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Water Research Feb 2024Adsorption processes with carbon-based adsorbents have received substantial attention as a solution to remove uranium from drinking water. This study investigated...
Adsorption processes with carbon-based adsorbents have received substantial attention as a solution to remove uranium from drinking water. This study investigated uranium adsorption by a polymer-based spherical activated carbon (PBSAC) characterised by a uniformly smooth exterior and an extended surface of internal cavities accessible via mesopores. The static adsorption of uranium was investigated applying varying PBSAC properties and relevant solution chemistry. Spatial time-of-flight secondary ion mass spectrometry (ToF-SIMS) was employed to visualise the distribution of the different uranium species in the PBSAC. The isotherms and thermodynamics calculations revealed monolayer adsorption capacities of 28-667 mg/g and physical adsorption energies of 13-21 kJ/mol. Increasing the surface oxygen content of the PBSAC to 10 % enhanced the adsorption and reduced the equilibrium time to 2 h, while the WHO drinking water guideline of 30 µgU/L could be achieved for an initial concentration of 250 µgU/L. Uranium adsorption with PBSAC was favourable at the pH 6-8. At this pH range, uranyl carbonate complexes (UOCO, UO(CO), (UO)CO(OH)) predominated in the solution, and the ToF-SIMS analysis revealed that the adsorption of these complexes occurred on the surface and inside the PBSAC due to intra-particle diffusion. For the uranyl cations (UO, UOOH) at pH 2-4, only shallow adsorption in the outermost PBSAC layers was observed. The work demonstrated the effective removal of uranium from contaminated natural water (67 µgU/L) and meeting both German (10 µgU/L) and WHO guideline concentrations. These findings also open opportunities to consider PBSAC in hybrid treatment technologies for uranium removal, for instance, from high-level radioactive waste.
Topics: Drinking Water; Uranium; Charcoal; Adsorption; Polymers; Hydrogen-Ion Concentration
PubMed: 38118222
DOI: 10.1016/j.watres.2023.120825 -
Chemosphere Feb 2024Aged microplastics are ubiquitous in the aquatic environment, which inevitably accumulate metals, and then alter their migration. Whereas, the synergistic behavior and...
Aged microplastics are ubiquitous in the aquatic environment, which inevitably accumulate metals, and then alter their migration. Whereas, the synergistic behavior and effect of microplastics and Hg(II) were rarely reported. In this context, the adsorptive behavior of Hg(II) by pristine/aged microplastics involving polystyrene, polyethylene, polylactic acid, and tire microplastics were investigated via kinetic (pseudo-first and second-order dynamics, the internal diffusion model), Langmuir, and Freundlich isothermal models; the adsorption and desorption behavior was also explored under different conditions. Microplastics aged by ozone exhibited a rougher surface attached with abundant oxygen-containing groups to enhance hydrophilicity and negative surface charge, those promoted adsorption capacity of 4-20 times increment compared with the pristine microplastics. The process (except for aged tire microplastics) was dominated by a monolayer chemical reaction, which was significantly impacted by pH, salinity, fulvic acid, and co-existing ions. Furthermore, the adsorbed Hg(II) could be effectively eluted in 0.04% HCl, simulated gastric liquids, and seawater with a maximum desorption amount of 23.26 mg/g. An artificial neural network model was used to predict the performance of microplastics in complex media and accurately capture the main influencing factors and their contributions. This finding revealed that aged microplastics had the affinity to trap Hg(II) from freshwater, whereafter it released the Hg(II) once transported into the acidic medium, the organism's gastrointestinal system, or the estuary area. These indicated that aged microplastics could be the sink or the source of Hg(II) depending on the surrounding environment, meaning that aged microplastics could be the vital carrier to Hg(II).
Topics: Microplastics; Plastics; Adsorption; Deep Learning; Mercury; Water Pollutants, Chemical
PubMed: 38163463
DOI: 10.1016/j.chemosphere.2023.141067 -
Environmental Pollution (Barking, Essex... Nov 2023While both mercury (Hg) and microplastics (MPs) are well-studied global pollutants, comparatively little is known about the interactions between them and the...
While both mercury (Hg) and microplastics (MPs) are well-studied global pollutants, comparatively little is known about the interactions between them and the mobilization of Hg from MPs into organisms. We examined the affinity of Hg(II) to artificially weathered MPs, including polyamide (w-PA), polyethylene (w-PE), polyethylene terephthalate (w-PET), polyester fibers (w-PEST), polyvinyl chloride (w-PVC), and polylactic acid (w-PLA), along with crumb rubber (CR) and PE collected from a wastewater treatment plant (WWTP-PE). WWTP-PE, CR, and w-PEST had particularly high Hg(II) affinities, which can be attributed to electrostatic interaction and pore filling. The adsorption followed a pseudo-second-order kinetic process and fitted the Freundlich model, suggesting multi-step (mass transfer and intraparticle diffusion) and heterogeneous adsorptions. Hydrochemical conditions (pH, dissolved organic matter (DOM), salinity and co-existent metal ions) all impacted Hg-MP behavior. Changes in Hg speciation and MP surface properties contributed to the different Hg(II) adsorption capacities for the MPs. Weathering of MPs generally increased the adsorption of Hg(II) onto MPs, but CR, PET and PEST did not follow this trend. Less than 3% of adsorbed Hg(II) was mobilized from the MPs in freshwater, but that increased up to 73% under simulated avian digestive conditions, suggesting increased bioavailability of Hg(II) from ingested MPs. Overall, weathered MPs adsorb and retain Hg(II) under environmentally relevant conditions but desorb much of it in simulated avian digestion fluid, suggesting that birds that ingest MPs may have increased Hg(II) exposure.
Topics: Microplastics; Plastics; Mercury; Adsorption; Rubber; Polyethylene; Water Pollutants, Chemical
PubMed: 37757936
DOI: 10.1016/j.envpol.2023.122621 -
International Journal of Biological... Dec 2023In this study, carbon dots (CDs) and titanate nanofibers (TNs) were mixed with TEMPO-oxidized nanocellulose (TOCNC) to prepare fluorescent nanocellulose aerogels (FNAs)...
In this study, carbon dots (CDs) and titanate nanofibers (TNs) were mixed with TEMPO-oxidized nanocellulose (TOCNC) to prepare fluorescent nanocellulose aerogels (FNAs) by a Schiff base reaction. The resulting FNA can detect the adsorption of Cr through the fluorescence quenching in CDs and promote the removal of Cr through the synergistic effect of CDs in photocatalysis. The optimized FNA has a maximum adsorption capacity of 543.38 mg/g, higher than most reported Cr adsorbents. This excellent performance is due to the porous structure of the aerogel, which gives it a high specific surface area of 20.53 m/g and provides abundant adsorption sites. Simultaneously, CDs can enhance the amino-induced Cr adsorption, improve the photocatalytic performance of TNs, and expose more adsorption sites through electrostatic adsorption of amino-induced reduction products (Cr). This study explores the preparation of visualized nanosorbents with enhanced photocatalytic removal of Cr and provides a new direction for nanoscale photocatalysts.
Topics: Carbon; Adsorption; Coloring Agents; Water Pollutants, Chemical
PubMed: 37793519
DOI: 10.1016/j.ijbiomac.2023.127206 -
Environmental Monitoring and Assessment Aug 2023The recovery of organophosphate pesticides (OPPs) from aqueous solutions is imperative considering their agricultural and environmental implications. Among various...
The recovery of organophosphate pesticides (OPPs) from aqueous solutions is imperative considering their agricultural and environmental implications. Among various mitigation approaches used for OPPs' removal, adsorption offers many advantageous features for OPPs abatement owing to its benign nature, cost-effective processing, and non-requirement of excessive equipment. This research describes the adsorptive removal of three organophosphate pesticides (OPPs) namely chlorpyrifos (CPF), methyl parathion (MP), and malathion (MAL) by HKUST-1 (HKUST = Hong Kong University of Science and Technology) metal-organic framework (MOF). The synthesis of HKUST-1 MOFs was confirmed by various spectroscopic and microscopic techniques. The adsorption kinetics was systematically investigated by varying three parameters to include solution pH, contact time, and initial pesticide concentration. Among all the three pesticides, HKUST-1 showed enhanced removal of CPF in terms of pH, resulting in an adsorption capacity of 1.82 mg·g. However, under the effect of contact time at 60 min, the adsorption capacity of HKUST-1 for PM, MAL, and CPF were computed to be 1.83, 1.79, and 0.44 mg·g, respectively. Besides, HKUST-1 showed a remarkable performance towards adsorptive removal of MAL (14.01 mg·g at 10 mg·L concentration) with linear increase in adsorption capacity as the function of initial pesticide concentration. The MOFs were also able to retain ca. 50% of their adsorption efficiency over the course of five cycles of adsorptive removal of CP. In the future, a comprehensive data table showing the performance of various MOFs against various OPPs can be constructed on the basis of parameters used in this study.
Topics: Metal-Organic Frameworks; Adsorption; Environmental Monitoring; Insecticides; Chlorpyrifos; Malathion; Pesticides; Organophosphorus Compounds
PubMed: 37592149
DOI: 10.1007/s10661-023-11662-3 -
Environmental Research Dec 2023Co-pyrolysis biomass and alkaline metals can effectively improve the adsorption performance of heavy metals (HM). Nevertheless, the researchers have ignored the...
Co-pyrolysis biomass and alkaline metals can effectively improve the adsorption performance of heavy metals (HM). Nevertheless, the researchers have ignored the relationship between the change of alkaline metal morphology and adsorption during pyrolysis. In this article, according to control the pyrolysis time (30, 60, and 180 min) synthesized Magnesium (Mg) modified biochar (MBCX) by using MgCl·6HO and soybean straw under 400 °C. The sorption capacities of MBC60 and MBC180 for Pb/Cd increased by 38.65%/213.29%, 44.57%/230.36%, and the selectivity coefficient of Pb/Cd increased by 113.28%/209.49%, 213.58%/253.62%, respectively, compared with MBC30. Additionally, the characterization results demonstrated that MgO dominated the surface phases of MBC60 and MBC180, whereas MgCl dominated the surface phases of MBC30. Moreover, according to the results of DFT calculation, the adsorption energy (E) of MgO for Pb (-0.537 eV) and Cd (-0.347 eV) was lower than that of MgCl (Pb: 0.37 eV, Cd: -0.185 eV), so that, MBC60 and MBC180 had higher sorption capacities for Pb and Cd than MBC30. Therefore, this work provides a new sight to clear the mechanism for modified biochar by alkali metal oxide and practical and theoretical guidance for adsorbent preparation with high adsorption ability for HMs.
Topics: Cadmium; Magnesium; Lead; Magnesium Oxide; Adsorption; Pyrolysis; Charcoal
PubMed: 37813135
DOI: 10.1016/j.envres.2023.117215 -
Advanced Materials (Deerfield Beach,... Mar 2024Reducible metal oxide nanozymes (rNZs) are a subject of intense recent interest due to their catalytic nature, ease of synthesis, and complex surface character. Such... (Review)
Review
Reducible metal oxide nanozymes (rNZs) are a subject of intense recent interest due to their catalytic nature, ease of synthesis, and complex surface character. Such materials contain surface sites which facilitate enzyme-mimetic reactions via substrate coordination and redox cycling. Further, these surface reactive sites are shown to be highly sensitive to stresses within the nanomaterial lattice, the physicochemical environment, and to processing conditions occurring as part of their syntheses. When administered in vivo, a complex protein corona binds to the surface, redefining its biological identity and subsequent interactions within the biological system. Catalytic activities of rNZs each deliver a differing impact on protein corona formation, its composition, and in turn, their recognition, and internalization by host cells. Improving the understanding of the precise principles that dominate rNZ surface-biomolecule adsorption raises the question of whether designer rNZs can be engineered to prevent corona formation, or indeed to produce "custom" protein coronas applied either in vitro, and preadministration, or formed immediately upon their exposure to body fluids. Here, fundamental surface chemistry processes and their implications in rNZ material performance are considered. In particular, material structures which inform component adsorption from the application environment, including substrates for enzyme-mimetic reactions are discussed.
Topics: Protein Corona; Oxides; Nanostructures; Adsorption
PubMed: 37000888
DOI: 10.1002/adma.202211261 -
Chemosphere Feb 2024During the years, adsorption has garnered considerable attention being one of the most cost-effective and efficient methods for separating contaminants out of liquid... (Review)
Review
During the years, adsorption has garnered considerable attention being one of the most cost-effective and efficient methods for separating contaminants out of liquid phase. A comprehensive understanding of adsorption mechanisms entails several crucial steps, including adsorbent characterization, batch and column adsorption tests, fitting of predefined kinetic and isotherm models, and meticulous thermodynamic analysis. These combined efforts serve to provide clarity and insights into the intricate workings of adsorption phenomena. However, the vast amount of literature published in the field each year is riddled with ill-considered model selections and incorrect parameter analyses. Therefore, the aim of this paper is to establish guidelines for the proper employment of these numerous kinetic, isotherm, and fixed-bed models in various applications. A thorough review has been undertaken, encompassing more than 45 kinetic models, 70 isotherm models, and 45 fixed bed models available hitherto, with their classification determined based on the adsorption mechanisms expounded within each of them. Moreover, five general approaches for modifying fixed-bed models were provided. The physical meanings, assumptions, and interconversion relationships of the models were discussed in detail, along with the information criterion used to evaluate their validity. In addition to commonly used activation energy and Gibbs energy analysis, the methods for calculating site energy distribution were also summarized.
Topics: Adsorption; Thermodynamics; Physics; Kinetics; Water Pollutants, Chemical; Hydrogen-Ion Concentration
PubMed: 37995976
DOI: 10.1016/j.chemosphere.2023.140736 -
International Journal of Biological... Jan 2024Recent reports had shown that microplastics could be transferred to organisms through various channels, severely and adversely affecting organisms' health and their...
Recent reports had shown that microplastics could be transferred to organisms through various channels, severely and adversely affecting organisms' health and their physiological functions. Therefore, there remained an urgency to adopt an effective and environmentally friendly method to extract microplastics from water. In this paper, a cationic-modified d-DCPG aerogel with a three-dimensional network structure was successfully prepared by a directional freeze-drying technology in which double-aldehyde-modified cellulose nanofiber (CNF) was used as the matrix, betaine chloride hydrazide (GT) provided modification, and polyvinyl alcohol (PVA) provided cross-linking function. Aerogels had an excellent adsorption capacity (145.05 mg/g) for microplastics in aqueous environment, and when the pH was from 10 to 4, it exhibited an excellent adsorption efficiency from 90.01 % to 97.61 %; an excellent adsorption efficiency after 8 cycles (>89 %); pseudo-second-order kinetics and Freundlich adsorption isotherm had a high fitting effects on the adsorption process and adsorption results, respectively. And ultraviolet analysis also verified the occurrence of adsorption behavior. These results showed that d-DCPG aerogels had an excellent application prospects in microplastics removal in river, lake, reservoir, and marine environments.
Topics: Adsorption; Microplastics; Plastics; Aldehydes; Betaine; Cations
PubMed: 38000571
DOI: 10.1016/j.ijbiomac.2023.128326 -
Chemosphere Oct 2023Phenoxyacetic acid herbicides are widely used in agriculture for controlling weeds. These organic compounds are persistent and recalcitrant, often contaminating water...
Phenoxyacetic acid herbicides are widely used in agriculture for controlling weeds. These organic compounds are persistent and recalcitrant, often contaminating water and soil. Therefore, we studied five pristine biochars (BCs), and southern yellow pine (SYP) based self-activated carbon (SAC) for the adsorptive removal of 2,4-Dichlorophenoxyacetic acid (2,4-D) herbicide. Among the tested adsorbents, SYP-SAC-15 demonstrated higher (>90%) 2,4-D removal from water. The SYP-SAC-15 was produced using a facile and green route where the biomass pyrolysis gases worked as activating agents creating a highly porous structure with a surface area of 1499.79 m/g. Different adsorption kinetics and isotherm models were assessed for 2,4-D adsorption on SYP-SAC-15, where the data fitted best to pseudo-second order (R > 0.999) and Langmuir (R > 0.991) models, respectively. Consequently, the adsorption process was mainly dominated by the chemisorption mechanism with monolayer coverage of SYP-SAC-15 surface with 2,4-D molecules. At the optimum pH of 2, the maximum 2,4-D adsorption capacity of SYP-SAC-15 reached 471.70 mg/g. Furthermore, an increase in the water salinity demonstrated a positive influence on 2,4-D adsorption, whereas humic acid (HA) showed a negative impact on 2,4-D adsorption. The regeneration ability of SYP-SAC-15 showed excellent performance by retaining 71.09% adsorption capability at the seventh adsorption-desorption cycle. Based on the operating pH, surface area, spectroscopic data, kinetics, and isotherm modeling, the adsorption mechanism was speculated. The 2,4-D adsorption on SYP-SAC-15 was mainly governed by pore filling, electrostatic interactions, hydrogen bonding, hydrophobic and π-π interactions.
Topics: Herbicides; Charcoal; Adsorption; Water; Water Pollutants, Chemical; Hydrogen-Ion Concentration; 2,4-Dichlorophenoxyacetic Acid; Kinetics
PubMed: 37536539
DOI: 10.1016/j.chemosphere.2023.139715