This paper describes the effect of surface nanomodification of porous adsorbents. Two commercial activated carbons (ACs), AG-5 and NWC coconut shell based, were used as adsorbents. The adsorbents were modified with carbon nanotubes (CNTs) by chemical vapour deposition. The CNTs were synthesized in the presence of a metal-oxide catalyst prepared using a citrate solgel method. The concentration of metal ions was evaluated by a spectrophotometric method. Experimental results show that the nanomodification of ACs increased their equilibrium adsorption of heavy metals (Ni²⁺ and Co²⁺) by 10–30%. Besides, the adsorption behaviour of these metal ions on the standard and nanomodified ACs was determined based on adsorption isotherms. A theoretical description of the adsorption mechanism is presented, and equilibrium constants were calculated. Experimental data on the adsorption of the heavy-metal ions on the nanomodified carbons were successfully fitted to the Langmuir and Freundlich models.

The batch sorption kinetics described by a nonlinear equation with a variable equilibrium parameter for the interface was considered. It was shown that a difference equation of this type can...

This paper considers the synthesis of a novel nanocomposite based on reduced graphene oxide and oxidized carbon nanotubes modified with polyaniline and phenol-formaldehyde resin and developed through the carbonization of a pristine aerogel. It was tested as an efficient adsorbent to purify aquatic media from toxic Pb(II). Diagnostic assessment of the samples was carried out through X-ray diffractometry, Raman spectroscopy, thermogravimetry, scanning and transmission electron microscopy, and infrared spectroscopy. The carbonized aerogel was found to preserve the carbon framework structure. The sample porosity was estimated through nitrogen adsorption at 77 K. It was found that the carbonized aerogel predominantly represented a mesoporous material having a specific surface area of 315 m²/g. After carbonization, an increase in smaller micropores occurred. According to the electron images, the highly porous structure of the carbonized composite was preserved. The adsorption capacity of the carbonized material was studied for liquid-phase Pb(II) extraction in static mode. The experiment results showed that the maximum Pb(II) adsorption capacity of the carbonized aerogel was 185 mg/g (at pH 6.0). The results of the desorption studies showed a very low desorption rate (0.3%) at pH 6.5 and a rate of about 40% in a strongly acidic medium.

The possibility of deriving a model of the kinetics of batch sorption processes is considered by transforming a nonlinear difference kinetic equation with a nonconstant equilibrium parameter...

The present paper describes an investigation of the adsorption of lead ions (Pb²⁺) on graphene-based nanocomposites obtained via exfoliation of hydrolyzed expanded graphite intercalation compound. Three types of these nanocomposites - suspension of graphene nanoplatelets (SGN), paste of multi-layered oxidized graphene (PMOG), and paste of few-layered oxidized graphene (PFOG) - were used to extract Pb²⁺ from 1,040 mg L^-1 aqueous solutions of Pb (NO₃)₂, and the kinetic of the Pb²⁺ adsorption was studied. It was found that the kinetic data are best fitted by the pseudo-second-order model. The adsorption equilibrium was achieved within 30 min under normal conditions. The maximum Pb²⁺ adsorption capacity of SGN, PMOG and PFOG was found to be 457, 103 and 38 mg g^-1, respectively. Considering the obtained results, it can be assumed that the phenolic and hydroxyl oxygen-containing functional groups located at the surface of the adsorption materials under study play an important role in the Pb²⁺ removal process.