The Effect Of Ionic Charge To Carbon Nanotubes Suspension By Chemical Flocculation

With the widespread use of nano materials,nanomaterials inevitably enter the natural water.Studies have shown that nanomaterials are ecologically toxic and threaten biological health.However,the current water quality standards do not limit the nanoparticles.Therefore,it is necessary to study the removal efficiency and the influencing factors of nanoparticles in drinking water treatment.This paper chooses MWCNTs as the target pollutant,respectively with twelve sodium dodecyl benzene sulfonate(SDBS),sixteen alkyl three methyl bromide(CTAB)and octyl phenyl polyoxyethylene ether(TX-100)three dispersants were prepared by dispersing MWCNTs s suspension.And the effects of p H,Na Cl concentration and cation,such as Na+,Ca2+,Mg2+,anions such as SO42-,and HPO42-,HCOO-(OOCCHOHCHOHCOO)2-to three MWCNTs suspension flocculation destabilization effect and effective coagulant destabilization range(ECR),and the results are analyzed.PH has an important influence on the flocculation and destabilization of three kinds of MWCNTs suspensions.For the SDBS-MWCNTs and TX100-MWCNTs systems,the removal rate of MWCNT with the amount of PAC(PAC)is inverted "U" when p H=4.0 and p H=7.0 are used,and there is no stabilization phenomenon in p H=11.0.ECR becomes wider as p H rises.For the CTAB-MWCNTs system,with the change of p H gradually increased,no ECR was found.The critical concentration concentration(CCCs)of NaCl for SDBS-MWCNTs,CTAB-MWCNTs and TX-100 MWCNTs is about 70,29 and 20 mmol/L.The addition of electrolyte Na Cl can effectively change the flocculation interval of MWCNTs suspension.The influence of Na Cl on flocculation of three kinds of MWCNTs suspensions accords with DLVO theory.With the increase of concentration,the ability of compressive double layer increases,and the removal rate of MWCNTs increases and ECR becomes wider.With the addition of Ca2+ and Mg2+,the stability of the three kinds of MWCNTs decreased and the particle size increased.For SDBS-MWCNTs and CTAB-MWCNTs,the addition of Ca2+ and Mg2+ resulted in a decrease in MWCNTs removal and a narrowing of ECR.However,the removal rate of TX100-MWCNTs suspension increases and ECR becomes wider.For SDBS-MWCNTs and TX100-MWCNTs,HPO42-added made the MWCNTs Zeta,potential decreased most,other anion drops slightly to Zeta potential of MWCNTs,adding HCOO-ECR narrowed,remaining were able to make the MWCNTs anionic flocculation destabilization interval becomes wider,non inverted "U" curve,but HPO42-decreased the removal rate of water..For CTAB-MWCNTs,the high valent anion increased the particle size of CTAB-MWNCTs increased from 300 nm to about 5000 nm.Except for HCOO-,the removal rate of CTAB-MWCNTs was obviously increased by added other anions,and no ECR was found.