Adsorption Of 1-naphthylamine Research Articles

Synthesis of water-dispersible Fe3O4@β-cyclodextrin by plasma-induced grafting technique for pollutant treatment

A novel methodology for the synthesis of the water-dispersible Fe3O4 particles modified by β-cyclodextrin (denoted as Fe3O4@β-CD) was proposed using N2 plasma-induced grafting technique. The Fe3O4@β-CD composites were applied in the removal of inorganic and organic pollutants from aqueous solutions. The characteristic results of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that β-CD was grafted onto Fe3O4 particles. The grafted β-CD on Fe3O4 particles contributed to an enhancement of the adsorption capacity because of the strong abilities of the multiple hydroxyl groups and the inner cores of the hydrophobic cavity in β-CD to form complexes with metal ions and organic pollutants. The Fe3O4@β-CD composites had good dispersion in water and could be separated from solution by magnetic separation. The adsorption of 1-naphthylamine on the Fe3O4@β-CD composites was dependent on pH and ionic strength. The results indicate that the Fe3O4@β-CD composites are the promising material for the separation and preconcentration of inorganic and organic pollutants from aqueous solutions in environmental pollution cleanup.

Removal of 1-naphthylamine from aqueous solution by multiwall carbon nanotubes/iron oxides/cyclodextrin composite

The adsorption of 1-naphthylamine on multiwall carbon nanotubes/iron oxides/β-cyclodextrin composite (denoted by MWCNTs/iron oxides/CD) prepared by using plasma-induced grafting technique was investigated by batch technique under ambient conditions. The effect of contact time, pH, adsorbent content, temperature and initial 1-naphthylamine concentration, on 1-naphthylamine adsorption to MWCNTs/iron oxides/CD was examined. The adsorption of 1-naphthylamine on MWCNTs/iron oxides/CD was dependent on pH, adsorbent content, and temperature. The 1-napthylamien was adsorbed rapidly at the first 50 h, and thereafter attained the adsorption saturation at 80 h. The adsorption kinetic data were well described by the pseuso-second-order rate model. The adsorption isotherms were fitted by the Langmuir model better than by the Freundlich model. The maximum adsorption capacity of 1-naphthylamine was 200.0 mg/g. The adsorption thermodynamic parameters of standard enthalpy (Δ H 0), standard entropy changes (Δ S 0), and standard free energy (Δ G 0) were calculated from temperature dependent adsorption isotherms. The values of Δ H 0 and Δ G 0 suggested that the adsorption of 1-naphthylamine on MWCNTs/iron oxides/CD was endothermic and spontaneous. The electron-donor–acceptor interaction, Hydrophobic interaction, and Lewis acid–base interaction may play an important role in 1-naphthylamine adsorption. The results show that MWCNTs/iron oxides/CD is a promising magnetic nanomaterial for the preconcentration and separation of organic pollutants from aqueous solutions in environmental pollution cleanup.

Kinetics and thermodynamics of adsorption of ionizable aromatic compounds from aqueous solutions by as-prepared and oxidized multiwalled carbon nanotubes

The adsorption of 1-naphthylamine, 1-naphthol and phenol on as-prepared and oxidized multiwalled carbon nanotubes (MWCNTs) has been investigated. The results illustrated that both as-prepared and oxidized MWCNTs showed high adsorption capacity for the three ionizable aromatic compounds (IACs) studied. Oxidation of MWCNTs increased the surface area and the pore volume, and introduced oxygen-containing functional groups to the surfaces of MWCNTs, which depressed the adsorption of IACs on MWCNTs. Both Langmuir and Freundlich models described the adsorption isotherms very well and the adsorption thermodynamic parameters (DeltaG degrees, DeltaH degrees and DeltaS degrees) were measured. The adsorption for 1-naphthylamine, 1-naphthol and phenol is general spontaneous and thermodynamically favorable. The adsorption of phenol is an exothermic process, whereas the adsorption of 1-naphthylamine and 1-naphthol is an endothermic process. Results of this work are of great significance for the environmental application of MWCNTs for the removal of IACs from large volume of aqueous solutions.

Acidity of Zeolite Y—Probed by Adsorption of 1-Naphthylamine and Studied by Laser-Induced Fluorescence Spectroscopy

Proton transfer reactions between zeolite Y surface and 1-naphthylamine (NA) in the ground and excited states have been studied by laser-induced picosecond spectroscopy. The acidic form of zeolite Y readily protonates NA in the ground state. At low acid strength of the zeolite the excited state of the protonated NA transfers back the proton to the zeolite surface as indicated by the fluorescence spectra. At high acid strength of the zeolite the fluorescence comes from the protonated form of NA and from an adduct “X” previously found in highly concentrated HClO4 solutions. The concentrations of the protonated NA and X increase with the reduction in the unit cell size. The presence of these species is discussed in terms of the next nearest neighbor “NNN” theory of zeolite Y acidity and the role of the non-framework aluminum. The acidity of the zeolite is estimated, based on the fluorescence lifetimes of X, to vary from 3.7 to 17 M HClO4 depending on the unit cell size. Low loading levels of NA in the zeolite pores are best in studying the proton transfer reaction and for the estimation of the surface acidity of zeolite Y.