Enhanced dispersion of carbon nanotubes in water by plasma induced graft poly(N,N-dimethylacrylamide) and its application in humic acid capture

Humic acid (HA) is the main culprit of producing the carcinogenic, teratogenic, and mutagenic halogenated alkanes. In present work, multi-walled carbon nanotubes (MCNT) were grafted N,N-dimethyl-acrylamide (NDMA) to enhance its type and concentration of the functional groups by using plasma technique. The MCNT/NDMA composites exhibit better dispersion property and higher HA adsorption efficiency. The addition of amide group could strongly enhance the HA adsorption property of MCNT due to less acidic of MCNT/NDMA (pH(pzc) = 5.0) than MCNT (pH(pzc) = 4.5). The results highlight the effect of pH values, ionic strength, Pb(II) concentrations and the Pb(II) addition sequences. HA adsorption by MCNT/NDMA obeyed the Langmuir isotherm model, attributed to an outer-sphere surface adsorption mechanism through pi-pi interactions and coordination of amide group to the functional groups on HA. The presence of Pb(II) significantly effects the HA adsorption in the three difference addition sequences due to different mechanisms. (C) 2018 Elsevier B.V. All rights reserved.