Search Results (71)

Urochloa brizantha (Brizantha) is cultivated under varying altitudinal and management conditions. Twelve full-sun (monoculture) plots and twelve shaded (silvopastoral) plots were established, proportionally distributed at 170, 503, 661, and 1110 masl. Evaluations were conducted 15, 30, 45, 60, and 75 days after establishment. The conservation and integration of trees in silvopastoral systems reflected a clear anthropogenic influence, evidenced by the preference for species of the Fabaceae family, likely due to their multipurpose nature. Although the altitudinal gradient did not show direct effects on soil properties, intermediate altitudes revealed a significant role of CaCO₃ in enhancing soil fertility. These edaphic conditions at mid-altitudes favored the leaf area development of Brizantha, particularly during the early growth stages, as indicated by significantly larger values (p < 0.05). However, at the harvest stage, no significant differences were observed in physiological or productive traits, nor in foliar chemical components, underscoring the species’ high hardiness and broad adaptation to both soil and altitude conditions. In Brizantha, a significant reduction (p < 0.05) in stomatal size and density was observed under shade in silvopastoral areas, where solar radiation and air temperature decreased, while relative humidity increased. Nonetheless, these microclimatic variations did not lead to significant changes in foliar chemistry, growth variables, or biomass production, suggesting a high degree of adaptive plasticity to microclimatic fluctuations. Foliar ash content exhibited an increasing trend with altitude, indicating greater efficiency of Brizantha in absorbing calcium, phosphorus, and potassium at higher altitudes, possibly linked to more favorable edaphoclimatic conditions for nutrient uptake. Finally, forage quality declined with plant age, as evidenced by reductions in protein, ash, and In Vitro Dry Matter Digestibility (IVDMD), alongside increases in fiber, Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF). These findings support the recommendation of cutting intervals between 30 and 45 days, during which Brizantha displays a more favorable nutritional profile, higher digestibility, and consequently, greater value for animal feeding. Full article

Volcanic ash from explosive eruptions can significantly alter lake water chemistry through ash–water interactions, potentially influencing primary productivity. Alkaline (soda) lakes, mostly found in volcanic regions, are particularly sensitive due to their unique geochemical properties. However, the effects of volcanic ash on the biogeochemistry and phytoplankton dynamics of soda lakes remain poorly understood. This study presents the first nutrient release experiments using natural alkaline water from Lake Van (Türkiye) and volcanic ash from four volcanoes (Hekla, Arenal, Sakurajima, Rabaul-Tavurvur) with different compositions. Sixteen abiotic leaching experiments were conducted over contact durations ranging from 1 to 24 h. Results show rapid increases in pH (~0.4–0.5 units), enhanced silica and phosphate concentrations, and elevated levels of Na, K, Ca, Sr, and S. Nitrate and Mg were generally depleted. The low N:P ratio (~0.06) in Lake Van water indicated nitrogen limitation, partially mitigated by ash-derived inputs. Cyanobacteria dominated the phytoplankton community (95%), consistent with nitrogen fixation under low-nitrate conditions. Elevated silica may promote diatom growth, while changes in Mg/Ca ratios suggest possible impacts on carbonate precipitation and microbialite development. These findings highlight the biogeochemical and ecological relevance of volcanic ash inputs to soda lakes. Full article

Biochar-based adsorbents synthesized from agricultural wastes have emerged as economical and environmentally sustainable materials for water purification. In this study, coffee shell-derived biochars were synthesized via pyrolysis at 500 and 700 °C, with and without water washing, and comprehensively characterized to evaluate their potential for removing Rhodamine B (RhB) from aqueous solution. Structural and surface analyses indicated that a higher pyrolysis temperature enhanced pore development and aromaticity, whereas water washing effectively removed inorganic ash, thereby exposing additional active sites. Among all samples, water-washed biochar pyrolyzed at 700 °C (WCB700) exhibited the highest surface area (273.6 m²/g) and adsorption capacity (193.5 mg/g). The adsorption kinetics conformed to a pseudo-second-order model, indicating chemisorption, and the equilibrium data fit the Langmuir model, suggesting monolayer coverage. Mechanism analysis highlighted the roles of π–π stacking, hydrogen bonding, electrostatic interaction, and pore filling. Additionally, WCB700 retained more than 85% of its original capacity after five regeneration cycles, demonstrating excellent stability and reusability. This study presents an economical approach to valorizing coffee waste as well as provides mechanistic insights into optimizing biochar surface chemistry for enhanced dye removal. These findings support the application of engineered biochar in scalable and sustainable wastewater treatment technologies. Full article

It is of strategic significance to extract germanium (Ge) in an ecological way for sustainable development. Adsorbents that already adsorb Ge have disadvantages such as poor selectivity and low adsorption capacity. In this study, a novel adsorbent material based on rice husk functionalized with tannic acid was developed for the efficient extraction of Ge from simulated coal fly ash leachate. The adsorption capacity of tannic acid-functionalized rice husk (TA-EPI-ORH) for Ge was 19.9 times higher than that of untreated rice husk, demonstrating significantly improved performance. The results showed that the adsorption process of Ge by TA-EPI-ORH is consistent with pseudo-second-order kinetic and Freundlich isotherm model. TA-EPI-ORH had excellent selective adsorption properties, with adsorption of 1.40 mg L⁻¹ Ge exceeding 95% and solid-liquid partition coefficients of 4380 mL g⁻¹, even in the presence of nine impurity metal ions (average concentration: 479.08 mg L⁻¹). When compared with the two main coexistence ions—aluminum (Al) and calcium (Ca)—both of which have the relatively highest concentrations (Al: 1594.20 mg L⁻¹, Ca: 1740.13 mg L⁻¹), the separation factors for Ge still maintain relatively high level with SF(Ge/Al) = 42.57 and SF(Ge/Ca) = 39.93. Compared to existing studies, TA-EPI-ORH exhibits superior selective adsorption performance even with the presence of more interfering ions. After elution of the adsorbed Ge from TA-EPI-ORH, the extraction rate of Ge with low initial concentration (1.40 mg L⁻¹) reached 85.17%, while the extraction rates of Al and Ca were only 1.02% and 1.18%, respectively. Further research revealed that the catechol groups on the surface of TA-EPI-ORH formed stable complexes with Ge, whereas the complexes with coexisting ions (e.g., Ca and Al) were unstable, thereby ensuring high selectivity for Ge. This green chemistry-based functionalization of rice husk not only enables high-value utilization of agricultural waste but also provides a sustainable and eco-friendly strategy for efficient Ge separation and recovery. Full article

Along with the principal rare earth (REE) minerals such as monazite, xenotime, and bastnasite, Y-and REE-bearing zircon and associated minerals survive the combustion process and are found in coal-combustion fly ash. Beneficiated fly ash from a power plant burning an eastern-Kentucky-sourced coal blend was found to have zircon (ZrSiO₄), baddeleyite (ZrO₂), fergusonite (YNbO₄), yttriaite (Y₂O₃), and xenotime (YPO₄). Previous studies of the same fly had also identified monazite with a broad REE suite. Scanning electron microscopy–electron dispersive spectroscopy (EDS) and transmission electron microscopy (TEM)–EDS as well as other TEM-based techniques revealed a variety of zircon associations, including heavy-REE suites with Y, Nb, and Hf. Hafnium is a common accessory element in zircons and the Y and Nb may be present as fergusonite (YNbO₄) intermixed with zircon. Full article

Emissions from domestic coal burning are generally recognized as the cause of the lung cancer epidemic in Xuanwei City, Yunnan Province, China. To examine the physicochemical characteristics of airborne particles emitted from burning this locally sourced coal, PM_2.5 samples were collected from Hutou village which has high levels of lung cancer, and Xize village located approximately 30 km from Hutou without lung cancer cases. Transmission Electron Microscopy-Energy Dispersive X-ray (TEM-EDX) analysis was employed to study the physiochemical features and chemistry of individual particles. Sulfur and silica are the most abundant elements found in the airborne particles in both of the two villages. Fewer elements in aerosol particles were found in Xize village compared with Hutou village. Based on the morphologies and chemical compositions, the particles in Xuanwei can be classified into five types including composite particles (38.6%); organic, soot, tar balls, and biologicals (28.3%); sulfate (14.1%); fly ash (9.8%); and minerals (9.2%). The particles in Hutou village are abundant in the size range of 0.4–0.8 μm while that in Xize is 0.7–0.8 μm. Composite particles are the most common types in all the size ranges. The percentage of composite particles shows two peaks in the small size range (0.1–0.2 μm) and the large size ranges (2–2.3 μm) in Hutou village while that shows an even distribution in all size ranges in Xize village. Core-shell particles are typical types of composite particles, with the solid ‘core’ consisting of materials such as fly ash or mineral grains, and the shell or surface layer being an adhering soluble compound such as sulfates or organics. The heterogeneous reactions of particles with acidic liquid layers produce the core-shell structures. Typically, the equivalent diameter of the core-shell particles is in the range of 0.5–2.5 μm, averaging 1.6 μm, and the core-shell ratio is usually between 0.4 and 0.8, with an average of 0.6. Regardless of the sizes of the particles, the relatively high core-shell ratios imply a less aging state, which suggests that the core-shell particles were relatively recently formed. Once the coal-burning particles are inhaled into the human deep lung, they can cause damage to lung cells and harm to human health. Full article

Contamination by heavy metals (HMs) such as Pb, Cd, Cr, and Hg poses significant risks to the environment and human health owing to their toxicity and persistence. Geopolymers (GPs) have emerged as promising materials for immobilizing HMs and reducing their mobility through physical encapsulation and chemical stabilization. This study explored the novel use of isotactic polypropylene functionalized in the molten state with maleinized hyperbranched polyol polyester (PP-g-MHBP) as an additive in coal fly ash (CFA)-based GPs to enhance HM immobilization. Various characterization techniques were employed, including compressive strength tests, XRD, ATR-FTIR, SEM-EDX, XPS analyses, and TCLP leaching tests, to assess immobilization effectiveness. These results indicate that although the addition of PP-g-MHBP does not actively contribute to the chemical interactions with HM ions, it acts as an inert filler within the GP matrix. CFA/PP-g-MHBP-based GPs demonstrated significant potential for Cd²⁺ immobilization up to 3 wt% under acidic conditions, although the retention of Pb²⁺, CrO₄²⁻, and Hg²⁺ varied according to the specific chemistry of each metal, weight percentage of the added metal, matrix structure, and regulatory standards. Notably, high immobilization percentages were achieved for CrO₄²⁻ and Hg²⁺, although the leaching concentrations exceeded US EPA limits. These findings highlight the potential of CFA/PP-g-MHBP-based GPs for environmental applications, emphasizing the importance of optimizing formulations to enhance HM immobilization under varying conditions. Full article

We used WRF-Chem to simulate ash transport from eruptions of Chile’s Calbuco volcano on 22–23 April 2015. Massive ash and SO₂ ejections reached the upper troposphere, and particulates transported over South America were observed over Argentina, Uruguay, and Brazil via satellite and surface data. Numerical simulations with the coupled Weather Research and Forecasting–Chemistry (WRF-Chem) model from 22 to 27 April covered eruptions and particle propagation. Chemical and aerosol parameters utilized the GOCART (Goddard Chemistry Aerosol Radiation and Transport) model, while the meteorological conditions came from NCEP-FNL reanalysis. In WRF-Chem, we implemented a more efficient methodology to determine the Eruption Source Parameters (ESP). This permitted each simulation to consider a sequence of eruptions and a time varying ESP, such as the eruption height and mass and the SO₂ eruption rate. We used two simulations (GCTS1 and GCTS2) differing in the ash mass fraction in the finest bins (0–15.6 µm) by 2.4% and 16.5%, respectively, to assess model efficiency in representing plume intensity and propagation. Analysis of the active synoptic components revealed their impact on particle transport and the Andes’ role as a natural barrier. We evaluated and compared the simulated Aerosol Optical Depth (AOD) with VIIRS Deep Blue Level 3 data and SO₂ data from Ozone Mapper and Profiler Suite (OMPS) Limb Profiler (LP), both of which are sensors onboard the Suomi National Polar Partnership (NPP) spacecraft. The model successfully reproduced ash and SO₂ transport, effectively representing influencing synoptic systems. Both simulations showed similar propagation patterns, with GCTS1 yielding better results when compared with AOD retrievals. These results indicate the necessity of specifying lower mass fraction in the finest bins. Comparison with VIIRS Brightness Temperature Difference data confirmed the model’s efficiency in representing particle transport. Overestimation of SO₂ may stem from emission inputs. This study demonstrates the feasibility of our implementation of the WRF-Chem model to reproduce ash and SO₂ patterns after a multi-eruption event. This enables further studies into aerosol–radiation and aerosol–cloud interactions and atmospheric behavior following volcanic eruptions. Full article

In this study, the combined combustion characteristics and gaseous product emissions of coal slime and corn stover were compared at different blending ratios. The TG-DTG curves indicate that the optimal performance is achieved when the corn straw blending ratio is 20%. Furthermore, the TG-FTIR coupling results demonstrated an increase in gas species as the blending ratio increased. The composition analysis of ash samples formed at various combustion temperatures using XRD and XRF indicated that a portion of KCl in the fuel was released as volatile matter, while another part reacted with Al₂O₃ and SiO₂ components in the slime to form silica–aluminate compounds and other substances. Notably, interactions between the components of slime and potassium elements in corn stover primarily occurred within the temperature range of 800–1000 °C. These findings contribute to a comprehensive understanding of biomass and coal co-firing combustion chemistry, offering potential applications for enhancing energy efficiency and reducing emissions in industrial processes. Full article

This study focuses on three different regions of moso bamboo (Phyllostachys edulis): an inner layer (IB), middle layer (MB), and outer layer (OB), to comprehensively characterize the structural features, chemical composition (ash, extractives and lignin contents), and the lignin monomeric composition as determined by analytical pyrolysis. The results show that bamboo presents a gradient structure. From the IB to OB, the vascular bundle density and fiber sheath ratio increase, the porosity decreases (from 45.92% to 18.14%), and the vascular bundle diameter–chord ratio increases (from 0.85 to 1.48). In terms of chemical composition, the ash, extractives, and acid-soluble lignin content gradually decrease from IB to OB. The holocellulose content follows the trend: MB (66.3%) > OB (65.9%) > IB (62.8%), while the acid-insoluble lignin content exhibits the opposite trend: IB (22.6%) > OB (17.8%) > MB (17.7%). Pyrolysis products reveal the diversity of carbohydrates and lignin derivatives, with a lignin monomeric composition rich in syringyl and guaiacyl units and lower amounts of H-units: the IB has an H:G:S relation of 18:26:55, while 15:27:58 is the ratio for the MB and 15:40:45 for the OB; S/G ratio values were, respectively, 1.22, 1.46, and 0.99. A comprehensive analysis highlights significant gradient variations in the structure and chemistry of bamboo, providing robust support for the classification and refinement methods of bamboo residues for potential applications. Full article

There is a lack of published literature on coal deposits in Madagascar. The Imaloto Basin is a sub-basin of the Morondava Basin, Southwestern Madagascar, and hosts the Sakoa Coal Measures. The aim of this study was to increase our understanding of the petrography, geochemistry, and mineralogy of coal deposits hosted in the Imaloto Basin. Three coal seams (from the bottom: Main Seam, Upper Seam, and Top Seam) were intersected during a drilling program conducted by the Lemur Holdings in 2019. Coal samples were characterized using organic petrography (type and rank determination); the ash chemistry was assessed (XRF), and the mineralogy was considered using X-ray diffraction. The depositional environment at the time of peat accumulation was considered. The Main Seam samples are of better quality compared to the Upper Seam and Top Seam samples in terms of calorific value (CV) and ash yield. The coals are borderline Sub-bituminous Low Rank A to Bituminous Medium Rank D. An abundance of inertinite macerals was determined in the Main Seam, while the Upper and Top Seams are more vitrinite-rich. An unusual mineral, possibly albite or analcime, was determined in samples with a high Na content. The Imaloto coal samples show varied depositional settings (dry forest swamp, wet forest swamp, and piedmont plain), which influences coal quality. Full article

In the context of climate change and the circular economy, biochar agricultural and environmental applications have attracted a good deal of attention. Biochar has unique characteristics like surface area, porosity, water-holding capacity, pH, surface charge, and nutrients. This study reviews the biochar production from olive pomace (OP) and olive stone (OS) byproducts, its chemical and physical characterization, and its environmental application. The current review highlights the conditions for biochar production, the effects of pyrolysis temperature, and feedstock type on the physicochemical properties of biochar. High pyrolysis temperature (>500 °C) promotes a high specific surface area, high porosity (especially for OS biochars), and pH as well as the content of ash and fixed carbon, but generates low cation exchange capacity (CEC) and electrical conductivity (EC) and high values of O/C and H/C ratio. OP biochar also presents a high C amount, and ash content, i.e., rich in nutrients and high alkalizing capacity. OP biochar serves as an important source of plant nutrients, especially potassium. After adding both types of biochar, aggregate stability and the amount of water held in soil increase, and bulk density and bioavailability of trace elements decrease. Thus, biochar from olive mill wastes can be a potential plant nutrient reservoir, a good amendment to improve soil properties and long-term carbon sequestration. Results presented in this review can be used to build designer biochars from olive mill wastes to help solve environmental issues (water purification and pollutant remediation) and are suitable for improving soil physical chemistry characteristics and crop growth. Full article

Volcanic glass has been used extensively as a paleoaltimeter. Deuterium (²H) concentrations in glass have been found to be stable over geologic timescales, making δ²H (also known as δD) a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in volcanic ash. Here, we analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ash-flow tuff, and create a paleoisoscape to assess variations in δD across Oregon during that time. To this end, 16 ash samples were collected across central and eastern Oregon from various flow units within the RST. Samples were analyzed for δD using a temperature conversion elemental analyzer (TC/EA) connected to a mass spectrometer and elemental composition using a scanning electron microscope (SEM). We compared the isotopic results to modern water and published ancient water proxy data to better constrain changes in climate and topography across Oregon throughout the Neogene. We also estimated wt. % H₂O by calculating excess (non-stoichiometric) oxygen from SEM elemental data. We did not observe significant variations in δD among the flow units from single locations, nor was there a significant relationship between the prepared glass shard composition and wt. % H₂O or δD, supporting the use of volcanic glass as a reliable paleoenvironmental indicator. Our results show significant spatial variation in δD_water values of RST, ranging from −107‰ to −154‰. δD values of ancient glass were similar to modern water near the Cascade Mountains but became relatively negative to the east near the inferred eruptive center of the RST, suggesting that a significant topographic feature existed in the vicinity of the RST eruptive center that has since subsided. Full article

Coal gasification fine slag (CGFS) is a significant source of solid waste requiring improved treatment methods. This study primarily investigates the mechanism of ultrasonic treatment in optimising flotation-based decarbonization of CGFS and its impact on CGFS modified with surfactants. The objective is to maximise the carbon ash separation effect to support the clean and efficient utilisation of CGFS. Flotation experiments revealed optimal conditions at an ultrasonication power of 180 W for 2 min and a slurry concentration of 60 g/L, resulting in a residual ash content of 82.59%. Particle size analysis, scanning electron microscopy (SEM), and Brunner−Emmet−Teller (BET) measurements demonstrate the efficacy of ultrasound in extracting inorganic minerals from the surface and pores of residual carbon, consequently reducing both pore and particle sizes. Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses indicate alterations in the surface chemistry of CGFS induced by ultrasound treatment. The content of hydrophilic groups decreased from 31.64% to 29.88%, whereas the COO- group content decreased from 13.13% to 8.43%, consequently enhancing hydrophobicity. Adsorption experiments demonstrate an increase in surfactant adsorption capacity following ultrasonic treatment. Furthermore, ultrasonic treatment facilitates the desorption of surfactants previously adsorbed onto the surfaces of CGFS residue. Therefore, optimal flotation is obtained by applying ultrasonic pretreatment to CGFS before adding flotation chemicals. Upon the addition of Polysorbate (Tween-80), the residual ash content increased 90.17%. Full article

In the past few years, wind power has become a viable alternative in Brazil to diversify the energy mix and mitigate pollutant emissions from fossil fuels. Significant wind energy generation potential is inherent in the Brazilian Northeast state of Rio Grande do Norte, due to prevailing strong winds along the coastline and elevated regions. However, clean and renewable wind energy may lead to potential biodiversity impacts, including the removal of native vegetation during plant construction and operation. This case study explores the flash pyrolysis-based valorization of three commonly suppressed species, namely Cenostigma pyramidale (CP), Commiphora leptophloeos (CL), and Aspidosperma pyrifolium (AP), in a wind farm situated within the Mato Grande region of Rio Grande do Norte State. The study centers on determining their bioenergy-related properties and assessing their potential for producing phenolic-rich bio-oil. The investigation of three wood residues as potential sources of high-value chemicals, specifically phenolic compounds, was conducted using a micro-furnace type temperature programmable pyrolyzer combined with gas chromatography/mass spectrometry (Py–GC/MS setup). The range of higher heating values observed for three wood residues was 17.5–18.4 MJ kg⁻¹, with the highest value attributed to AP wood residue. The bulk density ranged from 126.5 to 268.7 kg m⁻³, while ash content, volatile matter content, fixed carbon content, and lignin content were within the respective ranges of 0.8–2.9 wt.%, 78.5–89.6 wt.%, 2.6–9.5 wt.%, and 19.1–30.6 wt.%. Although the energy-related properties signifying the potential value of three wood residues as energy resources are evident, their applicability in the bioenergy sector can be expanded via pelleting or briquetting. Yields of phenolic compounds exceeding 40% from the volatile pyrolysis products of CL and AP wood residues at 500 °C make them favorable for phenolic-rich bio-oil production. The findings of this study endorse the utilization of wood residues resulting from vegetation suppression during the installation of wind energy plants as potential feedstocks for producing bioenergy and sustainable phenolic compounds. This presents a solution for addressing a regional environmental concern following the principles of green chemistry. Full article