Elevated Adsorption of Lead and Arsenic over Silver Nanoparticles Deposited on Poly(amidoamine) Grafted Carbon Nanotubes

Abstract

An efficient adsorbent, CNTs–PAMAM–Ag, was prepared by grafting fourth-generation aromatic poly(amidoamine) (PAMAM) to carbon nanotubes (CNTs) and successive deposition of Ag nanoparticles. The FT–IR, XRD, TEM and XPS results confirmed the successful grafting of PAMAM onto CNTs and deposition of Ag nanoparticles. The absorption efficiency of CNTs–PAMAM–Ag was evaluated by estimating the adsorption of two toxic contaminants in water, viz., Pb(II) and As(III). Using CNTs–PAMAM–Ag, about 99 and 76% of Pb(II) and As(III) adsorption, respectively, were attained within 15 min. The controlling mechanisms for Pb(II) and As(III) adsorption dynamics were revealed by applying pseudo-first and second-order kinetic models. The pseudo-second-order kinetic model followed the adsorption of Pb(II) and As(III). Therefore, the incidence of chemisorption through sharing or exchanging electrons between Pb(II) or As(III) ions and CNTs–PAMAM–Ag could be the rate-controlling step in the adsorption process. Further, the Weber–Morris intraparticle pore diffusion model was employed to find the reaction pathways and the rate-controlling step in the adsorption. It revealed that intraparticle diffusion was not a rate-controlling step in the adsorption of Pb(II) and As(III); instead, it was controlled by both intraparticle diffusion and the boundary layer effect. The adsorption equilibrium was evaluated using the Langmuir, Freundlich, and Temkin isotherm models. The kinetic data of Pb(II) and As(III) adsorption was adequately fitted to the Langmuir isotherm model compared to the Freundlich and Temkin models.

Study on adsorption of hexavalent chromium by composite material prepared from iron-based solid wastes

“…It indicates that the kinetics of Cr(VI) adsorption by NMC-2 is more consistent with the pseudo second kinetic model. Therefore, it indicates that the kinetics of Cr(VI) adsorption by NMC-2 is more consistent with the pseudo second kinetic model, which further indicates that the process is a chemisorption process involving electron sharing or electron exchange, and the adsorption rate is controlled by chemisorption 29 – 31 . Also, this conclusion is in agreement with those obtained by other scholars using other adsorbents for Cr(VI) removal 19 , 21 , 32 .…”

Removal of Lead from Wastewater Using Synthesized Polyethyleneimine-Grafted Graphene Oxide

“…The maximum adsorption capacities (q m ) of Pb 2+ by PEI/GO and some other adsorbents are summarized in Table 8 . Compared to other reported adsorbents (commercial activated carbons [ 40 , 41 , 42 , 43 , 44 ], waste-based adsorbents/biosorbents [ 8 , 9 , 10 , 11 , 12 , 13 , 45 , 46 ], clays [ 47 , 48 , 49 ], magnetic nanoparticles [ 50 ], CNT composites [ 51 ], and silica-based sorbents [ 52 , 53 ], PEI/GO showed an excellent Pb 2+ adsorption capacity, and this can be attributed to the distinguished features of PEI/GO and, thus, the variety of possible adsorption mechanisms (eight possible interactions between Pb 2+ and PEI/GO), as mentioned earlier ( Figure 14 ).…”

Facilitated Adsorption of Mercury(II) and Chromium(VI) Ions over Functionalized Carbon Nanotubes

“…The ATR–FTIR spectrum of CNTs–COOH ( Figure 1 a) exhibited the bands at 612 and 1634 cm −1 corresponding to the A2u and E1u phonon modes of CNTs [ 53 ]. It showed the band due to the O–H bonds at 3360 cm −1 and the band of C=O bonds of –COOH groups existing over the surface of CNTs at 1698 cm −1 [ 54 ].…”