Carbon coated MFe2O4 (M=Fe, Co, Ni) magnetite nanoparticles: A smart adsorbent for direct yellow and moderacid red dyes

Hoang Vinh Tran,Hai Van Nguyen,Doanh Viet Vu,Thu Dieu Le,Binh Thanh Nguyen,Dang Hai Le 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2

We report here a simple approach for synthesis of carbon coated magnetite (C@MFe2O4, M=Co, Ni, Fe) with shell@core nanostructured composites that we used as magnetic-nanosorbents for direct yellow (DYG) and moderacid red (RS) as pollutant textile dyes removal via an adsorption process. The synthesized C@MFe2O4 was characterized by TEM, SEM, EDX, XRD, FT-IR and VSM techniques. TEM results indicated that C@MFe2O4 nanocomposites have 20-30 nm of MFe2O4 nanoparticle core and 2-3 nm in thickness of the amorphous carbon shell. The synthesized C@MFe2O4 nanocomposites have the zero point charge (pHZPC) at 5.5, which suggests that DYG and RS, anionic dyes can be adsorbed onto the C@MFe2O4 nanosorbents in the acidic medium. Adsorption of DYG and RS onto magnetic nanosorbents was optimized and adsorption thermodynamic parameters were evaluated, clearly indicating that the adsorption of RS onto synthesized magnetic-nanosorbents was facile more than that DYG. The adsorption isotherm data showed that the adsorption processes of DYG and RS onto Fe3O4 or C@MFe2O4 nanosorbents are more suitable for the Langmuir model than Freundlich model. The maximum adsorption capacity (qmax) of DYG dye onto Fe3O4, C@Fe3O4 and C@CoFe2O4 adsorbents was 14.641, 36.232 and 7.85mg g1, respectively; meanwhile, these values were 41.152, 61.728 and 39.683mg g1 for RS dye. These obtained data indicate that the developed Fe3O4, C@Fe3O4 and C@CoFe2O4 nanoparticles can be used as recoverable and recyclable adsorbents for not only organic pigments adsorption but also for heavy metal ion removal or protein extraction as well.

Leaching of yttrium and europium from fluorescent lamp phosphor powder using nitric acid: kinetics and optimization

Huynh Trung Hai,Ha Vinh Hung,Vu Minh Trang 한국자원공학회 2022 Geosystem engineering Vol.25 No.3

Rare earth elements (REEs) are recognized as one of the most critical elements and considered essential for the development of sustainable energy technologies, lasers, electronics, alloys, catalysts, and other applications. In order to meet the increasing demand to ensure those essential usages, the supply of REEs is however limited from the primary sources. Recovery of REEs from secondary resources, such as discarded electrical and electronic equipment, referred to as electronic waste (e-waste) is consequently crucial. Fluorescent lamps among such wastes are of special concern due to the high quantity of REEs present in them. This article discusses a potential hydrometallurgical method for recovering REEs (yttrium and europium) from fluorescent lamp waste via nitric acid leaching. The effects of leaching factors including acid concentration and temperature were examined. To assist the leaching yields of those metals, the effect of alkaline fusion was specifically examined. The kinetics of both processes, direct- and alkaline fusion-assisted leaching were investigated based on the shrinking core model. In the case of direct leaching, the metal dissolution was controlled by surface chemical reaction with apparent activation energies of 43.9 and 48.1 kJ/mol for yttrium and europium, respectively, in the temperature range 303–333 K. Pretreatment, viz., the alkaline fusion changed the subsequent leaching mechanism to diffusion control with apparent activation energies of 7.4 and 9.5 kJ/mol for the respective metal in the same temperature range. Optimization of the alkaline fusion-assisted acid leaching process was undertaken by applying response surface methodology (RSM) based on the central composite design (CCD). Under the alkaline fusion conditions such as soda/fluorescent powder mass ratio of 0.65 g/g, temperature of 1223 K and reaction time of 7200 s followed by acid leaching (nitric acid concentration – 3.5 M, temperature-323 K, pulp density – 30 g/L and leaching duration – 1200 s), the leaching efficiencies of 92.6% and 99.5% for yttrium and europium, respectively, could be achieved.

Electrochemical Detection of TNT by Differential Pulse Adsorptive Stripping Voltammetry at Carbon Paste Electrode Modified by 1-Butyl-3-methylimidazolium Tetrafluoroborate

Ha Thi Thu Vu,Hanh Thi Vinh Le,Yen Thi Hai Pham,Hung Quoc Le,Phong Hong Pham 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.3

Different kinds of materials for electrodes based on glassy carbon, carbon fibers, and modified by an ionic liquid (BMIMBF4) were used to determine 2,4,6-trinitrotoluene (TNT) in water environment by differential pulse adsorptive stripping voltammetry. The modified electrode based on BMIMBF4 showed a better performance than those based on the microelectrode and glassy carbon electrode (GCE) in term of sensitivity. The best performance was obtained with the ionic liquid-modified electrode with 80:10:10 (w/w/w) of the graphite powder/paraffin oil/BMIMBF4 composition in PBS, pH 8. The TNT concentration was linear in the range 1.5 to ~30 ppm for all studied electrodes (r = 0.9978) with a detection limit of 88.6 ppb using IL-CPE (ionic liquid-modified carbon paste electrode). This latter electrode was used to measure real samples taken from Red River, Vietnam. The recovery study for TNT in natural samples gave values from 99.7% to 103.3%. IL-CPE demonstrated long-term stability and reproducibility, with a relative standard deviation of 1.67%.

Biomedical and Environmental Applications of Chitosan-based Nanomaterials

( Jae Kweon Park ),( Lam Dai Tran ),( Hoang Vinh Tran ),( Trang Thu Mai ),( Thu Phuong Ha ),( Binh Hai Nguyen ),( Hoang Thai ),( Hoang Dinh Vu ),( Dien Gia Pham ),( Phuc Xuan Nguyen ) 한국키틴키토산학회 2011 한국키틴키토산학회지 Vol.16 No.1

Being naturally abundant resources and having many interesting physicochemical and biological properties, chitin/chitosan have been found useful in many fields. This paper describes the strategy to design a multifunctional, chitosan based nanomaterials and their biomedical and environmental applications. Different physicochemical methods including FESEM/TEM, PPMS were used to characterize the obtained nanomaterials. For each application, a series of specific characterizing methods were used for evaluating the applicability/capacity of materials.

Impact of long COVID-19 on posttraumatic stress disorder as modified by health literacy: an observational study in Vietnam

Han Thi Vo,Tien Duc Dao,Tuyen Van Duong,Tan Thanh Nguyen,Binh Nhu Do,Tinh Xuan Do,Khue Minh Pham,Vinh Hai Vu,Linh Van Pham,Lien Thi Hong Nguyen,Lan Thi Huong Le,Hoang Cong Nguyen,Nga Hoang Dang,Trung 질병관리청 2024 Osong Public Health and Research Persptectives Vol.15 No.1

Objectives: The incidence of posttraumatic stress disorder (PTSD) has increased, particularly among individuals who have recovered from coronavirus disease 2019 (COVID-19) infection. Health literacy is considered a “social vaccine” that helps people respond effectively to the pandemic. We aimed to investigate the association between long COVID-19 and PTSD, and to examine the modifying role of health literacy in this association.Methods: A cross-sectional study was conducted at 18 hospitals and health centers in Vietnam from December 2021 to October 2022. We recruited 4,463 individuals who had recovered from COVID-19 infection for at least 4 weeks. Participants provided information about their sociodemographics, clinical parameters, health-related behaviors, health literacy (using the 12-item short-form health literacy scale), long COVID-19 symptoms and PTSD (Impact Event Scale-Revised score of 33 or higher). Logistic regression models were used to examine associations and interactions.Results: Out of the study sample, 55.9% had long COVID-19 symptoms, and 49.6% had PTSD. Individuals with long COVID-19 symptoms had a higher likelihood of PTSD (odds ratio [OR], 1.68; 95% confidence interval [CI], 1.63–2.12; p<0.001). Higher health literacy was associated with a lower likelihood of PTSD (OR, 0.98; 95% CI, 0.97–0.99; p=0.001). Compared to those with long COVID-19 symptoms and the lowest health literacy score, those with long COVID-19 symptoms and a 1-point health literacy increment had a 3% lower likelihood of PTSD (OR, 0.97; 95% CI, 0.96–0.99; p=0.001).Conclusion: Health literacy was found to be a protective factor against PTSD and modified the negative impact of long COVID-19 symptoms on PTSD.