Study On The Preparation And Activation Of Porous Boron Nitride And The Adsorption Characteristics Of Heavy Metals At High Temperature

In the process of incineration of solid waste,heavy metals will be enriched on fly ash particles or directly released by gas through migration and transformation,which will cause great pollution to the environment.In this paper,porous boron nitride materials with high specific surface area were prepared by precursor method.The adsorption characteristics of porous boron nitride on heavy metals in high temperature flue gas were studied on a self built experimental platform.The effect of different pore forming agents on the specific surface area of porous boron nitride was studied by adding pore forming agent,and the best pore forming agent and dosage were determined.The results show that the use of boric acid and melamine as boron source and nitrogen source in pyrolysis under the conditions of the prepared samples for the porous boron nitride materials,and the surface area>400m~2/g.The total adsorption amount of porous boron nitride at 250?centigrade high temperature is 15.9mg/g,and the amount of adsorption is 3.4times as much as that of activated carbon,that is indicated that the adsorption performance of porous boron nitride on heavy metals under high temperature is stronger than that of activated carbon.It is found that porous boron nitride has a strong adsorption selectivity for Zn,and the maximum adsorption capacity of Zn can reach 32.74mg/g.When the simulated atmosphere is Zn alone,the adsorption amount of porous boron nitride to Zn is still up to 40.425mg/g at250?.The adsorption capacity of porous boron nitride for heavy metals is less than that of heavy metals in the simulated flue gas by using the sludge incineration flue gas as a heavy metal atmosphere.The reason is that there are a large number of fine particles in the flue gas of sludge incineration,and porous boron nitride can adsorb a large number of fine particles while adsorbing heavy metals.By comparing the specific surface area,when the pore forming agent is ammonium sulfate and the amount of 30wt%is added,the specific surface area of porous boron nitride can reach 474.37m2/g.The porosity of porous boron nitride is not obvious by the prematurely decomposing gas of pore forming agent.Therefore,the higher the decomposition temperature of the pore forming agent,the higher the specific surface area of the porous boron nitride prepared.