Study on Adsorption Performance of Modified Cotton Stalk Based Biochar for Heavy Metal Pollutants in Soil
In this study,acid-modified and alkali-modified biochar was prepared from cotton straw,and its morphology,struc-ture and adsorption properties were characterized.By SEM analysis,under the magnification of 2000 times,it was observed that the pore structure changed,more micropores and mesopore appeared,and the adsorption sites increased,which promoted the diffusion of adsorbants between pores.By infrared spectrum analysis,it can be seen that acid modification increases the number of carboxyl functional groups and the acid-binding sites for adsorbing pollutants.Alkali modification increases the number of hydroxyl functional groups,increases the degree of conjugation,and promotes adsorption.In atomic fluorescence and inductively coupled plasma mass spectrometry,the adsorption rate of modified biochar mixed with soil for heavy metal ions is greatly improved compared with that of the original soil mixed with soil,and the adsorption saturation will eventually be reached,with the maximum adsorption rates for As3+,Hg2+,Pb2+and Cd2+reaching 69.5%,98.9%,79.5%and 59.7%,respectively.The experimental results show that the modified cotton stalk based biochar has a good adsorption effect on the main heavy metal ions in soil,and has application value in soil remediation.
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