation of rice husk activated carbon with large specific capacitance,the high added-value materials such as zeolite X,H₂,Cl₂were obtained by using wastewater,meanwhile,it was possible to recycle the Na OH activator and distilled water.When compared to the regular production method,cooperative production process has advantages such as higher profitability,less pollution,and environmental protection.The eco-friendly technology for preparation of rice husk activated carbon co-production zeolite was feasible both technically and economically.