ABSTRACT
The recovery of materials and energy from end-of-life products is increasingly a fundamental factor in the sustainable development of various countries. Recovering metals from different types of waste is not only a practice in support of the environment, but is also a profitable economic activity. For this reason, exhausted automotive catalysts can become renewable sources of critical raw materials such as Pt, Pd, and Rh. However, recovering Pt and Pd from spent catalysts through an efficient, economical, and green method remains a challenge. This article presents a new leaching process for the hydrometallurgical recovery of Pt and Pd from exhausted automotive catalysts. The leaching solution consists of an aqueous mixture of hydrochloric acid, two organic acids (citric acid and acetic acid) and hydrogen peroxide. A complete factorial plan on two levels (2k) was performed in order to evaluate the main effects of the analyzed factors and their interactions. The factors that were presumed to be the most influential on the leaching of Pt and Pd were the concentrations of the different reagents and the reaction time. The optimal circumstances for achieving the largest recovery (over 80% Pt and 100% Pd) were achieved using the following conditions: a concentration of HCl of 5 M, a concentration of H2O2 of 10% wt./vol., a concentration of C2H4O2 of 10%vol./vol., and a reaction time of 3 h.
ABSTRACT
Due to the high incidence of kidney disease, there is an urgent need to develop wearable artificial kidneys. This need is further exacerbated by the coronavirus disease 2019 pandemic. However, the dialysate regeneration system of the wearable artificial kidney has a low adsorption capacity for urea, which severely limits its application. Therefore, nanomaterials that can effectively remove uremic toxins, especially urea, to regenerate dialysate are required and should be further investigated and developed. Herein, flower-like molybdenum disulphide (MoS2) nanosheets decorated with highly dispersed cerium oxide (CeO2) were prepared (MoS2/CeO2), and their adsorption performances for urea, creatinine, and uric acid were studied in detail. Due to the open interlayer structures and the combination of MoS2 and CeO2, which can provide abundant adsorption active sites, the MoS2/CeO2 nanomaterials present excellent uremic toxin adsorption activities. Further, uremic toxin adsorption capacities were also assessed using a self-made fixed bed device under dynamic conditions, with the aim of developing MoS2/CeO2 for the practical adsorption of uremic toxins. In addition, the biocompatibility of MoS2/CeO2 was systematically analyzed using hemocompatibility and cytotoxicity assays. Our data suggest that MoS2/CeO2 can be safely used for applications requiring close contact with blood. Our findings confirm that novel 2-dimensional nanomaterial adsorbents have significant potential for dialysis fluid regeneration. © 2022
ABSTRACT
Background: Nasal route of drug administration has gained popularity nowadays specially for drugs acting on nasopulmonary area. Atazanavir is an antiviral drug which has proved efficacy in different viral infection including COVID-19. Therefore the hypothesis is, if given through intra nasal route this formulation will be able to prevent the viral infection like COVID-19 by directly acting on the virus at its entry point. Objectives: This study aims to prepare a stable mucoadhesive microcrystal formulation of this antiviral drug with good permeation for intra nasal delivery. Materials and Methods: The formulation was prepared by high-speed homogenization process. Prepared microcrystals were estimated for in vitro drug release and permeation, drug excipient interaction study by DSC, FTIR and in vitro mucoadhesiveness study on agar gel plate. A short-term stability study was conducted on all formulations for 6 months. Results: The melting point and absorbance maxima of atazanavir were found as 200.9°C and 248 nm. The DSC and FTIR study results confirmed no drug excipient interaction was there in the formulation. The particle size of the formulations was found as 5-11 µm in range. Drug release was better and faster from the microcrystals as compare to pure powder drug. The flux for microcrystal formulation was found to be 100 whereas flux for the pure drug powder was 24. Formulations had sufficient mucoadhesive strength due to incorporation of HPMC 400 polymer and they were found stable after six months stability study. Conclusion: Lastly, it can be concluded that this formulation would be a promising system for the delivery through intra nasal route as it showed good drug release and permeation during a short time span in in vitro nasal condition with a particle size range suitable for intranasal delivery. However, further in vivo studies are required to confirm the hypothesis.
ABSTRACT
This paper reports the results obtained from the determination of ascorbic acid with platinum-based voltammetric sensors modified with potassium hexacyanoferrate-doped polypyrrole. The preparation of the modified electrodes was carried out by electrochemical polymerization of pyrrole from aqueous solutions, using chronoamperometry. Polypyrrole films were deposited on the surface of the platinum electrode, by applying a constant potential of 0.8 V for 30 s. The thickness of the polymer film was calculated from the chronoamperometric data, and the value was 0.163 μm. Cyclic voltammetry was the method used for the Pt/PPy-FeCN electrode electrochemical characterization in several types of solution, including KCl, potassium ferrocyanide, and ascorbic acid. The thin doped polymer layer showed excellent sensitivity for ascorbic acid detection. From the voltammetric studies carried out in solutions of different concentrations of ascorbic acid, ranging from 1 to 100 × 10−6 M, a detection limit of 2.5 × 10−7 M was obtained. Validation of the analyses was performed using pharmaceutical products with different concentrations of ascorbic acid, from different manufacturers and presented in various pharmaceutical forms, i.e., intravascular administration ampoules, chewable tablets, and powder for oral suspension.
ABSTRACT
OBJECTIVE: The new coronavirus disease 2019 (COVID-19) is a major health problem worldwide. The surveillance of seropositive individuals serves as an indicator to the extent of infection spread and provides an estimation of herd immunity status among population. Reports from different countries investigated this issue among healthcare workers (HCWs) who are "at risk" and "sources of risk" for COVID-19. This study aims to investigate the seroprevalence of COVID-19 among HCWs in one of the COVID-19 referral centers in Makkah, Saudi Arabia using three different serological methods. METHODS: In-house developed enzyme-linked immunoassay (ELISA), commercially available electro-chemiluminescence immunoassay (ECLIA), and microneutralization (MN) assay were utilized to determine the seroprevalence rate among the study population. 204 HCWs participated in the study. Both physicians and nurses working in the COVID-19 and non COVID-19 areas were included. Twelve out of 204 were confirmed cases of COVID-19 with variable disease severity. Samples from recovered HCWs were collected four weeks post diagnosis. RESULTS: The overall seroprevalence rate was 6.3% (13 out of 204) using the in-house ELISA and MN assay and it was 5.8% (12 out of 204) using the commercial ECLIA. Among HCWs undiagnosed with COVID-19, the seroprevalence was 2% (4 out 192). Notably, neutralizing antibodies were not detected in 3 (25%) out 12 confirmed cases of COVID-19. CONCLUSIONS: Our study, similar to the recent national multi-center study, showed a low seroprevalence of SARS-Cov-2 antibodies among HCWs. Concordance of results between the commercial electro-chemiluminescence immunoassay (ECLIA), in-house ELISA and MN assay was observed. The in-house ELISA is a promising tool for the serological diagnosis of SARS-CoV-2 infection. However, seroprevalence studies may underestimate the extent of COVID-19 infection as some cases with mild disease did not have detectable antibody responses.