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The sorption of Pb(II) onto polyacrylamidezirconium(IV) iodate,a hybrid inorganic–organic material, has been studied throughthe batch equilibrium technique. The experimental equilibrium datahave been analyzed using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevichisotherm models. The accuracy of the fit of isotherm models to theexperimental equilibrium data was assessed using error analysis.TheTemkin model yields the best fit between experimental and simulateddata. The kinetic data obtained at different concentrations have beenanalyzed using pseudo-first-order, pseudo-second-order, and intraparticlediffusion models. The experimental data obey the pseudo-second-orderkinetic model. The plot of qtversus t1/2suggests that intraparticle diffusion isnot the sole rate-controlling step; some degree of boundary layerdiffusion is also involved. The calculated thermodynamic parametersΔG°, ΔH°,and ΔS° indicate that the adsorption ofPb(II) onto the sorbent is a spontaneous, endothermic, and physicalsorption process. [ABSTRACT FROM AUTHOR]

The authors describe a method for solvent-free mechano-chemical synthesis of a bioinspired sorbent. A 2D ultra-thin carbon sheet similar to graphene oxide was prepared using a natural waste (onion sheet). The formation of 2D carbon sheets was confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy and ATR-IR. The surface morphology was characterized by field emission scanning electron microscopy and high-resolution tunneling electron microscopy. The carbon sheets were decorated with crystalline MnFe2O4 nanoparticles by solid-state reaction at room temperature. The presence of magnetic particles in the final product was confirmed by vibrating sample magnetometry and electron microscopy. The synergistic effect of carbon sheets and MnFe2O4 led to an enhanced sorption of arsenic species compared to bare carbon sheets or to MnFe2O4 nanoparticles. A column was prepared for the simultaneous preconcentration and determination of trace levels of As(III) and As(V) from water samples. The preconcentration factors are between 900 and 833 for As(III) and As(V) species, respectively. The linearity of the calibration plot ranges from 0.4–10 ng mL−1. The detection limits (at 3σ) for both As(III) and As(V) are 30 pg mL−1. The Student's t values for the analysis of spiked samples are lower than the critical Student's t values at a 95% confidence level. The recoveries from spiked water samples range between 99 and 102.8%. [ABSTRACT FROM AUTHOR]

Porous materials play a crucial role in the extraction of trace analytes; yet, the attainment of high selectivity and efficient regeneration continues to pose a considerable problem. In this study, we employed a green method to synthesize porous carbon microspheres. These microspheres were subsequently functionalized with aminophosphonic acid to facilitate the extraction of heavy metal ions from real samples. A comprehensive analysis of the aminomethylphosphorylated carbon microspheres was conducted using FTIR, SEM, EDX, TEM, BET and water contact angle measuring techniques. The potential optimization of analyte enrichment can be accomplished by the proposed solid-phase extraction (SPE) approach, which notably reduces spectrum interferences following sample purification. Following the IUPAC equation, the detection limit of the proposed method was found to be 0.04 ng mL -1 , after running 20 replicate blank tests. The primary focus of sequestration of trace metal ions is the formation of metal-ligand chelates within the carbon spheres, resulting in enhanced selectivity and extraction rates exceeding 99.9% from samples with low concentrations. The present studies show a significant preconcentration limit of 0.4 ng mL -1 and a substantial preconcentration factor of 500. The method was implemented to examine real food and water samples, and the obtained data exhibit significant accuracy with a relative standard deviation (RSD) of less than 5%., Competing Interests: The authors declare that they have no known competing financial interests., (This journal is © The Royal Society of Chemistry.)

In this study, we successfully synthesized polymeric graphitic carbon nitride (g-C 3 N 4 ) nanosheets through thermal means and proposed their application in solid-phase extraction (SPE) for the enrichment of trace Hg(ii). The nanosheets underwent characterization using scanning electron microscopy, tunnelling electron microscopy, and energy-dispersive X-ray spectroscopy. The column packed with polymeric carbon nitride nanosheets demonstrated effective extraction of trace Hg(ii) ions from complex samples. The g-C 3 N 4 nanosheets possess a zeta potential value of -20 mV, enabling strong interaction with positively charged divalent Hg(ii) ions. This interaction leads to the formation of stable chelates with the nitrogen atoms present in the polytriazine and heptazine units of the material. The proposed method exhibited a high preconcentration limit of 0.33 μg L -1 , making it suitable for analysing trace amounts of Hg(ii) ions. Moreover, the method's applicability was confirmed through successful analysis of real samples, achieving an impressive preconcentration factor of 200. The detection limit for trace Hg(ii) ions was determined to be 0.6 μg L -1 . To assess the accuracy of the method, we evaluated its performance by recovering spiked amounts of Hg(ii) and by analysing certified reference materials. The results indicated excellent precision, with RSD consistently below 5% for all the analyses conducted. In conclusion, the thermally synthesized polymeric carbon nitride nanosheets present a promising approach for solid-phase extraction and preconcentration of trace Hg(ii) from real samples. The method showcases high efficiency, sensitivity, and accuracy, making it a valuable tool for environmental and analytical applications., Competing Interests: There is no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Graphitic carbon nitride nanosheets were synthesized onto cellulose nanofiber surfaces utilizing an eco-friendly salt melt approach. The fabricated material CNF@C 3 N 4 selectively removes Ni(II) and Cu(II) from electroplating wastewater samples. The immobilization of g-C 3 N 4 on solid substrates eases handling of nanomaterial in a flow-through approach and mitigates sorbent loss during column operations. Characterization techniques such as scanning electron microscopy, tunneling electron microscopy, and X-ray photoelectron microscopy were employed to analyze the surface morphology and chemical bonding within the synthesized material. Selective Cu(II) and Ni(II) sorption predominantly arises from the soft-soft interaction between metal ions and associated nitrogen groups. An inner-sphere surface complexation mechanism effectively elucidated the interaction dynamics between the metal and CNF@C 3 N 4 . Experimental findings demonstrated satisfactory separation of Ni(II) and Cu(II) ions, with the extraction of 340.0 and 385.0 mg g -1 of material, respectively. Additionally, the devised technique was executed for the preconcentration and quantification of trace metals ions in water samples with a detection limit and limit of quantification of 0.06 and 0.20 μg L -1 , respectively., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)