Ernesto De la Torre

Dr. Ernesto De la Torre

avatar
Co-authors
avatar
Following
avatar
Followers

Research Focus & Metrics

Explore full metrics on Scilit

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
7 April 2020 in Molecules
Verified
Journal Article
Open access
PDF file
RTRita B. Cevallos Toledo
Rita B. Cevallos Toledo
CACarlos Aragón-Tobar
Carlos Aragón-Tobar
SGSebastian Gamez
Sebastian Gamez
ETErnesto De la Torre
Ernesto De la Torre
Carbon reactivation is a strategy to reduce waste and cost in many industrial processes, for example, effluent treatment, food industry, and hydrometallurgy. In this work, the effect of physical and chemical reactivation of granular activated carbon (AC) was studied. Spent activated carbon (SAC) was obtained from a carbon in pulp (CIP) leaching process for gold extraction. Chemical and physical reactivations were evaluated using several acid-wash procedures (HCl, HNO3, H2SO4) and thermal treatment (650–950 °C) methods, respectively. The effect of the reactivation processes on the mechanical properties was evaluated determining ball pan hardness and normal abrasion in pulp resistance. The effect on the adsorptive properties was evaluated via the iodine number, the gold adsorption value (k expressed in mg Au/g AC), and Brunauer–Emmett–Teller (BET) surface area. Initial characterization of the SAC showed an iodine number of 734 mg I2/g AC, a k value of 1.37 mg Au/g AC, and a BET surface area of 869 m2/g. The best reactivation results of the SAC were achieved via acid washing with HNO3 at 20% v/v and 50 °C over 30 min, and a subsequent thermal reactivation at 850 °C over 1 h. The final reactivated carbon had an iodine number of 1199 mg I2/g AC, a k value of 14.9 mg Au/g AC, and a BET surface area of 1079 m²/g. Acid wash prior to thermal treatment was critical to reactivate the SAC. The reactivation process had a minor impact (<1% change) on the mechanical properties of the AC.
5 January 2024 in Molecules
Verified
Journal Article
Open access
PDF file
CACarlos Aragón-Tobar
Carlos Aragón-Tobar
DEDiana Endara
Diana Endara
ETErnesto De la Torre
Ernesto De la Torre
Nowadays, deep eutectic solvents (DESs) are seen as environmentally friendly alternatives with the potential to replace traditional solvents used in hydrometallurgical processes. Although DESs have been successfully applied in the recovery of metals from secondary sources, there is still innovative potential regarding DESs as green leaching agents applied in the recovery of metals from primary sources like polysulfide ores. This study aimed to evaluate the characteristics of DESs as solvents for some of the main metals present in typical polymetallic concentrates, like Cu, Fe, Pb, and Zn. Thus, three DESs based on choline chloride (ChCl) were prepared: 1:2 ChCl-urea (also known as reline), 1:2 ChCl-ethylene glycol (also known as ethaline), and 1:2 ChCl-glycerol (also known as glyceline). Then, dissolution tests at 30 °C were carried out with these DESs and different metal- (Cu, Fe, Pb, and Zn) bearing compounds (sulfates, oxides, and sulfides). According to the dissolution tests, it was found that the solubility of the studied metals (expressed as g of metal per Kg of DES) was dictated by the bearing species, reaching the dissolution of the metals from sulfates with values as high as two orders of magnitude higher than the metal solubility values for metal oxides and sulfides.
29 September 2018 in Metals
Verified
Journal Article
Open access
PDF file
ETErnesto De la Torre
Ernesto De la Torre
EVEstefanía Vargas
Estefanía Vargas
CRCésar Ron
César Ron
SGSebastian Gamez
Sebastian Gamez
Waste electrical and electronic equipment (WEEE) has increased in recent decades due to the continuous advancement of technology in the modern world. These residues have various metals that are found in concentrations that make their recovery profitable. A group of metals of interest are the rare earths such as europium and yttrium, as well as semiconductors such as indium. Yttrium was recovered from cathode ray tubes that were manually dismantled. The resulted powder was leached with HNO3, and then the solution was submitted to solvent extraction with di-(2-ethylhexyl) phosphoric acid (DEHPA) using n-heptane as a diluent. For re-extraction, HNO3 was used again, and yttrium was precipitated by adding four times the stoichiometric amount of oxalic acid, reaching 68% yttrium purity. Indium was recovered from the liquid crystal display (LCD) screens for which the pulverized material was leached with H2SO4. Then, the indium sulfate was subjected to solvent extraction using DEHPA as an extractant, and diesel as a diluent. The re-extraction was carried out again with H2SO4, and the obtained acid solution was evaporated until the indium precipitated, reaching a recovery of 95%. The investigations that were carried out show that it is feasible to recover these metals in the form of oxides or phosphates with high commercial value.
30 July 2021 in Catalysts
Verified
Journal Article
Open access
PDF file
Stalin CoronelStalin Coronel
Stalin Coronel
DEDiana Endara
Diana Endara
ALAna Belen Lozada
Ana Belen Lozada
Lucia E. Manangon-PerugachiLucia E. Manangon-Perugachi
Lucia E. Manangon-Perugachi
ETErnesto De la Torre
Ernesto De la Torre
The photocatalytic oxidation of cyanide by titanium dioxide (TiO2) supported on activated carbon (AC) was evaluated in a continuous flow UV photo-reactor. The continuous photo-reactor was made of glass and covered with a wood box to isolate the fluid of external conditions. The TiO2-AC synthesized by the impregnation of TiO2 on granular AC composites was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), Scanning Electron Microscopy (SEM), and nitrogen adsorption-desorption isotherms. Photocatalytic and adsorption tests were conducted separately and simultaneously. The results showed that 97% of CN− was degraded within 24 h due to combined photocatalytic oxidation and adsorption. To estimate the contribution of only adsorption, two-stage tests were performed. First, 74% cyanide ion degradation was reached in 24 h under dark conditions. This result was attributed to CN− adsorption and oxidation due to the generation of H2O2 on the surface of AC. Then, 99% degradation of cyanide ion was obtained through photocatalysis during 24 h. These results showed that photocatalysis and the continuous photo-reactor’s design enhanced the photocatalytic cyanide oxidation performance compared to an agitated batch system. Therefore, the use of TiO2-AC composites in a continuous flow photo-reactor is a promising process for the photocatalytic degradation of cyanide in aqueous solutions.
14 February 2025 in Metals
Verified
Journal Article
Open access
PDF file
ARAlex Saul Redrován
Alex Saul Redrován
ETErnesto De la Torre
Ernesto De la Torre
CACarlos Aragón-Tobar
Carlos Aragón-Tobar
The thiosulfate–glycine–copper system has emerged as a promising alternative for gold recovery, offering significant advantages over cyanidation and ammoniacal thiosulfate leaching. Recognizing the limitations of thiosulfate degradation in ammoniacal systems, this study focused on optimizing the thiosulfate–glycine–copper system for gold recovery using an auriferous ore with (10 g t−1) of Au. The ore was associated with aluminosilicates such as grossular (64%) and clinochlore (12%). Leaching conditions were systematically varied, including thiosulfate (0.5–1 M), glycine (0.3–1.75 M), copper sulfate (2–10 mM), pH (9.3–10.5), temperature (20–60 °C), 6 h, and potassium permanganate concentrations (0.004–0.04 M), and dosing intervals were also optimized. Thus, the best conditions were thiosulfate (0.7 M), glycine (1.75 M), copper sulfate (5 mM), pH 9.3, 60 °C, and permanganate addition every 2 h. This system achieved 89.3% gold recovery in just 6 h, comparable to cyanidation (89.8% in 24 h) and ammoniacal thiosulfate (58% in 6 h), but without generating toxic effluents, such as in the cyanidation process. Additionally, a gold dissolution mechanism was proposed, highlighting glycine’s role in stabilizing cupric ions and enhancing thiosulfate efficiency. This study underscores the thiosulfate–glycine–copper system as a sustainable and effective method for gold recovery.
24 June 2020 in Molecules
Verified
Journal Article
Open access
PDF file
FEFreddy R. Escobar-Ledesma
Freddy R. Escobar-Ledesma
CACarlos Aragón-Tobar
Carlos Aragón-Tobar
PEPatricio Javier Espinoza-Montero
Patricio Javier Espinoza-Montero
ETErnesto De la Torre
Ernesto De la Torre
Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and reduce operating cost. In this research, the adsorption process of gold thiosulfate complex on thiol-modified activated carbon was studied. Thioglycolic acid (ATG) was impregnated in activated carbon, and its adsorption ability was tested with synthetic solutions of gold and sodium thiosulfate (Au 10 mg·L−1, Na2S2O3 0.1 mol·L−1, pH = 10.0). Carbon was characterized by infrared spectroscopy, SEM-EDS, PZC titration, hardness number measures, and proximal analysis. Synthetic solutions were also characterized by UV-vis spectroscopy and cyclic voltammetry. The percentage of volatile material increased from 10.0 to 13.9% due to the impregnation process of ATG. Infrared spectra show characteristic bands of C-H, S-H, and C-S bonds. In the adsorption tests, the ATG-impregnated carbon achieved 91% of gold recovery, while the same amount of ATG in the liquid phase stirred with unmodified activated carbon reached 90% of gold recovery. The 44.9% of gold recovered with activated carbon impregnated with ATG was eluted with sodium cyanide ([NaCN] = 0.2 mol·L−1; [NaOH] = 0.25 mol·L−1; [CH3CH2OH] = 30% V/V; pH = 12.0; t = 24 h). These results suggest the gold transferred from the thiosulfate complex to a new gold thiolate complex.