In this study, we investigated the effect of the scrubbing medium's particle size distribution on the scrubbing flotation performance of microcrystalline graphite. A simplex lattice mixture design ...approach using Design-Expert software was employed for proportioning testing of the scrubbing media. Three different sizes of scrubbing medium (A: 1 mm, B: 2 mm, and C: 3 mm) were mixed to obtain different particle size distributions. The results showed that a linear mixture model was suitable for fitting this mixture design, and the particle size distribution of the scrubbing medium was 3 mm. Hence, we studied the effect of scrubbing time on the flotation performance of the scrubbing flotation process. The flotation results indicated that graphite quality was enhanced by increasing the scrubbing time, and the optimum scrubbing time for this graphite was 45 min when maximum enrichment efficiency was acquired. Also, we investigated the effect of the scrubbing medium's particle size compositions on gangue entrainment in the scrubbing flotation process. It was concluded that the degree of entrainment under the composition of scrubbing size 1 mm (16.67%), 2 mm (16.67%), and 3 mm (66.66%) was reduced compared to the other two compositions (scrubbing size 2 mm (50%) and 3 mm (50%) as well as scrubbing size 3 mm (100%)). This conclusion was proved using analyses of froth bubble size and scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS).
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Dynamic Light Scattering (DLS) generated particle size distributions (PSD) of polymer-stabilized nanoparticles are dependent on the optimization parameters used to generate an ...inversion solution fit to the measured autocorrelation function. The accuracy of the DLS PSD average and polydispersity can be determined by comparing analyzed Transmission Electron Microscopy (TEM) images with the DLS results if the TEM measured sizes can be corrected for the thickness of the hydrated polymer corona that impacts particle hydrodynamics but is a collapsed, desiccated shell in the TEM images.
Nanoparticles were prepared by Flash NanoPrecipitation with either poly(ethylene glycol) (PEG) or hydroxypropyl methylcellulose acetate succinate (HPMCAS) stabilizing polymers. Solvated nanoparticle size distributions were measured by DLS in aqueous media. The same nanoparticle dispersions were lyophilized onto TEM grids and stained by ruthenium tetroxide (RuO4) vapor to improve electron contrast. Desiccated particle size distributions were generated by measuring a minimum of 300 particle diameters in the stained TEM images.
Using our protocol for staining soft matter nanoparticles in TEM measurements, we have quantitatively analyzed the correlation between DLS and TEM generated PSDs. Average diameters disagree by the hydrated polymer corona thickness for each stabilizer due to the high-vacuum TEM environment, with 21.4 nm for PEG and 51.2 nm for HPMCAS. While corrected average diameter agrees within 10% for each technique, DLS consistently over-estimates the standard deviation of the PSD by 100% compared to the TEM measurement.
This study investigates anaerobically-digested sludge (ADS) disintegration by activated peroxymonosulfate (PMS) with transition metal ions of Co2+, Cu2+, Fe2+, and Mn2+ (PMS-Me2+). The activating ...performances of Me2+ are quantitatively compared by capillary suction time (CST), extracellular polymeric substances (EPS), bound water content (BWC), particle size distribution, and metal speciation. At Me2+ dose of 1.2 mmol/g VSS, PMS-Fe2+ and PMS-Cu2+ achieve the lowest normalized CST, i.e., CST/CST0, of 0.47, and the higher normalized CST values of 0.71 and 0.74 are observed for PMS-Mn2+ and PMS-Co2+, respectively. BWC shows little extent of decrease upon PMS-Me2+ oxidation, and the most significant decrease from 89.5% to 88.3% is observed for PMS-Mn2+. PMS-Co2+ contributes to the decrease of DOC in total EPS fractions (DOCtot) from 698.0 mg/L to 496.6 mg/L, whereas the increased DOCtot to 713.6, 734.4, and 755.0 mg/L is observed with the introduction of Cu2+, Fe2+, and Mn2+, respectively. Fe2+ tends to transform to Fe3+ and the coagulation effect increases the median particle diameter (D50) from 15.8 μm to 91.1 μm. Comparatively, much lower D50 values of below 20.0 μm are observed for other divalent ions. The European Community Bureau of Reference (BCR) sequential extraction method is used to analyze the metal speciation in ADS sediment after PMS-Me2+ disintegration. The dominant species of Co and Mn are acid extractable fractions with the ratios of 91.0% and 87.3%, whereas the main Fe and Cu species are observed to be residual and oxidizable fractions. The pre-captured Me2+ ions with 50-days aging interestingly exhibit activating efficacy towards PMS, and CST values were observed to decrease by 11.5%, 30.5%, 11.8%, and 27.3% with the presence of pre-captured Co2+, Cu2+, Fe2+, and Mn2+ at 1.2 mmol/g VSS. This study proposes the potentially valuable strategy for the disintegration and dewatering of sludge with high contents of transition metal ions.
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•PMS-Me2+ processes positively enhance ADS disintegration and dewatering.•IOM release, EPS decomposition, and BWC decrease occur by PMS-Me2+ disintegration.•Different species distribution of Me2+ leads to different conditioning performance.•In PMS-Fe2+ in-situ Fe3+ exhibit coagulation efficiency to sharply increase D50.•50-days aged Me2+ exhibits good efficacy to active PMS for ADS disintegration.
The generation of small fragments from the environmental ageing of microplastics (MPs) is still a poorly known process. This work addresses the fragmentation of MPs obtained from marine debris ...consisting of polyethylene and polypropylene (PE and PP in environmental mixture) and polystyrene (PS) after exposure to accelerated ageing by irradiation and mechanical stirring. Number particle size distribution in the 1–100 μm range was assessed by combining laser diffractometry with particle counts from flow cytometry. The results showed the generation of a high number of small MP particles, which reached 105–106 items/mg of plastic with most fragments <2 μm. The results showed that environmentally aged MPs give rise to a larger number of small MPs in a pattern consistent with progressive fragmentation in the three spatial dimensions. The proportion of small MPs was much higher than that found in current sampling campaigns, suggesting a severe underestimation of the environmental presence of small MPs. We also demonstrated the generation of nanoplastics (NPs) in the fraction <1 μm from irradiated runs. The results showed that the mechanism that produced nanoplastics (NPs) from MPs was irradiation, which yielded up to 1011–1013 NPs/g with particle size in the few hundreds of nm range. Our results are relevant for the assessment of fate and risk of plastic debris in the environment showing that the number of small plastic fragments produced during the ageing of MPs is much larger than expect from the extrapolation of larger size populations.
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•Photoageing of polyethylene, polypropylene, and polystyrene marine plastic debris•Generation of 105–106 items/mg of small microplastics, mostly <2 μm•The number concentration of small microplastics decreased upon irradiation.•Organic carbon attributed to nanoplastics increased only upon irradiation.•Nanoplastics in 1 μm filtrates could reach a concentration as high as 1011–1013 NPs/g.
Photodynamic therapy (PDT) is considered a pioneering and effective modality for cancer treatment, but it is still facing challenges of hypoxic tumors. Recently, Type I PDT, as an effective strategy ...to address this issue, has drawn considerable attention. Few reports are available on the capability for Type I reactive oxygen species (ROS) generation of purely organic photosensitizers (PSs). Herein, we report two new Type I PSs,
α
-TPA-PIO and
β
-TPA-PIO, from phosphindole oxide-based isomers with efficient Type I ROS generation abilities. A detailed study on photophysical and photochemical mechanisms is conducted to shed light on the molecular design of PSs based on the Type I mechanism. The
in vitro
results demonstrate that these two PSs can selectively accumulate in a neutral lipid region, particularly in the endoplasmic reticulum (ER), of cells and efficiently induce ER-stress mediated apoptosis and autophagy in PDT.
In vivo
models indicate that
β
-TPA-PIO successfully achieves remarkable tumor ablation. The ROS-based ER stress triggered by
β
-TPA-PIO-mediated PDT has high potential as a precursor of the immunostimulatory effect for immunotherapy. This work presents a comprehensive protocol for Type I-based purely organic PSs and highlights the significance of considering the working mechanism in the design of PSs for the optimization of cancer treatment protocols.
Phosphindole oxide-based photosensitizers with Type I reactive oxygen species generation ability are developed and used for endoplasmic reticulum stress-mediated photodynamic therapy of tumors.
Environmental contamination by microplastics is now considered an emerging threat to biodiversity and ecosystem functioning. Soil ecosystems, particularly agricultural land, have been recognized as a ...major sink of microplastics, but the impacts of microplastics on soil ecosystems (e.g., above and below ground) remain largely unknown. In this study, different types of microplastics biodegradable polylactic acid (PLA), conventional high-density polyethylene (HDPE), and microplastic clothing fibers were added to soil containing the endogeic Aporrectodea rosea (rosy-tipped earthworm) and planted with Lolium perenne (perennial ryegrass) to assess the biophysical soil response in a mesocosm experiment. When exposed to fibers or PLA microplastics, fewer seeds germinated. There was also a reduction in shoot height with PLA. The biomass of A. rosea exposed to HDPE was significantly reduced compared to control samples. Furthermore, with HDPE present there was a decrease in soil pH. The size distribution of water-stable soil aggregates was altered when microplastics were present, suggesting potential alterations of soil stability. This study provides evidence that microplastics manufactured of HDPE and PLA, and synthetic fibers can affect the development of L. perenne, health of A. rosea and basic, but crucial soil properties, with potential further impacts on soil ecosystem functioning.
Binder-jet 3D-printing is a powder bed additive manufacturing process that selectively deposits binder on a powder bed layer-by-layer to fabricate a green part followed by a sintering step for ...densification. Gas-atomized alloy 625 powders of three different powder size distributions including 16–63 μm (full), 16–25 μm (fine) and 53–63 μm (coarse) powders were 3D-printed with green relative bulk densities of about 52%, 45% and 48%, respectively, followed by vacuum-sintering at temperatures between 1225 and 1300 °C for 4 h. For the fine and coarse powders with narrow size distribution, printing defects with high pore coordination numbers may form during the binder jetting process which cannot be removed during the final sintering stage even during supersolidus liquid phase sintering. However, the full particle size distribution gave higher green density with fewer large, highly coordinated pores so supersolidus liquid phase sintering was able to reach near-full density. Additionally, the fine powders gave non-uniform, anisotropic linear shrinkage during sintering which is unfavorable for designing complex structures. The results suggest that particle size distribution is a determining factor for supersolidus liquid phase sintering, pore removal and final microstructure, if printing parameters such as layer thickness, binder saturation, printhead binder droplet size and drying time are similar.
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•Binder-jet 3D-printing of gas-atomized alloy 625 powders of three different particle size distributions (PSD).•Formation of printing defects with high pore coordination numbers for the fine and coarse powders with narrow PSD.•Supersolidus liquid phase sintering can reach near-full density.•Higher linear shrinkage for the fine powders resulted in non-uniform, anisotropic dimensional variations during sintering.•PSD is a determining factor for supersolidus liquid phase sintering, pore removal and final microstructure.
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Metal-organic frameworks (MOFs) have recently achieved much attention to eliminating toxic pollutants because of their attractive attributes, including large specific surface area, ...ultra-high porosity, abundant active adsorption sites, tunable surface chemistry, well-controlled pore size distribution, and strong host–guest interactions. Among the many developed MOFs, the Zr-based MOFs, particularly the UiO-66 family, are considered extremely attractive for wastewater treatment applications. The fascinating properties of UiO-66 such as high thermal stability, superior chemical resistance towards several solvents, including benzene, acetone, different alcohols, dimethylformamide, acidic and basic solution, excellent chemical stability against various conditions such as air, water, and chloroform, and exceptional resistance to high external pressure, mainly due to strong Zr-O bond and high coordination number between the Zr clusters and organic ligands have led to numerous potential applications in wastewater treatment. This review primarily focuses on the latest efforts in applying UiO-66 MOFs as superior water-stable MOFs for efficient removal (adsorption/separation and degradation/reduction) of various water pollutants, including organic dyes, heavy metal ions, pharmaceuticals and personal care products, phosphate, and fluoride. The possible adsorption/separation and degradation/reduction mechanisms for removing water pollutants by UiO-66 and its modified derivatives are fully addressed. Thus, the review is expected to provide guidance and stimulate researchers to carefully investigate the real applications of UiO-66 MOFs in water and wastewater treatment applications.
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