Water pollution by dyes has been a major environmental problem to be tackled, and magnetic adsorbents appear as promising alternatives to solve it. Herein, magnetic activated carbons were prepared by ...the single-step method from Sapelli wood sawdust, properly characterized, and applied as adsorbents for brilliant blue dye removal. In particular, two magnetic activated carbons, MAC1105 and MAC111, were prepared using the proportion of biomass KOH of 1:1 and varying the proportion of NiCl
of 0.5 and 1. The characterization results demonstrated that the different proportions of NiCl
mainly influenced the textural characteristics of the adsorbents. An increase in the surface area from 260.0 to 331.5 m
g
and in the total pore volume from 0.075 to 0.095 cm
g
was observed with the weight ratio of NiCl
. Both adsorbents exhibit ferromagnetic properties and the presence of nanostructured Ni particles. The different properties of the materials influenced the adsorption kinetics and equilibrium of brilliant blue dye. MAC111 showed faster kinetics, reaching the equilibrium in around 10 min, while for MAC1105, it took 60 min for the equilibrium to be reached. In addition, based on the Sips isotherm, the maximum adsorption capacity was 98.12 mg g
for MAC111, while for MAC1105, it was 60.73 mg g
. Furthermore, MAC111 presented the potential to be reused in more adsorption cycles than MAC1105, and the use of the adsorbents in the treatment of a simulated effluent exhibited high effectiveness, with removal efficiencies of up to 90%.
The extensive use of pesticides in agriculture has significantly impacted the environment and human health, as these pollutants are inadequately disposed of into water bodies. In addition, pesticides ...can cause adverse effects on humans and aquatic animals due to their incomplete removal from the aqueous medium by conventional wastewater treatments. Therefore, processes such as heterogeneous photocatalysis and adsorption by nanocomposites have received special attention in the scientific community due to their unique properties and ability to degrade and remove several organic pollutants, including pesticides. This report reviews the use of nanocomposites in pesticide adsorption and photocatalytic degradation from aqueous solutions. A bibliographic search was performed using the ScienceDirect, American Chemical Society (ACS), and Royal Society of Chemistry (RSC) indexes, using Boolean logic and the following descriptors: “pesticide degradation” AND “photocatalysis” AND “nanocomposites”; “nanocomposites” AND “pesticides” AND “adsorption”. The search was limited to research article documents in the last ten years (from January 2012 to June 2022). The results made it possible to verify that the most dangerous pesticides are not the most commonly degraded/removed from wastewater. At the same time, the potential of the supported nanocatalysts and nanoadsorbents in the decontamination of wastewater-containing pesticides is confirmed once they present reduced bandgap energy, which occurs over a wide range of wavelengths. Moreover, due to the great affinity of the supported nanocatalysts with pesticides, better charge separation, high removal, and degradation values are reported for these organic compounds. Thus, the class of the nanocomposites investigated in this work, magnetic or not, can be characterized as suitable nanomaterials with potential and unique properties useful in heterogeneous photocatalysts and the adsorption of pesticides.
A range of carbon nanoparticles, agglomerates and mineral phases have been identified in burning coal waste pile materials from the Douro Coalfield of Portugal, as a basis for identifying their ...potential environmental and human health impacts. The fragile nature and fine particle size of these materials required novel characterization methods, including energy-dispersive X-ray spectrometry (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) techniques. The chemical composition and possible correlations with morphology of the nanominerals and associated ultra-fine particles have been evaluated in the context of human health exposure, as well as in relation to management of such components in coal-fire environments.
Exposure to coal and coal ashes can cause harmful effects in in vitro and in vivo systems, mainly by the induction of oxidative damage. The aim of this work was to assess cytotoxic and genotoxic ...effects using the V79 cell line treated with coal and coal fly ash particles derived from a coal power plant located in Santa Catarina, Brazil. Two coal samples (COAL11 and COAL16) and two coal fly ash samples (CFA11 and CFA16) were included in this study. COAL16 was co-firing with a mixture of fuel oil and diesel oil. The comet assay data showed that exposure of V79 cells to coal and coal fly ash particles induced primary DNA lesions. Application of lesion-specific endonucleases (FPG and ENDO III) demonstrated increased DNA effects indicating the presence of high amounts of oxidative DNA lesions. The cytokinesis-block micronucleus cytome assay analysis showed that exposure of V79 cells to high concentrations of coal and coal fly ash particles induced cytotoxic effects (apoptosis and necrosis) and chromosomal instability (nucleoplasmic bridges, nuclear buds, and micronucleus (MN) formation). These results may be associated with compounds contained in the surface of the particles as hazardous elements, ultrafine/nanoparticles, and polycyclic aromatic hydrocarbons (PAHs) which were detected in the samples.
Graphical abstract
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► Santa Catarina power plant is the largest capacity in South America. ► Diagnosis was conducted to check hazardous element mobility during coal combustion. ► Most elements are bound to organic ...matter and sulfides in coal. ► U, As, and Cr increased mobility, mainly in the easily-soluble fraction, in coal ashes. ► Dumping and use of coal ashes pose significant risks to environment and human health.
This paper reports about changes in mobility of hazardous elements contained in coal during combustion at a power plant in Santa Catarina (Brazil) and the environmental impact potential of ashes. Total and mobile element concentrations were determined by digestion and sequential extraction. Comparison of results within the mobile fraction showed that after combustion, oxidizable elements bound to organic matter and sulfides in coal were mostly transformed into elements easily soluble in water or slightly acidic conditions and, hence, most readily bioaccumulative in the environment in ashes, mainly U, Cr, and As. Capacity of ashes as a source of mobile pollutants was quantified by combining sequential extraction and annual production. Just considering the easily soluble fraction, coal ashes could leach up to 839tons of Al, 144tons of Fe, 100tons of Mn, 4.6tons of Zn, 3.1tons of Cr, 1.7tons of As, 1.5tons of Cu, 490kg of U, and 20kg of Pb every year. Bottom ashes are disposed of in landfill sites close to the plant. Fly ashes are recycled as construction material. Diagnostic processes do not consider checking for these highly mobile hazardous elements. Hence, uncontrolled dumping and use of these by-products may pose significant risks to environment and human health.
The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of ...occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of submicron, ultrafine and nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich submicron, ultrafine and nanoparticles within the ash may contain high proportions of toxic elements such as As, Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and submicron, ultrafine and nanominerals (e.g. oxides, sulphates, clays) in concentrations of up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials.
► We examine changes in the level of ultrafine and nanoparticles about coal–pyrite quality. ► Increasing information will increase human health quality in this area. ► Welfare effects depend on ex-ante or ex-post assumptions about quality information.
The sulfide oxidation and precipitation of Al-Fe-secondary minerals associated with abandoned acid mine drainage (AMD) from the abandoned copper mine waste pile at Touro, Spain, has been studied by ...sequential extraction (SE) combined with several techniques with the intent of understanding the role of these processes play in the natural attenuation of hazardous element contaminants in the AMD. In addition, the fragile nature of nanominerals and ultrafine particle (UFP) assemblages from contaminated sediment systems from the abandoned copper mine required novel techniques and experimental approaches. The investigation of the geochemistry of complex nanominerals and UFP assemblages was a prerequisite to accurately assess the environmental and human health risks of contaminants and cost-effective chemical and biogeological remediation strategies. Particular emphasis was placed on the study and characterization of the complex mixed nanominerals and UFP containing potentially toxic elements. Nanometer-sized phases in sediments were characterized using energy-dispersive X-ray spectrometer (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) images. The identification of the geochemical and mineralogical composition of AMD in Touro, as well as the different formation mechanisms proposed, complement the existing literature on secondary mineral assemblages and provide new emphasis to increase the understanding of extreme environments. The results also demonstrated that variations in the geochemical fractionation of hazardous elements in AMD were more influenced by the secondary mineral proportion and by AMD pH.
Open cast mining has a strong impact on the environment, the intensity depending on the morphology of the deposit and on the nature of the minerals. At Touro mine (NW Spain) there is a large area ...covered by tailings, one of which, called the “sedimentation bank”, was used to deposit sludge resulting from the extraction of copper in the flotation plant. Three zones were selected and the soils were sampled to analyse the changes brought about by vegetation on the chemical and mineralogical properties of the soils developed over the sedimentation bank and its development over time. The vegetation increased the pH, contents of organic material, nitrogen, clay and free oxides of Fe and Al, and the cationic exchange capacity of the soils. The decrease in the sulphide content, benefited by the vegetation process, led to a reduction in the total content of Cr and Cu. The vegetation also contributed towards the alteration of the primary minerals. The transformation of jarosite, the formation of nanocrystals of hematite, goethite, hydroxypolymers, and amorphous minerals that contained Cu, Cr and Pb were observed. Nevertheless the high Cu and Cr contents indicate that it is advisable to change the restoration process.
► We studied the influence of vegetation on different properties of contaminated soils. ► There is a decrease in soils sulphide content as the age of the vegetation increased. ► Vegetation favours the transformation of minerals such as jarosite. ► Vegetation facilitates the formation of amorphous minerals containing Cu, Cr and Pb. ► The restoration plan must be changed because Cu and Cr soil contents are still high.
Brazil's production and consumption of açai pulp (Euterpe oleracea) occur on a large scale. Most of the fruit is formed by the pit, which generates countless tons of residual biomass. A new purpose ...for this biomass, making its consumption highly sustainable, was presented in this study, where activated carbon (AC) was produced with zinc chloride for later use as an adsorbent. AC carbon formed by carbon and with a yield of 28 % was satisfactorily used as an adsorbent in removing the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Removal efficiency was due to the highly porous surface (Vp = 0.467 cm
g
; Dp = 1.126 nm) and good surface área (SBET = 920.56 m
g
). The equilibrium data fit the Sips heterogeneous and homogeneous surface model better. It was observed that the increase in temperature favored adsorption, reaching a maximum experimental capacity of 218 mg g
at 328 K. The thermodynamic behavior indicated a spontaneous, favorable, and endothermic behavior. The magnitude of the enthalpy of adsorption was in agreement with the physical adsorption. Regardless of the herbicide concentration, the adsorbent displayed fast kinetics, reaching equilibrium within 120 min. The linear driving force (LDF) model provided a strong statistical match to the kinetic curves. AC with zinc chloride (ZnCl
), created from leftover açai biomass, is a potential alternative as an adsorbent for treating effluents containing 2,4-D.
Sapelli wood sawdust-derived magnetic activated carbon (SWSMAC) was produced by single-step pyrolysis using KOH and NiCl
2
as activating and magnetization agents. SWSMAC was characterized by several ...techniques (SEM/EDS, N
2
adsorption/desorption isotherms, FTIR, XRD, VSM, and pH
PZC
) and applied in the brilliant blue FCF dye adsorption from an aqueous medium. The obtained SWSMAC was a mesoporous material and showed good textural properties. Metallic nanostructured Ni particles were observed. Also, SWSMAC exhibited ferromagnetic properties. In the adsorption experiments, adequate conditions were an adsorbent dosage of 0.75 g L
−1
and a solution pH of 4. The adsorption was fast, and the pseudo-second-order demonstrated greater suitability to the kinetic data. The Sips model fitted the equilibrium data well, and the maximum adsorption capacity predicted by this model was 105.88 mg g
−1
(at 55 °C). The thermodynamic study revealed that the adsorption was spontaneous, favorable, and endothermic. Besides, the mechanistic elucidation suggested that electrostatic interactions, hydrogen bonding, π–π interactions, and n–π interactions were involved in the brilliant blue FCF dye adsorption onto SWSMAC. In summary, an advanced adsorbent material was developed from waste by single-step pyrolysis, and this material effectively adsorbs brilliant blue FCF dye.
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