Highly Efficient and Rapid Lead(II) Scavenging by the Natural <i>Artemia</i> Cyst Shell with Unique Three-Dimensional Porous Structure and Strong Sorption Affinity

Heavy metal purification of water is a worldwide issue. In this work, we first find that the discarded <i>Artemia</i> cyst shell exhibits a unique three-dimensional porous structure, which can be recycled for efficient toxic Pb­(II) removal. The hierarchical skeleton comprised of the macro–meso–micropore confirmation as well as 17 types of amino acid species provides fast ion accessibility and a strong sorption affinity. The results prove that an extremely rapid Pb capture is obtained in less than 2 min, strong adsorption occurs in the presence of high concentration of Ca/Mg/Na ions, and selectivity is far beyond that of the commercial 001x7 (greater than 50 times). More importantly, an efficient application is achieved with a treatment capacity of 9100 kg wastewater/kg sorbent, which is 45 times greater than the performance of commercially activated carbon and ion-exchange resin. The effluent can be dramatically reduced to below 10 μg/L level (WHO). In addition, we can also regenerate the exhausted biomaterial <i>Artemia</i> shell for several cycles. All the results demonstrate that the unique structure and amino acid skeletons make discarded <i>Artemia</i> shells a new application for trace lead removal at low cost

Heavy-Metal Adsorption Behavior of Two-Dimensional Alkalization-Intercalated MXene by First-Principles Calculations

The two-dimensional (2D) layered MXene (Ti₃C₂(OH)_<i>x</i>F_2–<i>x</i>) material can be alkalization intercalated to achieve heavy-metal ion adsorption. Herein the adsorption kinetics of heavy-metal ions and the effect of intercalated sites on adsorption have been interpreted by first-principles with density functional theory. When the coverage of the heavy-metal ion is larger than 1/9 monolayer, the two-dimensional alkalization-intercalated MXene (alk-MXene: Ti₃C₂(OH)₂) exhibits strong heavy-metal ion absorbability. The hydrogen atoms around the adsorbed heavy-metal atom are prone to form a hydrogen potential trap, maintaining charge equilibrium. In addition, the ion adsorption efficiency of alk-MXene decreases due to the occupation of the F atom but accelerates by the intercalation of Li, Na, and K atoms. More importantly, the hydroxyl site vertical to the titanium atom shows a stronger trend of removing the metal ion than other positions

Study of molecular mechanism and extraction performance evaluation for separation of phenolics from alkaline wastewater through synergistic extraction

Phenols were a kind of pollutant in coal chemical wastewater with high concentration and difficult to decompose and have a significant impact on the subsequent biochemical treatment of the wastewater. In addition, phenols were a kind of weak electrolytes that partially dissociation oxidation under weakly alkaline conditions, making recovery more difficult. In order to solve this problem, phenols were extracted from weak alkaline wastewater with a synergistic solvent. First, the interaction between solvents and phenols and the solvent effect of solvents were calculated by quantum chemistry and the synergistic extractant cyclohexanone/1-pentanol was determined to have significant advantages. Moreover, the synergistic extractant was further analyzed through independent gradient model based on Hirshfeld partition analysis, atoms in molecule topology analysis, electrostatic potential analysis. Results indicated that the synergistic extract can provide multiple hydrogen bond interactions with phenol due to the double action sites of the C=O group of ketone and the -OH group of alcohol. In addition, the efficacy of the extractant was validated by multistage extraction, indicating partial dissociation oxidation of hydroquinone to benzoquinone under weakly alkaline conditions, with removal rates of 99.5% and 99.2% for phenol and hydroquinone, respectively. In general, the synergistic extractant can effectively remove phenols.</p

Efficient Phosphate Sequestration in Waters by the Unique Hierarchical 3D <i>Artemia</i> Egg Shell Supported Nano-Mg(OH)₂ Composite and Sequenced Potential Application in Slow Release Fertilizer

<i>Artemia</i> nauplii are important bait or food sources in aquaculture, but the egg shells after incubation are always subjected to discarding as natural wastes; therefore, application and utilization of the <i>Artemia</i> egg-shell wastes will be an important issue. Herein, we reported a new hybrid biomaterial by encapsulating nano-Mg­(OH)₂ onto discarded <i>Artemia</i> egg shells for phosphate sequestration enhancement. The unique hierarchically 3D-layered structure of <i>Artemia</i> egg shells can endow well-defined nano-Mg­(OH)₂ morphology and efficient phosphate adsorption performances. The results of the final hybrid biomaterial exhibit a wide pH dependent sorption process, strong affinity toward phosphate removal, and large sorption capacity. Moreover, the exhausted adsorbent shell–Mg-P can be further utilized as slow-release fertilizer without regular chemical regeneration. The efficient slow-release behaviors of phosphorus onto Shell–Mg–P for 30 days indicated the potential applicability as fertilizers. Additionally, the actual seedling tests further confirm that the shell–Mg–P can be readily used as a slow-release fertilizer for the soil improvement and crop productivity

Sorption Enhancement of Lead Ions from Water by Surface Charged Polystyrene-Supported Nano-Zirconium Oxide Composites

A novel hybrid nanomaterial was fabricated by encapsulating ZrO₂ nanoparticles into spherical polystyrene beads (MPS) covalently bound with charged sulfonate groups (−SO₃^–). The resultant adsorbent, Zr–MPS, exhibited more preferential sorption toward Pb­(II) than the simple equivalent mixture of MPS and ZrO₂. Such observation might be ascribed to the presence of sulfonate groups of the polymeric host, which could enhance nano-ZrO₂ dispersion and Pb­(II) diffusion kinetics. To further elucidate the role of surface functional groups, we encapsulated nano-ZrO₂ onto another two macroporous polystyrene with different surface groups (i.e., −N­(CH₃)₃⁺/–CH₂Cl, respectively) and a conventional activated carbon. The three obtained nanocomposites were denoted as Zr–MPN, Zr–MPC, and Zr–GAC. The presence of −SO₃^– and −N­(CH₃)₃⁺ was more favorable for nano-ZrO₂ dispersion than the neutral −CH₂Cl, resulting in the sequence of sorption capacities as Zr–MPS > Zr–MPN > Zr–GAC > Zr–MPC. Column Pb­(II) sorption by the four nanocomposites further demonstrated the excellent Pb­(II) retention by Zr–MPS. Comparatively, Zr–MPN of well-dispersed nano-ZrO₂ and high sorption capacities showed much faster breakthrough for Pb­(II) sequestration than Zr–MPS, because the electrostatic repulsion of surface quaternary ammonium group of MPN and Pb­(II) ion would result in a poor sorption kinetics. This study suggests that charged groups in the host resins improve the dispersion of embedded nanoparticles and enhance the reactivity and capacity for sorption of metal ions. Suitably charged functional groups in the hosts are crucial in the fabrication of efficient nanocomposites for the decontamination of water from toxic metals and other charged pollutants

Synthesis of MXene/Ag Composites for Extraordinary Long Cycle Lifetime Lithium Storage at High Rates

A new MXene/Ag composite was synthesized by direct reduction of a AgNO₃ aqueous solution in the presence of MXene (Ti₃C₂(OH)_0.8F_1.2). The as-received MXene/Ag composite can be deemed as an excellent anode material for lithium-ion batteries, exhibiting an extraordinary long cycle lifetime with a large capacity at high charge–discharge rates. The results show that Ag self-reduction in MXene solution is related to the existence of low-valence Ti. Reversible capacities of 310 mAh·g^–1 at 1 C (theoretical value being ∼320 mAh·g^–1), 260 mAh·g^–1 at 10 C, and 150 mAh·g^–1 at 50 C were achieved. Remarkably, the composite withstands more than 5000 cycles without capacity decay at 1–50 C. The main reasons for the long cycle life with high capacity are relevant to the reduced interface resistance and the occurrence of Ti­(II) to Ti­(III) during the cycle process

Efficient Removal and Recovery of Ag from Wastewater Using Charged Polystyrene-Polydopamine Nanocoatings and Their Sustainable Catalytic Application in 4‑Nitrophenol Reduction

This study addresses the long-standing challenges of removing and recovering trace silver (Ag) ions from wastewater while promoting their sustainable catalysis utilization. We innovatively developed a composite material by combining charged sulfonated polystyrene (PS) with a PDA coating. This composite serves a dual purpose: effectively removing and recovering trace Ag+ from wastewater and enabling reused Ag for sustainable applications, particularly in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The PS–PDA demonstrated exceptional selectivity to trace Ag+ recycling, which is equal to 14 times greater than the commercial ion exchanger. We emphasize the distinct roles of different charged functional groups in Ag+ removal and catalytic reduction performance. The negatively charged SO3H groups exhibited the remarkable ability to rapidly enrich trace Ag ions from wastewater, with a capacity 2–3 times higher than that of positively-N+(CH3)3Cl and netural-CH2Cl-modified composites; this resulted in an impressive 96% conversion of 4-NP to 4-AP within just 25 min. The fixed-bed application further confirmed the effective treatment capacity of approximately 4400 L of water per kilogram of adsorbent, while maintaining an extremely low effluent Ag+ concentration of less than 0.1 mg/L. XPS investigations provided valuable insights into the conversion of Ag+ ions into metallic Ag through the enticement of negatively charged SO3H groups and the in situ reduction facilitated by PDA. This breakthrough not only facilitates the efficient extraction of Ag from wastewater but also paves the way for its environmentally responsible utilization in catalytic reactions

XRD patterns of xerogels.

<p>(A) GO sheets; (B) C16Py-GO gels in DMF (a), THF (b), and pyridine (c); (C) BPy-GO gels in DMF (a), cyclopentanone (b), and THF (c); (D) CTAB-GO gels in DMF (a), cyclopentanone (b), cyclohexanone (c), 1,4-dioxane (d), and THF (e).</p

SEM images of xerogels. GO sheets (a), C16Py-GO gels ((b) DMF, (c) THF, and (d) pyridine), BPy-GO gels ((e) DMF, (f) cyclopentanone, and (g) THF), and CTAB-GO gels ((h) DMF, (i) cyclopentanone, (j) cyclohexanone, (k) 1,4-dioxane, and (l) THF).

<p>SEM images of xerogels. GO sheets (a), C16Py-GO gels ((b) DMF, (c) THF, and (d) pyridine), BPy-GO gels ((e) DMF, (f) cyclopentanone, and (g) THF), and CTAB-GO gels ((h) DMF, (i) cyclopentanone, (j) cyclohexanone, (k) 1,4-dioxane, and (l) THF).</p

TG curves of xerogels.

<p>(A) GO sheet and C16Py-GO gels in DMF, THF, and pyridine; (B) GO sheet and BPy-GO gels in DMF, cyclopentanone, and THF; (C) GO sheet and CTAB-GO gels in DMF, cyclopentanone, cyclohexanone, 1,4-dioxane, and THF.</p