Search Results (204)

Biopolymers have gained significant attention due to their environmental advantages, with insects emerging as a promising but underutilized source of chitin and chitosan. In this study, chitosan was extracted from the larval exuviae of Tenebrio molitor through sequential demineralization, deproteinization, and deacetylation steps. For selected analyses, the extracted chitosan was further purified via reprecipitation from an acid solution using a basic precipitant (1 M NaOH). Chitosan was then characterized using chemical and instrumental methods. The results indicated that the chitosan had a medium degree of deacetylation (72.27%) and viscosity-average molecular weight (612 kDa), along with minimal ash (0.33%) and amino acid (0.14%) content, suggesting high product quality. FTIR analysis identified characteristic functional groups present, and SEM analysis highlighted a fibrous and porous microstructure in the purified chitosan. The prepared films exhibited favorable properties, including low thickness (0.0197 mm), high swelling degree (335.07%), moderate water solubility (46.99%), and moisture content of 32.39%, supporting their practical applicability. T. molitor exuviae thus represents a sustainable and environmentally friendly source of high-quality chitosan, with beneficial structural and functional properties, supporting its use in a wide array of value-added applications. Full article

In recent years, recovering critical elements from coal has attracted considerable interest due to their significant potential and resulting advantages. A prime example is the coal-hosted Al-Ga-Li-REE deposit within the Jungar Coalfield of Inner Mongolia, northern China, where lithium (Li), gallium (Ga), and aluminum (Al) are successfully extracted from coal ash. However, the specific forms in which these elements exist, crucial for developing effective extraction methods, remain unquantified. This research investigated the distribution of Li, Ga, Nb, Zr, and rare earth elements (REEs) within the coal. The study employed a combination of analytical techniques, including inductively coupled plasma mass spectrometry (ICP-MS), sequential chemical extraction (SCE), scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS), and X-ray powder diffraction analysis (XRD). The analyzed coals exhibited enriched levels of Li, Ga, Zr, Nb, and REEs. Kaolinite and boehmite were the primary mineral constituents, along with minor amounts of calcite, pyrite, rutile, goyazite, and chlorite. Sequential chemical extraction revealed that Li and Ga are primarily associated with aluminosilicate phases (71.84%–84.39%) and, to a lesser degree, organic matter (12.15%–25.09%). Zirconium and Nb were also predominantly found within aluminosilicates (68.53%–95.96%). REEs occur mainly in carbonate (28.28%–60.78%), aluminosilicate (11.6%–33.08%), and organic (22.04%–29.42%) fractions. Full article

Inonotus obliquus, a medicinal mushroom valued for its bioactive compounds, has not been previously characterized from Romanian sources. This study presents the first comprehensive chemical and biological screening of I. obliquus, introducing novel polymer-based encapsulation systems to enhance the stability and bioavailability of its bioactive constituents. Two distinct delivery systems were designed to enhance the functionality of I. obliquus extracts: (i) microencapsulation in maltodextrin (MIO) and (ii) a sequential approach involving preparation of silver nanoparticle-loaded I. obliquus (IO–AgNPs), followed by microencapsulation to yield the hybrid MIO–AgNP system. Comprehensive metabolite profiling using GC–MS and ESI–QTOF–MS revealed 142 bioactive constituents, including terpenoids, flavonoids, phenolic acids, amino acids, coumarins, styrylpyrones, fatty acids, and phytosterols. Structural integrity and successful encapsulation were confirmed by XRD, FTIR, and SEM analyses. Both IO–AgNPs and MIO–AgNPs demonstrated potent antioxidant activity, significant acetylcholinesterase inhibition, and robust antimicrobial effects against Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli. Cytotoxicity assays revealed pronounced activity against MCF-7, HCT116, and HeLa cell lines, with MIO–AgNPs exhibiting superior efficacy. The synergistic integration of maltodextrin and AgNPs enhanced compound stability and bioactivity. As the first report on Romanian I. obliquus, this study highlights its therapeutic potential and establishes polymer-based nanoencapsulation as an effective strategy for optimizing its applications in combating microbial resistance and cancer. Full article

Assessing available phosphorus (P) in paddy fields is challenging due to waterlogging-induced reducing conditions. This study tested the applicability of the Truog, Bray 2, and Mehlich 3 extraction methods in both air-dried and incubated soils, as well as the ascorbic-acid-reduced Bray 2 (AR Bray 2), which simulates reducing conditions, for evaluating rice growth under P fertilization. In addition, to investigate the chemical characteristics of the extraction methods, active Al and Fe and P sequential extractions were measured. Soil samples from four representative regions in Yamagata Prefecture were used. Pot cultivation tests using ‘Haenuki’ and ‘Tsuyahime’ cultivars were conducted with varying P fertilizer levels. Variations in P availability across soil types were influenced by levels of active Al and Fe. Sequential extractions identified NaHCO₃-P and NaOH-P fractions as important for P availability. Bray 2 in both soils and AR Bray 2 were the most effective methods, showing a strong saturating exponential correlation with rice growth and P uptake, whereas Mehlich 3 and Truog showed weaker correlations. Bray 2 and AR Bray 2 show potential but require further evaluation for practical application due to the small number of soils. Future efforts should prioritize developing methods that account for P dynamics under reducing conditions, thereby improving P management strategies and supporting sustainable rice production. Full article

Excess phosphorus (P) and nitrogen (N) in wastewater contribute to eutrophication, driving the need for low–cost and sustainable recovery technologies. This study presents a novel adsorbent synthesized from spent coffee grounds biochar (CB) chemically modified with Mn²⁺/Zn²⁺/Fe³⁺ (oxy)hydroxide nanoparticles (CB–M) for simultaneous removal of phosphate and ammonium. Batch adsorption experiments using both synthetic solution and municipal wastewater were conducted to evaluate the material’s adsorption performance and practical applicability. Kinetic, isotherm, thermodynamic, and sequential extraction analyses revealed that CB–M achieved maximum phosphate adsorption capacities ranging from 42.6 to 72.0 mg PO₄³⁻·g⁻¹ across temperatures of 20–33 °C, reducing effluent phosphate concentrations to below 0.01 mg·L⁻¹. Ammonium removal was moderate, with capacities ranging between 2.8 and 2.95 mg NH₄⁺·g⁻¹. Thermodynamic analysis indicated that phosphate adsorption was spontaneous and endothermic, dominated by inner–sphere complexation, while ammonium uptake occurred primarily through weaker, reversible ion exchange mechanisms. Sequential extraction showed over 70% of adsorbed phosphate was associated with Fe-Mn-Zn phases, indicating the potential for use as a slow–release fertilizer. The CB–M retained structural integrity and exhibited partial desorption, supporting its reusability for nutrient recovery. Compared to other biochars, CB–M demonstrated superior phosphate selectivity at a neutral–pH, avoided the use of hazardous metals, and transformed coffee waste into a multifunctional material for wastewater treatment and soil amendment. These findings underscore the potential of CB–M as a circular economy solution for nutrient recovery without introducing secondary contamination. Full article

Microalgae are a promising source of valuable compounds, including proteins, pigments, lipids, vitamins, and ingredients for cosmetics and animal feed. Despite their potential, downstream processing remains a major bottleneck in microalgae biorefineries, particularly in achieving high extraction efficiency with low energy and chemical input. While several extraction methods exist, few balance efficiency with selectivity and sustainability. Recently, mild and selective techniques such as Pulsed Electric Field (PEF) and Enzymatic Hydrolysis (EH) have gained attention, both individually and in combination. This review provides the first comprehensive comparative analysis of PEF and EH, emphasizing their mechanisms of action, specific cellular targets, and potential for integration into a cascaded, wet-route biorefinery process. Studies involving PEF, EH, and their sequential application (PEF-EH and EH-PEF) are analyzed, focusing on microalgae species, operational conditions, and extraction yields. The advantages and challenges of each method, including compound selectivity, environmental impact, and economic feasibility, are critically evaluated. The goal is to gain insight into whether the synergistic use of PEF and EH can enhance the recovery of intracellular compounds while improving the overall sustainability and efficiency of microalgae-based bioprocessing. Full article

The innovative recycling of waste tires into fuel is essential for promoting sustainable development, enhancing waste valorization, and advancing waste-to-energy technologies. For the processing of fr. ≤ 200 °C, separated from the liquid products of the pyrolysis process of waste tires, polycondensation with formaldehyde and extraction with a polar solvent (N-methyl-2-pyrrolidone) was used. Due to the sequential application of these processes, a raffinate product is produced that contains significantly fewer undesirable compounds, such as reactive unsaturated hydrocarbons and aromatics, which can negatively affect gasoline. Additionally, this raffinate demonstrates chemical stability during storage. Due to its operational properties, the obtained raffinate can serve as a high-quality component for gasoline production, which is advisable when mixed with low-octane gas condensate. As a result of compounding, Euro 4 gasoline is obtained with an octane number equal to 93 according to the experimental method. The possibility of effectively using the extract (concentrate of aromatic and unsaturated compounds) as a plasticizer for waterproofing mastic was shown. Overall, the valorization of waste tire pyrolysis processing contributes to waste reduction and is consistent with promoting sustainable industrial innovation by replacing primary petrochemical feedstocks with secondary feedstocks and supporting the development of alternative energy sources. Full article

As a biodegradable material, chitin possesses exceptional physical and chemical properties, making it valuable in various industrial sectors. Compared to chitin, its derivative, chitosan, offers even more versatile applications due to its higher solubility and reactivity. As the key precursor for chitosan production, chitin is typically harvested from shrimp and crab exoskeletons. However, the quest for alternative sources has intensified to reduce reliance on crustacean-derived chitin. Black soldier fly (BSF, Hermetia illucens), particularly its puparium, has emerged as a promising alternative, though it is typically considered waste. In this study, we investigated different combinations and sequences of extraction treatments for chitin from the BSF puparium. The results demonstrate that sequential treatments of demineralization (DM), deproteination (DP), and decolorization (DC) produce chitin with the lowest ash, lipid, and protein contents—approximately 1.01%, 1.99%, and 3.01%, respectively, yielding degrees of DM and DP at 94.77% and 92.24%, and a chitin purity of 93.98%. In contrast, combining DP and DC following the DM treatment facilitates partial chitosan transformation with a degree of deacetylation (DD) of 65.90%, offering a direct alternative for producing chitosan without an additional deacetylation process. Full article

Arabinoxylan (AX), an abundant and highly valuable component in wheat bran, has its structure and function influenced by the extraction method. A two-step extraction method, involving sequential extraction with a dilute alkali followed by a concentrated alkali–urea mixture, was employed to extract AX from wheat bran. This approach aimed to obtain AX with a high phenolic acid content while achieving a relatively high extraction yield. The dilute alkali extraction could effectively retain the phenolic acid content in the AX extract (≤89 μg/g). However, its yield and sugar content were relatively low. In contrast, the alkali–urea extraction could achieve a relatively high yield (≤55%) and sugar content (≤75%). Different pretreatments (defatting, deproteinization, and delignification) were performed before extraction, causing significant changes to the chemical composition and cell wall structural characteristics of destarched wheat bran, which, in turn, affected the yield and composition of the AX extracts. Deproteinization effectively increased the sugar content, phenolic acid content, and overall yield of the extracts. Different pretreatment and extraction methods significantly affected the DPPH radical scavenging rate and Fe²⁺ chelating rate of the AX extracts but had little impact on the ABTS radical scavenging rate. The antioxidant activity of AX extracted using alkali–urea was unexpectedly higher than that extracted using a dilute alkali. This suggests that the antioxidant activity of AX does not entirely depend on its phenolic acid content but is influenced by various other factors. Full article

Infiltration swales are a prospective key component of water-sensitive urban planning. The utilization of appropriate soil amendments is intended to facilitate the retention of pollutants from the stormwater runoff of traffic areas. Little is known about the possibility of utilizing processed construction and demolition waste (CDW) as an amendment to improve pollutant retention. We conducted batch and field tests to investigate (i) the leaching of metals and other elements from soil substrates containing CDW and (ii) their retention potential for copper (Cu) and zinc (Zn) when charged with real traffic area runoff. To gain a comprehensive understanding of the chemical interactions, we (iii) employed sequential extractions using an optimized protocol from treated and untreated soil substrates. In batch tests, the potential of vanadium leaching from technosols amended with brick-dominated CDW was apparent. When charged with traffic area runoff, the retentions of Cu and Zn in the technosols were comparable to those of the control soil without CDW. However, the simulation of high rainfall intensities reduced Cu and Zn retention in the technosols and the control. The results from the subsequent sequential extraction of Cu and Zn imply shifts in the chemical binding in the technosols compared to the control. Full article

The Hg fractions in three sediment cores of the eutrophic estuary in northern Taiwan were determined by the Bloom sequential extraction method, which chemically divided the sedimentary Hg into five fractions: water-soluble (F1); human stomach acid (F2); organo-chelated (F3); elemental Hg (F4), and residual (F5). The pH, redox potential, and dissolved total Hg in sediment pore waters, grain size, and total organic carbon (TOC) in sediment cores were analyzed, and the results were interpreted. The three sediment cores were in an anoxic environment. The total Hg concentrations in the sediment cores ranged between 110 and 369 ng/g, and most values exceeded the guideline value (ERL, 150 ng/g) of the EPA, U.S.A. However, the total Hg concentrations were mainly dominated by the non-labile Hg fraction (the elemental and the residual fraction), accounting for an average of 60% of the total Hg pool. The organo-chelated fraction accounted for an average of 29% of the total Hg pool. The amounts of the labile fraction (F1 + F2) of Hg in sediment cores of the middle and lower estuary were generally <2% of the total Hg pool. However, the F2 fraction in the sediment core of the upper estuary exceeded 10% of the total Hg pool. This result implied that Hg still poses a potential risk to the benthic organisms in the DRE based on the risk assessment code method. The profile variations between the labile and non-labile Hg fractions exhibited a negatively well-linear correlation, suggesting the transformation of the labile and moderately labile Hg fraction into the non-labile Hg fraction in sediment cores during the sediment burial processes. In addition, the TOC content seemed to play an important role in controlling the sediment Hg fractions in sediment cores. Full article

Sustainable agro-waste revaluation is critical to enhance the profitability and environmental footprint of the olive oil industry. Herein, the valorization of olive leaf pruning waste from five cultivars (‘Caiazzana’, ‘Carolea’, ‘Itrana’, ‘Leccino’, and ‘Frantoio’) employed green extraction methods to recover compounds with potential health benefits. Sequential ultrasound-assisted maceration (UAM) in n-hexane and ethanol was compared with a compressed fluid extraction strategy consisting of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) for their efficiency in recovering distinct classes of bioactives. Chemical profiling by UHPLC-HR-MS/MS (ultra-high-performance liquid chromatography high-resolution tandem mass spectrometry) and GC-MS (gas chromatography mass spectrometry) showed that UAM-EtOH effectively extracted polyphenols (especially luteolin derivatives) and triterpenes (notably maslinic acid), while PLE yielded the highest amount of secoiridoids (e.g., secologanoside). PLE extracts showed better antiradical activities, putatively due to a higher content of flavonoids, secoiridoids, and HCA derivatives than UAM-EtOH ones, as these latter also contained 20–40% (cultivar-dependent) of triterpenes. SFE extracts with a higher concentration of fatty acids and triterpenes showed moderate antioxidant activities but very high AChE inhibition. This study highlights the importance of selecting appropriate extraction methodologies based on the target bioactive compounds and underscores the potential of olive leaf extracts for sustainable bio-products. Full article

Phosphorus (P) is an essential macronutrient for plants. The focus of this work is to recover P from biosolids and their derived biochar. The effect of three different pyrolysis temperatures (400 °C, 500 °C, and 600 °C) and two carrier gases (CO₂ and N₂) on P fractionation and the speciation of P on biochars produced from two biosolids were investigated. The Hedley chemical sequential extraction method and ³¹P liquid NMR were used for P characterization and quantification. Higher pyrolysis temperatures increased P fixation and decreased short-term P bioavailability. Carrier gas had also significant effects on P fractionation in the biochars. Biochar produced in a CO₂ environment had slightly higher water-soluble P, NaHCO₃-P_i, NaOH-P_i, and residual P than in biochar prepared in a N₂ environment, while HCl-P showed the opposite trend. Additionally, the predominant molecular configuration of P was present in the inorganic form identified by ³¹P liquid NMR spectra, while organic P transformed into inorganic P with increasing pyrolysis temperature. Full article

Silver nanoparticles are one of the most commonly used forms of silver (Ag) in nanotechnology applications due to their antibacterial properties and electrical and thermal resistance. The increasing production and use of products containing nanoparticles has led to their release into and contamination of soil and water. This review summarizes the literature on the fate, behavior (adsorption/desorption, precipitation/oxidative dissolution, transformation), and transport/mobility of Ag forms in soils (Ag⁺ ions and Ag nanoparticles—AgNPs). The behavior of Ag⁺/AgNPs in soil is a complex process. It depends on many factors, including the characteristics of the Ag forms (ions, nanoparticle size, ligand type used for coating, surface charge, initial Ag concentration), the soil properties (organic matter and clay mineral content, textural properties, point of zero charge, cation exchange capacity, surface functional groups), and the solute properties (pH–Eh, ionic strength, cation type, oxygen content). The binding of Ag⁺ and AgNPs is significantly positively correlated with Al/Fe/Mn oxide and SOM content and depends on the surface charge of the minerals and CEC, which controls adsorption processes. Very important parameters to consider are the pH and Eh of the solution, which determine the durability of the ligands, the aggregation rate and the oxidation process of AgNPs, as well as the presence of sulfide and chloride and the Cl/Ag ratio, which determine the stability/mobility of Ag. Since AgNPs can be oxidized to Ag⁺ ions during their life cycle, it is necessary to consider the behavior of both forms of Ag in soils. Understanding the transport and behavior of Ag in soil is essential for the environmental risk assessment and management of wastes containing Ag. Full article

Slow pyrolysis was carried out in biosolids under three different temperatures (400, 500 and 600 °C) and two different carrier gases (CO₂ and N₂) on a fluidized bed reactor. The total concentration, chemical fractionation, and plant availability of the heavy metals in biochar were assessed by standard methods. The total concentration of Fe, Zn, Cu, Mn, Cr, Ni and Pb increased with the conversion of biosolids to biochar and with increasing pyrolysis temperature. The community’s Bureau of Reference (BCR) sequential extraction identified the migration of metals from toxic and bioavailable to potentially stable available or non-available forms at higher pyrolysis temperatures. Diethylenetriamine penta-acetic acid (DTPA)-extractable metals (Cu, Zn, Cd, Cu, Fe and Pb) were significantly lower in biochar compared to biosolids. By replacing N₂ with CO₂, the total metal concentration of heavy metals was significantly different for Mn, Ni, Cd, Pb and As. There were larger amounts of metals in the residual and oxidizable fractions compared to when N₂ was used as a carrier gas. Consequently, the biochar produced at higher temperatures (500 and 600 °C) in the N₂ environment exhibited lower potential ecological risks than in CO₂ environments (69.94 and 52.16, respectively, compared to values from 75.95 to 151.38 for biochars prepared in N₂). Overall, the results suggest that the higher temperature biochar can support obtaining environmentally safe biochar and can be effective in attenuating the ecological risks of biosolids. Full article