| At present,with the public's increasing demand for quality of life and the strengthening of environmental protection concepts,the treatment of environmental pollution has gradually entered the field of vision of the industry and scientific research circles,and various scientific researchers have carried out relatively sufficient research on this.At present,heavy metal pollution is one of the relatively large pollution sources in environmental pollution.One of the current research hinders is a comparative difficulty in environmental heavy metal content.Therefore,it is necessary to develop efficient environmental heavy metal detection techniques.In recent years,the excellent performance of biomass carbon/layered biohydrooxide(LDHS)composites in heavy metal pollution has been widely concerned by relevant researchers.In this paper,the Co Fe(Al)-LDHs@BC composite material was synthesized by pyrolysis and hydrothermal method,and the basic structure and shape of the material were analyzed using various XRD,SEM,TEM,FT-IR,BET,XPS and other characterization tests.The detection limit of the composite material to heavy metal ions in water was studied by electrochemical analysis method.Firstly,the biomass charcoal material was prepared by the pyrolysis method.Using hemp stalk as the biomass raw material,the biomass raw material was pyrolyzed in a tube furnace at 600?under a nitrogen atmosphere to obtain the biomass charcoal material.Secondly,the modified biomass charcoal material was prepared by the hydrothermal method.By adjusting the molar ratio of metal salt ions,hydrothermal reaction time,and hydrothermal reaction temperature,Co Fe-LDHs@BC composite materials with different molar ratios were prepared.The optimal hydrothermal synthesis condition of Co Fe-LDHs@BC composite material is 95?,and the reaction time is 8 h.The structure and morphology of composite materials are also different when the molar ratio of metal ions is different.Among them,the Co Fe-LDHs@BC2-1 composite material with a molar ratio of cobalt to iron of 2 has the largest specific surface area,which is 183.1 m2·g-1.A large number of Co Fe-LDHs particles accumulate on the surface and voids of biomass charcoal.The existence of defective oxygen and chemically adsorbed oxygen effectively enhances the active adsorption of the material,which is beneficial to the Co Fe-LDHs@BC material to effectively adsorb and trap heavy metal ions.Using square wave stripping voltammetry(SWVSV)in electrochemical workstation,the prepared composite material was used to detect heavy metal ions such as Pb(?),Cd(?),Cu(?),Hg(?)in water,and the results showed that Co Fe The detection limit of-LDHs@BC2-1for heavy metals is 1.568×10-10 mol·L-1,1.732×10-10 mol·L-1,9.563×10-11 mol·L-1,1.412×10-10 mol·L-1.All are nmol·L-1 level,and can realize the simultaneous detection of four heavy metal ions.Finally,using the same synthesis method as described above,a modified CoAl-LDHs@BC composite material was prepared.The results showed that the best hydrothermal synthesis conditions were 90?,and the hydrothermal reaction was 6 h.FTIR results clearly show that CoAl-LDHs@BC composites have functional groups such as OH,C-O-C,C=O,C=C,M-O-C,etc.These functional groups can be used as active binding sites to improve the material's adsorption of heavy metals in water.The SEM test shows that the CoAl-LDHs in the material are grown on the biomass charcoal in a flower-like structure.Among them,the CoAl-LDHs@BC2-1 material with a molar ratio of cobalt and aluminum of 2 has the best morphology.The BET result clearly shows that CoAl-LDHs@BC2-1 has the largest specific surface area,which is 168.4 m2·g-1,which is higher than the other two samples.The detection results of the three ions of Cd(?),Hg(?)and Pb(?)in the solution show that the detection limit of the best sample Co Fe-LDHs@BC2-1 for heavy metals is 1.568×10-10 mol·L-1,1.732×10-10 mol·L-1,9.563×10-11 mol·L-1,1.412×10-10mol·L-1,reaching the level of nmol·L-1,and can simultaneously detect three kinds of heavy metal ions. |
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