Separations

16 pages, 2607 KiB

Open AccessArticle

Cyclone Shapes for Sand and Microplastic Separation: Efficiency and Reynolds Number Relationships

by Insun Kang, Wonjun Seo, Seokyeon Im and Kwonse Kim

Separations 2024, 11(8), 222; https://doi.org/10.3390/separations11080222 (registering DOI) - 23 Jul 2024

In this study, three geometries were analyzed for sand and microplastic separation to confirm the applicability of cyclones. This research aimed to apply plastic-based samples such as Styrofoam, PET, PP, and PU to an analytical model, characterized by separating sand spread on Korean beaches into different outlets using a cyclone model. Regarding the numerical analysis, the results of sand particle separation were analyzed by designing a general cyclone (Type A), a cone-shaped cyclone (Type B), and a cone-shaped cyclone (Type C) with double the cone length, for four microplastics in three shapes. The results of the analysis of the characteristics showed that Type B, which has a conical shape, achieved an efficiency of 99.3–100% for sand, 72.7% for Styrofoam, and 95.7–100% for other plastics at an exit speed of 5–7 m/s, after which the efficiency decreased as the speed increased. Type C showed an efficiency of 92.2–100% for sand, 66.6–70.8% for Styrofoam, and 61% for PET at 5–10 m/s. Type C showed a maximum efficiency of 95.5% for PP and 73.4% for PU at 11 m/s. As the speed increased, the efficiency decreased. This is believed to be due to differences in the Reynolds number range, which helps separate particles depending on their shape; therefore, the applicability of the cone-shaped cyclone separator for sand and microplastic separation was confirmed, and it was found that an optimal speed condition exists in relation to the Reynolds number. Full article

13 pages, 10666 KiB

Open AccessArticle

Efficient Photocatalytic Degradation of Triclosan and Methylene Blue by Synthesized Ag-Loaded ZnO under UV Light

by Myriam Chems, Lázaro Adrián González-Fernández, Manuel Sanchez Polo, Abdellah Anouar and Ventura Castillo Ramos

Separations 2024, 11(8), 221; https://doi.org/10.3390/separations11080221 (registering DOI) - 23 Jul 2024

Abstract

Industrial discharge of hazardous organic and synthetic chemicals, such as antibacterials and dyes, poses severe risks to human health and the environment. This study was conducted to address the urgent need for efficient and stable zinc-oxide-based photocatalysts to degrade such pollutants. A novel approach to synthesizing silver-loaded zinc oxide (Ag@Z) catalysts was introduced by using a simple and efficient combination of hydrothermal and precipitation methods. Comprehensive characterization of Ag@Z photocatalysts was performed using XRD, XPS, Raman, UV–vis adsorption, FTIR, and SEM, revealing an enhancement of structural, optical, and morphological properties in comparison to pure zinc oxide. Notably, the 5%Ag@Z catalyst exhibited the highest degradation efficiency among the other synthesized catalysts under UV-C light irradiation, and enhanced the degradation rate of pure zinc oxide (Z) by 1.14 and 1.64 times, for Triclosan (TCS) and Methylene Blue (MB), respectively. the effect of catalyst dose and initial concentration was studied. A mechanism of degradation was proposed after investigating the effect of major reactive species. The 5%Ag@Z catalyst increased the photostability, which is a major problem of zinc oxide due to photocorrosion after reusability. We found that 50% and 74% of energy consumption for the photocatalytic degradation of TCS and MB by 5%Ag@Z, respectively, was saved in compassion with zinc oxide. The remarkable photocatalytic performance and the good recovery rate of Ag@Z photocatalysts demonstrate their high potential for photocatalytic degradation of organic contaminants in water. Full article

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13 pages, 1366 KiB

Open AccessArticle

Five Significant Phenols from Phyllostachys glauca McClure Leaves Extracted Using Ultrasound-Assisted Deep Eutectic Solvent Extraction

by Jianqiang Hei, Jianjun Wang, Jin Wang, Daoqi Zhang, Wenting Song, Hang Xun, Xuefeng Guo and Xi Yao

Separations 2024, 11(8), 220; https://doi.org/10.3390/separations11080220 (registering DOI) - 23 Jul 2024

Abstract

Phyllostachys glauca McClure leaves (PML), as economical natural product material, contain abundant phenols, particularly flavonoids, with significant biological activities that contribute to their widespread applications in food, pharmaceutical, and cosmetic industries. To study the significant phenols in PML, an ultrasound-assisted deep eutectic solvent extraction method with high efficiency and low toxicity was established for extracting the phenols from PML and the bamboo leaves of 17 other bamboo species. Using the Ultra Performance Liquid Chromatography (UPLC) method, the content of phenols in the leaves of the 18 bamboo species was determined. PML were found to contain neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, isoorientin, and orientin at contents of 0.793 ± 00.17 mg/g, 0.491 ± 0.0081 mg/g, 0.485 ± 0.0043 mg/g, 0.465 ± 0.0021 mg/g, and 0.044 ± 0.0005 mg/g, respectively, with a total content of 2.278 mg/g. These contents were significantly higher than those found in the leaves of 17 other bamboo species. Additionally, the significant phenols, neochlorogenic acid, chlorogenic acid, and cryptochlorogenic acid were found simultaneously in the leaves of 15 bamboo species, especially in PML. Therefore, PML can be viewed as the natural product material with considerable application values, owing to its abundant phenols, and can exhibit its importance in utilizing neochlorogenic acid, chlorogenic acid, and cryptochlorogenic acid as resources. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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Separations, Volume 11, Issue 8 (August 2024) – 3 articles

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