Search Results (2,682)

Direct thermal decomposition of rare-earth chlorides into rare-earth oxides (REOs) in a single step presents a short-process, wastewater-free, and environmentally friendly alternative to the conventional precipitation–calcination method, which produces large amounts of saline wastewater. While earlier reviews have primarily focused on summarizing reaction conditions and thermodynamic parameters, they have seldom discussed the critical variations in pyrolysis behavior across different rare-earth elements. This review highlights a novel classification of rare-earth chlorides into fixed-valence and variable-valence groups, revealing how their respective oxidation states govern thermodynamic stability, reaction pathways, and chlorine release behavior. Furthermore, a systematic comparison is provided on the effects of additives, temperature, and gas partial pressure on product purity, particle size, and microstructure, with particular attention to the mechanisms underlying oxychloride intermediate formation. Beyond fundamental reaction principles, this work uniquely evaluates the design and performance of existing pyrolysis reactors, outlining both opportunities and challenges in scaling up direct rare-earth chloride (RECl_x) pyrolysis for industrial REO production. By integrating mechanistic insights with reactor engineering considerations, this review offers advancements over previous descriptive summaries and proposes a strategic pathway toward sustainable rare-earth processing. Full article

Microbiologically Influenced Corrosion (MIC) significantly endangers steel infrastructure, particularly in marine and buried environments, causing considerable economic and environmental damage. Sulphate-reducing bacteria (SRB) are primary supporters of MIC, accelerating iron corrosion through hydrogen sulfide production. Conventional mitigation strategies, including protective coatings and cathodic protection, often face challenges such as limited effectiveness against SRB and the aggressiveness of saltwater corrosion. This study explores a novel approach by directly introducing zinc oxide (ZnO) nanoparticles into the microbial medium to inhibit SRB activity and reduce MIC. Iron metal coupons were immersed in seawater under three conditions: control (seawater only), seawater with SRB, and SRB with ZnO nanoparticles. These coupons were used as electrodes in microbial fuel cells to obtain real-time voltage readings. At the same time, corrosion was evaluated using cyclic voltammetry (CV), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), mass loss, and pH measurements. Results demonstrate that ZnO nanoparticles significantly inhibited SRB growth, as confirmed by the antibiotic susceptibility test (ABST). It was revealed that the corrosion rate increased by 21.3% in the presence of SRB compared to the control, whereas the ZnO-added electrode showed a 21.7% reduction in corrosion rate relative to the control. SEM showed prominent corrosive products on SRB-exposed coupons. ZnO-added coupons exhibited a protective layer with grass-like whisker structures, and EDX results confirmed reduced sulfur and iron sulfide deposits, indicating suppressed SRB metabolic activity. ABST confirmed ZnO’s antimicrobial properties by producing clear inhibition zones. ZnO nanoparticles offer the dual benefits of antimicrobial activity and corrosion resistance by forming protective self-coatings and inhibiting microbial growth, making them a scalable and eco-friendly alternative to traditional corrosion inhibitors. This application can significantly extend the lifespan of iron structures, particularly in environments prone to microbial corrosion, demonstrating the potential of nanomaterials in combating microbiologically influenced corrosion (MIC). Full article

Chitin, one of the most abundant natural polysaccharides, has gained increasing attention for its structural diversity and potential in biomedicine, agriculture, food packaging, and advanced materials. Conventional chitin production from crustacean shell waste faces limitations, including seasonal availability, allergenic protein contamination, heavy metal residues, and environmentally harmful demineralization processes. Chitin from fungi and microalgae provides a sustainable and chemically versatile alternative. Fungal chitin, generally present in the α-polymorph, is embedded in a chitin–glucan–protein matrix that ensures high crystallinity, mechanical stability, and compatibility for biomedical applications. Microalgal β-chitin, particularly from diatoms, is secreted as high-aspect-ratio microrods and nanofibrils with parallel chain packing, providing enhanced reactivity and structural integrity that are highly attractive for functional materials. Recent progress in green extraction technologies, including enzymatic treatments, ionic liquids, and deep eutectic solvents, enables the recovery of chitin with reduced environmental burden while preserving its native morphology. By integrating sustainable sources with environmentally friendly processing methods, fungal and microalgal chitin offer unique structural polymorphs and tunable properties, positioning them as a promising alternative to crustacean-derived chitin. Full article

Rare earth elements (REEs) make up integral components in personal electronics, healthcare instrumentation, and modern energy technologies. REE leaching with organic acids is an environmentally friendly alternative to traditional extraction methods. Our previous study demonstrated that batch ultrasound-assisted organic acid leaching of REEs can significantly decrease environmental impacts compared to traditional bioleaching. The batch method is limited to small volumes and is unsuitable for industrial implementation. This study proposes a novel approach to increase reaction volume using a continuous ultrasound-assisted organic acid leaching method. Laboratory experiments showed that continuous ultrasound-assisted leaching increased the leaching rate (µg/h) 11.3–24.5 times compared to our previously reported batch method. Techno-economic analysis estimates the cost of the continuous approach using commercially purchased organic acids is $9465/kg of extracted REEs and $4325/kg of extracted REEs, using gluconic acid and citric acid, respectively. The sensitivity analysis reveals that substituting commercially purchased organic acids with microbially produced biolixiviant can reduce the process cost by approximately 99% while minimally increasing energy consumption. Environmental assessment shows that most of the emissions stemmed from the energy required to power the ultrasound reactor. We concluded that increased leaching capacity using a continuous ultrasound-assisted approach is feasible, but process modifications are needed to reduce the environmental impact. Full article

The persistence of the synthetic plastic waste problem makes it one of the most pressing environmental challenges. Sustainable material is an alternative approach to reduce petroleum plastics. In this research, our work aims to convert two biomaterials, water hyacinth (WH) and cassava chip (CC), into value-added biopolymer composite sheets (BCS). The raw materials of both WH and CC were prepared and characterized using physical and chemical treatments. Alkali treatments and chemical modifications were applied to remove lignin, protein, lipid, and other inhibiting components. After that, the two main raw materials of the WH and CC components were varied (100:0, 90:10, 80:20, 70:30, and 60:40, respectively) to investigate the optimal conditions for mixing, blending, and forming processes. Finally, mechanical properties (tensile strength), physical properties (surface morphology using a scanning electron microscope (SEM), crystalline structure by X-ray diffraction (XRD), and water solubility were also evaluated. The results obtained obviously revealed that the BCS reached an optimal ratio of 80:20 and exhibited outstanding properties. We were successful in exploring the potential use of a combination of two kinds of biopolymers under optimal conditions to produce an effective and environmentally friendly BCS in a manner that promotes a sustainable bio-circular economy and zero-waste concepts. Full article

Damping-off disease hinders rice seedling growth and reduces yield. Current control methods, such as seed or soil sterilization, rely on chemicals that cause environmental pollution and promote pathogen resistance. As a sustainable alternative, we targeted the damping-off resistance-related gene OsDGTq1 using CRISPR/Cas9. Field experiments first verified OsDGTq1’s significance in resistance. The CRISPR/Cas9 system, delivered via Agrobacterium-mediated transformation, was used to edit OsDGTq1 in rice cultivar Ilmi. Lesions from major damping-off pathogens, Rhizoctonia solani and Pythium graminicola, were observed on G₀ plants. All 37 regenerated plants contained T-DNA insertions. Among them, edits generated by sgRNA1-1, sgRNA1-2, and sgRNA1-3 resulted in the insertion of two thymine bases as target mutations. Edited lines were assigned names and evaluated for agronomic traits, seed-setting rates, and pathogen responses. Several lines with edited target genes showed distinct disease responses and altered gene expression compared to Ilmi, likely due to CRISPR/Cas9-induced sequence changes. Further studies in subsequent generations are needed to confirm the stability of these edits and their association with resistance. These results confirm that genome editing of OsDGTq1 alters resistance to damping-off. The approach demonstrates that gene-editing technology can accelerate rice breeding, offering an environmentally friendly strategy to develop resistant varieties. Such varieties can reduce chemical inputs, prevent pollution, and minimize seedling loss, ultimately enhancing food self-sufficiency and stabilizing rice supply. Full article

The transmission of viruses and bacteria via surfaces remains a persistent challenge for healthcare systems, leading to high public health costs and significant environmental impact due to the widespread use and disposal of single-use products. This study aims to evaluate the feasibility of using surface-covering films, based on biopolymers and inorganic nanoparticles, with strong antiviral and antibacterial properties, as a strategy to prevent infection transmission while offering a sustainable alternative to disposable materials. To this end, we developed a sprayable chitosan-based solution embedded with copper oxide nanoparticles (CH.CA@Cu). The solution demonstrated antibacterial activity against both Gram-positive and Gram-negative bacteria as well as virucidal activity, predominantly within one minute of exposure, against a wide range of viruses. After spraying various materials, the resulting film surfaces exhibited excellent adherence and uniform coverage, maintaining their integrity after contact. A field trial conducted in high-traffic environments confirmed the coating’s effectiveness. This long-lasting antiviral action supports their implementation, since the coated surface can continuously deactivate viruses regardless of infective doses of exposure, thereby reducing viral transmission. These findings will expand biopolymers’ current applicability while guiding us toward the adoption of green and eco-friendly technologies, thus reducing waste production. Full article

Geopolymers, as a novel class of low-carbon and eco-friendly cementitious material, exhibit outstanding durability and promote the resource utilization of industrial solid wastes. However, as a promising alternative to ordinary Portland cement, its susceptibility to carbonation-induced degradation may limit its widespread application. To address this challenge, this study systematically examined the effects of magnesium oxide (MgO) content and the metakaolin-to-fly ash ratio on the carbonation performance, mechanical properties, pH value, and microstructures of metakaolin–fly ash-based (MF-based) geopolymer pastes. The findings revealed that an increase in the fly ash ratio correlated with a decline in the compressive strength of MF-based geopolymer pastes. Conversely, the incorporation of MgO significantly enhanced the compressive strength, with higher fly ash ratios leading to more substantial improvements in strength. Furthermore, the addition of MgO and fly ash effectively mitigated the penetration of carbonation and the associated decrease in the pH value of the MF-based geopolymer pastes. Specifically, compared to the control group without MgO (M8F2-0%), MF-based geopolymer pastes with 4% and 8% MgO additions exhibited reductions in carbonation depth of 69.4% and 80.4%, respectively, after 28 days of carbonation, while pH values were observed to be 1.22 and 1.15 units higher, respectively. Additionally, microscopic structural analysis revealed that the inclusion of MgO resulted in a reduction in pore size, porosity, and mean pore diameter within the geopolymer pastes. This improvement was mainly attributed to the promotion of hydration processes by MgO, leading to the formation of fine Mg(OH)₂ crystals within the high-alkalinity pore solution, which enhances microstructural densification. In conclusion, the incorporation of MgO significantly improves the carbonation resistance and mechanical performance of MF-based geopolymers. It is recommended that future studies explore the long-term performance under combined environmental actions and evaluate the economic and environmental benefits of MgO-modified geopolymers for large-scale applications. Full article

Grape production is one of the most agronomically important activities worldwide. However, it is threatened by diseases caused by phytopathogenic microorganisms, which cause severe economic losses. The primary strategy to control phytopathogenic fungi is the application of fungicides; however, they affect the environment and induce resistance in fungi. Nanomaterials, especially those green-synthesized, emerge as an eco-friendly and sustainable alternative to control fungal pathogens. The objective of this work is to evaluate the sensitivity of fungal phytopathogens to biosynthesized copper-oxide nanoparticles (CuONPs). Nanoparticles were evaluated as preventive and corrective treatments in grapevine green tissues and fruits under field conditions, using in vitro and in vivo experimental approaches. Interestingly, corrective treatment was highly effective and showed little accumulation of Cu on the fruits, even less than a commercial copper-based fungicide. Moreover, we report that Aspergillus niger causes lesions in photosynthetic tissues and severe disease symptoms in grapes. We also describe for the first time the presence of Alternaria alternata causing lesions, mainly on the stems and young leaves of grapevine plants in Mexico. These pathogens were inhibited by the biosynthesized CuONPs. All these findings show the effectiveness of using CuONPs to control phytopathogenic fungi, even under field conditions, shedding light on their potential use in agriculture with a less environmental impact than the commercial fungicides and agrochemicals currently used. Full article

Conventional plant disease management primarily depends on chemical pesticides. However, with the rising concerns related to human health, environmental sustainability, and the emergence of resistant pathogens, biocontrol agents (BCAs) have gained more attention as eco-friendly alternatives. Among the potential biocontrol agents, yeasts stand out due to their safety, adaptability, and diverse antagonistic mechanisms, ranging from competition and enzyme secretion to volatile compound production and immunity induction. Despite their potential, yeast-based BCAs face limitations in field efficacy, regulation, and an incomplete understanding of their molecular interactions. Most current studies focus on simple, pairwise interactions, overlooking the complexity of agroecosystems, where plants, pathogens, and BCAs interact within broader microbial communities. This review addresses the importance of understanding tripartite interactions among plants, pathogens, and yeasts, supported by integrated transcriptomic and comparative genomic approaches, as well as meticulous observations of phenotypic expressions to uncover strain-specific defense mechanisms and mode of action. By referring to well-studied models like Blumeria graminis f.sp. hordei–Hordeum vulgare–Pseudozyma flocculosa and Trichoderma tripartite systems, we highlight the underexplored potential of yeasts to modulate plant immunity and influence pathogen behavior through complex molecular crosstalk. Bridging these knowledge gaps through integrating proteomic, metabolomic, and transcriptomic analyses, we can better harness yeasts in sustainable and targeted biocontrol strategies. Full article

Biofuels represent a sustainable alternative that supports global energy development without compromising environmental balance. This work introduces a novel hardware–software platform for the experimental characterization of biomass solid yield during the slow pyrolysis process, integrating physical experimentation with advanced computational modeling. The hardware consists of a custom-designed pyrolizer equipped with temperature and weight sensors, a dedicated control unit, and a user-friendly interface. On the software side, a two-step kinetic model was implemented and coupled with three optimization algorithms, i.e., Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and Nelder–Mead (N-M), to estimate the Arrhenius kinetic parameters governing biomass degradation. Slow pyrolysis experiments were performed on wheat straw (WS), pruning waste (PW), and biosolids (BS) at a heating rate of 20 °C/min within 250–500 °C, with a 120 min residence time favoring biochar production. The comparative analysis shows that the N-M method achieved the highest accuracy (100% fit in estimating solid yield), with a convergence time of 4.282 min, while GA converged faster (1.675 min), with a fit of 99.972%, and PSO had the slowest convergence time at 6.409 min and a fit of 99.943%. These results highlight both the versatility of the system and the potential of optimization techniques to provide accurate predictive models of biomass decomposition as a function of time and temperature. Overall, the main contributions of this work are the development of a low-cost, custom MATLAB-based experimental platform and the tailored implementation of optimization algorithms for kinetic parameter estimation across different biomasses, together providing a robust framework for biomass pyrolysis characterization. Full article

Access to clean water remains a global challenge, particularly in areas where populations rely on surface water. These water sources must be treated. Coagulation with chemicals causes environmental problems and adverse effects on human health. Natural coagulants obtained from papaya (Carica papaya) waste are presented as an alternative that is safe for human health, non-polluting, and biodegradable. The effectiveness of these natural coagulants is compared to that of aluminum sulfate using jar tests and synthetic and natural surface water, with statistical tools to model treatment processes. All coagulants have competitive results, reaching turbidity remotion levels above 90%. However, in equivalent tested ranges, natural coagulants require lower dosages and perform better with high initial water turbidity due to their polymeric bridging mechanisms and adsorption processes through the action of their functional groups, as detected by FTIR analysis. Additional testing with contaminated water from the Valsequillo dam confirms the use of these coagulants to treat water, with papaya seed coagulant yielding the best results and requiring lower doses, making it a competitive alternative. It can be concluded that papaya-based coagulants obtained from waste can be used as an eco-friendly alternative to aluminum sulfate in physicochemical treatments to purify surface water for human consumption. Full article

In Hungary, on-site mixed stabilization of cohesive soil is considered only as soil improvement not a proper pavement layer, therefore its bearing capacity is not taken into account when designing pavement. It was our hypothesis that on low-volume roads built on cohesive soil, lime or lime–cement stabilization can be an alternative to granular base layers. A case study was conducted to obtain initial results and to verify the research methodology. The efficacy of lime stabilization was evaluated across eight experimental road sections, with a view of assessing its structural and economic performance in comparison with crushed stone base layers reinforced with geo-synthetics. The results of the testing demonstrated elastic moduli of 120–180 MPa for the lime-stabilized layers, which closely matched the 200–280 MPa range observed for the crushed stone bases. The results demonstrated that lime stabilization offers a comparable load-bearing capacity while being the most cost-effective solution. Furthermore, this approach enhances sustainability by enabling the utilization of local soils, reducing reliance on imported materials, minimizing transport-related costs, and lowering carbon emissions. Lime stabilization provides a durable, environmentally friendly alternative for road construction, effectively addressing the challenges of material scarcity and rising construction costs while supporting infrastructure resilience. The findings highlight its potential to replace traditional base layers without compromising structural performance or economic viability. Full article

Plastic waste, particularly polyethylene terephthalate (PET), poses a growing environmental challenge. This study investigates the feasibility of incorporating recycled PET into clay bricks as a sustainable alternative in construction. Bricks were fabricated with 0%, 5%, 10%, and 15% PET content. Clay characterization included particle size distribution, Atterberg limits, and moisture content. Physical and mechanical tests evaluated dimensional variability, void percentage, warping, water absorption, suction, unit compressive strength ($f_b^{\prime }$), and prism compressive strength ($f_m^{\prime }$). Statistical analysis (Shapiro–Wilk, p < 0.05) validated the results. PET addition improved physical properties—reducing water absorption, suction, and voids—while slightly compromising mechanical strength. The 15% PET mix showed the best overall performance ($f_b^{\prime }$ = 24.00 kg/cm²; $f_m^{\prime }$ = 20.40 kg/cm²), with uniform deformation and lower absorption (18.7%). Recycled PET enhances key physical attributes of clay bricks, supporting its use in eco-friendly construction. However, reduced compressive strength limits its structural applications. Optimizing PET particle size, clay type, and firing conditions is essential to improve load-bearing capacity. Current formulations are promising for non-structural uses, contributing to circular material strategies. Full article

P(3HB) is a biodegradable and biocompatible polymer, which can replace petroleum-derived plastics. Previous studies have shown that Azotobacter vinelandii strain OP-PhbP3⁺, which overexpresses the phasin protein PhbP3, produces high concentrations of P(3HB) and undergoes early autolysis, facilitating polymer release. The aim of the present study was to evaluate the performance of this strain for P(3HB) production in 3 L bioreactors and assess the feasibility of a simplified recovery process. After 36 h of cultivation, rapid cell lysis was observed, resulting in a ~50% decrease in the protein content of the cell dry weight, without reducing P(3HB) concentration, which reached 4.6 g L⁻¹. Flow cytometry analysis revealed significant morphological changes during cultivation, which was consistent with the strain’s lytic behavior. The biomass recovered at 36 h was washed with SDS, obtaining a yield of 92.5% (respect to P(3HB) initial) and a purity of 97.6%. An alternative extraction procedure using the non-halogenated solvent cyclohexanone (CYC) resulted in an even higher yield of 97.8% with a purity of 99.3% of P(3HB). Notably, the weight average molecular weight of the polymer remained stable at 8000 kDa during the entire process. Overall, the combination of PhbP3 over-expression and environmentally friendly solvents, such as CYC, enabled efficient P(3HB) production with high yield and purity while preserving polymer quality. Full article