Effect Of Humic Acid Source And Extraction Times On Dispersion Of Carbon Nanotubes

Dispersion of carbon nanotubes(CNTs)can greatly affect their environmental behaviors and risks.In nature,natural organic molecular mixing system plays a controlling role in the dispersion of CNTs.However,the composition and structure of natural organic matter and its effect on the dispersion of CNTs are different from the effect of single dispersant system on the dispersion of CNTs,and there are still insufficient studies on the correlation between them.In this study,humic acid(HAs)extracted from different soils of Heilongjiang black soil(B-HAs),Yunnan red soil(R-HAs)and Shandong yellow soil(Y-HAs)was used as experimental samples.The structure,composition and molecular weight distribution of HAs extracts were determined by elemental analysis,ultraviolet spectrophotometry,¹³C NMR,and high performance liquid phase.On this basis,we correlated the dispersion of CNTs in the mixed organic molecular systems,identified the dominant factors of the dispersion mechanism,and established a new correlation standard between the component diversity index and the dispersion characteristics of CNTs in the mixed organic molecular systems using statistical Shannon-Weiner index.The results showed that the dispersion of multi-walled carbon nanotubes(MH)was positively correlated with the aromaticity of HAs.B-HAs(r=0.98,p<0.05),R-HAs(r=0.90,p<0.05),Y-HAs(r=0.99,p<0.05)were negatively correlated with adiposity.Y-HAS(r=0.96,p<0.05)indicated that the aroma of natural organic matter in the mixed system with the same soil origin played a leading role in the dispersion of CNTs.However,for relatively complex mixed systems,the dispersion of CNTs between different sources of humic acids was not associated with aromatic or fatty properties(r=0.37,p=0.22).With statistical parameters for description of the system components of diversity,the results show that,for different sources of humic acid diversity index and hydroxylation multi-walled carbon nanotube suspension of carbon nanotubes(MH)research was a B-HAs the same(r=0.97,p<0.05),R-HAs(r=0.97,p<0.05),the Y-HAs the(r=0.95,p<0.05),and for the same source from the diversity index and MH suspended also appear positive correlation(r=0.89,p<0.001),therefore,Diversity index can be used as an evaluation method to evaluate the effect of MH suspension.This study will establish a theoretical and methodological reserve for environmental behavior prediction and risk assessment of carbon-based nanomaterials.