The aim of this paper was to propose and test a continuous cobalt recovery process from waste mobile phone batteries. The procedure started with dismantling, crushing, and classifying the materials. A study on leaching with sulfuric acid and hydrogen peroxide was carried out with subsequent selective separation of cobalt by means of liquid–liquid extraction. The best extraction conditions were determined based on a sequence of experiments that consisted of selecting the best extractant for cobalt, then assessing the impact of extractant concentration, pH, and contact time on the extraction yield. With these conditions, an extraction isotherm was obtained and correlated with a mathematical model to define the number of extraction stages for a countercurrent process using the McCabe–Thiele method. Then, a similar study was done for stripping conditions and, as a last step, cobalt electroplating was performed. The proposed process offers a solution for the treatment of these batteries, avoiding potential problems of contamination and risk for living beings, as well as offering an opportunity to recover valuable metal.

The objective of this work is to develop a thermodynamic model considering non-stoichiometric restrictions. The model validation was done from experimental works using a bench-scale fluidized bed gasifier with wood chips, dairy manure, and sorghum. The model was used for a further parametric study to predict the performance of a pilot-scale fluidized biomass gasifier. The Gibbs free energy minimization was applied to the modified equilibrium model considering a heat loss to the surroundings, carbon efficiency, and two non-equilibrium factors based on empirical correlations of ER and gasification temperature. The model was in a good agreement with RMS < 4 for the produced gas. The parametric study ranges were 0.01 < ER < 0.99 and 500 °C < T < 900 °C to predict syngas concentrations and its LHV (lower heating value) for the optimization. Higher aromatics in tar were contained in WC gasification compared to manure gasification. A wood gasification tar simulation was produced to predict the amount of tars at specific conditions. The operating conditions for the highest quality syngas were reconciled experimentally with three biomass wastes using a fluidized bed gasifier. The thermodynamic model was used to predict the gasification performance at conditions beyond the actual operation.

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Button cell batteries are used in clocks, thermometers, remote controls, toys and other devices, and they are usually discarded in the trash once its useful life is over. Some models of these batteries contain silver oxide. In this paper we propose liquid-liquid extraction as separation process to recover the metal. First, silver determination is performed in different models of these batteries and leaching with nitric acid is carried out. Affinity study is done between several commercial extractants for silver. The best performing extractant is the bis(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA). Furthermore, a study of the extraction yields as a function of extractant concentration and time is performed. The distribution isotherm is determined; complex extracted in organic phase and stripping conditions have been identified. With the aim of obtaining industrial application, a number of steps for a countercurrent process were defined by the McCabe-Thiele method. Finally, a study was done in micropilot scale. The results show that it is possible to recover silver from this type of waste.

In this study the characterization of an aluminosilicate synthesized from commercial Al₂(SO₄)₃ and colloidal SiO₂ is presented, as well as its capacity for the removal of copper from aqueous solution. Characterization of the synthesized material was performed using X-ray diffraction, BET nitrogen adsorption-desorption, mass titration and the Boehm method. In order to obtain stable agglomeration and enhance its surface area (165 - 243 m²/g) and solid adsorbing capabilities, the molar ratio SiO₂:Al₂O₃ (1:3, 1:1 and 3:1) was studied, the solubility of the preparation material, synthesis-procedure time and solution pH function were also examined. The maximum capacity to remove copper ions from an aqueous solution by synthesized aluminosilicate was 16 mg/g at pH 4 and 25℃. The Langmuir model fitted better to the copper adsorption experimental data