Preconcentration and speciation of arsenic by using a graphene oxide nanoconstruct functionalized with a hyperbranched polyethyleneimine

A new pre-concentration procedure based on poly(styrene-co-maleamide and imide) copolymers modified with 2-hydrazinobenzothiazole prior to spectrophotometric monitoring of inorganic as (as As(III)) in edible vegetable oils

This study describes the development of 2-hydrazinobenzothiazole modified-amide/imide co-polymers for the extraction/pre-concentration of trace As(III), from edible vegetable oils. Their characterization was realized by help of instrumental techniques. The method is based on pH-dependent complexation between As(III) and co-polymeric chelators in presence of 35-fold excess As(V), their selective extraction into the mixed micellar phase, and detected at pH 2.0 and 6.0 by UV-vis spectrophotometer. The variables affecting extraction efficiency were optimized. From pre-concentration of 20-mL sample, the good linear relationships were obtained in range of 1-40 and 3-75 µg/L with DLs of 0.32 and 1.00 µg/L. The accuracy was verified by analysis of a certified sample without and with spiking. The method was applied into the analysis of iAs levels of samples. The results show that the functional co-polymers are efficient chelators, and exhibit great potential for the selective extraction of As(III) from edible vegetable oils.

Blocking chemical warfare agent simulants by graphene oxide/polymer multilayer membrane based on hydrogen bonding and size sieving effect

Chemical warfare agents (CWAs) are toxic materials that cause death by contact with the skin or by respiration. Although studies on detoxification of CWAs have been intensively conducted, studies that block CWAs permeation are rare. In this study, for blocking CWAs, a multilayer thin film composed of linear polyethylenimine (LPEI) and graphene oxide (GO) is simply prepared through a spray-assisted Layer-by-Layer (LbL) assembly process. LPEI could change its morphology dependent on pH, which is known as a representative hydrogen donor and acceptor. By controlling the shape of the polymer chain, a heterogenous film could have a loose or dense inner structure. CWAs mainly move through diffusion and have hydrogen bonding sites. Therefore, the heterogeneous film can limit CWAs movement based on controlling pathways and hydrogen bonds within the film. The protective effect of this membrane is investigated using dimethyl methylphosphonate (DMMP), a nerve gas simulant. DMMP vapor transmittance rate (DVTR) and N₂ permeance of LPEI/GO are 67.91 g/m² day and 34,293.04 GPU. It means that the protection efficiency is 72.65%. Although this membrane has a thin thickness (100 nm), it shows a high protective effect with good breathability. And water/DMMP selectivity of the membrane is 66.63. Since this multilayer membrane shows efficient protection performance with a simple preparation method, it has a high potential for applications such as protective suits and masks.

Activated carbon fiber modified with hyperbranched polyethylenimine and phytic acid for the effective adsorption and separation of In(iii)

The PA–HPEI–OACF constructed with PA, HPEI, and ACF displays excellent performance in the adsorption and separation of In(iii).

Semiautomatic method for the ultra-trace arsenic speciation in environmental and biological samples via magnetic solid phase extraction prior to HPLC-ICP-MS determination

A novel magnetic functionalized material based on graphene oxide and magnetic nanoparticles (MGO) was used to develop a magnetic solid phase extraction method (MSPE) to enrich both, inorganic and organic arsenic species in environmental waters and biological samples. An automatic flow injection (FI) system was used to preconcentrate the arsenic species simultaneously, while the ultra-trace separation and determination of arsenobetaine (AsBet), cacodylate, As^III and As^V species were achieved by high performance liquid chromatography combined with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The sample was introduced in the FI system where the MSPE was performed, then 1 mL of eluent was collected in a chromatographic vial, which was introduced in the autosampler of HPLC-ICP-MS. Therefore, preconcentration and separation/determination processes were automatic and conducted separately. To the best of our knowledge, this is the first method combining an automatic MSPE with HPLC-ICP-MS for arsenic speciation, using a magnetic nanomaterial based on MGO for automatic MSPE. Under the optimized conditions, the LODs for the arsenic species were 3.8 ng L^-1 AsBet, 0.5 ng L^-1 cacodylate, 1.1 ng L^-1 As^III and 0.2 ng L^-1 As^V with RSDs <5%. The developed method was validated by analyzing Certified Reference Materials for total As concentration (fortified lake water TMDA 64.3 and seawater CASS-6 NRC) and also by recovery analysis of the arsenic species in urine, well-water and seawater samples collected in Málaga. The developed method has shown promise for routine monitoring of arsenic species in environmental waters and biological fluids.

A new method for highly efficient separation and determination of arsenic species in natural water using silica modified with polyamines

A simple and highly efficient method for the determination of highly toxic arsenic species using non-covalently aminated silica is proposed. The polyamines including poly(hexamethyleneguanidine), poly(4,9-dioxadodecane-1,12-guanidine), hexadimethrine, and poly(diallyldimethylammonium) were tested as silica modifiers. The prepared adsorbents allow effective preconcentration of anionic species of arsenic from aqueous solutions. It was found that As(V) can be quantitatively extracted from solutions at pH 4.5-7.0 by the anion exchange mechanism in less than 5 min, while neutral at this pH As(III) was not adsorbed at these conditions. A reaction with 2,3-dimercapto-1-propanesulphonic acid, which resulted in the formation of the negatively charged complex of As(III) with adsorbents was used for its quantitative extraction from solutions with a pH of 3.5-6.5. A system of two cartridges filled with poly(diallyldimethylammonium) modified silica and the on-line reaction of As(III) with 2,3-dimercapto-1-propanesulphonic acid proceeding between the cartridges was used for separate preconcentration and determination of As(V) and As(III) at pH 5. The proposed method was used for four-year monitoring of natural water pollution by arsenic in the area of residence of the indigenous peoples of Tyva Republic (Russia).

The amino - functionalized magnetic graphene oxide combined with graphite furnace atomic absorption spectrometry for determination of trace inorganic arsenic species in water samples

A novel adsorbent of magnetic graphene oxide (GO) chemically modified by cysteamine hydrochloride (Fe₃O₄@SiO₂/GO-NH₂) through thiol-ene click chemistry reaction was synthesized. The prepared Fe₃O₄@SiO₂/GO-NH₂ exhibit selective adsorption to As(V) with high adsorption capacity (52.66 mg g^-1). Taking Fe₃O₄@SiO₂/GO-NH₂ as the adsorbents, a new method of magnetic solid phase extraction (MSPE) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed in determining trace-level inorganic arsenic species (As(III) and As(V)) in environmental water and bottled water samples. Various experimental parameters affecting the MSPE have been optimized. Under the optimal experimental parameters, the limit of detection of the established method for As(V) was 1.02 ng L^-1, the relative standard deviations were 7.9% (intra-day, c = 50 ng L^-1, n = 5) and 4.6% (inter-day, c = 50 ng L^-1, n = 7), respectively, and the enrichment factor of the method was 392. GBW08666 and GBW08667 (certified reference material) were analyzed to confirm the accuracy of the method, and the results were matched well with the certified values. The established MSPE-GFAAS method was successfully applied in analyzing trace/ultratrace As(III) and As(V) in real water samples.

Layer by layer assembled functionalized graphene oxide-based polymer brushes for superlubricity on steel-steel tribocontact

This study demonstrates a simple and multistep approach for a covalent functionalization of chemically-prepared graphene oxide (GO) using branched polyethylenimine (PEI) through nucleophilic addition reaction to prepare GO-PEI. Further layer-by-layer (LBL) assembly on functionalized GO-PEI with anionic polyelectrolyte, poly(acrylic acid sodium salt) (PAA) and poly(sodium 4-styrenesulfonate) (PSS) have been undertaken to fabricate polymer brushes (PB). The physicochemical structures of GO, GO-PEI and LBL assembled PB [GO-PEI-PAA and GO-PEI-PSS] have been explored using standard spectral and morphological analysis. The macrotribological results demonstrated that GO-PEI-PAA/GO-PEI-PSS (0.5 wt%) as paraffin oil dispersible additives significantly decreased the coefficient of friction (COF) and wear at different contact pressures of steel-steel tribopairs. The influence of contact pressure and load-bearing ability of the polymer-grafted GO as nanolubricants have been examined carefully. The COF of PB particles provided a reduction of 85% (low pressure, ∼0.9 MPa) and 66.65% (high pressure, ∼1.35 GPa) compared to lube paraffin oil and exhibited a lower specific wear rate (2.26 × 10-8 mm3 N-1 m-1) at macrotribological pin/ball-on-disc trials, revealing superior lubricity. The PB containing nanolubricants also exhibited high load-bearing ability (till ∼1000 N load, Pm ∼6.1 GPa) with considerably lower COF and wear, which were investigated using a four-ball tribotester. Among the functionalized polymeric GO particles, PSS polyelectrolyte containing GO-PEI-PSS showed better COF and wear reduction ability with extremely high load-bearing capacity due to the strong interfacial adhesion properties of PSS to generate strong protective synergetic lubricating tribofilm into the rubbing interfaces, which is comprehensively investigated by post-tribological analysis.

Recent Advances of Graphene-Based Strategies for Arsenic Remediation

The decontamination of water containing toxic metals is a challenging problem, and in the last years many efforts have been undertaken to discover efficient, cost-effective, robust, and handy technology for the decontamination of downstream water without endangering human health. According to the World Health Organization (WHO), 180 million people in the world have been exposed to toxic levels of arsenic from potable water. To date, a variety of techniques has been developed to maintain the arsenic concentration in potable water below the limit recommended by WHO (10 μg/L). Recently, a series of technological advancements in water remediation has been obtained from the rapid development of nanotechnology-based strategies that provide a remarkable control over nanoparticle design, allowing the tailoring of their properties toward specific applications. Among the plethora of nanomaterials and nanostructures proposed in the remediation field, graphene-based materials (G), due to their unique physico-chemical properties, surface area, size, shape, ionic mobility, and mechanical flexibility, are proposed for the development of reliable tools for water decontamination treatments. Moreover, an emerging class of 3D carbon materials characterized by the intrinsic properties of G together with new interesting physicochemical properties, such as high porosity, low density, unique electrochemical performance, has been recently proposed for water decontamination. The main design criteria used to develop remediation nanotechnology-based strategies have been reviewed, and special attention has been reserved for the advances of magnetic G and for nanostructures employed in the fabrication of membrane filtration.

Dopamine-modified magnetic graphene oxide as a recoverable sorbent for the preconcentration of metal ions by an effervescence-assisted dispersive micro solid-phase extraction procedure

Nanomagnetic graphene oxide modified with dopamine (GO-Fe3O4-DA) was synthesized via a very simple procedure. Using GO-Fe3O4-DA as the new adsorbent, the effervescence-assisted dispersive micro solid-phase extraction procedure was exploited for the preconcentrative extraction of Cu(ii), Pb(ii) and Ni(ii) ions. Structural characteristics of the adsorbent were studied via FT-IR, FE-SEM, EDX and XRD analyses. The rapid dispersion and high adsorption capability of GO-Fe3O4-DA, along with the rapid separation of the adsorbent from the aqueous phase by a magnet, led to a decrease in the extraction time of the target metal ions. In effect, high extraction percentages were attained in a very short time period. In this work, the relative standard deviations (RSD; n = 3) calculated for the proposed method were 1.09, 1.25 and 1.03% for the Pb(ii), Cu(ii) and Ni(ii) ions, respectively, the calibration curve was dynamically linear in the range of 0.25 to 50 μg L-1, and the limits of detection were obtained as 0.5, 0.1, and 0.7 μg L-1. The procedure was also implemented on real sausage (herbal and meaty) samples and a water sample, vouchsafing the success of the proposed method in tackling real samples with a complicated matrix.

A Schiff base modified graphene oxide film for anodic stripping voltammetric determination of arsenite

A protocol is described for chemical modification of graphene oxide with a Schiff base derived from diethylenetriamine and 2-hydroxy-4-methoxybenzophenone. The base was grafted onto an indium tin oxide (ITO) film and applied to electroanalytical determination of arsenite. Successful grafting was confirmed by Fourier transform-infrared spectroscopy, spectrophotometry, field emission scanning electron microscopy and cyclic voltammetry. Secondly, the coated ITO film served as a working electrode for the stripping voltammetric determination of arsenite. The analytical signal is generated by selective oxidation of metal species via multi-donor sites present in the derivatized Schiff base. The electroanalytical protocol was optimized by investigating the effects of deposition time, working potential, frequency and amplitude of square wave anodic stripping voltammetry. The method has attractive features including (a) the usage of a non-metallic, non-toxic and cost-effective material; (b) improved sensitivity (with limit of detection as low as 156 pM) due to better adsorption of arsenite in the Schiff base pockets on the ITO, and (c) the application to the determination of arsenite in real samples. Graphical abstract Schematic representation of the fabrication of a Schiff base-functionalized graphene oxide on an indium tin oxide (SB@SiO2@GO@ITO) electrode for selective electrochemical sensing of arsenite due to adsorption on multi-donor sites.

Applications of three-dimensional graphenes for preconcentration, extraction, and sorption of chemical species: a review

This review (with 115 refs) summarizes applications of 3-dimensional graphene (3DGs) and its derivatives in the fields of preconcentration, extraction, and sorption. Following an introduction into the field (including a definition of the materials treated here), the properties and synthetic strategies for 3DGs are described. The next section covers applications of 3DG-based adsorbents in solid phase extraction of organic species including drugs, phthalate esters, chlorophenols, aflatoxins, insecticides, and pesticides. Another section treats applications of 3DGs in solid phase microextraction of species such as polycyclic aromatic hydrocarbons, alcohols, and pesticides. We also describe how the efficiency of assays may be improved by using these materials as a sorbent. A final section covers conclusions and perspectives. Graphical abstract Graphical abstract contains poor quality and small text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.Tiff file of graphical abstract was attached. Schematic presentation of synthesis of three-dimensional graphene (3DG) from two-dimensional graphene (2DG) with self-assembly, template-assisted and direct deposition methods. Application of 3DG-based nanoadsorbents in direct immersion-solid phase microextraction (DI-SPME), headspace-SPME (HS-SPME), magnetic-solid phase extraction (Magnetic-SPE), dispersive-SPE, and magnetic sheet-SPE.

Efficacy of engineered GO Amberlite XAD-16 picolylamine sorbent for the trace determination of Pb (II) and Cu (II) in fishes by solid phase extraction column coupled with inductively coupled plasma optical emission spectrometry

Graphene oxide (GO) was immobilized innovatively through azo spacer arm onto the surface of polymeric Amberlite XAD-16 resin in order to expose all oxygen functionalities freely available for metal ions coordination and further modification with picolylamine which governs selectivity. The GO Amberlite XAD-16 picolylamine enables the development of SPE column coupled with ICP-OES for preconcentration and determination of Pb (II) and Cu (II) in water and fish samples. Elution was performed by mild acid (2M HCl) no other carcinogenic organic solvent was used, prevents ligand leaching. Under optimized conditions, the preconcentration factors of 150 and detection limits 1.434 and 0.048 µg L⁻¹ for Pb (II) and Cu (II)  were obtained respectively.