Study of the Electrooxidation of a Zinc Concentrate

Zinc has wide industrial applications; consequently, its extraction procedures have been extensively studied. Hydrometallurgy is one of the most common methods employed for zinc recovery. However, the electrooxidation of sphalerite and the effect of the pyrite content in the concentrate have not been investigated; thus, in this work, zinc recovery from low-iron sphalerite mineral with a relatively high pyrite content (EBHSS), in a sulfate medium was further explored. The reaction mechanism of the anodic dissolution of the EBHSS mineral was established by microelectrolysis using mineral carbon paste electrodes; these results were used to determine adequate conditions for the macroelectrolysis of the sample. The macroelectrolysis indicated that EBHSS has a low electrodissolution rate; additionally, different analyses of the species produced in the macroelectrolysis showed that the ohmic drop registered in the collector had no influence in the passivation of the EBHSS surface. It was also determined that the dissolution of EBHSS was driven by the charge transfer of the sphalerite particles, which are not very efficient for electronic conductivity. Experiments using doped EBHSS led to an increase of the electrodissolution rate, which consequently increased the recovered zinc.

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Critical importance of pH and collector type on the flotation of sphalerite and galena from a low-grade lead–zinc ore

Scientific Reports ◽

10.1038/s41598-021-82759-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Abdolrahim Foroutan ◽

Majid Abbas Zadeh Haji Abadi ◽

Yaser Kianinia ◽

Mahdi Ghadiri

Keyword(s):

Iron Ore ◽

Low Grade ◽

Zinc Recovery ◽

Flotation Process ◽

Ph Values ◽

Lead And Zinc ◽

Optimum Ph ◽

Iron And Zinc ◽

Lead Zinc ◽

Zinc Concentrate

AbstractCollector type and pulp pH play an important role in the lead–zinc ore flotation process. In the current study, the effect of pulp pH and the collector type parameters on the galena and sphalerite flotation from a complex lead–zinc–iron ore was investigated. The ethyl xanthate and Aero 3418 collectors were used for lead flotation and Aero 3477 and amyl xanthate for zinc flotation. It was found that maximum lead grade could be achieved by using Aero 3418 as collector at pH 8. Also, iron and zinc recoveries and grades were increased in the lead concentrate at lower pH which caused zinc recovery reduction in the zinc concentrate and decrease the lead grade concentrate. Furthermore, the results showed that the maximum zinc grade and recovery of 42.9% and 76.7% were achieved at pH 6 in the presence of Aero 3477 as collector. For both collectors at pH 5, Zinc recovery was increased around 2–3%; however, the iron recovery was also increased at this pH which reduced the zinc concentrate quality. Finally, pH 8 and pH 6 were selected as optimum pH values for lead and zinc flotation circuits, respectively.

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Influence of Nitrogen-Doped Carbon Dot and Silver Nanoparticle Modified Carbon Paste Electrodes on the Potentiometric Determination of Tobramycin Sulfate: A Comparative Study

Chemosensors ◽

10.3390/chemosensors9030052 ◽

2021 ◽

Vol 9 (3) ◽

pp. 52

Author(s):

Nermine V. Fares ◽

Passant M. Medhat ◽

Christine M. El Maraghy ◽

Sherif Okeil ◽

Miriam F. Ayad

Keyword(s):

Silver Nanoparticle ◽

Carbon Nanodots ◽

Carbon Paste ◽

X Ray Diffraction ◽

Loteprednol Etabonate ◽

Carbon Paste Electrodes ◽

Transmission Electron ◽

Nernstian Slope ◽

Nitrogen Doped Carbon ◽

Modified Carbon Paste Electrodes

Two inexpensive and simple methods for synthesis of carbon nanodots were applied and compared to each other, namely a hydrothermal and microwave-assisted method. The synthesized carbon nanodots were characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis), photoluminescence (PL), Fourier transform-infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized microwave carbon nanodots had smaller particle size and were thus chosen for better electrochemical performance. Therefore, they were used for our modification process. The proposed electrodes performance characteristics were evaluated according to the IUPAC guidelines, showing linear response in the concentration range 10−6–10−2, 10−7–10−2, and 10−8–10−2 M of tobramycin with a Nernstian slope of 52.60, 58.34, and 57.32 mV/decade for the bare, silver nanoparticle and carbon nanodots modified carbon paste electrodes, respectively. This developed potentiometric method was used for quantification of tobramycin in its co-formulated dosage form and spiked human plasma with good recovery percentages and without interference of the co-formulated drug loteprednol etabonate and excipients.

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Polyvinyl Chloride Modified Carbon Paste Electrodes for Sensitive Determination of Levofloxacin Drug in Serum, Urine, and Pharmaceutical Formulations

Sensors ◽

10.3390/s21093150 ◽

2021 ◽

Vol 21 (9) ◽

pp. 3150

Author(s):

Fatehy M. Abdel-Haleem ◽

Sonia Mahmoud ◽

Nour Eldin T. Abdel-Ghani ◽

Rasha Mohamed El Nashar ◽

Mikhael Bechelany ◽

...

Keyword(s):

Bacterial Infections ◽

Pharmaceutical Preparation ◽

Pharmaceutical Formulations ◽

Selectivity Coefficient ◽

Pvc Membrane ◽

Carbon Paste ◽

Serum Samples ◽

Carbon Paste Electrodes ◽

Antibiotic Drug

Levofloxacin (LF) is a medically important antibiotic drug that is used to treat a variety of bacterial infections. In this study, three highly sensitive and selective carbon paste electrodes (CPEs) were fabricated for potentiometric determination of the LF drug: (i) CPEs filled with carbon paste (referred to as CPE); (ii) CPE coated (drop-casted) with ion-selective PVC membrane (referred to as C-CPE); (iii) CPE filled with carbon paste modified with a plasticizer (PVC/cyclohexanone) (referenced as P-CPE). The CPE was formulated from graphite (Gr, 44.0%) and reduced graphene oxide (rGO, 3.0%) as the carbon source, tricresyl phosphate (TCP, 47.0%) as the plasticizer; sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (St-TFPMB, 1.0%) as the ion exchanger; and levofloxacinium-tetraphenylborate (LF-TPB, 5.0%) as the lipophilic ion pair. It showed a sub-Nernstian slope of 49.3 mV decade−1 within the LF concentration range 1.0 × 10−2 M to 1.0 × 10−5 M, with a detection limit of 1.0 × 10−5 M. The PVC coated electrode (C-CPE) showed improved sensitivity (in terms of slope, equal to 50.2 mV decade−1) compared to CPEs. After the incorporation of PVC paste on the modified CPE (P-CPE), the sensitivity increased at 53.5 mV decade−1, indicating such improvement. The selectivity coefficient (log KLF2+,Fe+3pot.) against different interfering species (Na+, K+, NH4+, Ca2+, Al3+, Fe3+, Glycine, Glucose, Maltose, Lactose) were significantly improved by one to three orders of magnitudes in the case of C-CPE and P-CPE, compared to CPEs. The modification with the PVC membrane coating significantly improved the response time and solubility of the LF-TPB within the electrode matrix and increased the lifetime. The constructed sensors were successfully applied for LF determination in pharmaceutical preparation (Levoxin® 500 mg), spiked urine, and serum samples with high accuracy and precision.

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