Search Results (1,308)

The preparation of highly efficient adsorbents capable of simultaneously removing dyes and heavy metals is of great importance. Crab shell-derived biochar (BC) was successfully modified with magnesium and iron oxides (magnetic MgO@BC) via a simple impregnation–carbonization method. A series of characterizations revealed that magnetic MgO@BC possessed hierarchical porous structure with abundant oxygenated functional groups and good magnetic separability. The results of batch adsorption experiments showed that the actual maximum adsorption capacities of magnetic MgO@BC were 301.06, 1344.11 and 3232.10 mg/g for Cd²⁺, Pb²⁺ and CR, respectively. In addition, the adsorption of Cd²⁺, Pb²⁺, and CR exhibited minimal influence from pH and coexisting ions, except for Cd²⁺ adsorption, which was significantly affected by divalent cations. For Cd²⁺ and Pb²⁺ adsorption, the Langmuir model provided good fits for the adsorption isotherms, whereas CR adsorption was more suitable for the Freundlich model. The adsorption kinetic fitting results indicate that Cd²⁺ adsorption aligned well with the pseudo-first-order model, while Pb²⁺ and CR fitted better with the pseudo-second-order model. Regeneration tests revealed that after four cycles, Cd²⁺, Pb²⁺ and CR still maintained 85.87%, 52.43%, and 96.09% removal efficiencies, respectively. SEM, FTIR, XRD, and XPS results demonstrated that the mechanism for CR adsorption involved π-π interactions, electrostatic attraction, and hydrogen bonding. The adsorption mechanism of heavy metals was primarily governed by ion exchange, cation-π interactions, surface coordination, and coprecipitation mechanisms, where Pb²⁺ exhibited stronger and more preferential adsorption behavior. Binary adsorption experiments confirmed competitive and synergistic effects depending on pollutant pairs. This study offers a novel perspective on the preparation and mechanism of biochar materials for the efficient and synergistic removal of dyes and heavy metals. Full article

Bamboo powder waste generated from bamboo processing serves as an ideal feedstock for biochar (BC). This study employed potassium hydroxide (KOH) to modify biochar derived from bamboo powder waste, activating it at different temperatures (700 °C, 800 °C, and 900 °C) to yield samples designated KBC-700, KBC-800, and KBC-900, respectively. The physicochemical properties and pore structures of the modified biochar were characterized using SEM, specific surface area and pore size analysis, FT-IR, Raman spectroscopy, XRD, and zeta potential measurements. The adsorption performance of the modified biochar toward PFOA was investigated using kinetic and thermodynamic models, examining the effects of the solution pH, adsorbent dosage, and temperature. Results indicate that KBC-900 exhibits a significantly enhanced specific surface area (up to 2924.7 m² g⁻¹), reduced surface oxygen-containing functional groups, increased carbon skeleton aromatization, and expanded mesoporous channels. Under initial conditions of pH = 3 and reaction temperature of 298 K, KBC-900 achieved a PFOA adsorption capacity of 366.7 mg g⁻¹ with a removal efficiency of 91.67%. The adsorption process conformed to pseudo-first-order and pseudo-second-order kinetic models as well as the Freundlich model. The adsorption equilibrium was reached within 12 h, indicating multi-layer adsorption dominated by chemisorption on a heterogeneous surface. Thermodynamic parameters indicate the adsorption reaction is an exothermic process. After five cycles of regeneration, KBC-900 maintained a removal efficiency of 75.69%. This study provides an efficient and reliable solution for removing PFOA from water. Full article

To tailor surface chemistry and wettability for advanced membrane applications, this study investigates PES-, PES–PVP-, and PES–GO-based nanofiber membranes modified through oxygen plasma treatment. The plasma process introduced reactive functional groups, including SO₃H, C=O, and OH, onto the fiber surfaces, converting the membranes from hydrophobic to super-hydrophilic and enhancing their surface reactivity. This modification enabled tunable wettability, allowing controlled adjustment of the membrane’s hydrophilic behavior. Overall, the results demonstrate the effectiveness of plasma engineering in developing versatile nanofiber membranes with customizable surface properties for a wide range of applications. Full article

The development of oxidation-resistant and regenerable materials remains a major challenge for mercury removal from contaminated waters and industrial effluents. In this study, a zwitterionic mesoporous silica gel functionalized with L-cysteine (SG-3PS-Cys) was synthesized, where the thiol group is covalently anchored to the silica framework, preventing oxidative degradation while preserving –NH₃⁺ and –COO⁻ groups for Hg(II) coordination. Spectroscopic analyses (FTIR, XPS, and ¹³C NMR) confirmed the formation of a stable, thiol-free binding environment in which mercury interacts through carboxylate oxygen atoms, electrostatically stabilized by neighboring ammonium groups. The material exhibited a high surface area (134 m² g⁻¹) and uniform mesoporosity (9.8 nm), achieving a maximum Hg(II) uptake of 82.7 mg g⁻¹ at pH 3 with rapid kinetics and cooperative S-type isotherms. The adsorbent retained 72% of its capacity after five regeneration cycles and maintained 38.7% selectivity toward Hg(II) in multicomponent solutions. DFT-based surface energy distribution analysis supported the zwitterionic coordination mechanism, revealing energetically homogeneous and high-affinity binding domains. Beyond its chemical stability, the material introduces a sustainable route for mercury remediation, linking surface energy, electrostatic effects, and porosity to achieve durable performance under acidic and complex aqueous conditions. These findings provide a mechanistic and design framework for the next generation of non-thiol adsorbents capable of selective and reusable Hg(II) removal in environmentally relevant scenarios. Full article

The escalating global demand for large-scale, cost-effective, and sustainable high-quality protein has positioned single-cell protein (SCP) production from one-carbon (C1) gases as a highly promising solution. In this study, eight chemolithoautotrophic hydrogen-oxidizing bacteria (HOB) were isolated from mangrove sediments. Based on the 16S rRNA gene sequence analysis, they belonged to genera Sulfurimonas, Sulfurovum, Thiomicrolovo, and Marinobacterium. Among these, Thiomicrolovo sp. ZZH C-3 was identified as the most promising candidate for SCP production based on the highest biomass and protein content, and was selected for further characterization. Strain ZZH C-3 is a Gram-negative, short rod-shaped bacterium with multiple flagella. It can grow chemolithoautotrophically by using molecular hydrogen as an energy source and molecular oxygen as an electron acceptor. Genomic analysis further confirmed that ZZH C-3 harbors a complete reverse tricarboxylic acid (rTCA) cycle gene set for carbon fixation, and diverse hydrogenases (Group I, II, IV) for hydrogen oxidation. Subsequently, its cultivation conditions and medium composition for SCP production were systematically optimized using single-factor experiments and response surface methodology (RSM). Results showed that the optimal growth conditions were 28 °C, pH 7.0, and with 1 g/L (NH₄)₂SO₄ as the nitrogen source, 5–10% oxygen concentration, 9.70 mg/L FeSO₄·7H₂O, 0.17 g/L CaCl₂·2H₂O, and 1.90 mg/L MnSO₄·H₂O. Under the optimized conditions, strain ZZH C-3 achieved a maximum specific growth rate of 0.46 h⁻¹. After 28 h of cultivation, the optical density at 600 nm (OD₆₀₀) reached 0.94, corresponding to a biomass concentration of 0.60 g/L, and the protein content ranked at 73.56%. The biomass yield on hydrogen (Y_H2) was approximately 3.01 g/g H₂, with an average H₂-to-CO₂ consumption molar ratio of about 3.78. Compared to the model HOB Cupriavidus necator, strain ZZH C-3 exhibited a lower H₂/CO₂ consumption ratio, superior substrate conversion efficiency, and high protein content. Overall, this study not only validated the potential of mangrove HOB for SCP production but also offers new insights for future metabolic engineering strategies designed to enhance CO₂-to-biomass conversion efficiency. Full article

To elucidate the microscopic adsorption mechanism of dodecylbenzenesulfonate (DBS⁻) on the surface of anatase TiO₂, this study was conducted based on density functional theory, using the DMol³ module for calculations. Four representative initial configurations including orientation differences in sulfonate, the benzene ring, and the alkyl chain were constructed. The contribution of each functional fragment to adsorption stability and interfacial electron transfer behavior were investigated through geometric optimization, energy calculation, Mulliken population, molecular electrostatic potential analysis, Fukui function, and density-of-states analysis. The results showed that configuration a-101 exhibited a lying orientation and multi-stage synergetic adsorption, with the largest adsorption energy (−210.29 kJ/mol), and it was the most stable configuration. The sulfonate group had the most negative electrostatic potential, and the highest occupied orbital was mainly located on its oxygen atom (O). Additionally, the f⁻ value of the Fukui function of O was the highest, serving as the key electrophilic reaction active site, and formed a Ti-O coordination bond with surface Ti⁴⁺. The benzene ring acted as an electron acceptor and participated in adsorption through π-d weak coupling. Adsorption induced the transfer of an about 0.7 e charge from DBS⁻ to TiO₂. The 2p orbitals of O and the 3d orbitals of Ti overlapped in the range of −5.0~0.45 eV, forming a coordination bond. 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

Aligned with circular bioeconomy principles, which aim to establish closed-loop systems that maximize resource utilization and renewal while minimizing waste, this study developed and characterized innovative catalysts derived from waste almond shells. These shells were carbonized and functionalized to create active surfaces containing Lewis and Brønsted acid sites. Modification was achieved through treatment with ZnCl₂ to introduce Lewis acid (LA) sites and with sulfuric acid to generate Brønsted acid (BA) sites. Detailed instrumental analyses enabled assessment of catalyst morphology, textural parameters, and surface functional groups. A physical mixture of the two catalysts was used to convert glucose into 5-hydroxymethylfurfural (HMF), yielding a maximum HMF yield of 76.8%. The results indicate that the collaborative action of Lewis and Brønsted acid sites, along with oxygen-containing surface groups, contributes to catalyst efficiency. These insights facilitate targeted catalyst optimization by adjusting surface texture and functional groups. Full article

TiO₂ nanoparticles were synthesized by a simple sol–gel route followed by high-temperature calcination at 800 °C, aiming to obtain an anatase-dominant reference photocatalyst with enhanced structural stability after severe thermal treatment. Raman spectroscopy and X-ray diffraction confirmed that anatase is the major crystalline phase, with only a minor rutile contribution after calcination at 800 °C. Nitrogen adsorption–desorption measurements revealed a narrow mesoporous contribution arising from interparticle voids and a relatively high specific surface area (108 m² g⁻¹) despite the severe thermal treatment, while electron microscopy showed nanometric primary particles assembled into compact agglomerates. Surface hydroxyl groups were identified by Fourier-transform infrared spectroscopy, consistent with sol–gel-derived TiO₂ systems. Diffuse reflectance UV–Vis spectroscopy combined with Kubelka–Munk and Tauc analysis yielded an optical band gap of 3.12 eV, typical of anatase TiO₂. Methylene blue (MB) was used as a probe molecule to evaluate photocatalytic activity under ultraviolet and visible light irradiation. Under UV illumination, degradation kinetics were governed by band-gap excitation and reactive oxygen species generation, whereas a slower but reproducible reference behavior under visible light was predominantly associated with surface-related effects and dye sensitization rather than intrinsic visible-light absorption. Overall, the results establish this anatase-dominant TiO₂ as a reliable high-temperature reference photocatalyst, retaining measurable activity after calcination at 800 °C and exhibiting UV-driven behavior as the dominant contribution. Full article

Polypropylene microplastics (PP-MPs) represent a persistent class of marine pollutants due to their hydrophobicity, high crystallinity, and resistance to environmental degradation. This review summarizes recent advances in understanding the environmental behavior, physicochemical aging, and ecotoxicological risks of PP-MPs, with emphasis on microbial degradation pathways involving bacteria, fungi, algae, and filter-feeding invertebrates. The biodegradation of PP-MPs is jointly regulated by environmental conditions, polymer properties, and the structure and function of plastisphere communities. Although photo-oxidation and mechanical abrasion enhance microbial colonization by increasing surface roughness and introducing oxygenated functional groups, overall degradation rates remain low in marine environments. Emerging mitigation strategies include biodegradable polymer alternatives, multifunctional catalytic and adsorptive materials, engineered microbial consortia, and integrated photo–biodegradation systems. Key research priorities include elucidating molecular degradation mechanisms, designing programmable degradable materials, and establishing AI-based monitoring frameworks. This review provides a concise foundation for developing ecologically safe and scalable approaches to PP-MP reduction and sustainable marine pollution management. Full article

Pesticide residues from agriculture pose persistent threats to ecosystems and human health. Precipitation and surface runoff facilitate the transport of pesticide residues, leading to their subsequent accumulation in lakes and rivers. Microalgae-based bioremediation offers a promising and environmentally friendly approach for degrading and detoxifying these residues. This study employed liquid chromatography–mass spectrometry (LC-MS) to determine pesticide residues in various microalgal solutions. Using three-dimensional excitation-emission matrix (3D-EEM) spectroscopy and fluorescence regional integration (FRI), we quantified the dynamics of dissolved organic matter (DOM) and its relationship with pesticide degradation in the microalgal system. Over time, Tolypothrix tenuis exhibited the highest degradation rate for THX (95.7%), while Anabaena showed the most effective degradation for ATZ (53.8%). Based on structural analysis of degradation products, three potential degradation pathways for THX and ATZ under microalgae action were proposed. Moreover, the degradation process may also involve reactive oxygen species and intracellular enzymes. Hydroxylation and carboxylation were the primary reactions involved in THX degradation, leading to ring opening and subsequent mineralization. In ATZ, the initially removed groups included methyl and carbonyl groups, with the final products undergoing hydroxylation and subsequent mineralization to water and carbon dioxide. This study, conducted within the context of aquatic environmental protection, investigates the threat of pesticide residues to aquatic ecosystems. It further elucidates the associated environmental impacts and degradation mechanisms from a microalgal perspective. Full article

Titanium (Ti) and its alloys are widely used in biomedical applications due to their biocompatibility and corrosion resistance; however, surface modifications are required to enhance biological functionality. Surface functionalization using natural biomolecules has emerged as a promising strategy to improve early cell–surface interactions and biocompatibility of implant materials. In this study, Ti6Al4V alloy surfaces were biofunctionalized using Spirulina platensis (S. platensis) biomass and protein extract to evaluate morphological, chemical, and biological effects. The functionalization process involved activation with piranha solution, silanization with 3-aminopropyltriethoxysilane (APTES), and subsequent biomolecule immobilization. Surface characterization by scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) confirmed the successful incorporation of microalgal components, including nitrogen-, phosphorus-, and oxygen-rich organic groups. Biomass-functionalized surfaces exhibited higher phosphorus and oxygen content, while protein-coated surfaces showed nitrogen-enrich chemical signatures, reflecting the distinct molecular compositions of the immobilized biomolecules. Cell adhesion assays demonstrated enhanced early cell attachment on biofunctionalized surfaces, particularly in samples functionalized with 5 g/L biomass for three hours, which showed significantly greater cell attachment than both the control and protein-treated samples. These findings highlight the complementary yet distinct roles of S. platensis biomass and protein extract in modulating surface chemistry and cell–material interactions, emphasizing the importance of tailoring biofunctionalization strategies to optimize early biological responses on titanium-based implants. Full article

The surface chemistry of biochar plays a pivotal role in the adsorption and stabilization of soil organic carbon (SOC); however, sorption-mediated mechanisms remain insufficiently understood for biochars derived from invasive plants. In this study, Solanum rostratum biomass, an aggressive invasive weed in northern China, was pyrolyzed at 400–600 °C in 2023 to produce biochars with varying surface functionalities and structural features. FTIR, Raman, XPS, and SEM analyses revealed that increasing pyrolysis temperature led to decreased oxygen-containing functional groups and enhanced aromatic condensation, reflecting a transition from hydrogen bonding to π–π and hydrophobic sorption mechanisms. Soil incubation experiments using sandy loam soil showed that biochar produced at 500 °C significantly increased the stable carbon pool (SCP) to 52.4%, compared to 30.6% in unamended soils. It also reduced cumulative CO₂ release from 1.74 mg g⁻¹ to 1.21 mg g⁻¹ soil, indicating improved carbon retention. Bacterial 16S rRNA gene sequencing revealed that biochar amendments significantly altered community composition and increased deterministic assembly, particularly under 500 °C biochar, suggesting a sorption-driven niche filtering effect. These findings demonstrate that S. rostratum-derived biochar, especially at intermediate pyrolysis temperatures, enhances both carbon sequestration and microbial habitat structure. This has direct implications for improving degraded soils in arid farming regions, offering a dual strategy for invasive biomass management and climate-resilient agriculture. Full article

This review examines the feasibility of electrochemical synthesis of poly-L-arginine (PArg) using repetitive cyclic voltammetry in neutral aqueous phosphate-buffered saline. Previous studies on electrochemical deposition of PArg onto different carbonaceous electrode materials are discussed with respect to the already reported mechanistic models. Some controversial interpretations are of interest, predominantly the formation of peptide bonds during the electropolymerisation of L-arginine. Several alternative anodic pathways are considered via the possibilities and limitations of ways of attaching L-arginine molecules to the electrode surface. Furthermore, the role of oxygen-containing surface groups is discussed, as this aspect has been largely overlooked in the context of L-arginine deposition, despite the O-terminating character of the electrode surface and its effect on the reactivity of the nucleophilic guanidine group in L-arginine. Also, the application of extremely high potentials around +2 V vs. Ag/AgCl/3 mol L⁻¹ KCl is considered, as it can lead to the generation of reactive oxygen species that may interfere with or even govern the entire deposition process. Thus, the absence of such considerations may raise doubts about the peptide nature of the electrochemically assisted polymerisation of this basic amino acid. Finally, it seems that the identity of the electrochemically synthesised PArg does not correspond to that of this polymer prepared by conventional methods, such as solid-phase peptide synthesis, solution-phase synthesis, or N-carboxy-anhydride polymerisation, and therefore the whole process remains unproved. Full article

A multifunctional diagnosis and treatment carrier, ZIF-8@CDs, based on carbon quantum dots (CDs) and the zeolitic imidazolate framework-8 (ZIF-8) metal–organic framework which serves as a core structure for constructing the responsive delivery platform, is developed in this paper. The anticancer drug doxorubicin (DOX) and Survivin oligo (siRNA) are loaded to form a ZIF-8@CDs/DOX@siRNA dual loading platform. CDs of 5–10 nm are synthesized by the solvent method and combined with ZIF-8. Electron microscopy shows that the composites are nearly spherical particles of approximately 200 nm, and the surface potential decreases from +36 mV before loading CDs to +25.7 mV after loading. The composite system shows unique advantages: (1) It has Fenton-like catalytic activity, catalyzes H₂O₂ to generate hydroxyl radicals, and consumes glutathione in the tumor microenvironment. The level of reactive oxygen species (ROS) in the ZIF-8@CDs group is significantly higher than that in the control group. (2) To achieve visual diagnosis and treatment, its fluorescence intensity is superior to that of the traditional Fluorescein isothiocyanate (FITC)-labeled vector; (3) It has a high loading capacity, with the loading amount of small nucleic acids reaching 36.25 μg/mg, and the uptake rate of siRNA by liver cancer cells is relatively ideal. The ZIF-8@CDs/DOX@siRNA dual-loading system is further constructed. Flow cytometry shows that the apoptosis rate of HepG2 cells induced by the ZIF-8@CDs/DOX@siRNA dual-loading system is 49%, which is significantly higher than that of the single-loading system (ZIF-8@CDs/DOX: 34.3%, ZIF-8@CDs@siRNA: 24.2%) and the blank vector (ZIF-8@CDs: 12.6%). The platform provides a new strategy for the integration of tumor diagnosis and treatment through the multi-mechanism synergy of chemical kinetic therapy, gene silencing and chemotherapy. Full article