High amounts of phosphogypsum (PG) are generated in the production of phosphoric acid. Previous literature demonstrates that obtaining rare earth elements (REE) from PG is a promising alternative to ...managing this waste. However, the reported leaching efficiencies are low in most cases, or drastic leaching conditions are required. Therefore, this work aimed to study the leaching conditions of REE from PG to obtain high leaching efficiency values. Initially, a 24 factorial experimental design investigated the factors that affect the conventional acid leaching of REE from PG (leaching acid (citric and sulfuric acid), solid/liquid ratio, acid concentration, and temperature). Better leaching efficiency values of the sum of all REE (62.0% and 89.7% for citric and sulfuric acid, respectively) were obtained using an acid concentration of 3 mol L−1, solid/liquid ratio of 1/20 g mL−1, and temperature of 80 °C. Subsequently, the experiments optimization, performed through a central composite rotational design, indicated that the maximum leaching efficiency was achieved using a sulfuric acid concentration of 2.9 mol L−1, solid/liquid ratio of 1.7/20 g mL−1, and 55 °C. Under these conditions, the leaching efficiency of the sum of all REE was 90.0%. Leaching kinetics results showed that the equilibrium was reached in about 20 min for most REE. The mechanism investigation suggested that surface chemical reaction and diffusion through the boundary layer controlled the leaching.
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•Leaching of REE from phosphogypsum was optimized.•Sulfuric acid was the most efficient.•Citric acid was promising.•Maximum leaching efficiency was 90%.•Leaching equilibrium was reached in 20 min, except for Sc.
The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100nm size range by worldwide coal power plants represents serious ...environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples.
Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis.
► We examine changes in the level of ultrafine and nanoparticles of coal mining. ► Increasing geochemical information will increase human health information in this area. ► Electron bean and Tof-SIMS increase area information.
In this study, the residual pods of the forest species
Erythrina speciosa
were carbonized with ZnCl
2
to obtain porous activated carbon and investigated for the adsorptive removal of the drug ...paracetamol (PCM) from water. The PCM adsorption onto activated carbon is favored at acidic solution pH. The isothermal studies confirmed that increasing the temperature from 298 to 328 K decreased the adsorption capacity from 65 mg g
−1
to 50.4 mg g
−1
(C
0
= 175 mg L
−1
). The Freundlich model showed a better fit of the equilibrium isotherms. Thermodynamic studies confirmed the exothermic nature (ΔH
0
= −39.1066 kJ mol
−1
). Kinetic data indicates that the external mass transfer occurs in the first minutes followed by the surface diffusion, considering that the linear driving force model described the experimental data. The application of the material in the treatment of a simulated effluent with natural conditions was promising, presenting a removal of 76.45%. Therefore, it can be concluded that the application of residual pods of the forest species
Erythrina speciosa
carbonized with ZnCl
2
is highly efficient in the removal of the drug paracetamol and also in mixtures containing other pharmaceutical substances.
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•Physiological, geochemical and hydrological variables influencing pathogen migration.•An assessment algorithm for pathogen migration ability in subsurface environment.•Migration ...potential of SARS-CoV-2 in subsurface system is predicted.•Rating weights and databases for pathogen migration ability in subsurface environment.
The global outbreak of coronavirus infectious disease-2019 (COVID-19) draws attentions in the transport and spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in aerosols, wastewater, surface water and solid wastes. As pathogens eventually enter the subsurface system, e.g., soils in the vadose zone and groundwater in the aquifers, they might survive for a prolonged period of time owing to the uniqueness of subsurface environment. In addition, pathogens can transport in groundwater and contaminate surrounding drinking water sources, possessing long-term and concealed risks to human society. This work critically reviews the influential factors of pathogen migration, unravelling the impacts of pathogenic characteristics, vadose zone physiochemical properties and hydrological variables on the migration of typical pathogens in subsurface system. An assessment algorithm and two rating/weighting schemes are proposed to evaluate the migration abilities and risks of pathogens in subsurface environment. As there is still no evidence about the presence and distribution of SARS-CoV-2 in the vadose zones and aquifers, this study also discusses the migration potential and behavior of SARS-CoV-2 viruses in subsurface environment, offering prospective clues and suggestions for its potential risks in drinking water and effective prevention and control from hydrogeological points of view.
Anthropogenic occurring nanoparticles (NPs) have been one of the principal catalytic components of marine pollution throughout its history. The phosphogypsum (PG) factories present environmental ...risks and evident marine pollution in different parts of the world. Many of these factors continue to operate, however, some have already been abandoned by the private sector. The general objective of this manuscript is to analyze the real nanoparticles (NPs) present on a beach in southern Brazil to illustrate the need to create public policies and projects for environmental recovery. This work focused on real representative sampling of suspended sediments (SSs), and on a modern analytical procedure via advanced electron microscopes (field emission scanning electron microscope-FE-SEM and high resolution transmission electron microscope-HR-TEM coupled with an energy dispersive X-ray microanalysis system-EDS) to analyze NPs containing hazardous elements (HEs). The results presented in this work demonstrate who the size, morphology, among other physical-geochemical characteristics influence in the adsorption of HEs by the NPs and their respective agglomerates. This study is of great importance for carrying out the application of advanced techniques and methods to better understand the formation and transport of NPs on beaches, which allows assisting in the management of waste from plaster factories on a global scale.
•South Brazilian coastal zone (Santa Catarina State) is theme to intensive anthropogenic difficulties.•Macro and microfauna is poorly diversified at shallowest stations undergoing to phosphogypsum rejects deposits.•In general human health danger indices exceeded the safety limits to nanoparticles contacts.
This paper reports a high efficiency uptake of captopril (CPT), employing magnetic graphene oxide (MGO) as the adsorbent. The graphene oxide (GO) was produced through an oxidation and exfoliation ...method, and the magnetization technique by the co-precipitation method. The nanomaterials were characterized by FTIR, XRD, SEM, Raman, and VSM analysis. The optimal condition was reached by employing GO·Fe3O4 at pH 3.0 (50 mg of adsorbent and 50 mg L−1 of CPT), presenting values of removal percentage and maximum adsorption capacity of 99.43% and 100.41 mg g−1, respectively. The CPT adsorption was dependent on adsorbent dosage, initial concentration of adsorbate, pH, and ionic strength. Sips and Elovich models showed the best adjustment for experimental data, suggesting that adsorption occurs in a heterogeneous surface. Thermodynamic parameters reveal a favorable, exothermic, involving a chemisorption process. The magnetic carbon nanomaterial exhibited a high efficiency after five adsorption/desorption cycles. Finally, the GO·Fe3O4 showed an excellent performance in CPT removal, allowing future application in waste management.
Herein, the methylene blue (MB) biosorption from the agroindustrial residue (cassava bagasse) is reported. The cassava bagasse residue presented an irregular surface, anionic character, and low ...specific surface area. The experiments were performed in batch mode. The biosorption behavior was investigated through the experimental variables, initial concentration of MB, pH, and temperature. The maximum biosorption capacity (170.13 mg g
−1
) reached 328 K and pH 10.0. The equilibrium and kinetics were better fitted by the Sips and general order (
R
2
≥ 0.997 and
R
2
adj
≥ 0.996) models, respectively. Furthermore, the thermodynamic study revealed a spontaneous (
ΔG
0
< 0) and endothermic process. Finally, the results showed cassava bagasse is a potential material for biosorption dyes from the aqueous medium. In addition, the biosorbent has a low aggregate cost and high availability, which contributes to the destination of large amounts of waste and inspires engineering applications.
Graphical Abstract
This work focused on developing an active bilayer film based on natural extract. Thus, the jaboticaba peel extract (JPE) was produced and characterized and showed promising application as a natural ...additive in biopolymeric materials. The zein fiber and bilayer films were produced using a chitosan film (casting) and zein fiber (electrospinning), with and without JPE. All samples were evaluated according to thickness, solubility in water, water vapor permeability, and main diameter, and for these, zein fiber, chitosan/zein fiber, and chitosan/zein fiber + 3% JPE showed values of 0.19, 0.51, and 0.50 mm, 36.50, 12.96, and 27.38%, 4.48 × 10
, 1.6 × 10
, and 1.58 × 10
(g m
Pa
s
), and 6.094, 4.685, and 3.620 μm, respectively. These results showed that the addition of a second layer improved the barrier properties of the material when compared to the monolayer zein fiber. The thermal stability analysis proved that the addition of JPE also improved this parameter and the interactions between the components of the zein fiber and bilayer films; additionally, the effective presence of JPE was shown through FTIR spectra. In the end, the active potential of the material was confirmed by antimicrobial analysis since the bilayer film with JPE showed inhibition halos against
and
.
Coal is the most abundant fossil fuel in the world. Because of the growth of coal mining, coal-fired power plants and coal-burning industries, the increase of the emission of particulates (coarse, ...fine or ultrafine) is of great concern. There is a relationship between increasing human morbidity and mortality and progressive environmental air pollution caused by these types of particles. Thus, the knowledge of the physico-chemical composition and ambient concentrations of coal-derived nanoparticles will improve pollution control strategy. Given the current importance of this area of research, the advanced characterization of this coal combustion-derived nanoparticles/nanominerals as well as hazardous elements is likely to be one of the hottest research fields in coming days. In this review, we try to compile the existing knowledge on coal-derived nanoparticles/nanominerals and discuss the advanced level of characterization techniques for future research. This review also provides some of aspects of health risks associated with exposure to ambient nanoparticles. In addition, the presence of some of the hazardous elements in coal and coal combustion activities is also reviewed.
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•The existing knowledge on nanominerals/nanoparticles in coal and CFAs are demonstrated.•We reviewed the advanced level characterization techniques for coal and coal residues.•Some aspects of health hazards caused due to coal combustion activities are discussed.
Modern microscopy studies are capable of revealing ultra-fine particles (UFPs) and nanoparticles (NPs) that are produced in the processes related to traffic vehicular, industrial, metropolitan, and ...marine aerosol dry deposition in the coastal zones. Especially, secondary aerosol passages complexes categories of NPs and UFPs, which can be accumulated on construction compounds and by dry deposition, encourages multiples monuments deterioration routes. The advanced electron microscopies method is one of the most utilized in environmental studies. Between the different industrial areas in the world, the Caribbean area is the most relevant symbols of air quality due to climatic conditions with strong winds, but this study shows that regionally the most industrialized region does not have an adequate air quality. In the present work, electron microscopy analyses are used to describe of the extent of ultra-fine particle and nanoparticles in walls in contact to weathering. Numerous phases were recognized by advanced mineralogy methods. Thanks to the new analytical procedure it was feasible to understand NPs and UFPs; the occurrence of potential hazardous elements (PHEs), most of them as minerals but also combined in multiple accumulations with Al–Cr–Fe–K–Mg–Pb–Si–Ti–Zn amorphous; and carbonaceous phases.
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•Potential dangerous elements have been investigated in ultra-fine and nanoparticles from Marine Aerosol.•Self-made passive sampler (SMPS) was examined in a coastline atmosphere with diverse contamination.•Multi-analytical approach was utilized for the nondestructive investigation of sampled UFP and NPs.•Dry accumulation is an important influence on the preservation of human cultural heritage.
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