Highly efficient removal of silver nanoparticles by sponge-like hierarchically porous thiourea-formaldehyde resin from Water

Green synthesis of superhydrophilic resin/graphene oxide for efficient analysis of multiple pesticide residues in fruits and vegetables

The escalating use of pesticides on fruits and vegetables has raised concerns about potential health risks. Therefore, we developed a superhydrophilic resin/graphene oxide (SR/GO) with rich adsorption interactions using an eco-friendly synthetic approach. SR/GO demonstrated excellent hydrophilicity, ensuring optimal contact with aqueous sample matrices. The multiple adsorption interactions, including π-π conjugation, hydrogen bonding, and electrostatic adsorption, facilitated multi-pesticide residue co-extraction. The synthesized SR/GO was applied to a miniaturized centrifugation-accelerated pipette-tip extraction method, coupled with high-performance liquid chromatography. The optimized method exhibited low consumption (15.0 mg adsorbent), and high efficiency, with low detection limits (1.4-2.9 ng g-1) and high recoveries (75.3-113.0%). Water-compatible SR/GO, along with a miniaturized extraction process, showcases a potent analytical approach for pesticide residue analysis in fruits and vegetables. The significance of this method lies in its ability to ensure agricultural and food safety by using a low-cost and efficient multi-pesticide residue analytical strategy.

Silicon-Carbon Dots-Loaded Mesoporous Silica Nanocomposites (mSiO2@SiCDs): An Efficient Dual Inhibitor of Cu2+-Mediated Oxidative Stress and Aβ Aggregation for Alzheimer's Disease

The redox-active metal ions, especially Cu2+, are highly correlated to Alzheimer's disease (AD) by causing metal ion-mediated oxidative stress and toxic metal-bound β-amyloid (Aβ) aggregates. Numerous pieces of evidence have revealed that the regulation of metal homeostasis could be an effective therapeutic strategy for AD. Herein, in virtue of the interaction of both amino-containing silane and ethylenediaminetetraacetic acid disodium salt for Cu2+, the silicon-carbon dots (SiCDs) are deliberately prepared using these two raw materials as the cocarbon source; meanwhile, to realize the local enrichment of SiCDs and further maximize the chelating ability to Cu2+, the SiCDs are feasibly loaded to the biocompatible mesoporous silica nanoparticles (mSiO2) with the interaction between residual silane groups on SiCDs and silanol groups of mSiO2. Thus-obtained nanocomposites (i.e., mSiO2@SiCDs) could serve as an efficient Cu2+ chelator with satisfactory metal selectivity and further modulate the enzymic activity of free Cu2+ and the Aβ42-Cu2+ complex to alleviate the pathological oxidative stress with an anti-inflammatory effect. Besides, mSiO2@SiCDs show an inspiring inhibitory effect on Cu2+-mediated Aβ aggregation and further protect the neural cells against the toxic Aβ42-Cu2+ complex. Moreover, the transgenic Caenorhabditis elegans CL2120 assay demonstrates the protective efficacy of mSiO2@SiCDs on Cu2+-mediated Aβ toxicity in vivo, indicating its potential for AD treatment.

Magnetic covalent organic framework for the adsorption of silver nanoparticles and recycled as surface-enhanced Raman substrate and high-efficiency catalysts for 4-nitrophenol degradation

A magnetic covalent organic framework Fe₃O₄@BM was prepared with melamine and 4-4'-biphenyldialdehyde as monomers and used as adsorbent for Ag NP removal. Fe₃O₄@BM was characterized by zeta potential analysis, transform infrared spectrometry, X-ray diffraction, thermogravimetric analysis, contact angle, and N₂ adsorption-desorption. Fe₃O₄@BM possessed plentiful amino groups, positive potential, and rapid separation performance, making it a promising adsorbent for silver nanoparticles. The adsorption process followed the pseudo-second-order kinetic equation and Langmuir isotherm model. The maximum adsorption capacity of Ag NPs calculated by the Langmuir isotherm model was 544.9 mg/g. The adsorption product Fe₃O₄@BM@Ag could be recycled and efficiently catalyze the degradation of 4-nitrophenol within 6 min. Meanwhile, the recycled Fe₃O₄@BM@Ag could also be used as a surface-enhanced Raman substrate for DTNB detection, and the limit of detection of DTNB reached as low as 10^-7 mol/L. This work prepared a promising adsorbent Fe₃O₄@BM for Ag NP adsorption and provided a sustainable approach for the recycling of the adsorption product Fe₃O₄@BM@Ag.

Fe3O4-Mg(OH)2 nanocomposite as a scavenger for silver nanoparticles: Rational design, facile synthesis, and enhanced performance

Silver nanoparticles (AgNPs) are considered as emerging contaminants because of their high toxicity and increasing environmental impact. Removal of discharged AgNPs from water is crucial for mitigating the health and environmental risks. However, developing facile, economical, and environment-friendly approaches remains challenging. Herein, an Fe₃O₄-Mg(OH)₂ nanocomposite, as a novel magnetic scavenger for AgNPs, was prepared by loading Fe₃O₄ nanoparticles on Mg(OH)₂ nanoplates in a one-pot synthesis. Batch removal experiments revealed that the maximum removal capacities for the two model AgNPs (citrate- or polyvinylpyrrolidone-coated AgNPs) were 476 and 442 mg/g, respectively, corresponding to partition coefficients 8.03 and 4.89 mg/g/μM. Removal feasibilities over a wide pH range of 5-11 and in real water matrices and scavenger reusability with five cycles were also confirmed. Both Fe₃O₄ and Mg(OH)₂ components contributed to the removal; however, their nanocomposites exhibited an enhanced performance because of the high specific surface area and pore volume. Chemical adsorption and electrostatic attraction between the coatings on the AgNPs and the two components in the nanocomposite was considered to be responsible for the removal. Overall, the facile synthesis, convenient magnetic separation, and high removal performance highlight the great potential of the Fe₃O₄-Mg(OH)₂ nanocomposite for practical applications.

Green synthesis of phloroglucinol-urotropine porous polymer: Ingenious miniaturized solid phase extraction for efficient purification and determination of polycyclic aromatic hydrocarbons in lotus roots

Polycyclic aromatic hydrocarbons (PAHs) posed a serious threat to food safety and human health due to long-term emission. In this work, a new method was established using phloroglucinol-urotropine porous polymer (PU-PP) in a pipette tip for solid phase extraction (PT-SPE) for the first time and used prior to determination of four PAHs (phenanthrene, anthracene, fluoranthene, and pyrene) in lotus roots. Synthesis of the PU-PP adsorbent was green compared with alternatives; urotropine was used as a cross-linker and ethanol-water as the solvent. PU-PP-based PT-SPE had the advantages of low solvent consumption, good purification, practicability, stability, and low-cost. The proposed pre-purification method offered low limits of detection (0.09-0.28 ng/g) and good recoveries (84.6-114.3 %, RSDs ≤ 5.6 %) for determination of the four PAHs, which were detected at trace concentrations in samples. This new method provides an alternative for monitoring trace pollutants in aquatic plant ingredients.

Recent developments in the removal of metal-based engineered nanoparticles from the aquatic environments by adsorption

Nowadays, metal-based engineered nanoparticles (m-ENPs) are ubiquitous in aquatic environments for their wide applications in all walks of life. m-ENPs have been demonstrated to exert ecotoxicity, cytotoxicity and genotoxicity towards organisms and even humans. Therefore, the removal of m-ENPs from water has recently become a hot global concerned issue. Adsorption is widely investigated for this purpose, owing to its advantages of low cost, easy operation, high removal efficiency and potential recycling use of both the adsorbents and adsorbates. As the adsorption and related technologies were hardly comprehensively overviewed for the removal of m-ENPs, herein, the present review particularly focuses on this topic. The fundamentals to the technology, including adsorption isotherm, adsorption dynamics, the adsorption process with the special emphasis on the relationship between surface area and porosity of the adsorbent and the adsorption capacity, etc., are fully discussed. As the kernel of the adsorption method, adsorbents with diversified chemical and physical properties in different types are comprehensively elaborated. The primary factors affecting the adsorption, and adsorption mechanisms are well summarized. Particularly, the regeneration of the adsorbents and the reuse of adsorbed m-ENPs are highlighted for the sustainability. Finally, challenges and prospects in this field are outlined. Overall, this review aims to provide valuable references for the development of new adsorbents with more efficient and practical applications to remove m-ENPs and direct the future study.

Adsorption behavior of silver quantum dots by a novel super magnetic CoFe2O4-biochar-polymeric nanocomposite

Recent industrial development and research progress in nanotechnology have led to the release of a number of nanomaterials with particle sizes (1-10 nm) which are categorized as quantum dots (QDs) in aquatic system. Disposal away of such QDs will cause potential pollution to the environment. Therefore, removal of disposed QDs from wastewater represents a challenging research subject for scientists and engineers. Hence, the objective of this study is devoted to assess the process of coagulative removal of silver quantum dots (Ag-QDs), as an example, from water by a novel super magnetic nanocomposite. Such material was aimed to prepare from the chemical combination and reaction of a generated Citrus sinensis and Citrus reticulata peels biochar (SMCsr-B) with spinel cobalt ferrite (CoFe₂O₄) as a super-magnetic source. The produced (SMCsr-B) was then crosslinked with polyurea-formaldehyde polymer (PUF) using EDA in only two minutes via microwave irradiation to produce (SMCsr-B/PUF). The SEM, EDX, FT-IR, XRD, and XPS analyses of the assembled (SMCsr-B/PUF) nanocomposite were acquired to confirm surface morphology and chemical structure. Controlling experimental factors were investigated as pH, time, and Ag-QDs pollutant concentration using microwave irradiative removal technique to establish the efficiency of coagulative adsorption of Ag-QDs onto (SMCsr-B/PUF). The solution (pH 5) was proved to exhibit the higher removal percentages of Ag-QDs in 15-25 s. SMCsr-B/PUF nanocomposite exhibited high removal efficiency as 93.12%, 92.39% and 92.48% upon using 20, 40 and 60 mg L^-1 of Ag-QDs, respectively in presence of 10 mM NaCl. The kinetic and equilibrium adsorption data were best fitted to Freundlich model. The prepared SMCsr-B/PUF was successfully utilized as an efficient super magnetic nanocomposite for removal and recovery of Ag-QDs from aqueous environment.

Villi-like poly(acrylic acid) based hydrogel adsorbent with fast and highly efficient methylene blue removing ability

Organic dye-containing wastewater has become an increasingly serious environmental problem due to the rapid development of the printing and dyeing industry. Hydrogel is a promising adsorbent for organic dyes because of its unique three-dimension network structure and versatile functional groups. Though many efforts have been made in hydrogel adsorbents recently, there is still a critical challenge to fabricate hydrogel adsorbent with high adsorption capacity and high efficiency at the same time. To address this concern, we developed a calcium hydroxide nano-spherulites/poly(acrylic acid -[2-(Methacryloxy)ethyl]trimethyl ammonium chloride) hydrogel adsorbent with novel villi-like structure. The hydrogels were prepared through a simple free radical copolymerization method using calcium hydroxide nano-spherulites as crosslinker. The resultant hydrogel adsorbents showed a maximum adsorption capacity of 2249 mg/g in a 400 mg/L methylene blue solution and a high removal ratio of 98% in 1 h for a 50 mg/L methylene blue solution. In addition, the adsorption behaviors of our hydrogel adsorbents could be well described by pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Furthermore, this kind of hydrogel adsorbent showed selective adsorption behavior for methylene blue. Altogether, the hydrogel adsorbent developed in this work has a high capacity and high efficiency in organic dye removing and promised a great potential in wastewater treatment application.

Synthesis of V-notched half-open polymer microspheres via facile solvent-tuned self-assembly

Polymer microspheres with a special V-notched half-open architecture were synthesized in a mixed solvent of water/ethanol (1 : 1 v/v) at room temperature.