| Biomass is a type of renewable resource,and the recycling of waste biomass has attracted wide attention from the academic circle.Compared with burning,pyrolysis is an effective means to recycle waste materials.Biomass pyrolysis products mainly include biochar,bio-oil and pyrolysis gas.Pyrolysis gas is rich in small molecular hydrocarbons.Here,carbon nanotubes(CNTs)were synthesized by chemical vapor deposition(CVD)method with pyrolysis gas used as the carbon source.It not only achieved the resource utilization of waste gas,but also reduced the economic cost of CNTs prepared by traditional CVD method.The waste gases from biomass pyrolysis were usually discharged into the atmosphere with carrier gas,causing air pollution.These gases often contained rich small molecules of hydrocarbons.In this study,the biomass pyrolysis gas was used as the carbon source to synthesize CNTs materials by using the rapid pyrolysis and slow pyrolysis coupling equipments,which the pyrolysis gas was fast produced in rapid pyrolysis and deposited on catalyst in slow pyrolysis.The whole experiment device and operation method were simplified by exploring the optimum conditions of CNTs,and the production of CNTs was also improved.We achieved a facile method for the synthesis of CNTs in 5 min via an uninterrupted fast pyrolysis of biomass,during which the pyrolytic gas was fast produced and deposited on nickel foam without further purification and reheating.On the basis of the systematic investigation on the effects of feedstocks(cellulose,lignin,and sawdust),pyrolysis temperature,and retention time,it was found that cellulose was the optimal precursor to produce considerable CNTs while the optimum temperature was at range of 700 to 800℃,and the conversion rate could reach 2.6%.The mechanism of influencing the growth of CNTs was explored by analyzing the composition of pyrolysis gas under different conditions,and result showed that the formation of CNTs mainly influenced by the composition and concentration of components of pyrolysis gas.Obviously,this study provided a new method for the rapid and economical synthesis of CNTs.The synthesis of CNTs showed efficient adsorption performance to carbamazepine(CBZ).The adsorption of CBZ was a rapid process,and the adsorption equilibrium could be achieved within 20 minutes.The adsorption isotherm of CNTs was investigated,according to the correlation coefficient,the two isotherm models of Langmuir and Freundlich can be consistent with the adsorption isotherm data.The maximum adsorption capacity of CNTs to CBZ reached 106.38 mg/g by model equation The removal ability of CNTs for CBZ,further demonstrated that CNTs prepared by one-step method in the laboratory has great prospects for environment application. |
