Geochemistry and the optics of geospatial analysis as a preposition of water quality on a macroscale.

The water treatment depends exclusively on the identification of residues containing toxic chemical elements accumulated in NPs (nanoparticles), and ultrafine particles sourced from waste piles located at old, abandoned sulfuric acid factories containing phosphogypsum requires global attention. The general objective of this study is to quantify and analyze the hazardous chemical elements present in the leachate of waste from deactivated sulfuric acid factories, coupled in NPs and ultrafine particles, in the port region of the city of Imbituba, Santa Catarina, Brazil. Samples were collected in 2020, 2021, and 2022. Corresponding images from the Sentinel-3B OLCI satellite, taken in the same general vicinity, detected the levels of absorption coefficient of Detritus and Gelbstoff (ADG443_NN) in 443 m-1, chlorophyll-a (CHL_NN (m-3)), and total suspended matter (TSM_NN (g m-3) at 72 points on the marine coast of the port region. The results of inductively coupled plasma atomic-emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) demonstrate that the leaching occurring in waste piles at the port area of Imbituba was the likely source of hazardous chemical elements (e.g., Mg, Sr, Nd, and Pr) in the environment. These leachates were formed due to the presence of coal pyrite and Fe-acid sulfates in said waste piles. The mobility of hazardous chemical elements potentiates changes in the marine ecosystem, in relation to ADG443_NN (m-1), CHL_NN (m-3), and TSM NN (g m-3), with values greater than 20 g m-3 found in 2021 and 2022. This indicated changes in the natural conditions of the marine ecosystem up to 30 km from the coast in the Atlantic Ocean, justifying public initiatives for water treatment on a global scale.

Nanoparticles in terrestrial sediments and the behavior of the spectral optics of Sentinel-3B OLCI Satellite images in a river basin of UNESCO World Cultural and Natural Heritage.

The dangerous chemical elements associated with nanoparticles (NPs) and ultra-fine sediment particles in hydrological bays have the capacity to move contaminants to large oceanic regions. The general objective of this study is to quantify the major chemical elements present in NPs and ultra-fine particles in aquatic sediments sampled from Guanabara Bay and compare these data to values determined through spectral optics using the Sentinel-3B Satellite OLCI (Ocean Land Color Instrument) during the winter and summer seasons of 2018, 2019, 2020, 2021, and 2022. This is done to highlight the impacts anthropogenic environmental hazards have on the marine ecosystem and human beings. Ten aquatic sediment field collection points were selected by triangulated irregular network (TIN). Samples were subjected to analysis by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersion spectroscopy (EDS), and transmission electron microscopy (TEM), which enabled a detailed analysis using scanning transmission electron microscopy (STEM). Geospatial analyses using Sentinel-3B OLCI Satellite images considered Water Full Resolution (WFR) at 300 m resolution, in neural network (NN), normalized at 0.83 µg/mg. A maximum average spectral error of 6.62% was utilized for the identification of the levels of Absorption Coefficient of Detritus and Gelbstoff (ADG443_NN) at 443 m-1, Chlorophyll-a (CHL_NN) (m-3), and Total Suspended Matter (TSM_NN) (g m-3) at 581 sample points. The results showed high levels of ADG443_NN, with average values as high as of 4444 m-1 (summer 2021). When related to the analyses of nanoparticulate sediments and ultrafine particles collected in the field, they showed the presence of major chemical elements such as Ge, As, Cr, and others, highly toxic to human health and the aquatic environment. The application of satellite and terrestrial surveys proved to be efficient, in addition to the possibility of this study being applied to other hydrological systems on a global scale.

Human viral pathogens in the wastewater-source water-drinking water continuum: Evidence, health risks, and lessons for future outbreaks in low-income settings.

Human viral pathogens, including SARS-CoV-2 continue to attract public and research attention due to their disruption of society, global health, and the economy. Several earlier reviews have investigated the occurrence and fate of SARS-CoV-2 in wastewater, and the potential to use such data in wastewater-based epidemiology. However, comprehensive reviews tracking SARS-CoV-2 and other viral pathogens in the wastewater-water-drinking water continuum and the associated risk assessment are still lacking. Therefore, to address this gap, the present paper makes the following contributions: (1) critically examines the early empirical results to highlight the occurrence and stability of SARS-CoV-2 in the wastewater-source water-drinking water continuum, (2) discusses the anthropogenic and hydro(geo)logical processes controlling the circulation of SARS-CoV-2 in the wastewater-source water-drinking water continuum, (3) discusses the risky behaviour, drivers and high-risk settings in the wastewater-source water-drinking water continuum, (4) uses the available empirical data on SARS-CoV-2 occurrence in the wastewater-source water-drinking water continuum to discuss human health risks from multiple exposure pathways, gendered aspects of SARS-CoV-2 transmission via shared on-site sanitation systems, and (5) develops and risk mitigation strategy based on the available empirical evidence and quantitative human risk assessment data. Finally, it presents a comprehensive research agenda on SARS-CoV-2/COVID-19 to guide the mitigation of future similar outbreaks in low-income settings.

Detection of atmospheric aerosols and terrestrial nanoparticles collected in a populous city in southern Brazil.

The main objective of this study is to analyze hazardous elements in nanoparticles (NPs) (smaller than 100 nm) and ultrafine particles (smaller than 1 µm) in Porto Alegre City, southern Brazil using a self-made passive sampler and Sentinel-3B SYN satellite images in 32 collection points. The Aerosol Optical Thickness proportion (T550) identification was conducted using images of the Sentinel-3B SYN satellite at 634 points sampled in 2019, 2020, 2021, and 2022. Focused ion beam scanning electron microscopy analyses were performed to identify chemical elements present in NPs and ultrafine particles, followed by single-stage cascade impactor to be processed by high-resolution transmission electron microscopy. This process was coupled with energy-dispersive X-ray spectroscopy and later analysis via secondary ion mass spectrometry. Data was acquired from Sentinel-3B SYN images, normalized to a standard mean of 0.83 µg/mg, at moderate spatial resolution (260 m), and modeled in the Sentinel Application Platform (SNAP) software v.8.0. Statistical matrix data was generated in the JASP software (Jeffreys's Amazing Statistics Program) v.0.14.1.0 followed by a K-means cluster analysis. The results demonstrate the presence of between 1 and 100 nm particles of the following chemical elements: Si, Al, K, Mg, P, and Ti. Many people go through these areas daily and may inhale or absorb these elements that can harm human health. In the Sentinel-3B SYN satellite images, the sum of squares in cluster 6 is 168,265 and in cluster 7 a total of 21,583. The use of images from the Sentinel-3B SYN satellite to obtain T550 levels is of great importance as it reveals that atmospheric pollution can move through air currents contaminating large areas on a global scale.

Adsorption of perfluorooctanoic carboxylic and heptadecafluorooctane sulfonic acids via magnetic chitosan: isotherms and modeling.

This paper evaluates the adsorption mechanism of perfluorooctanoic carboxylic acid (PFCA) and heptadecafluorooctane sulfonic acid (HFOSA) on magnetic chitosan for the first time via a statistical physics modeling. Magnetic chitosan (MC-CoFe2O4) was produced from shrimp wastes and used in standard batch adsorption systems to remove PFCA and HFOSA. The experimental isotherms indicated that the maximum adsorption capacities ranged from 14 to 27.12 mg/g and from 19.16 to 45.12 mg/g for PFCA and HFOSA, respectively, where an exothermic behavior was observed for both compounds. The adsorption data were studied via an advanced model hypothesizing that a multilayer process occurred for these adsorption systems. This theoretical approach indicated that the total number of formed layers of PFCA and HFOSA adsorbates is about 3 (Nt = 2.83) at high temperatures (328 K) where a molecular aggregation process was noted during the adsorption. The maximum saturation-multilayer adsorption of PFCA and HFOSA on magnetic chitosan was 30.77 and 50.26 mg/g, respectively, and the corresponding adsorption mechanisms were successfully investigated. Two energies were responsible for the formed adsorbate layer directly on the surface and the vertical layers were computed and interpreted, reflecting that physical interactions were involved to bind these molecules on the adsorbent surface at different temperatures where the calculated adsorption energies ranged from 14 to 31 kJ/mol. Overall, this work provides theoretical insights to understand the adsorption mechanism of PFCA and HFOSA using the statistical physics modeling and its results can be used to improve the adsorbent performance for engineering applications.

Transforming a volcanic rock powder waste into an efficient adsorbent to remove dyes (acid green 16 and acid red 97) and metals (Ag+, Co2+, and Cu2+) from water.

This study searched for the best synthesis route for producing an adsorbent from the alkaline fusion of volcanic rock powder waste. The samples synthesized under different conditions of temperature and alkalizing ratio/precursor material, nine in total (NP.F, NP.F1, NP.F2, ...NP.F8 ), were used in the adsorption of acid green 16 (AG 16) and acid red 97 (AR 97) dyes and Ag+, Co2+, and Cu2+ ions. Subsequently, the 22 central composite rotational design (CCRD) was applied, and the effects of the alkalizing ratio (NaOH)/volcanic rock (VR) and temperature (T) on the synthesis process were analyzed in terms of their influence on the physical properties of the materials and in the process of adsorption of contaminants. From the experimental design, it can be seen that the independent variables alkalizing ratio/volcanic rock and temperature greatly influence the characteristic and synthesis of adsorbent materials by alkaline fusion, which in turn reflects on the results achieved in the adsorption of contaminants. Therefore, the temperature of 550 °C and NaOH/VR ratio equal to 1 was the most satisfactory synthesis route to obtain high values of adsorption capacity (q, mg g-1) and removal (R, %) for all studied contaminants, as well as the optimization of the physical characteristics of the material. For example, the adsorption capacity of dye AG 16 was 49.1 mg g-1, and for Ag+ was 66.2 mg g-1, while the removal percentages were 97.6% and 93.4%, respectively. This approach made it possible to transform volcanic rock powder wastes into an efficient adsorbent to treat contaminated waters with dyes and metals.

Ivermectin adsorption by commercial charcoal in batch and fixed-bed operations.

Emerging contaminants were used during the COVID-19 pandemic, including ivermectin. Studies that limit the optimal adsorption parameters of ivermectin are scarce in the literature. In this study, we analyzed the adsorption of ivermectin with a high surface area and porosity charcoal. Isotherms were better fitted to the Koble-Corrigan model. The maximum capacity was 203 µg g-1 at 328 K. Thermodynamics indicated a spontaneous and endothermic behavior. The equilibrium was quickly reached within the first few minutes regardless of the ivermectin concentration. The linear driving force (LDF) model fitted the kinetic data (qexp = 164.8 µg g-1; qpred = 148.1 µg g-1) at 100 µg L-1 of ivermectin. The model coefficient (KLDF) and diffusivity (Ds) increased with increasing drug concentration. Two sloped curves were obtained in the column experiments, with a breakthrough time of 415 min and 970 min. The capacity of the column (qeq) was 76 µg g-1. The length of the mass transfer zone was 9.04 and 14.13 cm. Therefore, it can be concluded that the adsorption of ivermectin is highly sensitive to changes in pH, being favored in conditions close to neutrality. Commercial activated charcoal was highly efficient in removing the studied compound showing high affinity with very fast kinetics and a good performance in continuous operation mode.

Preparation of carbonaceous materials from flotation-sludge of the poultry industry and its application in the methylene blue adsorption.

In this work, different carbonaceous materials based on floated sludge from a poultry industry wastewater treatment plant (PI-WTP) were synthesized. These materials were characterized and investigated in methylene blue dye (MB) adsorption. The influences of the initial pH solution, adsorbent dosage, kinetics, equilibrium, and thermodynamics were evaluated in the adsorption experiments. A simulation of a real textile effluent was also carried out to evaluate the adsorbent. The results of the adsorbents' characterization demonstrated that adding ZnCl2 + lime, followed by pyrolysis and acid leaching, significantly improved the material's properties, leading to abundant porosity and high surface area. The adsorption experiments indicated that the natural pH of the solution (8.0) and the AC-II dosage of 0.75 g L-1 are optimal for MB removal. Elovich and Sips' models (with a maximum adsorption capacity of 221.02 mg g-1 at 328 K) best fitted the experimental kinetic and equilibrium data, respectively. The adsorption process is spontaneous and endothermic according to thermodynamic parameters. The discoloration efficiency of the simulated effluent was 67.8%. In conclusion, the floated sludge, a residue produced on a large scale that needs to be disposed of correctly, can be converted into a value-added material (carbonaceous adsorbent) and applied to treat colored effluents.

Activated carbon prepared from Brazil nut shells towards phenol removal from aqueous solutions.

The Brazil nut shell was used as a precursor material for preparing activated carbon by chemical activation with potassium hydroxide. The obtained material (BNSAC) was characterized, and the adsorptive features of phenol were investigated. The characterization showed that the activated carbon presented several rounded cavities along the surface, with a specific surface area of 332 m2 g-1. Concerning phenol adsorption, it was favored using an adsorbent dosage of 0.75 g L-1 and pH 6. The kinetic investigation revealed that the system approached the equilibrium in around 180 min, and the Elovich model represented the kinetic curves. The Sips model well represented the equilibrium isotherms. In addition, the increase in temperature from 25 to 55 °C favored the phenol adsorption, increasing the maximum adsorption capacity value (qs) from 83 to 99 mg g-1. According to the estimated thermodynamic parameters, the adsorption was spontaneous, favorable, endothermic, and governed by physical interactions. Therefore, the Brazil nut shell proved a good precursor material for preparing efficient activated carbon for phenol removal.

Nanoparticles containing hazardous elements and the spatial optics of the Sentinel-3B OLCI satellite in Amazonian rivers: a potential tool to understand environmental impacts.

The Amazon River is the longest river in the world. The Tapajós River is a tributary to the Amazon. At their junction, a marked decrease in water quality is evident from negative impacts from the constant activity of clandestine gold mining in the Tapajós River watershed. The accumulation of hazardous elements (HEs), capable of compromising environmental quality across large regions is evident in the waters of the Tapajós. Sentinel-3B OLCI (Ocean Land Color Instrument) Level-2 satellite imagery with Water Full Resolution (WFR) of 300 m was utilized to detect the highest potential for the absorption coefficient of detritus and gelbstoff in 443 m-1 (ADG443_NN), chlorophyll-a (CHL_NN) and total suspended matter concentration (TSM_NN), at 25 points in the Amazon and Tapajós rivers (in 2019 and 2021). Physical samples of riverbed sediment collected in the field at the same locations were analyzed for NPs and ultra-fine particles to verify the geospatial findings. The riverbed sediment samples collected in the field were studied by Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM), with selected area electron diffraction (SAED), following laboratory analytical procedures. The Sentinel-3B OLCI images, based on the Neural Network (NN) were calibrated by the European Space Agency (ESA), with a standard average normalization of 0.83 µg/mg, containing a maximum error of 6.62% applied to the sampled points. The analysis of the riverbed sediment samples revealed the presence of the following hazardous elements: As, Hg, La, Ce, Th, Pb, Pd, among several others. The Amazon River has significant potential to transport ADG443_NN (55.475 m-1) and TSM_NN (70.787 gm-3) in sediments, with the possibility of negatively impacting marine biodiversity, in addition to being harmful to human health over very large regions.

Wood waste-based functionalized natural hydrochar for the effective removal of Ce(III) ions from aqueous solution.

In this study, a sustainable and easily prepared hydrochar from wood waste was studied to adsorb and recover the rare earth element cerium (Ce(III)) from an aqueous solution. The results revealed that the hydrochar contains several surface functional groups (e.g., C-O, C = O, OH, COOH), which largely influenced its adsorption capacity. The effect of pH strongly influenced the Ce(III) removal, achieving its maximum removal efficiency at pH 6.0 and very low adsorption capacity under an acidic solution. The hydrochar proved to be highly efficient in Ce(III) adsorption reaching a maximum adsorption capacity of 327.9 mg g-1 at 298 K. The kinetic and equilibrium process were better fitted by the general order and Liu isotherm model, respectively. Possible mechanisms of Ce(III) adsorption on the hydrochar structure could be explained by electrostatic interactions and chelation between surface functional groups and the Ce(III). Furthermore, the hydrochar exhibited an excellent regeneration capacity upon using 1 mol L-1 of sulfuric acid (H2SO4) as eluent, and it was reused for three cycles without losing its adsorption performance. This research proposes a sustainable approach for developing an efficient adsorbent with excellent physicochemical and adsorption properties for Ce(III) removal.

Trends in Bioactive Multilayer Films: Perspectives in the Use of Polysaccharides, Proteins, and Carbohydrates with Natural Additives for Application in Food Packaging.

The harmful effects on the environment caused by the indiscriminate use of synthetic plastics and the inadequate management of post-consumer waste have given rise to efforts to redirect this consumption to bio-based economic models. In this sense, using biopolymers to produce materials is a reality for food packaging companies searching for technologies that allow these materials to compete with those from synthetic sources. This review paper focused on the recent trends in multilayer films with the perspective of using biopolymers and natural additives for application in food packaging. Firstly, the recent developments in the area were presented concisely. Then, the main biopolymers used (gelatin, chitosan, zein, polylactic acid) and main methods for multilayer film preparation were discussed, including the layer-by-layer, casting, compression, extrusion, and electrospinning methods. Furthermore, we highlighted the bioactive compounds and how they are inserted in the multilayer systems to form active biopolymeric food packaging. Furthermore, the advantages and drawbacks of multilayer packaging development are also discussed. Finally, the main trends and challenges in using multilayer systems are presented. Therefore, this review aims to bring updated information in an innovative approach to current research on food packaging materials, focusing on sustainable resources such as biopolymers and natural additives. In addition, it proposes viable production routes for improving the market competitiveness of biopolymer materials against synthetic materials.

Citrus fruit residues as alternative precursors to developing H2O and CO2 activated carbons and its application for Cu(II) adsorption.

Due to its toxicity, the presence of Cu(II) ions released in aquatic environments presents a serious threat to the environment and human health. In search of sustainable and low-cost alternatives, there are citrus fruit residues, which are generated in large quantities by the juice industries and can be used to produce activated carbons. Therefore, the physical route was investigated for producing activated carbons to reuse citrus wastes. In this work, eight activated carbons were developed, varying the precursor (orange peel-OP, mandarine peel-MP, rangpur lime peel-RLP, and sweet lime peel-SLP) and the activating agent (CO2 and H2O) to remove Cu(II) ions of the aqueous medium. Results revealed promising activated carbons with a micro-mesoporous structure, a specific surface area of around 400 m2 g-1, and a pore volume of around 0.25 cm3 g-1. In addition, Cu (II) adsorption was favored at pH 5.5. The kinetic study showed that the equilibrium was reached within 60 min removing about 80% of Cu(II) ions. The Sips model was the most suitable for the equilibrium data, providing maximum adsorption capacities (qmS) values of 69.69, 70.27, 88.04, 67.83 mg g-1 for activated carbons (AC-CO2) from OP, MP, RLP, and SLP, respectively. The thermodynamic behavior showed that the adsorption process of Cu(II) ions was spontaneous, favorable, and endothermic. It was suggested that the mechanism was controlled by surface complexation and Cu2+-π interaction. Desorption was possible with an HCl solution (0.5 mol L-1). From the results obtained in this work, it is possible to infer that citrus residues could be successfully converted into efficient adsorbents to remove Cu(II) ions from aqueous solutions.

Brilliant blue FCF dye adsorption using magnetic activated carbon from Sapelli wood sawdust.

Sapelli wood sawdust-derived magnetic activated carbon (SWSMAC) was produced by single-step pyrolysis using KOH and NiCl2 as activating and magnetization agents. SWSMAC was characterized by several techniques (SEM/EDS, N2 adsorption/desorption isotherms, FTIR, XRD, VSM, and pHPZC) 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.

Adsorptive behavior of multi-walled carbon nanotubes immobilized magnetic nanoparticles for removing selected pesticides from aqueous matrices.

The present work synthesized two new materials of functionalized multi-walled carbon nanotubes (MWCNT-OH and MWCNT-COOH) impregnated with magnetite (Fe3O4) using solution precipitation methodology. The resulting MWCNT-OH-Mag and MWCNT-COOH-Mag materials were characterized by scanning electron microscopy coupled with energy dispersion X-ray spectroscopy, Fourier transform infrared, X-ray diffraction, atomic force microscopy, and electrical force microscopy. The characterization results indicate that the -OH functional groups in the MWCNT interact effectively with magnetite iron favoring impregnation and indicating the regular distribution of nanoparticles on the surface of the synthesized materials. The adsorption efficiency of the MWCNT-OH-Mag and MWCNT-COOH-Mag materials was tested using the pollutants 2,4-D and Atrazine. Over batch studies carried out under different pH ranges, it was found that the optimal condition for 2,4-D adsorption was at pH 2, while for Atrazine, it was found at pH 6. The rapid adsorption kinetics of 2,4-D and Atrazine reaches equilibrium within 30 min. The pseudo-first-order model described 2,4-D adsorption well. The General-order model described better atrazine adsorption. The magnetically doped adsorbent functionalized with -OH surface groups (MWCNT-OH-Mag) demonstrated superior adsorption performance and increased Fe-doped sites. The Sips model described the adsorption isotherms accurately. MWCNT-OH-Mag presented the greatest adsorption capacity at 51.4 and 47.7 mg g-1 for 2,4-D and Atrazine, respectively. Besides, electrostatic forces and complexation rule the molecular interactions between metals and pesticides. The leaching and regeneration tests of the synthesized materials indicate high stability in an aqueous solution. Furthermore, experiments with wastewater samples contaminated with the model pollutants indicate that the novel adsorbents are highly promising for enhancing water purification by adsorptive separation.

Hazardous elements in urban cemeteries and possible architectural design solutions for a more sustainable environment.

The general objective of this study is to identify the presence of hazardous elements in the soils of five urban cemeteries in the city of Passo Fundo, in southern Brazil, and to design solutions (architecturally) for future cemeteries to be more sustainable by mitigating toxicological risks to the population residing in the area. A total of 250 soil samples were obtained from points within the cemeteries and in areas surrounding the two oldest cemeteries at a distance of up to 400 m. Twelve architects who design cemeteries primarily focused on sustainability were interviewed, and presented their suggestions for sustainable urban cemetery design. The Building Information Modeling (BIM) computer modeling system was utilized to present a visual representation of suggested architectural features by these architects. The concentration of Pb in the vicinity of cemeteries deserves special attention, as concentrations of this neurotoxin exceed the federal limits set by Brazil. Soil Pb values were found to exceed the limit of 72 mg kg-1 up to a distance of 400 m from the walls of cemeteries A and B, indicating the presence of a danger to human health even at greater distances. This manuscript highlights construction features that enable future burial structures to adequately mitigate the very real problem of contaminants entering the environment from current cemetery design. Two-thirds of the technicians interviewed for this manuscript, each of whom specialize in Brazilian cemetery design, highlighted the importance of revitalizing urban vegetation both when constructing and revitalizing urban vertical cemeteries.

Cassava bagasse as an alternative biosorbent to uptake methylene blue environmental pollutant from water.

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 (R2 ≥ 0.997 and R2adj ≥ 0.996) models, respectively. Furthermore, the thermodynamic study revealed a spontaneous (ΔG0 < 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.

Adsorptive Features of Magnetic Activated Carbons Prepared by a One-Step Process towards Brilliant Blue Dye.

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 NiCl2 of 0.5 and 1. The characterization results demonstrated that the different proportions of NiCl2 mainly influenced the textural characteristics of the adsorbents. An increase in the surface area from 260.0 to 331.5 m2 g-1 and in the total pore volume from 0.075 to 0.095 cm3 g-1 was observed with the weight ratio of NiCl2. 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-1 for MAC111, while for MAC1105, it was 60.73 mg g-1. 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%.

Euterpe oleracea-based biochar for clonazepam adsorption: synthesis, characterization, adsorption properties, and toxicity assays.

The consumption of açaí fruit (Euterpe oleracea) has largely increased worldwide, resulting in a significant increase in the demand for its pulp. As a result, the small producing communities end up with large amounts of açaí endocarp residues, creating local environmental pollution problems. Therefore, chemical and physical routes were investigated for producing açaí endocarp adsorbents to propose a locally viable solution for this problem. The adsorption properties of the produced biochars were tested for clonazepam (CZM) removal, and the toxicity of the final solutions was evaluated. The results revealed that the chemical route generated biochar with about twice the surface area and pore volume (762 m2 g-1 and 0.098 cm3 g-1) than the physical route (498 m2 g-1 and 0.048 cm3 g-1). Furthermore, the Sips isotherm better described the CZM adsorption equilibrium for both biochars, with qs values of 26.94 and 61.86 mg g-1 for the physical- and chemical-activated adsorbents. Moreover, recycling studies were performed, and the chemical-activated biochar was stable for up to three cycles, reaching removal rates superior to 80%. Besides, the final toxicity decreased after the adsorptive treatment. Therefore, chemical activation can be used as a simple and effective method for producing stable and compelling adsorbents as an elegant way of adding value to the residues from açaí production, helping solve local environmental problems.

Preparation of alumina-supported Fe-Al-La composite for fluoride removal from an aqueous matrix.

Using groundwater for human consumption is an alternative for places with no nearby surface water resources. Fluoride is commonly found in groundwater, and the consumption of this water for a prolonged time in concentrations that exceed established limits by WHO and Brazilian legislation on water potability (1.5 mg L-1) can cause harmful problems to human health. For this reason, fluoride removal is an important step before water consumption. In this work, activated alumina was impregnated with Fe-Al-La composite and employed for the first time as an adsorbent for fluoride removal from an aqueous environment. XRD, SEM/EDS, FT-IR, and point of zero charge were used to characterize the prepared adsorbent. The adsorptive performance of adsorbent material was investigated by employing a 23-central composite design (CCD), and the obtained experimental conditions were pH = 6.5 and adsorbent dosage = 3.0 g L-1. A maximum adsorption capacity of 8.17 mg g-1 at 298 K and pH = 6.5 was achieved by Langmuir isotherm to describe the adsorption. The kinetic model that better described experimental data was Avrami, with the kav parameter increasing with the initial concentration from 0.076 to 0.231 (min-1)nav. The nature of adsorption was found to be homogeneous, and it occurs in a monolayer. The fluoride removal performance for the prepared adsorbent was higher than granular activated alumina, showing that supporting Fe-Al-La at the alumina surface increased its fluoride adsorption capacity from 16 to 42% at the same experimental conditions. Finally, the influence of co-existing ions Cl-, SO42-, and NO3- was evaluated in fluoride adsorption, and the material presented great selectivity to fluoride. Thus, Fe-Al-La/AA adsorbent is a promising material for fluoride removal from water.