Study On The Preparation Of Cornstalk Carbon Materials And The Adsorption Properties Of Heavy Metals

Cornstalk is an abundant agriculture waste on earth,which can be used as as composite materials in different fields including electrode,sensor,catalysis,remediation of heavy metal pollution.In this study,pyrolysis kinetics of cornstalk was investigated at different temperature and different heating rate.The samples were characterized by?GA,BET,SEM and FTIR.And then the carbon derived from cornstalk was used as an adsorbent of heavy metals.The adsorption behaviors of the adsorbents are investigated,the main conclusions are as follows:?1?The pyrolysis temperature and the heating rate are the important factors affecting the cornstalk charcoal.The higher the temperature and the quicker the heating rate,the higher specific surface area is usually achieved.However,the more serious the structure is destroyed,too.According to the analysis of SEM,FTIR and kinetics,the preferred heating rate is 15 K·min^-1,and the pyrolysis temperature is 873 K.?2?Cornstalk charcoal can adsorb Cd²⁺and Pb²⁺well,and its adsorption capacity of Cr?VI?is not so good.In the case of the adsorption of Cd²⁺and Pb²⁺,the analysis of adsorption kinetics indicates that the adsorption capacity is determined mainly by the chemisorption which is accompanied by physical adsorption.In terms of the adsorption of Cr?VI?,physical adsorption is the main adsorption mechanism.?3?A gram-negative bacterium GLD cultivated in Lab can adsorb heavy-metal ions well.When it mixes with cornstalk charcoal to adsorb heavy metal ions,GLD can improve the adsorption capacity cooperatively.And its addition is also helpful to separate charcoal from heavy metal solution.Although,GLD can help to adsorb Cd²⁺and Pb²⁺well,its adsorption of Cr?VI?is not good enough.?4?Cornstalk charcoal modified with iron oxide or Sodium Dodecyl Benzene Sulphonate?SDBS?can adsorb Cr?VI?well.In the case of iron oxide,the more iron oxide adds,the better adsorption efficiency achieves.At the same time,the addition of iron oxide and SDBS accelerates the adsorption time.The max adsorption capacity can be achieved in 0.5 h.Subsequently,some Cr?VI?will desorb from cornstalk charcoal till a balance is formed.Chemisorption is the main factor to decide the adsorption capacity.