The slag from the extraction processes of metals from their ores may contain valuable components that, if adequately recovered, can be reintroduced in the technological life cycle.

Commercially available oxidized (carboxylic groups) and nonoxidized multiwalled carbon nanotubes were studied as adsorbents of cerium(III) in batch operation mode. Several variables affecting the rare earth adsorption were investigated, including: the stirring speed applied to the system, the pH of the solution, and the metal concentration and carbon dosages. Although the removal of cerium from the solution is different and dependent upon the adsorbent type—(i) adsorption in nonoxidized multiwalled carbon nanotubes, (ii) cation exchange in the case of using oxidized multiwalled carbon nanotubes—the adsorption kinetics, the rate law and the isotherm models are the same for both adsorbents: pseudo-second order, film diffusion, and Langmuir Type-1, respectively. Cerium is desorbed from loaded adsorbents using acidic solutions.

Spark ablation coupled with excitation in an argon inductively coupled plasma is applied to the analysis of remelted ferrovanadium. A medium-voltage spark at a high-repetition rate was used as the sampling technique for samples prepared using a high-frequency remelting system. Problems of sample fracturing were avoided by dilution of the ferroalloy with pure iron. Calibration graphs were obtained with samples prepared from a commercial ferrovanadium alloy, previously analysed using standard wet chemical methods and diluted with pure iron at two different dilution ratios. The two FeV to Fe dilution ratios were selected in order to cover the desired range of concentrations. When using an Fe line as the internal standard, the relative standard deviations for the major element (V) are below 0.3% (V content, 35-80°/0). The limits of determination for the minor elements (Mn, Cu, Al and Si) are below the required IS0 specifications. The accuracy of the developed method was tested by the analysis of three reference materials.

The behavior of oxidized and non-oxidized multiwalled carbon nanotubes (MWCNTs) in the adsorption of lanthanum(III) from aqueous solutions is described. Metal uptake is studied as a function of several variables such as the stirring speed of the system, pH of the aqueous solution and metal and nanomaterial concentrations. The experimental results are fitted to various kinetic and isotherm models, the rate law being fitted to the film diffusion and particle diffusion models, when the non-oxidized and the oxidized nanomaterials are used to remove lanthanum from the solution, respectively. Sulfuric acid solutions seem to be appropriate to recover the metal from La-loaded nanomaterials.

The behaviour of oxidized and non-oxidized multiwalled carbon nanotubes in the adsorption of lanthanum(III) from aqueous solutions is described. Metal uptake is studied as a function of several variables such as the stirring speed of the system, pH of the aqueous solution and metal and nanomaterial concentrations. The experimental results are fitted to various kinetics and isotherm models, being the rate law fitted to the film diffusion and particle diffusion models, when the non-oxidized and the oxidized nanomaterials are used to remove lanthanum from the solution, respectively. Sulphuric acid solutions seem to be appropriate to recover the metal from La-loaded nanomaterials.