A Highly Adsorptive Magnetic Biochar Prepared From Crayfish Shell For Adsorption Of Cu(Ⅱ) And Pb(Ⅱ) In Aqueous Solution

In recent years,with the acceleration of social development and the vigorous development of science and technology,people have begun to pay attention to environmental safety issues.In the early years,metallurgy,mining and other industries have been extensively developed.The consequent heavy metal pollution problems now need to be addressed.Because of its rich oxygen-containing functional groups and porous structure,biochar has excellent applications as an adsorbent,and the raw materials for preparing biochar are generally various wastes or scraps,so the cost is very low.Crayfish shell is a common waste on the dining table.Using it as an experimental raw material solves the problem of garbage disposal and can also make the waste reused.This article mainly studied the adsorption performance of potassium ferrate modified crayfish shell biochar for Cu(Ⅱ)and Pb(Ⅱ).Through a series of experimental exploration and characterization,the adsorption conditions and adsorption mechanism of biochar were investigated.The specific research content is as follows:(1)Preparation of modified biochar(MB)from crayfish shells by modification with potassium ferrate.Through the characterization of biochar materials,it is found that the biochar modified with potassium ferrate has strong magnetic properties,and can be easily separated from the aqueous solution after using the modified biochar to remove heavy metal ions in the aqueous solution;(2)The experiment explored the adsorption performance of biochar on Cu(Ⅱ)and Pb(Ⅱ)under different preparation conditions and different adsorption conditions.Through the study of the best adsorption conditions for Cu(Ⅱ)and Pb(Ⅱ),it was found that MB When the preparation temperature is 600 ℃ and the mass ratio of potassium ferrate to crayfish shell biomass is 1/1(g/g),the adsorption effect of biochar prepared is the best,the best adsorption effect when pH=4;(3)According to the kinetic fitting data,it is shown that when the biochar adsorbs Cu(Ⅱ)and Pb(Ⅱ),respectively,they are in line with the pseudo-second-order kinetic model,which indicates that the biochar has an effect on Cu(Ⅱ)and Pb(Ⅱ).Adsorption is mainly based on chemical adsorption;(4)According to the results of thermodynamic fitting data,the Langmuir isotherm model for the adsorption of Cu(Ⅱ)and Pb(Ⅱ)by biochar is more consistent with the fitting results,which shows that the adsorption of biochar on Cu(Ⅱ)and Pb(Ⅱ)The adsorption is mainly single-molecule adsorption.When adsorbing Cu(Ⅱ),MB600 can reach 417.05mg/g,and when adsorbing Pb(Ⅱ),the maximum adsorption capacity can reach 974.10 mg/g.The adsorption capacity of magnetic biochar MB600 for Cu(Ⅱ)and Pb(Ⅱ)exceeds most of the previous adsorption capacity of magnetic biochar;(5)The adsorption mechanism of biochar was studied by XPS,XRD,SEM and FTIR.The analysis showed that the adsorption of Cu(Ⅱ)and Pb(Ⅱ)by biochar was mainly through the interaction between calcium carbonate and carbon matrix on the biochar.Interaction with Cu(II)and Pb(II)for cation exchange and complexation reaction,so that Cu(II)and Pb(II)are precipitated on the magnetic biochar in the form of carbonate and oxide;(6)In the adsorption regeneration experiment,the magnetic biochar MB600 cannot be regenerated after adsorbing Cu(Ⅱ).MB600 has the ability to adsorb Pb(Ⅱ)after desorption with EDTA-Ca2 Na with a concentration of 0.5M;MB600 has good adsorption capacity for Cu(Ⅱ)and Pb(Ⅱ),and its high magnetic properties can be easily separated in the post-treatment part of adsorption.Therefore,the potassium ferrate-modified crayfish shell biochar MB600 has good application prospects.