Removal of Cr(VI) from Waters by Multi-Walled Carbon Nanotubes: Optimization and Kinetic Investigations

Abstract

The adsorption of chromium(VI) from aqueous solutions onto multi-walled carbon nanotubes (MWCNTs) has been investigated under various experimental conditions of initial metal concentration, agitation speed, aqueous pH, temperature and adsorbent dosage to assess the equilibrium and kinetic parameters. It was found that the kinetic data were fitted with the pseudo-first-and pseudo-second-order models, whereas the chromium(VI) adsorption data were fitted with the Langmuir and Freundlich equilibrium models to give the characteristic parameters of each model. According with the evaluation, both isotherm models are useful to represent the measured adsorption data. The adsorption of chromium(VI) is also dependent on the temperature, and the corresponding thermodynamic parameters including ΔH°, ΔG° and ΔS° were estimated from the experimental data, indicating the exothermic and non-spontaneous nature of the metal adsorption onto the MWCNTs. Chromium(VI) desorption was investigated by the use of aqueous hydrazine sulfate solutions.

Adsorption of reduced chromium(VI) ions by vitamin C tablets onto a tellurato‐functionalized cellulose derivative and its composite with Cyanobacteria green algae in aqueous media

“…Table 6 lists the uptake of Cr(VI) ions reported in the literature for a variety of different sorbents. [67][68][69][70][71][72][73][74][75][76] This comparison does not truly reflect the relative adsorption performances; however, as other parameters such as the nature of sorbents (functional groups) and adsorption conditions (pH, temperature, sorbent dose, time, and initial concentration of adsorbate) play a role. In the present study, Cr(VI) was reduced to Cr(III) ions using the ecofriendly vitamin C Tablets as a source of ascorbic acid, that is, the methodology applied in this study was efficient for…”

On the Adsorption of Cerium(III) Using Multiwalled Carbon Nanotubes

“…From several years ago, we have used the two particular adsorbents mentioned below in the removal of several metals from aqueous solutions [4,[34][35][36][37][38]. The reason is that both materials are easily accessible in the market and, based in our experience, represented good alternatives with respect to other adsorbents, at least in terms of availability and price.…”

New Bioadsorbent Derived from Winemaking Waste Cluster Stalks: Application to the Removal of Toxic Cr(VI) from Liquid Effluents

“…Several techniques for chromium removal from wastewaters have been reported, including chemical precipitation [8], electrochemical precipitation [9], solvent extraction [10], ion exchange [11], and adsorption process [5,12,13]. Due to its simplicity, effectiveness, and low cost, the adsorption process has been extensively investigated for metal removal from aqueous solutions.…”