Graphene oxide dispersed with ferrite nano - particles as magnetic solid phase extraction adsorbent for chlorpyrifos and diazinon

Magnetic graphene oxide, Fe3O4-GO has been synthesized through oxidation of graphite via modified Hummer’s method followed by a one step co-precipitation method. Fe3O4-GO was used in the extraction of two organophosphorus pesticides (OPPs), namely chlorpyrifos and diazinon using magnetic solid phase extraction (MSPE) technique. The GO and Fe3O4-GO synthesised was characterized using Fourier transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FESEM). Optimum conditions obtained from the optimization process were as follows: 80 mL sample volume, 50 mg of adsorbent, 10 min extraction time followed by desorption process using 500 µL of acetonitrile. Under the optimum conditions, Fe3O4-GO MSPE method showed excellent linearity in the range of 0.1-10 µg L-1 with coefficient of determination (R2) of 0.9997 for both OPPs. Precision studies found that the repeatability of this Fe3O4-GO MSPE method (RSD, n = 3) were 9.95% and 9.05% for chlorpyrifos and diazinon respectively. Meanwhile the reproducibility (RSD, n = 9) observed was 11.45% for chlorpyrifos and 13.35% for diazinon. The limit of detection (LOD = 3 S/N) for chlorpyrifos was 0.034 µg L-1 and 0.40 µg L-1 for diazinon. Lake water sample was spiked with 0.5 µg L-1 of each of the OPPs after confirming the non-detection in the sample using gas chromatography-electron capture detector (GC-ECD). Percentage recoveries of the two OPPs from lake water samples were found to be 57.71% for chlorpyrifos and 73.86% for diazinon. The Fe3O4-GO MSPE method was found to be susceptible to matrix effect from the lake water sample analysed. The Fe3O4-GO MSPE method was also applied to the determination of the two OPPs from tomato sample using matrix-matched calibration curve in the range of 1-50 µg L-1. Good coefficient of determination (R2) value of 0.9963 and 0.9897 for chlorpyrifos and diazinon respectively was observed. Both OPPs were found to be present in the tomato sample analysed (0.19 µg L-1 of chlorpyrifos and 7.88 µg L-1 of diazinon

Ferrite-calcium alginate as magnetic solid phase extraction adsorbent of copper(II) ions in water prior to flame atomic absorption spectroscopy

A magnetic solid phase extraction (MSPE) procedure using ferrite-calcium alginate (Fe3O4-CaAlg) as adsorbent for Cu(II) ions prior to flame atomic absorption spectroscopy (FAAS) was developed. The extraction of Cu(II) ions using Fe3O4-CaAlg MSPE is simpler and faster than the conventional method such as solid phase extraction and traditional method such as liquid-liquid extraction. The simple extraction is based on the use of magnetisable adsorbent to extract Cu(II) ions, which can be readily isolated from water samples as a matrix with an external magnet. The adsorbent was prepared by mixing sodium alginate solution with Fe3O4 magnetic particles and calcium chloride solution to form magnetic alginate beads. Important parameters influencing the extraction and desorption process including type and volume of desorption solvent, agitation time, extraction time, weight of adsorbent and ample volume were optimized. Under the optimized conditions, calibration graph (external standard method) with coefficient of determination (R2) of 0.974 in the linearity range 20-100 µg/L was observed. Good limit of detection (1.70 µg/L), and limit of quantification (5.6 µg/L) was obtained. Acceptable repeatability (n = 3) with RSDs 2.37% while reproducibility (n = 9) with RSD 5.15% were obtained for Cu(II) ions using the developed MSPE method. Finally, the proposed method was successfully applied for the determination of Cu(II) ion in tap water sample with relative recovery of 78.9% and 4.72% RSD. However, the proposed method was found to be less suitable for the determination of Cu(II) ion in river water sample with lower relative recovery (45.7% , 1.76% RSD) indicating that the method is sensitive to the matrix

Use of pristine papaya peel to remove Pb(II) from aqueous solution

In this study, Carica papaya agro-waste (papaya peel) was employed for Pb(II) uptake from single-solute solutions. The papaya peel-derived (PP) adsorbent namely as raw-PP was employed in sets of batch experiments to evaluate its Pb(II) uptake capacity. To assess the surface characteristics of the adsorbents, the scanning electron microscope (SEM) coupled with energy disperse X-ray (EDX), and Fourier transform infrared spectroscopy (FT-IR) analysis were utilized. The removal amount of Pb(II) using the adsorbent was determined by atomic adsorption spectrometry (AAS). The effects of pH, contact time, initial concentration of Pb(II) and adsorbent dosage were investigated throughout batch processes. The pH value=3 for the Pb(II) adsorption process using the raw-PP was observed as optimum solution pH. The optimum initial concentration of Pb(II) in the solution for raw-PP adsorbent found to be 100 mg/L where the amount of Pb(II) removed was 33.82 mg/g. At the agitating time of 90 min, the adsorption processes using the developed adsorbent reached equilibrium utilizing dosages of 50 mg of raw-PP as an adsorbents. The experimental results obtained using the raw-PP exhibits the high capability and metal affinity of papaya peel waste with removal efficiency percentage of > 85 %. The evaluation results show that the equilibrium adsorption of Pb(II) was best expressed by Freundlich isotherm model (R2 > 0.99). The experimental results confirmed that raw-PP potentially can be employed as low cost adsorbent for Pb(II) uptake from aqueous solutions. The study suggests that future chemical modification of PP may offer increasing of its metal removal capacity

Maturity impact on physicochemical composition and polyphenol properties of extra virgin olive oils obtained from Manzanilla, Arbequina, and Koroneiki varieties in Iran

Abstract This study investigated the physicochemical properties and polyphenol composition of extra virgin olive oils (EVOOs) extracted from three olive cultivars. The investigated cultivars were Arbequina, Koroneiki, and Manzanilla, grown in Olive Research Station in Rudbar county, Gilan province, Iran, at three ripening stages. Several parameters were analyzed, including peroxide and acidity values, unsaponifiable matter, oxidative stability, total aliphatic alcohols, fatty acids (FAs), sterols, and triacylglycerol composition. The results showed that as maturity increased, parameters such as oil content, acidity value, and iodine value, rise, while parameters including peroxide value, oxidative stability, aliphatic alcohols, and unsaponifiable matter decreased (p  .05). The MUFA/PUFA ratio and total sterol content declined during the olive ripening stages (p < .05). The triterpenes decreased in Arbequina and Koroneiki cultivars but increased in Manzanilla cultivar during the maturity stages. According to the data, oleuropein decreased while oleuropein aglycone, oxidized aldehyde, and hydroxylic form of oleuropein increased for all EVOOs during maturation. Apigenin, quercetin, ligstroside aglycone, aldehyde and hydroxylic form, ferulic acid, caffeic acid, and catechin decreased during the ripening of fruits (p < .05). The main triglycerides were triolein (OOO), palmitodiolein (POO), dioleolinolein (OOL), and palmitooleolinolein (PLO) in all EVOOs. In addition, the olive cultivar and harvesting date influence the physicochemical properties and polyphenol composition of EVOOs extracted from olive varieties grown in one region. In conclusion, the results can present helpful information to determine the optimum maturity stage for the investigated olive cultivars

Development of magnetic graphene oxide adsorbent for the removal and preconcentration of As(III) and As(V) species from environmental water samples

New-generation adsorbent, Fe3O4@SiO2/GO, was developed by modification of graphene oxide (GO) with silica-coated (SiO2) magnetic nanoparticles (Fe3O4). The synthesized adsorbent was characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. The developed adsorbent was used for the removal and simultaneous preconcentration of As(III) and As(V) from environmental waters prior to ICP-MS analysis. Fe3O4@SiO2/GO provided high adsorption capacities, i.e., 7.51 and 11.46 mg g−1 for As(III) and As(V), respectively, at pH 4.0. Adsorption isotherm, kinetic, and thermodynamic were investigated for As(III) and As(V) adsorption. Preconcentration of As(III) and As(V) were studied using magnetic solid-phase extraction (MSPE) method at pH 9.0 as the adsorbent showed selective adsorption for As(III) only in pH range 7–10. MSPE using Fe3O4@SiO2/GO was developed with good linearities (0.05–2.0 ng mL−1) and high coefficient of determination (R2 = 0.9992 and 0.9985) for As(III) and As(V), respectively. The limits of detection (LODs) (3× SD/m, n = 3) obtained were 7.9 pg mL−1 for As(III) and 28.0 pg mL−1 for As(V). The LOD obtained is 357–1265× lower than the WHO maximum permissible limit of 10.0 ng mL−1. The developed MSPE method showed good relative recoveries (72.55–109.71 %) and good RSDs (0.1–4.3 %, n = 3) for spring water, lake, river, and tap water samples. The new-generation adsorbent can be used for the removal and simultaneous preconcentration of As(III) and As(V) from water samples successfully. The adsorbent removal for As(III) is better than As(V)

New magnetic graphene-based inorganic-organic sol-gel hybrid nanocomposite for simultaneous analysis of polar and non-polar organophosphorus pesticides from water samples using solid-phase extraction

A new graphene-based tetraethoxysilane-methyltrimethoxysilane sol-gel hybrid magnetic nanocomposite (Fe3O4@G-TEOS-MTMOS) was synthesised, characterized and successfully applied in magnetic solid-phase extraction (MSPE) for simultaneous analysis of polar and non-polar organophosphorus pesticides from several water samples. The Fe3O4@G-TEOS-MTMOS nanocomposite was characterized using Fourier transform-infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy and X-ray diffraction. Separation, determination and quantification were achieved using gas chromatography coupled with micro electron capture detector. Adsorption capacity of the sorbent was calculated using Langmuir equation. MSPE was linear in the range 100–1000 pg mL−1 for phosphamidon and dimethoate, and 10–100 pg mL−1 for chlorpyrifos and diazinon, with limit of detection (S/N = 3) of 19.8, 23.7, 1.4 and 2.9 pg mL−1 for phosphamidon, dimethoate, diazinon and chlorpyrifos, respectively. The LODs obtained is well below the maximum residual level (100 pg mL−1) as set by European Union for pesticides in drinking water. Acceptable precision (%RSD) was achieved for intra-day (1.3–8.7%, n = 3) and inter-day (7.6–17.8%, n = 15) analyses. Fe3O4@G-TEOS-MTMOS showed high adsorption capacity (54.4–76.3 mg g−1) for the selected OPPs. No pesticide residues were detected in the water samples analysed. Excellent extraction recoveries (83–105%) were obtained for the spiked OPPs from tap, river, lake and sea water samples. The newly synthesised Fe3O4@G-TEOS-MTMOS showed high potential as adsorbent for OPPs analysis

Headspace Extraction of Chlorobenzenes from Water Using Electrospun Nanofibers Fabricated with Calix[4]arene-Doped Polyurethane–Polysulfone

Chlorobenzenes (CBs) are persistent and potentially have a carcinogenic effect on mammals. Thus, the determination of CBs is essential for human health. Hence, in this study, novel polyurethane–polysulfone/calix[4]arene (PU-PSU/calix[4]arene) nanofibers were synthesized using an electrospinning approach over in-situ coating on a stainless-steel wire. The nanosorbent was comprehensively characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) techniques. The SEM analysis depicted the nanofiber’s unique morphology and size distribution in the range of 50–200 nm. To determine the levels of 1,2,4-trichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,3,4-tetrachlorobenzene in water samples, freshly prepared nanosorbent was employed using headspace-solid phase microextraction (HS-SPME) in combination with gas chromatography micro electron capture detector (GC-µECD). Other calixarenes, such as sulfonated calix[4]arene, p-tert-calixarene, and calix[6]arene were also examined, and among the fabricated sorbents, the PU–PSU/calix[4]arene showed the highest efficiency. The key variables of the procedure, including ionic strength, extraction temperature, extraction duration, and desorption conditions were examined. Under optimal conditions, the LOD (0.1–1.0 pg mL−1), the LDR (0.4–1000 pg mL−1), and the R2 > 0.990 were determined. Additionally, the repeatability from fiber to fiber and the intra-day and inter-day reproducibility were determined to be 1.4–6.0, 4.7–10.1, and 0.9–9.7%, respectively. The nanofiber adsorption capacity was found to be 670–720 pg/g for CBs at an initial concentration of 400 pg mL−1. A satisfactory recovery of 80–106% was attained when the suggested method’s application for detecting chlorobenzenes (CBs) in tap water, river water, sewage water, and industrial water was assessed

Equilibrium and kinetic study of novel methyltrimethoxysilane magnetic titanium dioxide nanocomposite for methylene blue adsorption from aqueous media

Novel magnetic titanium dioxide nanoparticles decorated with methyltrimethoxysilane (Fe3O4@TiO2-MTMOS) were successfully fabricated via a sol–gel method at room temperature. The synthesized material was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis and vibrating sample magnetometry. The removal efficiency of the adsorbent was evaluated through the adsorption of methylene blue (MB) dye from water samples. The adsorption isotherm and kinetics were evaluated using various models. The Langmuir model indicated a high adsorption capacity (11.5 mg g−1) of Fe3O4@TiO2-MTMOS. The nanocomposite exhibited high removal efficiency (96%) and good regeneration (10 times) compared to Fe3O4 and Fe3O4@TiO2 at pH = 9.0. Based on the adsorption mechanism, electrostatic interaction plays a main role in adsorption since MB dye is cationic in nature at pH = 9, whereas the adsorbent acquired an anionic nature. The newly synthesized Fe3O4@TiO2-MTMOS can be used as a promising material for efficient removal of MB dye from aqueous media

Magnetic solid-phase extraction based on modified ferum oxides for enrichment, preconcentration, and isolation of pesticides and selected pollutants

Recently, a simple, rapid, high-efficiency, selective, and sensitive method for isolation, preconcentration, and enrichment of analytes has been developed. This new method of sample handling is based on ferum oxides as magnetic nanoparticles (MNPs) and has been used for magnetic solid-phase extraction (MSPE) of various analytes from various matrices. This review focuses on the applications of modified ferum oxides, especially modified Fe3O4 MNPs, as MSPE adsorbent for pesticide isolation from various matrices. Further perspectives on MSPE based on modified Fe3O4 for inorganic metal ions, organic compounds, and biological species from water samples are also presented. Ferum(III) oxide MNPs (Fe2O3) are also highlighted