Search Results (143)

The decarbonization of essential water supply infrastructure is a critical challenge for water-stressed and geographically constrained regions, particularly islands where both water and electricity systems are highly dependent on external or fossil-based resources. In Northern Cyprus, approximately 70% of domestic water demand is met through imported water via pipeline, while electricity generation relies predominantly on fuel oil, resulting in high greenhouse gas emissions and environmental burden. This study evaluates an integrated renewable energy-based supply system using a medium-scale concentrating solar power (CSP) plant with parabolic trough collectors coupled to thermal desalination. The proposed configuration is assessed as an alternative energy-driven infrastructure option for reducing dependence on imported water and fossil-based electricity. System performance was evaluated by estimating electricity and freshwater production under local climatic conditions, demonstrating that the proposed configuration can meet both the associated electrical energy requirements and domestic water demand in the selected region. A cradle-to-gate life cycle assessment (LCA) was conducted to quantify the environmental impacts of the integrated system and support sustainability-oriented decision-making. The LCA results identify residual fossil-based electricity, phosphoric acid consumption, and brine discharge as the main environmental hotspots. Overall, the findings show that CSP-driven desalination can provide a viable and more sustainable option for integrated energy and water supply in water-scarce coastal regions with high solar potential, highlighting its relevance for renewable energy integration, water-energy nexus planning, and resource-efficient infrastructure development. Full article

This work describes the development of a core–shell magnetic nanoadsorbent (Fe₃O₄@TiO₂) designed for the selective recovery of rare earth elements (REEs) from electronic waste. The synthesis involved the co-precipitation of magnetite coated with an anatase-phase TiO₂ layer, subsequently functionalized with organophosphorus groups using glycolic acid and phosphoric acid. This surface modification, verified via FT-IR spectroscopy and zeta potential analysis, provided the material with a high density of active sites. Adsorption studies with lanthanum revealed that the process follows pseudo-second-order kinetics, reaching equilibrium in only 15 min with a theoretical model-calculated capacity of 19.4 ± 0.8 mg/g at pH 5. The material demonstrated high stability and reusability, maintaining 75% of its adsorption capacity after five cycles with a corresponding H₂SO₄ desorption efficiency of 58–60%. Finally, the nanoadsorbent was validated on real LCD screen leachates following an upstream pH 5.0 pre-neutralization and filtration stage designed to remove massive baseline concentrations of iron and copper. Although residual copper and chromium acted as the primary competitors within the remaining complex matrix, the material effectively partitioned REEs (Gd, Y, Ce, Pr, Nd, and Sm) present at ultra-low trace levels (μg/L), demonstrating its potential for urban mining and the circular economy. Full article

In this study, the effects of the type and content of phosphorus-based flame retardants, namely melamine polyphosphate (MPP) and aluminum diethylphosphinate (AlDPi), as well as their hybrid systems (MPP:AlDPi ratios of 1:1, 1:3, and 3:1), on the fire performance of acrylonitrile-butadiene-styrene (ABS) composites were investigated. The obtained results indicate that the synergistic action of MPP and AlDPi, including simultaneous inhibition of combustion in the gas phase and action in the condensed phase, leads to a significant improvement in the fire-retardant properties of ABS composites. For unmodified ABS, the peak Heat Release Rate (pHRR) and Total Heat Released (THR) values were 808.7 kW/m² and 86.5 MJ/m², respectively, while for the ABS/MPP_15/AlDPi_5, these values decreased to 292.9 kW/m² and 32.3 MJ/m². Simultaneously, the Effective Heat of Combustion (EHC) decreased from 22.3 to 15.5 MJ/kg, indicating inhibition of combustion processes in the gas phase. Fourier Transform Infrared Spectroscopy (FTIR) analysis of post-combustion residues (peaks 1280 and 1168 cm⁻¹) confirmed the contribution of additives to the formation of phosphorous derivatives in the condensed phase. The hybrid system ABS/MPP_15/AlDPi_5 exhibited the most favorable fire performance in cone calorimeter tests, characterized by reduced heat release and fire growth parameters. This was confirmed by the calculated fire performance indicators, including Fire Growth Rate Index (FIGRA), Maximum Average Rate of Heat Emission (MARHE), Fire Potential Index (FPI), and Flame Retardancy Index (FRI). Full article

For agricultural films, spectral matching, UV protection, and environmental durability are essential for efficient crop production. A self-cleaning silane-crosslinked red/blue dual-emission carbon dot/polyvinyl alcohol composite film (KH/RB-CQDs/PVA) was fabricated via a covalent anchoring strategy. RB-CQDs were synthesized by a two-step hydrothermal method using o-phenylenediamine: initial blue-emitting carbon cores formed, then phosphoric acid-assisted secondary treatment covalently bridged residual precursor-derived red fluorophores onto cores through pyrophosphate bonds, as evidenced by TEM, XPS, ³¹P NMR, HPLC-MS and DFT. This rigid bridging suppressed excessive core growth and energy transfer while spatially separating dual emission, endowing excellent photostability (>95% fluorescence retention after 50 min UV and 30 d storage). Subsequently, KH-560 was employed to construct a robust covalent crosslinked network anchoring RB-CQDs in PVA and forming rough Si-O-Si surface structures, confirmed by SEM and XPS. The resulting film exhibited 16.16% quantum yield, 291% tensile strength enhancement, 95% UV shielding, and <1% contaminant residue. Chlorophyll fluorescence kinetics, gas-exchange analyses, and photosynthetic response curves demonstrated that KH/RB-CQDs/PVA increased the potato net photosynthetic rate by 55.46% and tuber yield by 76% through synergistic optimization of photosystem II electron transport and RuBisCO-mediated carbon assimilation. This work provides a molecular design principle for high-performance intelligent agricultural films. Full article

Waterborne polyurethane (WPU) is widely used in flexible films and textile finishing, but its intrinsic flammability, severe melt dripping, and sensitivity to polar additives restrict its fire-safe applications. Herein, a phosphorous acid-protonated chitosan (PCS) was designed as an emulsion-adaptable bio-based modifier and incorporated into cationic WPU via a facile aqueous blending route, yielding transparent multifunctional composite films and flame-retardant textile coatings. Unlike conventional flame-retardant WPU systems that rely on reactive monomers or suffer from poor emulsion compatibility, this work proposes an emulsion-compatible strategy based on PCS, enabling the simultaneous integration of dispersion stability, flame retardancy, and antibacterial functionality within a single system. PCS could be stably accommodated in the WPU latex without visible precipitation or demulsification after centrifugation, and the resulting films preserved a continuous matrix structure with uniformly distributed PCS-rich nanodomains. Rheological analyses revealed that the polar groups of PCS established strong intermolecular associations with urethane segments, strengthening the physical network. The char residue at 700 °C increased from 0.7 wt% for neat WPU to 32.7 wt% for WPU/PCS-5. Meanwhile, WPU/PCS-5 achieved a limiting oxygen index of 35.4% and a UL-94 V-0 rating, while its peak heat release rate and total heat release were reduced by 73.4% and 41.8%, respectively. The composite films also showed nearly complete antibacterial efficiency against Escherichia coli and Staphylococcus aureus. As a textile coating, WPU/PCS-5 enabled immediate self-extinguishing of cotton fabric, increased the limiting oxygen index from 18.5% to 27.2%, and reduced the damaged length from 30.0 to 11.0 cm. This work demonstrates that an emulsion-compatible strategy based on PCS can effectively integrate dispersion stability, fire safety, multifunctionality, and coating applicability into WPU materials. Full article

Pyranose oxidases (POXs, EC 1.1.3.10) are a class of fungal FAD-dependent oxidoreductases with potential for lignocellulosic bioconversion because they generate H₂O₂ during sugar oxidation. Despite their known catalytic properties, the role of these enzymes in promoting lignocellulose enzymatic saccharification remains largely unexplored. In this study, POXs from Phanerochaete chrysosporium (PcPOX) and Trametes versicolor (TvPOX) were comparatively evaluated through biochemical characterization, kinetic analysis, molecular simulation, and supplementation for lignocellulose hydrolysis. PcPOX exhibited a broader substrate spectrum and a slightly higher optimum temperature, whereas TvPOX demonstrated greater stability under acidic and hydrolysis-relevant conditions and a longer half-life at 50 °C. TvPOX also showed a numerically lower apparent K_m toward D-glucose, while the apparent catalytic efficiencies were comparable between the two enzymes. Molecular simulation results suggested more stable glucose binding in TvPOX. Accordingly, TvPOX was selected for hydrolysis experiments and was shown to increase the measured glucan conversion of phosphoric acid-swollen cellulose, Avicel, and corncob residue. Mixture design analysis further indicated that this positive effect depended on balanced peroxide regulation, with low catalase supplementation providing better performance. These results identify TvPOX as a promising auxiliary enzyme for cellulase-based lignocellulosic saccharification. Full article

Wheat straw is an abundant agricultural residue with high potential for carbohydrate-based bioconversion, yet its efficient utilization is limited by lignocellulosic recalcitrance. This study systematically investigated Organosolv extraction of wheat straw (Triticum aestivum) with the goal of achieving near-complete enzymatic hydrolysis at minimized process severity and energy demand. Process severity was evaluated using the P-Factor concept. In preliminary screening, acid catalysts and liquor ratios were assessed. Strong acids clearly outperformed weak acids: at comparable severity, 5% (w/w, DM) H₂SO₄ or p-toluenesulfonic acid (PTSA) yielded glucose yields of 83 ± 2.4% and 81 ± 6.2%, respectively, whereas weak acids (phosphoric, lactic, acetic) and a catalyst-free control resulted in only ~20–41% glucose yield. Liquor ratio strongly affected extraction performance; a ratio of 1:19 provided the highest glucose yield (85 ± 1.4%) and robust mixing compared to 1:12–1:15 (67–68%). Two novel pretreatment strategies applied prior to Organosolv extraction, namely Hot-Water Pretreatment (HWP) and Water Pretreatment (WP), significantly increased hydrolysability compared to untreated straw (58 ± 3%), reaching 79 ± 2% for HWP and 86 ± 5% for WP. DoE-based experiments (135–170 °C; P-Factor 3.0–4.0) showed that increasing temperature from 135 to 150 °C markedly improved hydrolysability (e.g., WP: 74 ± 3% to 96 ± 3%), while further increasing to 170 °C provided no additional benefit. Response-surface modeling predicted a maximum hydrolysability of approximately 88% for HWP but complete hydrolysis for WP within 152–170 °C, indicating a broad operational window. Overall, combining simple Water-based Pretreatment with severity-optimized Organosolv extraction enables energy-efficient, near-complete hydrolysis at lower operating temperatures, reducing both energy demand and pressure requirements, and thereby offering advantages in process cost and scalability. Full article

Triazine herbicides are widely used for weed control in agricultural systems, and their occurrence in water bodies has been frequently reported worldwide. This study assessed the efficiency of a hydrochar derived from the epicarp and mesocarp of passion fruit residues for the removal of three triazine herbicides (atrazine, ametryn, and metribuzin), with the aim of developing a material suitable for application in water remediation programs. The adsorption capacity of biomass and hydrochar derived from passion fruit residues was evaluated with and without activation using 0.5 mol L⁻¹ phosphoric acid. The adsorption of herbicides was not significantly affected by pH within the range of 4 to 8. The acid hydrochar, which exhibited the highest removal capacity among the evaluated adsorbents, presented adsorption capacities of 18.05, 10.83, and 5.05 µg g⁻¹ for atrazine, ametryn, and metribuzin, respectively. These values correspond to removal efficiencies of approximately 62%, 72%, and 52% at initial concentrations of 0.33, 0.25, and 0.15 mg L⁻¹. The adsorption equilibrium time varied among the herbicides, reaching 4 h for atrazine and ametryn and 5 h for metribuzin. The adsorption dynamics between the adsorbents and adsorbates were best described by the pseudo-second-order kinetic model for ametryn and metribuzin, while atrazine had a higher correlation with the Elovich equation. The Weber–Morris model did not adequately describe the adsorption process. Among the isotherms tested, the Freundlich model provided the best fit for all three herbicides. The desorption rates of the acid hydrochar were 51%, 13%, and 83% for atrazine, ametryn, and metribuzin, respectively. Therefore, hydrochar derived from passion fruit residues represents a promising alternative for the remediation of triazine herbicides. Full article

Rare earth elements (REEs), as significant associated resources in sedimentary phosphate deposits, are commonly processed via the conventional hydrochloric acid wet-process phosphoric acid route (IMI process). In this method, phosphate and rare earth elements are typically leached simultaneously, which subsequently complicates their separation. In this study, a dolomitic rare earth-bearing phosphate concentrate from the Zhijin region of Guizhou Province was selected as the research subject. A stepwise phosphorus-prioritized leaching process was proposed, whereby precise regulation of hydrochloric acid dosage and reaction temperature enabled the preferential leaching of phosphorus (91.27%) and the directed enrichment of rare earth elements in the leaching residue (enrichment ratio of 4.7), thereby achieving efficient phosphorus–rare earth separation at the source. Subsequent process mineralogical analyses of the phosphate concentrate and the leaching residue revealed that rare earth elements occur in fluorapatite predominantly through isomorphic substitution. Following preferential phosphorus leaching, the residual Ca combines with F to form CaF₂, while rare earth elements become concentrated within the leaching residue. Finally, kinetic investigations and response surface analyses demonstrated that the preferential phosphorus leaching process is governed by diffusion through the solid product layer. Among the influencing factors, hydrochloric acid dosage (A), leaching temperature (C), and the interactions between leaching time and the solid–liquid ratio (B, D) were identified as the most significant parameters affecting phosphorus leaching efficiency. This study elucidates, from a mechanistic perspective, the governing principles of phosphorus dissolution and rare earth enrichment within the hydrochloric acid preferential leaching system, thereby providing important theoretical support and technical guidance for simultaneously achieving efficient phosphorus extraction and targeted rare earth enrichment within the hydrochloric acid wet-process phosphoric acid production route. Full article

Given the rising demand for phosphate, a critical mineral for many countries due to its essential role in fertilizer production and global food security, reprocessing waste generated during phosphate mining has become increasingly important to mitigate demand pressures and reduce the environmental impact of the mining industry. This study aims to develop a sustainable hydrometallurgical process to recover residual phosphate from a lithology present in mining waste rock. To this end, a thermodynamic analysis was first performed to assess reaction feasibility during leaching and precipitation. A two-step process was then proposed: the first step involves leaching carbonates (mainly calcite) using acetic acid, optimized through response surface methodology based on a Box–Behnken design; the second step consists of precipitating calcium with phosphoric acid to produce a value-added by-product (brushite) while simultaneously regenerating the acetic acid. A preliminary economic assessment was conducted to evaluate process feasibility. The results show that acetic acid is highly selective for carbonates, yielding a phosphate concentrate containing 30% P₂O₅ with complete phosphate recovery under the following conditions: 3.4 molL⁻¹ acid concentration, 28 °C reaction temperature, a liquid-to-solid ratio of 6 mLg⁻¹ (14.2% solids), and a reaction time of 49 min. In the precipitation step, a calcium recovery of 97% was achieved under optimal conditions (20 °C, 15 min, 500 rpm stirring, and a P:Ca ratio of 1). Furthermore, the preliminary economic assessment indicates that the developed process, based on the use of an organic acid and its recycling, generates a net profit, confirming its economic viability and its contribution to environmentally sustainable phosphate processing. Full article

The disposal of end-of-life fluorescent lamps presents significant environmental challenges due to their mercury (Hg) content and the loss of valuable rare earth elements (REEs) contained in phosphor powders, highlighting the need for sustainable recycling strategies. This study proposes an integrated hydrometallurgical process for simultaneous mercury removal and material recovery from spent fluorescent lamps. Various leaching agents were initially evaluated for mercury dissolution, and 10% NaOCl was identified as the most effective solution. The optimized system was applied to linear T8 lamps using a combined milling–leaching approach, followed by size-based separation of metallic, glass, and phosphor fractions. Dissolved mercury was precipitated at pH 11 using Na₂S, forming crystalline α-HgS (cinnabar), as confirmed by XRD, and reducing the residual mercury concentration to 2.7 µg/L. The metallic fraction was recovered as an aluminum-based alloy containing 20.6 wt.% Cu and 10.9 wt.% Zn with low iron content, while the phosphor-rich fraction yielded approximately 50% REE extraction, followed by oxalate precipitation of yttrium-based compounds. The developed process enables efficient mercury stabilization and selective recovery of valuable materials, supporting environmentally secure and resource-efficient fluorescent lamp recycling. Full article

This work investigates the potential of wollastonite-based brushite cement (WBC) for the stabilization and solidification of radioactive waste contaminated by ⁹⁰Sr. This phosphate binder was formed by the reaction of wollastonite (CaSiO₃) with a phosphoric acid solution containing borax and metallic cations (Al³⁺, Zn²⁺). Two cement pastes were investigated: a commercial binder (WBC-C) and an optimized formulation (WBC-O), produced using a zinc-free mixing solution with a higher aluminum content than that of WBC-C. Mineralogical characterizations using XRD, TGA, XRF, SEM-EDX, and Raman spectroscopy showed that both materials mainly contained amorphous hydrated silica and calcium aluminophosphate, along with crystalline brushite, residual wollastonite, and quartz. The stability of WBC-C under γ-irradiation was evaluated up to a dose of 1 MGy. The only observable effect was water radiolysis, leading to dihydrogen production at yields comparable to Portland cement matrices and geopolymers. Strontium leaching, assessed using the ANSI/ANS-16.1-2003 (R2008) procedure, followed a two-stage release mechanism combining surface wash-off and diffusion. The apparent diffusion coefficient D_a of Sr in WBC-C was markedly lower than typical values reported for Portland cement matrices. WBC-O exhibited enhanced Sr retention, possibly due to its higher aluminum content, which refines mesopores and reduces diffusion pathways accessible to Sr. WBC binders therefore appear to be promising candidates for strontium immobilization. Full article

Tetracycline is a low-cost broad-spectrum antibiotic and widely used in medicine and aquaculture. Its residues are usually released into the environment through wastewater, which may lead to the spread of antibiotic resistance genes and pose ecological risks. To address this environmental issue, a hierarchical lignin-derived porous carbon (LPHC) was synthesized using renewable biomass lignin as the precursor through a combined phosphoric acid-activated hydrothermal pretreatment. The resulting LPHC was used to effectively remove tetracycline from aqueous solutions. Characterization results indicated that LPHC had a high specific surface area (1157.25 m²·g⁻¹), a well-developed micro-mesoporous structure, and abundant surface oxygen-containing functional groups, which enhanced its interaction with target pollutants. Adsorption experiments showed that LPHC exhibited excellent adsorption performance for tetracycline, with a maximum adsorption capacity of 219.81 mg·g⁻¹. The adsorption process conformed to the Langmuir isotherm model, indicating that monolayer chemical adsorption was dominant. Mechanism analysis further confirmed that the adsorption process was controlled by multiple synergistic interactions, including pore filling, π-π electron donor–acceptor interactions, hydrogen bonding, and electrostatic attraction. This work proposes a feasible strategy to convert waste biomass into high-performance and environmentally friendly adsorbents, which provides technical feasibility for sustainable water purification technologies. Full article

Enhancing the flame retardancy of polymeric materials by adding only eco-friendly ammonium polyphosphate (APP) while simultaneously maintaining high-temperature resistance has become a challenge. Talcum has been introduced as a cooperative agent into the silicone rubber/APP system to investigate the effect of talcum on flame retardancy, thermal stability, and high-temperature resistance. The machining process induces the orientation of talcum in the system. The ceramifiable silicone rubber blends containing oriented talcum (e.g., sample SA₆T₄) exhibited superb flame retardancy, including an LOI of 29.4%, a UL-94 rating of V-0, and a peak heat release rate (PHRR) of 250.2 kW·m⁻². More importantly, the blends present excellent thermal stability and high-temperature resistance, characterized by outstanding self-supporting properties and dimensional stability. Based on the structural analysis of the blends and their residues, the made of action for the improved flame retardancy may be attributed to the formation of a compact barrier layer. This layer is formed by oriented talcum platelets combined with phosphoric acid, from the thermal decomposition of APP, promoting crosslinking, thereby achieving a good inhibition barrier to inhibit heat feedback from the condensation zone. The excellent thermal stability and high-temperature resistance of the ceramifiable silicone rubber blends may be ascribed to a cooperative effect between APP and talcum at high temperatures, which facilitates the formation of ceramic structures. The novel ceramifiable silicone rubber composite has potential applications as flame-retardant sealing components for rail transit equipment and encapsulation materials for new energy battery modules. Full article

This study presents an approach to synthesizing LTA-type zeolite from spodumene residue generated during a lithium extraction process. A residue was obtained after leaching β-spodumene with 2 mol/L phosphoric acid. After solid–liquid separation, the delithiated residue was first treated with 2 mol/L sodium hydroxide and then subjected to hydrothermal synthesis using sodium aluminate as an additional aluminum source. The resulting material was characterized by XRD, SEM-EDS, XPS, and FTIR, which collectively confirmed the formation of a crystalline material exhibiting the structural features, elemental composition, and morphological characteristics consistent with LTA-type zeolite. Additional analyses, including BET surface area, particle size distribution, and zeta potential measurements, were performed to further evaluate the physicochemical properties of the synthesized zeolite. The spodumene leach residue (SLR)-derived zeolite was further tested for its adsorption performance in heavy metal ions removal from a mixed ion solution containing Pb²⁺, Cu²⁺, Zn²⁺, and Ni²⁺ ions. The zeolite demonstrated a high selectivity for Pb²⁺, followed by moderate uptake of Cu²⁺, while Zn²⁺ and Ni²⁺ adsorption was minimal. These findings demonstrate that spodumene residue, a waste by-product of lithium processing, can be effectively upcycled into LTA zeolite suitable for heavy metal remediation in water treatment applications. Full article