Recovery of cobalt from dilute aqueous solutions using activated carbon–alginate composite spheres impregnated with Cyanex 272

Abstract

A novel adsorbent was designed for selective recovery of cobalt(II) from synthetic binary cobalt(II)-nickel(II) and cobalt(II)-manganese(II) solutions, a synthetic multi-element solution and a real aqueous waste stream from the petrochemical sector. The adsorbent consisted of shaped activated carbon-alginate spheres impregnated with Cyanex 272. The synthesis was followed by characterisation using SEM, infrared spectroscopy, BET analysis and elemental analysis. Good selectivity for cobalt(II) over nickel(II) could be achieved during adsorption, while this was not the case for cobalt(II) over manganese(II). Cobalt(II) and manganese(II) were therefore fully adsorbed and stripped using a dilute sulphuric acid solution. The adsorbent was shown to be reusable in a column setup. Finally, the adsorbent material was used for the purification of a real aqueous waste stream from the petrochemical sector.

Selective recovery and separation of rare earth elements by organophosphorus modified MIL-101(Cr)

“…It can be seen from Fig. 3a that an increase in pH enhances the adsorption capacities of MIL-101-C50 and MIL-101-H50, indicating that the functional groups of HDEHP and Cyanex-272 can be deprotonated and exchanged with Er 3+ ions [50]. The pK a values of HDEHP and Cyanex-272 in pure water are reported to be 2.75 and 3.73 [57][58][59], respectively, signifying stronger acidity of HDEHP than Cyanex-272.…”

“…Possible changes in the structure and morphological properties of MIL-101-C50 were, however, not detected from XRD data and SEM images. The observable divergence of adsorption and desorption branches at low-pressure (p/p 0 < 0.42) of N 2 sorption isotherm may indicate specific interactions between nitrogen and alkyl chains [47][48][49][50] of grafted Cyanex-272. However, the complex interactions prevented reliable estimates of the pore size and volume.…”

“…The bands at 1071 and 1048 cm − 1 of MIL-101-C50 can be attributed to symmetric P-O stretching. At lower frequencies, all phosphorous-grafted adsorbents showed a sharp peak in the range of 960-908 cm − 1 , which can be ascribed to P-O stretching [50][51][52][53]. The presence of these new peaks in the structure provides strong evidence for successful functionalization of MIL-101.…”

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.…”