جستجوی مقالات مرتبط با کلیدواژه "leaching" در نشریات گروه "شیمی"

This study assessed the potential for recycling the Ni-Co-Mn (NCM) cathode from spent Lithium-Ion Batteries (LIBs) using Tangerine Peel (TP) as a reducing agent in CH3COOH media. The impact of various parameters, including CH3COOH concentration (ranging from 1-6 M), temperature (ranging from 30-100 ºC), leaching time (ranging from 0.33 to 7 h), TP/NCM (0.1-2 g/g), was investigated. The results indicated that adding TP improved the recovery of Ni, Co, Mn, and Li. The temperature was the most critical parameter in the reductive leaching process as it facilitated the hydrolysis of TP compounds into glucose. Generally, increasing leaching time, CH3COOH, and TP concentration improved the recovery. Dissolution of Li was less dependent on reducing agent concentration, while strong dependence was observed for Ni, Co, and Mn elements. Based on parameter optimization results, optimal levels were obtained for time (6 h), temperature (100 °C), CH3COOH concentration (3 M), and TP/NCM (2 g/g). The FT-IR analysis of TP suggests the presence of cellulose, lignin, and hemicellulose bonds in the spectrum. The FT-IR profile of TP hydrolysis in acetic acid reveals the peaks for CH3COOH and glucose structure. Interestingly, the IR profile of leaching samples in the presence and absence of TP did not display any discernible differences, indicating that glucose molecules produced during leaching were immediately consumed by spent LIBs compounds and did not persist.

Silver is an element with the highest thermal and electrical conductivity, making it ideal for electrical applications. One of the most commonly consumed electronic wastes containing silver is Printed Circuit Boards (PCBs). To reduce the amount of PCB waste and increase the availability of silver, an environmentally friendly solvent called Deep Eutectic Solvent (DES) is proposed to extract silver from PCB waste. This study aims to synthesize DES-glyceline and investigate the behavior and effectiveness of silver extraction using this DES glyceline. The optimum mole ratio of choline chloride and glycerol to synthesize DES was 1:2. The density of DES-glyceline was measured by a pycnometer, about 1.1378 g/L. The FT-IR spectra showed a broadening peak of the O-H band and its shifting from 3273 cm-1 in glycerol to 3124 cm-1 in DES-glyceline. The NMR characterization demonstrated the deshielding effect of O-H proton in glycerol, from 3.44 ppm to 4.63 ppm and 5.19 ppm. Both results indicate the formation of hydrogen bonds attributed to DES formation. The success of silver extraction by DES-glyceline was proven by cyclic voltammetry, resulting in an anodic peak at 0.132 V and a cathodic peak at -0.037 V. XRF characterization showed that the silver concentration contained in the initial PCB sample was 178.59 ppm. The recovery optimum condition for silver from PCB extraction was at the temperature of 120°C and at the time of 16 hours with a leaching percentage of almost 85%. This environmentally friendly, low-cost, low toxicity, and high biodegradability DES-glyceline shows tremendous promise for efficiently recovering silver from PCB e-waste.

Today, there has been a significant emphasis on developing sustainable and environmentally friendly processes in various industries, including hydrometallurgy. This study focuses on the process of leaching chalcopyrite concentrate using an ionic liquid called 1-butyl-3-methyl-imidazolium hydrogen sulfate ([Bmim][HSO4]). To study the impact of various parameters on the chalcopyrite leaching, such as temperature, [Bmim][HSO4] and H2O2 concentration, speed of stirring, solid-to-liquid ratio, and their interactions, design expert software was used. Employing the CCD layout of RSM matrix, 32 experiments were designed and executed. The results showed that the temperature, oxidizing agent concentration, and ionic liquid concentration, as well as the interaction between the oxidizing agent concentration with the ionic liquid concentration and temperature, have the most significant effect on the dissolution of chalcopyrite. Also, the highest amount of copper extraction (90.32%) was obtained at 40°C using 40% [Bmim][HSO4], 30% H2O2, ratio of solid-to-liquid 10 g/L, and speed of stirring 300 rpm. The examination of kinetic studies employing the SCM showed that the process of extracting copper from chalcopyrite utilizing BmimHSO4 ionic liquid follows from the chemical reaction, and in this condition, the activation energy is 49.61 kJ/mol. Finally, evaluation of surface morphology and characteristics of leaching residue using XRD and SEM/EDX analyses revealed that most of the CuFeS2 has been dissolved and elemental sulfur is the major solid product that exists in the chalcopyrite leaching residue.

The hydrochloric acid leaching of cadmium, nickel, and cobalt from the dismantled powder of spent rechargeable nickel-cadmium batteries was optimized by the response surface methodology. The optimized parameters included HCl concentration, powder mass, temperature, and solid/solution contact time. The optimal values were 100 mL of 2.6 M HCl, 4.4 g of powder, temperature 48.6 °C, and time 3.19 h. The concentrations of Cd, Ni, and Co in the leach solution were 13500, 12150, and 900 mg/L, respectively. The designed process involved a two-step solvent extraction/back-extraction procedure using 0.5 mol/L trioctylamine (TOA) in dichloromethane as the organic phase. The first step consisted of four successive extraction experiments of the metals from the aqueous phase into the organic phase. The results of this step showed that 92.7% of cadmium and 26.7% of cobalt are extracted into the organic phase. In contrast, nickel ions remain quantitatively in the source phase. The different stability of the anionic chloride complexes of cadmium and cobalt leads to different extractability of these metals. By employing an appropriate back-extraction procedure a selective separation of these ions was achieved. The extracted Cd(II) and Co(II) ion pairs (i.e. [TOAH+][MCl¯3], M is Cd or Co) were back-extracted into the stripping phase by using ammonia solutions as a suitable complexing reagent for these metal ions. Selective back-extraction of cadmium (86.3%) from the organic phase by using 0.5 M NH3 solution has resulted. The second step included five consecutive extraction experiments on the raffinate of the preceding step. The total extraction of cobalt into the accumulated organic phase reached 83.0%. Efficient recovery of the extracted cobalt (79.3%) was obtained by a single back-extraction experiment using 7 M NH3. The investigated design allows for improving Ni/Co ratio from 13.9 in the starting aqueous solution to 106 in the ultimate raffinate.

Taguchi Method is used as a statistical approach to optimize the process parameters and improve the quality of components that are produced. The present study aimed to illustrate the leaching optimization of Sarcheshmeh copper concentrate using Taguchi’s experimental design. Various operating parameters such as acid concentration (CA), temperature (T), solid percentage (%S), O2 flow rate (O2), extra oxidizing agent (OxA), NaCl concentration(CNaCl), and contact time (t), each at three levels, were selected and their effect on the copper extraction (R%) was analyzed. L27 Orthogonal Array (OA) was employed as the experimental design and the results were analyzed using analysis of variance (ANOVA) and analysis of mean (ANOM). The experiment results indicated that (T) variable was the most significant parameter with 81% contribution to the response. It is also observed that the interactions between (CA and OxA), (CA and Cox), (CA and CNaCl) had no significant effect on the copper dissolution process. Furthermore, (T), (%S), (O2), (CNaCl) and (t) parameters were found to be statistically significant at 95% confidence level for the desired response. The study showed that Taguchi’s method was suitable to optimize the experiments for increasing leaching efficiency.

An experimental study was conducted to determine the effects of the leaching parameters on impurity ion concentrations of the liquid phase in ulexite leaching. Powdered ulexite ore was leached in an aqueous medium with sulfur dioxide. The Taguchi experimental design approach and statistical methods were used to evaluate the effects of the leaching parameters (solid/liquid ratio, temperature, pH, particle size, time) on impurity ion concentrations (concentrations of magnesium, calcium, iron ions) in the liquid phase. The average B2</sub>O3</sub> leaching ratio of ulexite ore was found as 98.56 % (± 0.95). Statistically effective leaching parameters on impurity concentrations (and delta values for concentrations) were found as pH (770 ppm) for magnesium, solid/liquid ratio (372 ppm) </em>for calcium ion concentrations. The examined parameters were not found effective for iron ion concentrations.

The leaching kinetics of smithsonite ore in acetic acid solutions, an environmental friend, and natural reagent was investigated. The influence of parameters such as reaction temperature, particle size, solid-liquid ratio and acid concentration was studied in order to reveal the leaching kinetics of smithsonite ore. In this study, experimental and statistical methods were carried out in order to analyze the kinetics data to investigate a kinetics model which describes the dissolution. The results indicate that the unreacted shrinking core model for fluid-solid heterogeneous reactions was favorable for the leaching process. The apparent activation energy of the leaching process was found as 74 kJ/ mol. It was determined that the leaching rate of smithsonite was controlled by the chemical reaction below.

The optimization of vegetable oil leaching from spent nickel catalyst is reported in this work. Different solvents including; methyl ethyl ketone (MEK), acetone, hexane and toluene were employed. The leaching time in the range 1 to 5 h was studied. The leaching optimization shows that the use of MEK for 3 h provides the best results.
This was followed by the recovery of nickel from spent catalysts in the form of nickel sulfate. In pursue of finding a robust, inexpensive, simple and fast technique for on-line concentration measurement of nickel solution from leaching, the spectrophotometer technique was evaluated. The findings were then validated against titration method using EDTA.

Leaching of molybdenite concentrate with hydrogen peroxide in sulfuric acid solution was investigated to determine the effects of reaction time, reaction temperature, H2O2 concentration, H2SO4 concentration, pulp density and rotation speed on molybdenum extraction and molybdenite dissolution kinetics, using the Taguchi method. From analysis of variance (ANOVA) for molybdenum extraction, the most significant factors were H2O2 concentration, pulp density and reaction temperature. The optimal factor levels to maximize extraction were determined. As the leaching process does not result in an ash layer, only chemically controlled kinetic model was applied. ANOVA for the reaction rate constant showed that H2O2 concentration made the greatest contribution to the model, and reaction time and temperature were also statistically significant factors. The reaction rate constant increased with increasing temperature and H2O2 concentration. The order of reaction with respect to H2O2 and activation energy for the dissolution were determined to be 1.21 and 46.5 kJ/mol, respectively, and a semi-empirical rate equation was derived.

Computer circuit boards (CCBs) are valuable because of their precious metal contents. In this regard، the recovery of gold from CCBs has attracted great interest. In this work، we report the recovery of gold from CCBs with different reductants. The CCBs were first crushed mechanically to obtain particles with sizes less than 0. 1 mm. The powders were then leached with nitric acid to remove undesired metals. The remaining was then treated with aqua regia to dissolve gold ion. The dissolved gold was then precipitated from the leachate with hydrazine، ferrous sulfate or oxalic acid and the effect of these reductants on the recovery of gold was studied. We were able to recover more than 99% of gold from CCBs with purity of about 99. 5%.