Catalytic Gasification Characteristics Of Activated Carbon Prepared By Hyperaccumulators

The phytoremediation technology has received extensive attention due to its low cost and the permanent effect of treatment,and has now entered a large-scale application.Along with the phytoremediation technology,a large number of products are produced,which is called hyperaccumulators.The hyperaccumulators contain a lot of heavy metal elements.If improperly disposed,the heavy metals in the plants will return to the ecological environment in various forms,causing pollution again.Therefore,it is very urgent to explore suitable disposal techniques for phytoremediation techniques.This paper firstly summarizes the traditional methods and new methods for the treatment of hyperaccumulators at home and abroad,analyses the advantages and disadvantages of different disposal methods.After combining the characteristics of hyperaccumulators,this paper proposes a new treatment of activated carbon from hyperaccumulators.The paper also explains the significance of the research and the application scenarios.The single factor experiment scheme was used to investigate the effects of pyrolysis time,pyrolysis duration,activation temperature,activation time and impregnation ratio on heavy metal migration during the preparation of activated carbon.The experimental results showed that the temperature had a great influence on the migration of heavy metals,and the heavy metal migration in the pyrolysis stage and the activation stage were not completely consistent.The stability of the pyrolysis stage was: Ni?Zn>Cu>Cr>Pb?Cd,the stability of the activation stage was: Cr>Zn>Pb>Ni?Cu>Cd.Among them,the stability of Cu and Ni decreased,and the stability of Cr increased.The addition of KOH could change the stability of some heavy metals during heating.The heat treatment can enrich the heavy metals in the bottom slag,which is beneficial to the utilization of heavy metals in the subsequent process.Choosing a suitable temperature can improve the economics of the process.The activated carbon prepared by hyperaccumulators was used as a catalyst for the original coal gasification,and the dynamic characteristics of the gasification catalysis were investigated by a microcomputer thermobalance.The results showed that the maximum gasification temperature decreased with the increase of active carbon addition ratio,and the activation energy also decreased in different proportions after adding activated carbon prepared by hyperaccumulators.The activated carbon prepared by different conditions and different raw materials was added to the raw coal as a catalyst.It was found that the catalytic performance of activated carbon prepared by hyperaccumulators was better than that of activated carbon prepared from ordinary biomass.The difference in catalytic performance is presumed to be caused by heavy metals in hyperaccumulators.Through the experiment of the tube furnace,it was found that under the gasification conditions of 700,800,and 900 °C,the carbon conversion rate of the raw coal was significantly improved after adding the activated carbon prepared by the hyperaccumulators.The higher the amount of addition,the higher the carbon conversion rate was.At 1 000 ° C,the carbon conversion rate of raw coal was 99.97%,so after adding activated carbon,the carbon conversion rate is basically unchanged.The gas production characteristics at 1000 ° C were also studied,and it is found that after adding 10% activated carbon prepared by the hyperaccumulators,the gas production quality of the raw coal is improved.Through the research in this paper,the effects of temperature,duration and impregnation on the migration of heavy metals during the preparation of activated carbon were preliminarily explored.And,the experiments of thermogravimetric and tubular furnaces also confirmed the gasification catalysis of activated carbon prepared by hyperaccumulators on coal.