Synthesis of a magnetic SBA-15-NH2@Dual-Template Imprinted Polymer for solid phase extraction and determination of Pb and Cd in vegetables; Box Behnken design

Application Prospect of Ion-Imprinted Polymers in Harmless Treatment of Heavy Metal Wastewater

With the rapid development of industry, the discharge of heavy metal-containing wastewater poses a significant threat to aquatic and terrestrial environments as well as human health. This paper provides a brief introduction to the basic principles of ion-imprinted polymer preparation and focuses on the interaction between template ions and functional monomers. We summarized the current research status on typical heavy metal ions, such as Cu(II), Ni(II), Cd(II), Hg(II), Pb(II), and Cr(VI), as well as metalloid metal ions of the As and Sb classes. Furthermore, it discusses recent advances in multi-ion-imprinted polymers. Finally, the paper addresses the challenges faced by ion-imprinted technology and explores its prospects for application.

A simple microwave-assisted synthesis of cobalt ferrite nanoparticles and its application for the determination of lead ions in rooibos (Aspalathus linearis) tea

In this study, a magnetic sorbent assisted dispersive solid phase extraction (DSPE) method was used to preconcentrate lead ions from rooibos tea samples for determination by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). Cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs) were synthesized by microwave assisted digestion. Limits of detection and quantification were calculated as 5.3 and 17.6 µg/L, respectively, in a linear dynamic range of 20-800 µg/L. The enhancement factor of the developed method was found to be 80-folds when compared to the detection limit of the regular FAAS system. The percent recoveries obtained for rooibos tea samples spiked at different concentrations were in the range of 77 - 125%, with high repeatability as indicated by low standard deviations. The findings of the study demonstrated that the CoFe2O4 MNPs-based extraction method is a straightforward, fast, affordable, safe, and eco-friendly approach to qualifying/quantifying lead with high precision in the selected beverage sample.

Hybrid Polymer-Silica Nanostructured Materials for Environmental Remediation

Due to the ever-growing global population, it is necessary to develop highly effective processes that minimize the impact of human activities and consumption on the environment. The levels of organic and inorganic contaminants have rapidly increased in recent years, posing a threat to ecosystems. Removing these toxic pollutants from the environment is a challenging task that requires physical, chemical, and biological methods. An effective solution involves the use of novel engineered materials, such as silica-based nanostructured materials, which exhibit a high removal capacity for various pollutants. The starting materials are also thermally and mechanically stable, allowing for easy design and development at the nanoscale through versatile functionalization procedures, enabling their effective use in pollutant capture. However, improvements concerning mechanical properties or applicability for repeated cycles may be required to refine their structural features. This review focuses on hybrid/composite polymer-silica nanostructured materials. The state of the art in nanomaterial synthesis, different techniques of functionalization, and polymer grafting are described. Furthermore, it explores the application of polymer-modified nanostructured materials for the capture of heavy metals, dyes, hydrocarbons and petroleum derivatives, drugs, and other organic compounds. The paper concludes by offering recommendations for future research aimed at advancing the application of polymer-silica nanostructured materials in the efficiency of pollutant uptake.

Cr(VI) anion-imprinted polymer synthesized on mesoporous silicon via synergistic action of bifunctional monomers for precise identification and separation of Cr(VI) from aqueous solution by fixed-bed adsorption

The novel Cr(VI) anion-imprinted polymer (Cr(VI)-IIP) was prepared by a surface imprinting technique with bifunctional monomers pre-assembly system based on mesoporous silicon (SBA-15). The synthesized Cr(VI)-IIP was characterized by Fourier transmission infrared spectra (FT-IR), energy dispersive spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffractometer, N₂ adsorption-desorption and thermogravimetric analysis (TGA), proving to be with a highly ordered mesoporous structure, as well as favorable thermal stability. The saturated adsorption amount was 96.32 mg/g, which was 2.7 times higher than that of non-imprinted polymer (NIP). Kinetic experiments showed that the adsorption equilibrium state was obtained within 70 min. In addition, in the selectivity experiments, Cr(VI)-IIP exhibited strong specific recognition ability for Cr(VI) and could realize the separation of Cr(VI) and Cr(III) from an aqueous solution. The dynamic adsorption experiments exhibited that the dynamic adsorption efficiency of Cr(VI)-IIP was as high as 71.57%. Meanwhile, the dynamic regeneration experiments showed that the adsorption amount of Cr(VI)-IIP did not decrease significantly after repeating for five times. All of the findings suggested that Cr(VI)-IIP could achieve precise identification as well as efficient separation of Cr(VI) from aqueous solution.

Design of experiments (DoE) to develop and to optimize extraction of psychoactive substances

The design of experiments (DoE) method was employed to optimize the adsorption processes of seven psychoactive substances in magnetic solid phase extraction. Fe₃O₄/GO/ZIF-8 was utilized as an adsorbent for the efficient extraction of psychoactive substances from environmental water samples. The analytes were ephedrine, methylephedrine, amphetamine, methamphetamine, morphine, papaverine, and thebaine, which were determined by ultrahigh performance liquid chromatography-tandem mass spectrometry. Plackett-Burman design was employed to identify the significant factors responsible for adsorption, and Box-Behnken design was used for further optimization to obtain the optimum values for each variable. The predicted and experimental values were found to be in good agreement. The coefficient of determination (R²) values of 0.9500-0.9976 indicated that the model was significant. The linear ranges were 1-100 ng mL^-1, and the correlation coefficient was good (r² ≥ 0.995). The EF with values of about 2.5 was obtained with recoveries in the range of 74.92-94.47%. The limits of detection (LOD) and limits of quantification (LOQ) were 0.086-0.353 ng mL^-1 and 0.286-1.175 ng mL^-1, respectively. The intra-day and inter-day RSDs were in the range of 0.17-1.87% and 0.06-2.21%, respectively. By using the DoE method, the errors associated with inferring the influence and interaction between various factors can be reduced. The combination of MSPE and DoE improves the recovery, precision, and simultaneous detectability of the target analytes. It has a high potential for psychoactive substance analysis in environmental water.

Insights into brewed tea waste as a green and low-priced adsorbent for solid-phase extraction of Cd(II) ions: isotherm, kinetic, and artificial neural network approach

In the present research, brewed tea waste (BTW) was utilized as a green, low-priced, and abundant adsorbent for separation/preconcentration of Cd(II) ions through solid-phase extraction method from water and foods for the first time. BTW was applied as a natural adsorbent, without using any chelating agent to bind Cd(II) ions or any chemical reagent for its modification. A three-layer artificial neural network model using backpropagation algorithm was utilized to explicate a prediction model for the extraction performance of Cd(II) ions by selecting the input parameters as solution pH, quantity of BTW, sample volume, eluent concentration and volume, and equilibrium time for desorption. The preconcentration factor, relative standard deviation, and detection limit were attained as 100, 3.03%, and 0.56 µg L−1, respectively. It was decided that the Langmuir isotherm model is acceptable to characterize the retention of Cd(II) ions on BTW. This result pointed out that the active binding sites on the BTW surface are homogeneously distributed. Adsorption capacity of BTW was achieved as 41.5 mg g−1 which is higher than several expensive and difficult-to-prepare adsorbents. Adsorption kinetics was elucidated by pseudo-second order kinetic model. After confirmed the accuracy of the method with spike/recovery studies, it was employed for Cd(II) determination in water (stream and sea water) and food (eggplant, lettuce, parsley, apple, and apricot) samples with high accuracy. The inferences of the study proved that the BTW offers a magnificent application prospect in the extraction of Cd(II) ions.