Remediation through the coordinated use of local rice husk residues for the selective adsorption of iron and nickel in real landfill leachate

Herein, we demonstrate the prospects of tackling several environmental problems by transforming a local rice husk residue into an effective adsorbent, which was then applied for the treatment of real landfill leachate (LL). The study focused on establishing (i) the effect of simple washing on morphological aspects, (ii) evaluating target adsorption capacity for total iron (Fe) and nickel (Ni), (iii) determining regeneration and reuse potential of the adsorbent and (iv) complying to the requirements of worldwide legislations for reuse of treated LL wastewater. The adsorbent was prepared by employing a simple yet effective purification process that can be performed in situ. The LL was collected post-membrane treatment, and the characterizations revealed high concentrations of Fe, Ni, and organic matter content. The simple washing affected the crystallinity, resulting in structural alterations of the adsorbents, also increasing the porosity and specific surface. The adsorption process for Ni occurred naturally at pH 6, but adjusting the pH to 3 significantly improved removal efficiency and adsorption capacity for total Fe. The kinetics were accurately described by the pseudo-second-order model, while the Langmuir model provided a better fit for the isotherms. The adsorbent was stable for 5 reuses, and the metals adsorbed were recovered through basic leaching. The removal capacities achieved underscore the remarkable effectiveness of the process, ensuring the treated LL wastewater meets rigorous global environmental legislations for safe use in irrigation. Thus, by employing the compelling methods herein optimized it is possible to refer to the of solving three environmental problems at once.

Valorization of winemaking residues as biochar for removing Ni(II) from real industrial painting process effluent in a fixed-bed column

In this work, the adsorption of nickel ions from a real effluent from a metal-mechanic industry was investigated in a fixed-bed column using biochar. Biochar was prepared from winemaking residues originating from the Beifiur® composting process. The use of wine industry residues as precursor materials for biochar production is established in biomass residue valorization using the existing logistics and the lowest possible number of manipulations and pre-treatments. The results found in the work showed that the optimal conditions for nickel adsorption in fixed-bed columns were bed height (Z) of 7 cm, initial nickel concentration (C0) of 1.5 mg L-1, and flow rate (Q) of 18 mL min-1. In this condition, the maximum adsorption capacity of the column was 0.452 mg g-1, the mass transfer zone (Zm) was 3.3 cm, the treated effluent volume (Veff) was 9.72 L, and the nickel removal (R) was 92.71%. The Yoon-Nelson and BDST dynamic models were suitable to represent the breakthrough curves of nickel adsorption. Finally, the fixed-bed column adsorption using biochar from winemaking residues proved to be a promising alternative for nickel removal from real industrial effluents.

Adsorption of rare earth elements on a magnetic geopolymer derived from rice husk: studies in batch, column, and application in real phosphogypsum leachate sample

There is a growing need to develop new strategies for rare earth element (REE) recovery from secondary resources. Herein, a novel approach to utilize biogenic silica (from rice husk) and metakaolin was employed to fabricate magnetic geopolymer (MGP) by incorporating metallic iron. The fabricated MGP adsorbent material was used to uptake Ce3+, La3+, and Nd3+ from synthetic solutions and real phosphogypsum leachate in batch and column modes. The MGP offers a negatively charged surface at pH above 2.7, and the uptake of REEs rises from pH 3 to 6. The kinetic study validated that the kinetics was much faster for Nd3+, followed by La3+ and Ce3+. A thermodynamic investigation validated the exothermic nature of the adsorption process for all selected REEs. The desorption experiment using 2 mol L-1 H2SO4 as the eluent demonstrated approximately 100% desorption of REEs from the adsorbent. After six adsorption-desorption cycles, the MGP maintained a high adsorption performance up to cycle five before suffering a significant decrease in performance in cycle six. The effectiveness of MGP was also assessed for its applicability in recovering numerous REEs (La3+, Ce3+, Pr3+, Sm3+, and Nd3+) from real leachate from phosphogypsum wastes, and the highest recovery was achieved for Nd3+ (95.03%) followed by Ce3+ (86.33%). The operation was also feasible in the column presenting suitable values of the length of the mass transfer zone. The findings of this investigation indicate that MGP adsorbent prepared via a simple route has the potential for the recovery of REEs from synthetic and real samples in both batch and continuous operations modes.

Recovery of Ce and La from phosphogypsum leachate by adsorption using grape wastes

The present research aimed to evaluate the use of grape stalk in the adsorption of lanthanum and cerium to identify the best operating conditions enabling the application of the bioadsorbent in REEs leached from phosphogypsum. The grape stalk was characterized and showed an amorphous structure with a heterogeneous and very porous surface. Also, it was possible to identify the groups corresponding to carboxylic acids, phenols, alcohols, aliphatic acids, and aromatic rings. The pH effect study showed that the adsorption process of La3+ and Ce3+ ions was favored at pH 5.0. The adsorption kinetics followed the pseudo-second-order model. In just 20 min, 80% saturation was reached, while equilibrium was reached after 120 min. The adsorption isotherms were appropriately adjusted to the Langmuir model, and the maximum adsorption capacities were obtained at 298 K, which were 35.22 mg g-1 for La3+ and 37.99 mg g-1 for Ce3+. Furthermore, the adsorption process was favorable, spontaneous, and exothermic. In the study's second phase, phosphogypsum was leached with a sulfuric acid solution. Then, the adsorption of REEs was carried out under the experimental conditions of pH after leaching and pH 5.0 (adjustment carried out with sodium hydroxide solution) at 298 K for 120 min and with adsorbent dosages of 1 and 5 g L-1. This process resulted in removal percentages above 95% for the most abundant REEs, such as neodymium, lanthanum, and cerium, at pH 5.0 and a dosage of 5 g L-1, demonstrating the effectiveness of the bioadsorbent used. These results indicate the potential of using grape residue as a promising bioadsorbent in recovering rare earth elements from phosphogypsum leachate.

From grape bagasse to graphene-like porous carbon nanosheets for CO2 capture

Graphene-based materials have increasingly attracted attention in recent years. It is a material is recognized worldwide due to its numerous applications in several sectors. However, graphene production involves several challenges: scalability, high costs, and high-quality production. This study synthesized graphene-like porous carbon nanosheets (GPCNs) through a thermochemical process under a nitrogen atmosphere using grape bagasse as a precursor. Three temperatures (700, 800, and 900 ºC) of the pyrolysis process were studied. Chemical graphitization and activation were used to form high-specific surface area materials: FeCl3.6H2O(aq) and ZnCl2(s) in a simultaneous activation-graphitization (SAG) method. The materials obtained (GPCN700, GPCN800, and GPCN900) were compared to previously produced chars (C700, C800, and C900). A high specific surface area and total pore volume were obtained for GPCN materials, and GPCN900 presented the highest values: 1062.7 m2g-1 and 0.635 cm3 g-1, respectively. The GPCN and char materials were classified as mesoporous and applied as adsorbents for CO2(g). The GPCN800 presented the best CO2(g) adsorbent, with a CO2(g) adsorption capacity of 168.71 mg g-1.

Valorization of a poultry industry floated sludge as a raw material to produce char and activated carbon for pharmaceutical compounds adsorption

This study was intended to valorize a floated sludge of a poultry slaughterhouse using it as a precursor to producing char and activated carbon, which were tested as adsorbents in removing ketoprofen and diclofenac sodium from the water. The addition of zinc chloride or calcium hydroxide was determinant for forming a porous carbonaceous structure with a high surface area in AC-FSP (656.54 m2 g-1), differently from that exhibited by the CHAR-FSP (8.11 m2 g-1). Kinetic and equilibrium studies indicated that the pseudo-second-order and the Sips models were suitable. The AC- FSP maximum adsorption capacity for ketoprofen and diclofenac sodium was 124.98 mg g-1 and 138.32 mg g-1, respectively. The adsorption was a spontaneous and endothermic process. It was concluded that AC-FSP is a more efficient and promising adsorbent than CHAR-FSP for the adsorption of drugs in contaminated wastewater. In addition, AC-FSP can be reused, maintaining good adsorption levels for about 5 cycles. Therefore, this study is aligned with the 2030 Agenda for global sustainability since converting waste (valueless) into an adsorbent is also directly linked to the circular economy and neutral carbon.

Geochemical fractionation of hazardous elements in fresh and drilled weathered South African coal fly ashes

The chemical reactions of dry-disposed ash dump, ingressed oxygen, carbon dioxide, and infiltrating rainwater affect mineralogical transformation, redistribution, and migration of chemical species. Composite samples of weathered coal fly ash taken at various depths and fresh coal fly ash were examined using organic petrographic, X-ray diffraction, X-ray fluorescence techniques, and successive extraction procedures. Results obtained show relative enrichment of glass, Al-Fe-oxides, calcite, and tridymite in the weathered CFA, but the fresh CFA is enriched in mullite, inertinite, maghemite, and ettringite. The enrichment of the weathered CFA in amorphous glass suggests higher reactivity when compared to fresh CFA. The evident depletion of soluble oxides in the weathered CFA is attributed to flushing of the soluble salts by percolating rainwater. Comparative enrichment of examined elements in water-soluble, exchangeable, reducible, and residual fractions of the weathered CFA is partly due to the slow release of adsorbed chemical species from the alumina-silicate matrix and diffusion from the deeper sections of the particles of coal fly ash. Sodium and potassium show enrichment in the oxidisable fraction of fresh CFA. The estimated mobility factor indicates mobility for Ca, Mg, Na, Se, Mo, and Sb and K, Sr, V, Cu, Cr, Se, and B in fresh and weathered CFAs, respectively.

Identification of mercury and nanoparticles in roots with different oxidation states of an abandoned coal mine

The morphology and composition of roots with different degrees of oxidation as a function of time were evaluated aiming to identify possible hazardous elements and nanoparticles. The roots were obtained from an abandoned coal mine located in the city of Criciúma, Santa Catarina, Brazil. From the roots, analyses were performed to identify nanoparticles (NPs) and ultrafine particles (UFPs), containing possible hazardous elements (PHEs) that cause potential environmental risks and impacts on human health. The identification of nanoscale materials requires greater robustness, so advanced integrated techniques have been used. The characterization of different types of roots was done by using focused ion beam (FIB), to evaluate nano-compound assemblies with high-resolution transmission electron microscopy/energy dispersive spectroscopy (HR-TEM/EDS). The results showed the presence of NPs containing Hg, Co, Cr, Ni, and V. The presence of these elements has increased consistently with the increase of C concentration in the roots, suggesting that the PHEs were gradually released from organic matter and inorganic minerals of coal. However, even with their decrease in roots, it was found that these elements still remained in the soil in significant quantities, even after 15 years of inactivation of the coal mine.

Conversion of MDF wastes into a char with remarkable potential to remove Food Red 17 dye from aqueous effluents

Medium density fiberboard (MDF) wastes were converted into an efficient char able to uptake Food Red 17 dye (FR17) from colored effluents. The yield of the pyrolysis process, in terms of char, was 29%. The produced char presented micro and mesoporous, with surface area of 218.8 m² g^-1 and total pore volume of 0.122 cm³ g^-1. Regarding to the FR17 adsorption, removal percentages of 90% were found at pH 2 and using 0.5 g L^-1 of char. Pseudo-first and pseudo-second order models were adequate to represent the adsorption kinetic profile, being the equilibrium reached within 20 min. Freundlich model was selected to represent the equilibrium data. The maximum adsorption capacity was 210 mg g^-1. The adsorption of FR17 on the char was endothermic and physical in nature. The char was efficient for 8 adsorption-desorption cycles, maintaining the same adsorption capacity. In brief, this work demonstrated a useful practice in terms of cleaner production. It was possible add value to MDF wastes, generating an efficient and reusable adsorbent to treat colored effluents containing FR 17 dye.

Water quality assessment of the Tubarão River through chemical analysis and biomarkers in the Neotropical fish Geophagus brasiliensis

The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.

Trends in adjuvant development for vaccines: DAMPs and PAMPs as potential new adjuvants

Aluminum salts have been widely used in vaccine formulations and, after their introduction more than 80 years ago, only few vaccine formulations using new adjuvants were developed in the last two decades. Recent advances in the understanding of how innate mechanisms influence the adaptive immunity opened up the possibility for the development of new adjuvants in a more rational design. The purpose of this review is to discuss the recent advances in this field regarding the attempts to determine the molecular basis and the general mechanisms underlying the development of new adjuvants, with particular emphasis on the activation of receptors of innate immune recognition. One can anticipate that the use of these novel adjuvants will also provide a window of opportunities for the development of new vaccines.

Characterization of Santa Catarina (Brazil) coal with respect to human health and environmental concerns

The current paper presents the concentration, distribution, and modes of occurrence of trace elements of 13 coals from south Brazil. The samples were collected in the state of Santa Catarina. Chemical analyses and the high ash yields indicate that all studied coals are rich in mineral matter, with SiO(2) and Al(2)O(3) dominating as determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Quartz is the main mineral species and is associated with minor levels of feldspars, kaolinite, hematite, and iron-rich carbonates. The contents of trace elements, including As, Pb, Cd, Ni, Cr, Mn, Be, V, U, Zn, Li, Cu, Tl, and Ni, in coals were determined. A comparison of ranges and means of elemental concentrations in Santa Catarina, Brazil, and world coals shows that the ranges of most elements in Santa Catarina coal are very close to the usual worldwide concentration ranges in coal.

Intranasal immunization with the cholera toxin B subunit-pneumococcal surface antigen A fusion protein induces protection against colonization with Streptococcus pneumoniae and has negligible impact on the nasopharyngeal and oral microbiota of mice

One of the candidate proteins for a mucosal vaccine antigen against Streptococcus pneumoniae is PsaA (pneumococcal surface antigen A). Vaccines targeting mucosal immunity may raise concerns as to possible alterations in the normal microbiota, especially in the case of PsaA, which was shown to have homologs with elevated sequence identity in other viridans group streptococci. In this work, we demonstrate that intranasal immunization with a cholera toxin B subunit-PsaA fusion protein is able to protect mice against colonization with S. pneumoniae but does not significantly alter the natural oral or nasopharyngeal microbiota of mice.