Adsorption of methylene blue and Congo red from aqueous solution by activated carbon and carbon nanotubes

Abstract

This study was conducted to determine the adsorption removal of dyes by powdered activated carbon (PAC, Norit) and multi-walled carbon nanotubes (MWCNTs, Chinese Academy of Science) from an aqueous solution. Methylene blue (MB) and Congo red (CR) were selected as model compounds. The adsorbents tested have a high surface area (PAC 835 m(2)/g, MWCNTs 358 m(2)/g) and a well-developed porous structure which enabled the effective treatment of dye-contaminated waters and wastewaters. To evaluate the capacity of PAC and MWCNTs to adsorb dyes, a series of batch adsorption experiments was performed. Both adsorbents exhibited a high adsorptive capacity for MB and CR, and equilibrium data fitted well with the Langmuir model, with the maximum adsorption capacity up to 400 mg/g for MB and 500 mg/g for CR. The separation factor, RL, revealed the favorable nature of the adsorption process under experimental conditions. The kinetics of adsorption was studied at various initial dye concentrations and solution temperatures. The pseudo-second-order model was used for determining the adsorption kinetics of MB and CR. The data obtained show that adsorption of both dyes was rapid in the initial stage and followed by slower processing to reach the plateau. The uptake of dyes increased with contact time, irrespective of their initial concentration and solution temperature. However, changes in the solution temperature did not significantly influence dye removal.

Recent Progress in Nanomaterials for Adsorptive Removal of Organic Contaminants from Wastewater

“…The kinetic study revealed that adsorption of both dyes was faster in initial stages and then become constant. The pseudo‐second order model describes the adsorption kinetics of both dyes . The magnetic nanoparticles gained much attention as they can be easily recovered from solution with the help of external magnet.…”

“…The pseudosecond order model describes the adsorption kinetics of both dyes. [16] The magnetic nanoparticles gained much attention as they can be easily recovered from solution with the help of external magnet. Recently, T. Ahamadand and his co-workers prepared amine functionalized MWCNTs by chemical modification method and then magnetic nanoparticles were embedded into it.…”

Congo Red Interactions with Single-Walled Carbon Nanotubes

“…It is therefore possible to form a non-covalent pi-pi interaction between CR molecules and the graphene surface of carbon nanotubes. Reports can be found in literature on the interaction of CR with carbon nanotubes [28][29][30][31] and the surface of graphene oxide [32,33].…”

“…In another paper [31] authors point to the possibility of using CNT for adsorbing dyes from aqueous solutions -in post-production wastes containing textile dyes. CR was used as a model compound in these studies and the results show an effective binding of CR by carbon nanotubes (with a maximum adsorption of 500 mg/g).…”

Dispersion of single-wall carbon nanotubes with supramolecular Congo red – properties of the complexes and mechanism of the interaction

“…A less known approach is based on the interaction of CNTs with a bis-azo dye – Congo red (CR) [27]. This original procedure was based on the prolonged (2 hours) manual grinding of CR and purified SWNTs in agate mortar with the addition of water to avoid agglomeration of dried CR powder.…”