Solid phase extraction of heavy metal ions based on a novel functionalized magnetic multi-walled carbon nanotube composite with the aid of experimental design methodology

The application progress of magnetic solid-phase extraction for heavy metal analysis in food: a mini review

The emerging sample pretreatment technique of magnetic solid-phase extraction (MSPE) has drawn the attention of researchers owing to its advantages of less reagent consumption, fast separation/enrichment process, high adsorption capacity, and simple operation. This paper presents a review of synthesis techniques, classification, and analysis procedures for MSPE in the detection of heavy metals in food. Magnetic adsorbents derived from silica, metal oxides, carbon, polymers, etc., are applied for the detection of heavy metals in food. Then, the recent development of the technology of MSPE for the analysis of heavy metal extraction in food is summarized in detail. Finally, the future outlook for the improvement of MSPE is also discussed.

A review on adsorption of heavy metals from wastewater using carbon nanotube and graphene-based nanomaterials

The rampant rise in world population, industrialization, and urbanization expedite the contamination of water sources. The presence of the non-biodegradable character of heavy metals in waterways badly affects the ecological balance. In this modern era, the unavailability of getting clear water as well as the downturn in water quality is a major concern. Therefore, the effective removal of heavy metals has become much more important than before. In recent years, the attention to better wastewater remediation was directed towards adsorption techniques with novel adsorbents such as carbon nanomaterials. This review paper primarily emphasizes the fundamental concepts, structures, and unique surface properties of novel adsorbents, the harmful effects of various heavy metals, and the adsorption mechanism. This review will give an insight into the current status of research in the realm of sustainable wastewater treatment, applications of carbon nanomaterials, different types of functionalized carbon nanotubes, graphene, graphene oxide, and their adsorption capacity. The importance of MD simulations and density functional theory (DFT) in the elimination of heavy metals from aqueous media is also discussed. In addition to that, the effect of factors on heavy metal adsorption such as electric field and pressure is addressed.

Simultaneous determination of 13 paralytic shellfish toxins and tetrodotoxin in marine shellfish by porous graphitic carbon solid-phase extraction and hydrophilic interaction chromatography-tandem mass spectrometry

The lethal neurotoxins, paralytic shellfish toxins (PSTs), and tetrodotoxin (TTX) have recently been found in marine shellfish from many coastal states. Herein, we applied a sensitive and reliable ultra-performance hydrophilic interaction chromatography (HILIC)-tandem mass spectrometry (MS) method to determine 13 PSTs and TTX in marine shellfish using a porous carbon solid-phase extraction (SPE). This in-house validation study required the development of a novel chromatographic separation using a HILIC-Z column, which was necessary to retain highly polar compounds. Using acetonitrile as the organic phase and ammonium formate-formic acid buffer as the aqueous phase, the quantitative analysis was carried out with an external standard method in the multiple reaction monitoring modes using positive electrospray ionization. To reduce interference, 1% aqueous acetic acid extracts of the shellfish samples were cleaned up by ion-pair SPE using a porous graphitic carbon cartridge. The calibration curves for PSTs and TTX were linear (R² > 0.995), and the sensitivity was good, with limits of detection (LODs) of 1.7-13.7 µg/kg, and limits of quantitation (LOQs) of 5.2-41.0 µg/kg. The recoveries were 76.5-95.5% with RSDs of 3.1-12.0%. Finally, We applied the method for the determination of PSTs and TTX in three batches of Nassarius showing excellent method accuracy against expected values.

Advances in preparation, mechanism and applications of various carbon materials in environmental applications: A review

Carbon-related materials are now widely investigated in a various industrial field due to their excellent and unique qualities. It must be tailored to the application in such a way that it fits the application. At the same time, it needs to be generated in sufficient quantities for commercial use, and the synthesis method is the major sticking point here. Because most new materials are discovered by chance, the synthesis process described here may not be the most effective way to create them. The research is merely a steppingstone to discovering a different approach, and it will continue until the substance is no longer being used. If you're developing materials for any purpose, synthesis processes are essential. Fullerene, carbon nanotubes (CNT), graphene, and MXene are only a few of the carbon-based compounds discussed in this overview study, which also gives a brief prognosis on the materials future. Furthermore, the environmental application of these carbon materials was discussed and commented.

Extraction and preconcentration of Ni(ii), Pb(ii), and Cd(ii) ions using a nanocomposite of the type Fe3O4@SiO2@polypyrrole-polyaniline

In this study, the application of Fe₃O₄@SiO₂@polypyrrole-polyaniline magnetic nanocomposite was studied for Ni(ii), Cd(ii), and Pb(ii) ions preconcentration extraction. In this regard, the silica layer prevents the Fe₃O₄ nanoparticles (NPs) from aggregating over a broad pH range value and simultaneously improves chemical stability and hydrophilicity. By using a Box-Behnken design, the effect of various parameters affecting the preconcentration was studied. FAAS was employed to quantify the eluted analytes. The detection limits are 0.09, 1.1, and 0.3 ng mL^-1 for Ni(ii), Cd(ii) and Pb(ii), ions, respectively. The relative standard deviations (RSDs%) were calculated for determining the method's precision, lower than 7.5%. The capacities of sorption are 75, 84, and 98 mg g^-1, respectively. With the usage of a certified reference material, the developed method was validated. After that, the validated method was employed to rapidly extract trace target ions from food samples and gave satisfactory results.

Heavy metal removal by biomass-derived carbon nanotubes as a greener environmental remediation: A comprehensive review

The concentrations of heavy metal ions found in waterways near industrial zones are often exceed the prescribed limits, posing a continued danger to the environment and public health. Therefore, greater attention has been devoted into finding the efficient solutions for adsorbing heavy metal ions. This review paper focuses on the synthesis of carbon nanotubes (CNTs) from biomass and their application in the removal of heavy metals from aqueous solutions. Techniques to produce CNTs, benefits of modification with various functional groups to enhance sorption uptake, effects of operating parameters, and adsorption mechanisms are reviewed. Adsorption occurs via physical adsorption, electrostatic interaction, surface complexation, and interaction between functional groups and heavy metal ions. Moreover, factors such as pH level, CNTs dosage, duration, temperature, ionic strength, and surface property of adsorbents have been identified as the common factors influencing the adsorption of heavy metals. The oxygenated functional groups initially present on the surface of the modified CNTs are responsible towards the adsorption enhancement of commonly-encountered heavy metals such as Pb²⁺, Cu²⁺, Cd²⁺, Co²⁺, Zn²⁺, Ni²⁺, Hg²⁺, and Cr⁶⁺. Despite the recent advances in the application of CNTs in environmental clean-up and pollution treatment have been demonstrated, major obstacles of CNTs such as high synthesis cost, the agglomeration in the post-treated solutions and the secondary pollution from chemicals in the surface modification, should be critically addressed in the future studies for successful large-scale applications of CNTs.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Sustainable technologies for water purification from heavy metals: review and analysis

We review and analyze current water purification technologies in the context of sustainability, and we introduce the Ranking Efficiency Product (REP) index, to evaluate their efficiency and implementation in this broader perspective.

Zwitterion-functionalized polymer microspheres as a sorbent for solid phase extraction of trace levels of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) prior to their determination by ICP-MS

This paper describes the preparation of zwitterion-functionalized polymer microspheres (ZPMs) and their application to simultaneous enrichment of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) from environmental water samples. The ZPMs were prepared by emulsion copolymerization of ethyl methacrylate, 2-diethylaminoethyl methacrylate and triethylene glycol dimethyl acrylate followed by modification with 1,3-propanesultone. The components were analyzed by elemental analyses as well as Fourier transform infrared spectroscopy, and the structures were characterized by scanning electron microscopy and transmission electron microscopy. The ZPMs were packed into a mini-column for on-line solid-phase extraction (SPE) of the above metal ions. Following extraction with 40 mM NH₄NO₃ and 0.5 M HNO₃ solution, the ions were quantified by ICP-MS. Under the optimized conditions, the enrichment factors (from a 40 mL sample) are up to 60 for the ions V(V), As(III), Sb(III) and Hg(II), and 55 for Cr(III) and Sn(IV). The detection limits are 1.2, 3.4, 1.0, 3.7, 2.1 and 1.6 ng L^-1 for V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II), respectively, and the relative standard deviations (RSDs) are below 5.2%. The feasibility and accuracy of the method were validated by successfully analyzing six certified reference materials as well as lake, well and river waters. Graphical abstract Zwitterion-functionalized polymer microspheres (ZPMs) were prepared and packed into a mini-column for on-line solid-phase extraction (SPE) via pump 1. Then V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) ions in environmental waters were eluted and submitted to ICP-MS via pump 2.

A novel aptamer-based online magnetic solid phase extraction method for the selective determination of 8-hydroxy-2'-deoxyguanosine in human urine

In this work, an innovative magnetic aptamer adsorbent (Fe₃O₄-aptamer MNPs) was synthesized for the selective extraction of 8-hydroxy-2'-deoxyguanosine (8-OHdG). Amino-functionalized-Fe₃O₄ was crosslinked with 8-OHdG aptamer by glutaraldehyde and fixed into a steel stainless tube as the sorbent of magnetic solid phase extraction (MSPE). After selective extraction by the aptamer adsorbent, the adsorbed 8-OHdG was desorbed dynamically and online analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS). The synthesized sorbent presented outstanding features, including specific selectivity, high enrichment capacity, stability and biocompatibility. Moreover, this proposed MSPE-HPLC-MS can achieve adsorption and desorption operation integration, greatly simplify the analysis process and reduce human errors. When compared with offline MSPE, a sensitivity enhancement of 800 times was obtained for the online method. Some experimental parameters such as the amount of the sorbent, sample flow rate and sample volume, were optimized systematically. Under the optimal conditions, low limit of detection (0.01 ng mL^-1, S/N = 3), limit of quantity (0.03 ng mL^-1, S/N = 10) and wide linear range with a satisfactory correlation coefficient (R² ≥ 0.9992) were obtained. And the recoveries of 8-OHdG in the urine samples varied from 82% to 116%. All these results revealed that the method is simple, rapid, selective, sensitive and automated, and it could be expected to become a potential approach for the selective determination of trace 8-OHdG in complex urinary samples.

Preconcentration and extraction of lead ions in vegetable and water samples by N-doped carbon quantum dot conjugated with Fe3O4 as a green and facial adsorbent

Magnetically N-doped Carbon quantum dots has been synthesized via a simple chemical method and applied as a sorbent for the preconcentration and extraction of trace amounts of Pb²⁺ from water and vegetable samples followed by flame atomic absorption spectrometric detection. The nanoparticles were characterized by X-ray diffraction, UV-vis spectra, Fourier transform infrared spectroscopy, vibrating sample magnetometer analysis and transmission electron microscopy. A central-composite design was used to find the optimum conditions for the preconcentration procedure through response surface methodology. The effects of various parameters such as the pH value, adsorption time, amount of adsorbent, desorption conditions (type, concentration and volume of the eluent and desorption time), sample volume and interfering ions have been studied. Under the optimized conditions, the calibration graph was linear in the range of 0.3-300μgL^-1 (R²=9992). The detection limit and pre-concentration factor were found to be 0.082μgL^-1 and 265, respectively.

Determination of Hg(II) ions in sea food samples after extraction and preconcentration by novel Fe3O 4@SiO 2@polythiophene magnetic nanocomposite

This work describes a novel Fe3O4@SiO2@polythiophene magnetic nanocomposite and its application in the preconcentration of Hg(II) ions. The parameters affecting the preconcentration procedure were opted by a Box-Behnken design through response surface methodology. Three factors (uptake time, magnetic nanosorbent amount, and pH of sample) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent as well as the elution time) were selected as main factors in the optimization study of the elution step. Following the sorption and elution of Hg(II), it was quantified by cold vapor atomic absorption spectrometry. Under the optimum condition, the limit of detection was 0.02 ng mL(-1) and all the relative standard deviations were less than 9.2 %. The obtained sorption capacity of this new sorbent was 59 mg g(-1). Finally, this nanocomposite was successfully applied to the rapid extraction of trace quantities of Hg(II) ions in sea food samples and satisfactory results were obtained.

Synthesis and application of a novel magnetic metal-organic framework nanocomposite for determination of Cd, Pb, and Zn in baby food samples

This work describes the synthesis and application of a novel magnetic metal-organic framework (MOF) [(Fe3O4-2,5-dimercapto-1,3,4-thiadiazole)/Cu3(benzene-1,3,5-tricarboxylate)2] to preconcentrate trace amounts of Cd(II), Pb(II), and Zn(II) ions. A Box–Behnken design was used to find the parameters affecting the preconcentration procedure through response surface methodology. Three variables including sorption time, amount of the magnetic sorbent, and sample pH were selected as affecting factors in the sorption step, and four parameters including type, volume, concentration of the eluent, and elution time were selected in the elution step for the optimization study. These values were 33 mg, 11 min, 5.7 EDTA, 4.3 mL, 0.64 mol L–l EDTA solution, 16 min, for amount of the magnetic sorbent, sorption time, sample pH, type, volume, and concentration of the eluent, and elution time, respectively. Following the sorption and elution steps, the ions were quantified by FAAS. The limits of detection were 0.10, 0.15, and 0.75 ng mL−1 for Cd(II), Zn(II), and Pb(II) ions, respectively. The relative standard deviations (RSD) of the method were less than 8.3% for five separate batch experiments in the determination of 25 μg L−1 of Cd(II), Zn(II), and Pb(II) ions. The sorption capacity of the magnetic MOF nanocomposite was 155 mg g−1 for Cd(II), 173 mg g−1 for Pb(II), and 190 mg g−1 for Zn(II). Finally, the magnetic MOF nanocomposite was successfully applied to rapidly extract trace amounts of heavy metal ions in baby food samples.

Solid phase extraction of heavy metal ions from agricultural samples with the aid of a novel functionalized magnetic metal–organic framework

This work describes synthesis of a novel magnetic metal–organic framework to preconcentrate the trace amounts of heavy metals. (a) Functionalized Fe₃O₄ by ethylenediamine. (b) Synthesis of the magnetic MOF nanocomposite.