| Carbon nanotubes have superior adsorption properties for environmental pollutants,this phenomenon makes them cause wide public concern in water treatment field.Due to the improvement of the production process,the price of carbon nanotubes dropped significantly.Therefore,the environmental applicability of carbon nanotubes gradually are improved.Because carbon nanotubes is not easy to be separated in an aqueous environment,magnetic nanotubes?magnetic MWCNTs?are becoming more and more popular for researchers.Therefore,the adsorption performance of magnetic carbon nanotubes has become a research hotspot.In recent years,researchs on magnetic MWCNTs regeneration performance are gradually increasing.However,there are still relatively a few studies on the regeneration of magnetic MWCNTs by microwave extraction.Therefore,humic acid was used as the target pollutant to study the adsorption and removal of humic acid by self-made magnetic MWCNTs under different water conditions.Then,the saturated magnetic MWCNTs were regenerated by microwave extraction.Research indicates:?1?The dispersant polyethylene glycol 1000 is beneficial to the adsorption of humic acid on magnetic MWCNTs.The mass ratio of MMnFe2O4:MMWCNTs is 1:2,dosing percentage of the dispersant polyethylene glycol 1000 is 5%,the adsorption of humic acid on magnetic MWCNTs was the best.?2?The surface roughness of magnetic MWCNTs increased,which can be seen from SEM and TEM.The characteristic peaks of tetrahedral compounds appear in the FTIR spectra,indicating that MnFe2O4 was successfully attached to the surface of MWCNTs to generate magnetic MWCNTs.?3?The adsorption process of humic acid on magnetic MWCNTs accords with the pseudo second-order adsorption kinetic model,tending to multi-molecular layer adsorption,belonging to the spontaneous process of thermodynamics.?4?pH and coexisting cations have great influence on the adsorption of magnetic MWCNTs.The acidic condition favors the adsorption of humic acid,the removal efficiency of humic acid decreased under the alkaline conditions.Low concentration and high valence cations are favorable for adsorption of humic acid,high concentration of cations reduces humic acid removal,cations in same valence state have the same effect.?5?Adsorption humic acid by magnetic multi-walled carbon nanotubes to study the effect of regeneration time,temperature,extraction solvent ratio?volume ratio of methanol and acetic acid?and liquid-solid ratio?volume of liquid/mass of solid?on magnetic carbon nanotubes regeneration.The results showed that factors affecting the regeneration of magnetic multi-walled carbon nanotubes are ordered as follows:regeneration time,temperature,extraction solvent ratio,liquid-solid ratio.Organic regenerated solvents are more favorable for the regeneration of magnetic MWCNTs.After four regenerations,the magnetic MWCNTs still have a good adsorption effect.And the loss of magnetic MWCNTs is very low,but the number of regeneration should not exceed five times. |
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