Adsorption of mercury ions from synthetic and real wastewater aqueous solution by functionalized multi-walled carbon nanotube with both amino and thiolated groups

Abstract

The functionalization of multi-walled carbon nanotubes (MWCNTs) was using with ethylenediamine and cyanuric chloride and sodium 2-mercaptoethanol as efficient ways to introduce amine and thiol functional groups onto the nanotube sidewalls. The synthesized amino and thiolated MWCNTs were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). A series of batch adsorption experiments were conducted to study the effect of pH, dose, metal concentration and temperature on Hg(II) uptake by the functionalized, MWCNTs. The isotherm data were analyzed for possible agreement with the Langmuir than Freundlich models, while the equilibrium data were fitted better by Langmuir model. The pseudo-first-order and pseudo-second-order rate equations were tested on kinetic

Thermodynamic and kinetic study of the intrinsic adsorption capacity of graphene oxide for malachite green removal from aqueous solution

“…The negative value of Gº for all temperatures indicates that the adsorption is a spontaneous process 38 .One can note that Gº values above -20 kJ/molare an indicator of physisorption, while values more negative than -40kJ/mol indicate chemisorption.When Gº is in the range between -20 and -40kJ/mol, both physisorption and chemisorption occur 1 .In this study, the Gº valuesare in between -20 and -40kJ/mol, indicating that the sorption process can be explained by taking both physisorption and chemisorption into consideration. The negative value of Sº indicates a tendency to lower disorder at the solid-solution interface during adsorption 57 .In addition, the negative value of Hº indicates that dye adsorption using GO is exothermic nature. At high temperature the thickness of the boundary layer decreases due to the increased tendency of the dye molecules to escape from the adsorbent surface to the solution, which results in a decrease in the adsorption capacity as the temperatureincreases 56 .…”

Engineered nanomaterials for water treatment and remediation: Costs, benefits, and applicability

“…Adsorption of heavy metals by C-ENMs has been reported in several studies [8,32,[405][406][407][408]. Metal adsorption capacities of pristine CNTs is quite low, but may be significantly improved by functionalization [409][410][411]. Functionalization increases the number of oxygen, nitrogen or other groups on the surface of CNTs, and also improves their dispersability, and thus, specific surface area [412,413].…”

“…2 As an example, using SWCNTs to remove lead (Pb) in water via adsorption could cost an average of $2.2/g-Pb, 3 assuming an average adsorption capacity of 75 mg-Pb/g-CNT and considering only the cost of the SWNCTs. The cost may be reduced by several factors since many C-ENMs may be recoverable and reusable several times [30,410,480]. CNTs are relatively more expensive than most other engineered nanomaterials; hence, C-ENM remediation/treatment may be rather expensive.…”

Adsorption Capacity of The As-Synthetic Graphene Oxide for The Removal of Alizarin Red S Dye from Aqueous Solution

“…Under the steady-state reaction condition, the negative DGº indicates the spontaneity of the ongoing adsorption process 30 . The negative value of DSº indicates a tendency to lower disorder at the solid-solution interface during the adsorption 31 .…”