Highly efficient low‐cost zeolite for cobalt removal from aqueous solutions: Characterization and performance

Abstract

Cobalt is considered to be a strategic metal, with a high market value due to its scarcity and difficulty of extraction. Its concentration in wastewater is much higher than that recommended by environmental agencies. In this work, adsorption is the selected process for cobalt removal and recovery and the adsorbent, a commercial natural zeolite, was chosen because of its wide availability, low price, and adequate particle size. The zeolite employed was clinoptilolite according to XRD and FTIR results. Other techniques like XRF have helped to show that the zeolite treated with acid has suffered dealumination process while the zeolite treated with sodium has kept its Si/Al ratio and it has incorporated sodium into its structure. The optimization of the adsorption process has allowed to enhance the removal of cobalt up to a 21%, exchanging the bare zeolite with NaCl 1 M, and up to a 42%, increasing the temperature to 333 K. In relation to the mechanism, adsorption of cobalt on clinoptilolite is an endothermic and spontaneous process where both external and intraparticle diffusion take place. A pseudo‐second‐order model can adequately describe the adsorption kinetics. Regarding to adsorption equilibrium, it is better described by Double Langmuir isotherm model. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S352–S365, 2019

Characterization of a natural zeolite with inverse gas chromatography to assess its feasibility as adsorbent

“…The ratio S c = K D /K A is equal to 0.028, what indicates that the surface of clinoptilolite has mainly acidic properties. This is in agreement with the fact, as previously had been demonstrated, 40 that this solid is adequate for the removal of metallic cations from aqueous solutions.…”

H-Clinoptilolite as an Efficient and Low-Cost Adsorbent for Batch and Continuous Gallium Removal from Aqueous Solutions

“…The stirring rate was fast enough to assure an effective mass transfer. This point was confirmed in a previous work [26]. The pH was kept free (the one provided by the gallium solution with H-clinoptilolite) ensuring that it was below 3.6 to avoid the precipitation of metal ions.…”

Sorption capacity of seaweed-like sodium titanate mats for Co2+ removal

“…Previously, researchers studied the sorbents for Co 2+ removal, such as sodium titanates, zeolites, hydroxyapatite, and clay minerals. [4][5][6][7][8][9][10][11][12][13] In comparison with past reports, among the adsorbents composed of inorganic materials, SST has shown a relatively high sorption capacity for Co 2+ . There are two possible reasons why the sorption capacity of SST was higher than TC.…”

“…2,3 In recent years, some organic or inorganic materials have been proposed as adsorbents for Co 2+ removal from wastewater. [4][5][6][7][8][9][10][11][12][13] Furthermore, several heavy metals and radionuclides can be removed using inorganic ion exchangers. 14 Sodium titanate compounds are used as a purication material for the removal of heavy metal ions and radionuclides from industrial wastewater.…”