A new amine based microextraction of lead (II) in real water samples using flame atomic absorption spectrometry

Synthesis of fenugreek gum-based metal-organic framework (FG/Zr-AIPA MOF) composite beads for sequestration of heavy metal ions from aqueous solution

Metal-organic frameworks (MOFs) are a prominent class of materials due to their large surface area and customized structures. This gives them specificity and high adsorption capacity while they lack mechanical strength and reusability. Integrating MOFs with polysaccharide matrix may retain MOF characteristics along with imparting structural integrity. In the present study, zirconium MOF-based fenugreek composite (FG/Zr-AIPA) beads were synthesised by a single droplet method and utilised for removal of Cr(VI), Pb(II) and Fe(III) from aqueous solution. The structure, morphology and composition of beads were evaluated by FTIR, XRD, TGA, BET, FESEM, EDX, XPS and zeta potential analysis. Adsorption isotherm, kinetics and thermodynamics were studied for Cr(VI), Pb(II) and Fe(III) adsorption. Adsorption kinetics and isotherm study revealed that all the metal ions were adsorbed through a monolayer chemisorption process. The maximum adsorption capacity was 344.43, 270.02 and 223.21 mg g-1 for Cr(VI), Pb(II) and Fe(III), respectively, based on the Langmuir isotherm study. The thermodynamics study revealed that the interaction between the metal ions and the composite beads was spontaneous and endothermic. The FG/Zr-AIPA composite beads exhibited good reusability for the removal of Cr(VI), Pb(II) and Fe(III). The results open new possibilities for the preparation of polysaccharide MOF-based composite beads which exhibit substantial potential for water treatment applications.

Introduction of a new and safe synthesis procedure for Ni-MOF-I in aqueous solution and its application for the extraction of some pesticides from different beverages

For the first time, this research introduces an analytical application of Ni-MOF-I, which was used as an adsorbent in a dispersive micro solid phase extraction procedure followed by dispersive liquid-liquid microextraction for the extraction and preconcentration of seven pesticides from different fruit juices. Also, Ni-MOF-I was synthesized by a new and green method with many advantages over the previously published synthesis procedures. For example, effortless and green synthesis, no need for autoclaves and ovens, and elimination of organic solvent usage are the main highlights. The synthesized Ni-MOF-I was characterized by applying nitrogen adsorption/desorption, energy-dispersive X-ray, scanning electron microscopy, Fourier transform infrared spectrophotometry, and X-ray diffraction analyses. The studied pesticides were extracted and preconcentrated by the proposed method. Then, the extracted analytes in the sedimented organic phase were injected into a gas chromatography-flame ionization detector. Acceptable analytical results such as low limits of detection (0.15-0.60 μg L-1) and quantification (0.50-2.0 μg L-1), reasonable extraction recoveries (51-80%), high enrichment factors (255-400), satisfactory relative standard deviation values of 4.8-7.2% (intra-day precision, n = 6) and 5.3-7.5% (inter-day precision, n = 4), and wide linear ranges were obtained. The proposed method can be introduced as an effective analytical technique based on Ni-MOF-I for the analysis of different pesticides in fruit beverages.

Application of Recently used Green Solvents in Sample Preparation Techniques: A Comprehensive Review of Existing Trends, Challenges, and Future Opportunities

Green solvents (GSs) has gained significant attention in recent years due to their potential as safer and more sustainable alternatives to traditional organic solvents. Solvents are used in a wide range of applications, from industrial processes to everyday products. Solvent emissions and losses can have a significant impact on the environment and human health, which is why many initiatives are being undertaken to get rid of or switch to eco-friendly alternatives. A key area of green chemistry that led to the concept of "green" solvents is the development of alternative solvents that are less toxic and more environmentally friendly than traditional organic solvents. The advantages of using green solvents over conventional ones are their environmental friendliness, biocompatibility, biodegradability, and simplicity of preparation. Different sample preparation techniques have successfully utilized green solvents to offer a sustainable separation media for the extraction of a variety of inorganic and organic compounds which are crucial for research in environmental samples. Recent developments in green analytical chemistry (GAC) have focused on how to prepare and use samples using environmentally sustainable solvents. The current study covers the advance and currently used green solvents with an emphasis on environmentally friendly sample preparation methods. This review aims to briefly summarize the current state of knowledge about the use of green solvents particularly ionic liquids, deep eutectic solvents and switchable solvents (SSs) with the perspective of GAC in sample preparation methods.

An eco-friendly and sensitive deep eutectic solvent-based liquid-phase microextraction procedure for extraction preconcentration of Pb (II) ions

In recent years, interest in green solvents, which are environmentally friendly, easy to prepare and biodegradable, and in their applications in chemistry has considerably increased. In the current study, a new and easy deep eutectic solvent-based liquid-phase microextraction method compatible with green chemistry principles was developed for preconcentration of Pb (II) ions. The amount of Pb (II) ions was determined with graphite furnace atomic absorption spectrometry (GFAAS). Various analytical parameters such as deep eutectic solvent (DES) ratio and amount, ligand amount, pH, sample volume were optimized and the effects of potential matrix ions on the method were investigated. The preconcentration factor of the method was found to be 160, while the limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.071 µg L^-1 and 0.236 µg L^-1, respectively. The developed procedure was performed to determine Pb (II) ions in lake and river waters, and the accuracy of the procedure was determined with certified reference wastewater (SPS-WW1) analysis.

Facile Strategy for Fabricating an Organosilica-Modified Fe3O4 (OS/Fe3O4) Hetero-nanocore and OS/Fe3O4@SiO2 Core-Shell Structure for Wastewater Treatment with Promising Recyclable Efficiency

The development of a sustainable process for heavy metal ion remediation has become a point of interest in various fields of research, including wastewater treatment, industrial development, and health and environmental safety. In the present study, a promising sustainable adsorbent was fabricated through continuous controlled adsorption/desorption processes for heavy metal uptake. The fabrication strategy is based on a simple modification of Fe₃O₄ magnetic nanoparticles with organosilica in a one-pot solvothermal process, carried out in order to insert the organosilica moieties into the Fe₃O₄ nanocore during their formation. The developed organosilica-modified Fe₃O₄ hetero-nanocores had hydrophilic citrate moieties, together with hydrophobic organosilica ones, on their surfaces, which facilitated the further surface coating procedures. To prevent the formed nanoparticles from leaching into the acidic medium, a dense silica layer was coated on the fabricated organosilica/Fe₃O₄ (OS/Fe₃O₄). In addition, the prepared OS/Fe₃O₄@SiO₂ was utilized for the adsorption of cobalt(II), lead(II), and manganese(II) from the solutions. The data for the adsorption processes of cobalt(II), lead(II), and manganese(II) on OS/(Fe₃O₄)@SiO₂ were found to follow the pseudo-second-order kinetic model, indicating the fast uptake of heavy metals. The Freundlich isotherm was found to be more suitable for describing the uptake of heavy metals by OS/Fe₃O₄@SiO₂ nanoparticles. The negative values of the ΔG° showed a spontaneous adsorption process of a physical nature. The super-regeneration and recycling capacities of the OS/Fe₃O₄@SiO₂ were achieved, comparing the results to those of previous adsorbents, with a recyclable efficiency of 91% up to the seventh cycle, which is promising for environmental sustainability.

Metal Organic Framework-Based Dispersive Solid-Phase Microextraction of Carbaryl from Food and Water Prior to Detection by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

In this work, metal organic frameworks (A100 Al-based MOFs) were used in dispersive solid-phase microextraction (DSPME) for the isolation and preconcentration of the carbaryl from vegetable, fruit and water samples. The A100 Al-based MOFs showed excellent behavior for the adsorption of carbaryl from a water–ethanol solution; additionally, carbaryl was easily desorbed with ethyl acetate for detection by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-TMS). The analytical process of DSPME together with UPLC-TMS provides the accurate monitoring of trace carbaryl residues. The results show that the optimal recovery% of carbaryl was obtained at a sample apparent pH of 5, with the application of 1 mL of ethyl acetate to elute the carbaryl from the A100 Al-based MOFs. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.01 mg.L−1 and 0.03 mg.L−1, respectively. The RSD% was 0.8–1.9, and the preconcentration factor was 45. DSPME and UPLC-TMS were successfully used for the isolation and detection of carbaryl in food and water samples.

Magnetic Dispersive Solid Phase Extraction Using Recycled-graphite for GO-Fe3O4-dithizone Composite Combined with FAAS for Determination of Lead in Environmental Samples

Magnetic dispersive solid phase extraction (MdSPE) was developed to determine the concentration of lead (Pb) in real water samples, while graphene oxide-magnetite-dithizone (GO-Fe₃O₄-DTZ) from the used graphite tubes (recycled graphite) of electrothermal technique was simply employed as a new sorbent to improve extraction efficiency, separated by external magnetic field and analyzed with FAAS. The synthesized sorbent was evaluated for its surface property, functional group and surface morphology by Zeta potential, Fourier transform infrared spectrophotometer (FTIR), and scanning electron microscope (SEM), respectively. The relevant measurement parameters, such as pH, extraction time, type and concentration of eluent, sample volume and reusability, were optimized. Under the optimal conditions, preconcentration factor was 13.33. The limit of detection (LOD) and limit of quantitation (LOQ) obtained were 0.070 and 0.23 mg/L, respectively. The relative standard deviation (%RSD) was 3.41%. Recovery values were 90.1 - 123%. In addition, the robustness of the method was affirmed in terms of tolerance limit obtained from interference studies.

Green and efficient removal of heavy metals from Porphyra haitanensis using natural deep eutectic solvents

BACKGROUND

Porphyra haitanensis now faces serious heavy metal pollution problems. Natural deep eutectic solvents (NADESs) have been recognized as a novel class of sustainable solvents, which can be used for heavy metal removal. In this study, 28 kinds of NADESs were prepared and investigated as eluent in the removal of lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and copper (Cu) from P. haitanensis for the first time, and the adsorption mechanism of NADESs was also studied.

RESULTS

The removals were greatly improved by NADESs compared with control where the removal rates of Pb, Cd, Cr, As and Cu were 17.4-87.54%, 57.54-100%, 9.8-48.59%, 21.32-78.24% and 11.68-79.73%, respectively. The optimal condition was 10% water content and solid-liquid ratio of 1:20. Moreover, the addition of 20% natural surfactant arabic gum can further increase the heavy metals removal rates of NADESs. The adsorption mechanism experiments showed that the pseudo second-order model and the Freundlich adsorption model can better explain the adsorption mechanism of NADESs on heavy metals removal.

CONCLUSION

Taken together, a green and efficient method for removing heavy metals from P. haitanensis was established. © 2020 Society of Chemical Industry.

An environmentally friendly and novel amine-based liquid phase microextraction of quercetin in food samples prior to its determination by UV-vis spectrophotometry

A novel and environmentally-friendly method, which includes determination of trace amounts of quercetin in samples by using UV-vis spectrophotometry after enrichment with amine-based liquid phase microextraction (LPME), has been developed. As extraction solvent, N,N-dimethyl-n-octylamine has been used and the quercetin concentration in extraction phase was determined by UV-vis spectrophotometry at 382.5 nm. Important analytical parameters such as pH, extraction solvent type and volume, sample volume, extraction time were optimized by the method. Quercetin in the sample solution was extracted to 200 μL of N,N-dimethyl-n-octylamine phase at pH 4.0. The detection limit (LOD) and the quantitation limit (LOQ) values for quercetin were calculated as 0.07 μg·mL^-1 and 0.24 μg·mL^-1, respectively. Accuracy studies for the food samples was carried out by addition and recovery experiments. The developed method has been successfully applied to different food samples including spinach, green pepper, red onion and dill weed.

Applying Al2O3@Ag@trithiocyanuric acid as an efficient metal ion scavenger for the selective extraction of iron (III) and lead (II) from environmental waters

In the present study, silver (Ag) atoms were chemically deposited on γ-alumina (Al₂O₃) nanospheres to be further functionalized with trithiocyanuric acid (TTC). The result was Al₂O₃@Ag@TTC composites, which were used for the selective extraction and preconcentration of Fe (III) and Pb (II) ions in seawater and river water samples. TTC is a potent scavenger of heavy metal ions with multiple nitrogen- and sulfur-containing functional groups. The concentrations of analytes were determined by flame atomic absorption spectrometry, and the structure of the synthetic adsorbent was characterized by spectral and microscopic techniques. Furthermore, the fundamental parameters influencing the extraction and desorption of the target ions were evaluated. Under optimized conditions, the calibration curve was linear in the range of 10-100 ng mL^-1 for both analytes. The detection limits of the proposed method for Fe (III) and Pb (II) ions were 1.5 ng mL^-1 and 0.8 ng mL^-1, respectively, with a relative standard deviation of less than 6.1% (n = 7). Moreover, the proposed method tolerated salinities of up to 50.0 g L^-1 without exhibiting any decrease in selectivity or recovery. The developed method was successfully applied to extract Fe (III) and Pb (II) ions from seawater and river water samples. The extraction recovery rates of the spiked ions were at least 93% for Fe (III) and 97 % for Pb (II).

A magnetic ion-imprinted polymer composed of silica-coated magnetic nanoparticles and polymerized 4-vinyl pyridine and 2,6-diaminopyridine for selective extraction and determination of lead ions

A novel, sensitive and highly selective magnetic ion-imprinted polymer for facile separation and preconcentration of trace quantities of Pb(ii) ions.