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The use of carboxylated graphene oxide (CGO) in the removal of organic pollutants from aquatic life is a recent and significant issue. In this study, EDTA-functionalized magnetite-carboxylated grap...

Folic acid (VB9) was used as an eco-friendly sequestering chemical compound to modify and develop a novel nanocomposite via surface immobilization and chemical bonding with nanosilica (Nano-SiO2) in the chloride form to generate Nano-SiO2@VB9. The synthesized materials were investigated and characterized by several means of SEM, HR-TEM, TGA, FT-IR, XRD and surface area determination. The tendency of Nano-SiO2@VB9 nanocomposite to extract and remove bivalent lead, cadmium and copper ions was studied and optimized under various variables including pH of contact medium, nanocomposite dose, contact time, effect of metal ion concentration and interfering cations-anions. The highest determined capacity values were 562.1, 973.8 and 152.1 mg g−1 for Cd(II), Pb(ІІ) and Cu(II), respectively. The optimum contact time for sorption of metal ions was identified as 25 min, while 10.0 mg of Nano-SiO2@VB9 nanocomposite was the optimum dosage to establish the maximum capacity values. The adsorbed ions were arranged in a multilayer surface and the equilibrium up-take of metal ions by Nano-SiO2@VB9 nanocomposite was favorably characterized by the Freundlich adsorption isotherm model. The potential applications of Nano-SiO2@VB9 for removal and preconcentration of Cu(II), Pb(II) and Cd(II) from real water samples using multistage microcolumn were also studied to confirm excellent percentage extraction values 94–100%, 100% and 57–81%, respectively.

A novel magnetic nanocomposite based on magnetite nanoparticles-functionalized-graphene oxide and hexadecyltrimethyl ammonium bromide has been synthesized (MAGO-CTAB) by a facile route for efficient, fast and sensitive binding with Sunset Yellow (SY). The MAGO-CTAB (27 ± 3 nm) has been successfully characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetization techniques. The influences of different experimental parameters on the % SY removal efficiency were fully investigated. The adsorption rates of SY by MAGO-CTAB were conducted by fitting the experimental data to four kinetic models. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D–R) adsorption isotherms were applied to study SY removal. The adsorption-desorption stability performance of the novel magnetic nanosorbent was evaluated and confirmed after 5 cycles. The designed MAGO-CTAB was successfully utilized for removal of SY from different food and soft drink samples with excellent recoveries values (98–103%).

Lauryl sulfate is utilized to functionalize magnetic graphene oxide (MGOLS) for fast removal of methylene blue (MB) using batch sorption experiments. The effects of different analytical parameters including medium pH, equilibration time, MGOLS dosage, initial MB concentration and temperature on the % MB removal are investigated. Among different isotherm and kinetic models, the experimental data were best fitted to the Langmuir and pseudo-second-order rate equations. The maximum Langmuir loading capacity reaches 624.42 mg g−1 for MGOLS under optimal conditions. Sorption kinetic of MGOLS is very fast: Approximately 96% of dye extraction was recorded within the first 2 minutes of this sorption process. The sorption mechanism is proposed and the feasibility, thermic and entropic characteristics were evaluated. Sorption and desorption performances of MGOLS are maintained almost constant over five cycles of sorption/desorption. The results concluded MGOLS as an efficient extractor for fast and feasible recovery of MB from aqueous matrices.

A chemical modification method is presented to establish a surface functionalization procedure of amino modified nanosilica (NS-amine) with 1-(3-cyanopropyl)-3-methylimidazolium-bis(trifluoromethylsulfonyl) type of ionic liquid, [CN-C3-MIm]+[NTf2]− for the formation of a novel NS-amine-IL nanocomposite. Based on the TEM analysis and DLS technique, the diameter of the proposed nanocomposite was found 25.4 ± 0.8 nm. The designed NS-amine-IL nanocomposite was additionally characterized using FT-IR, XRD, EDX, TGA, SEM and zeta potential. The sequestration performance of NS-amine-IL was investigated for remediation of bivalent lead and cadmium ions from aqueous solutions. The effects of medium acidity, contact time, NS-amine-IL dosage, interfering ions, temperature and initial adsorbates concentrations on the removal processes of investigated cations were excessively studied. The maximum extraction values of Pb(II) and Cd(II) were recorded at pH 4–5 and pH 7, respectively. The thermodynamic profiles of the adsorption process were searched at optimal conditions. The adsorption processes were feasibly endothermic and fitted well with the Langmuir isotherm and pseudo-second-order kinetics equation. The experimental data indicated that the novel nanocomposite was a promising material for the extraction of both metal ions from wastewater and soil samples with determined recoveries 98.0–99.0% ± 4.9.

In this manuscript, we have studied the removal of Cd(II) and Pb(II) ions from aqueous solution by using triethylenetetramine functionalized cellulose acetate grafted with the copolymer-manganese dioxide composite. The novel sorbent cellulose was extracted from the mangrove trees ( Avicennia marina ) and it was then acetylated and grafted with acrylamide. The sorbent composite was designed to interact simultaneously with higher metal loading by complexation-adsorption process. FT-IR, SEM, EDAX and TGA techniques were employed to characterize the cellulose modified composite. Sorption equilibria were established after 30 min and their data were described by Langmuir and Freundlich models. The functionalized hybrid cellulose composite showed maximum adsorption capacity 82.06 and 196.84 mg g −1 for Cd(II) and Pb(II), respectively. The studied metal ions were successfully recovered from real wastewater samples of different matrices.

In this study, the ease of magnetic separation was hybridized with the excellent hydrophilicity of both graphene oxide (GO) and dodecyl sulphate (DS) to synthesize a novel nanosorbent (Fe3O4@GO–DS; 10–25 nm) for simple, fast and efficient remediation of malachite green (MG) from aqueous media. The structure and morphology of Fe3O4@GO–DS were elucidated by FTIR, HRTEM, XRD and TGA techniques. Different analytical parameters including medium acidity, equilibration time, Fe3O4@GO–DS dose, initial MG concentration and temperature were optimized for maximum percentage MG removal efficiency. The experimental results indicated that Fe3O4@GO–DS had excellent sorption capacity (714.3 mg g−1 at pH 7.0 and 25 °C) which decreased from 98.75% to 95.60% after five sorption–desorption cycles. The adsorption isotherm data best-fitted to Langmuir model and the sorption reactions follow second order rate equations. Thermodynamic study is inspected and different mechanistic pathways are proposed for the sorption process.

Nanosilica (NSi) was functionalized by oxalic acid (NSi-Ox) and tartaric acid (NSi-Tar) using solvent-free microwave-assisted approach. The two surface-modified NSi sorbents were characterized by Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, and thermal gravimetric analysis. NSi-Ox and NSi-Tar sorbents were examined for the removal of Co(II) from aqueous solutions by the batch adsorption technique. Removal of Co(II) was carried out at different controlling parameters such as pH, contact time, sorbent mass, and interfering ions. The maximum Co(II) uptake values were identified as 733.3 and 1026.7 μmol g−1 for NSi-Ox and NSi-Tar, respectively, and these were higher than the identified value by NSi sorbent (440 μmol g−1). This trend is mainly due to the surface functionalization with several active groups. The adsorption isotherms were evaluated using Langmuir and Freundlich models and the results were better fitted to the Langmuir model (R2 = 0.983 and 0.989 for NSi-Ox and NSi-Tar, respectively). Kinetic studies were performed and the experimental data were found in good agreement with the pseudo-second-order model. The thermodynamic parameters were also determined. The potential applications of NSi sorbents for removal of Co(II) from drinking tap water and sea water samples were successfully achieved using microcolumn studies.

Chitosan, CS was chemically engineered by maleic anhydride via simple protocol to produce N-maleated chitosan, MCS which immobilized on anatase TiO2 to synthesize novel eco-friendly nanosorbent (51±3.8 nm), MCS@TiO2 for cost-effective and efficient removal of Pb(II) ions from aqueous media. The chemical structure, surface properties and morphology of MCS@TiO2 were recognized by FTIR, (1)H NMR, XRD, TEM, DLS and zeta-potential techniques. The relations between %removal of Pb(II) and different analytical parameters such as solution acidity (pH), MCS@TiO2 dosage, time of contact and initial Pb(II) concentration were optimized using response surface methodology (RSM) and Box-Behnken design (BBD) statistical procedures. The fitting of the experimental data to four different isotherm models at optimized conditions was carried out by various statistical treatments including the correlation coefficient (r), coefficient of determination (r(2)) and non-linear Chi-square (χ(2)) test analyses which all confirm the suitability of Langmuir model to explain the adsorption isotherm data. Also, statistics predicted that the pseudo-second-order model is the optimum kinetic model among four applied kinetic models to closely describe the rate equation of the adsorption process. Thermodynamics viewed the adsorption as endothermic and feasible physical process. EDTA could release the sorbed Pb(II) ions from MCS@TiO2 with a recovery above 92% after three sorption-desorption cycles. The novel synthesized nanosorbent is evidenced to be an excellent solid phase extractor for Pb(II) ions from wastewaters.

Food safety problems caused by tetracycline antibiotics residues are a significant concern due to their great risk to human health even at trace levels. In the current work, a highly sensitive and selective determination of similar chemical composition tetracycline (TC) and doxycycline (DC) antibiotics in milk samples was developed by offline solid phase extraction using β-cyclodextrin functionalized magnetic graphene oxide nanoparticles (β-CD-MGONPs) followed by differential pulse voltammetric determination with a β-cyclodextrin modified carbon paste (β-CD-MCP) sensor. β-CD-MGONPs was prepared, characterized by XRD, FTIR, TEM, and TGA and applied for the removal of TC/DC using batch adsorption experiments. The effects of medium acidity, equilibration time, adsorbent dose, initial antibiotic concentration, and ionic strength were extensively investigated using UV-Vis spectrophotometry at optimal adsorption conditions. The experimental data are well described by the Langmuir isotherm and pseudo-second-order kinetic model. The maximum adsorption capacity was found to be 666.7 mg g−1 for TC and 769.2 mg g−1 for DC. Furthermore, loss in the removal efficiency was 3.5–5.6% after three adsorption–desorption cycles. Then, the electrochemical response of the β-CD-MCP sensor following β-CD-MGONPs extraction was investigated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Under optimal electrochemical parameters, anodic differential pulse voltammetry (ADPV) at +320.0 mV and cathodic differential pulse voltammetry (CDPV) at −800.0 mV were selectively used to detect TC and DC, respectively. The response currents of the β-CD-MCP sensor exhibited a linear relationship towards TC/DC concentrations ranging from 0.5–90.0 ng L−1. The limit of detection (LOD) of TC or DC was calculated as 0.18 ng L−1. Other validation parameters confirmed the adequate applicability of the proposed system to detect TC/DC in milk samples. The proposed platform showed advantages of simplicity, rapidity, reliability, and low cost compared to other previously published reports.

A low cost and very sensitive method for the assessment of tyrosine in blood serum, urine and hair samples was developed. The method was based upon measuring the luminescence intensity of the nano optical sensor Eu–ciprofloxacin doped in a sol–gel matrix at 617 nm and in the presence of different concentrations of tyrosine in acetonitrile at pH = 9.1, λex = 380 nm. The significant quenching of the luminescence intensity of the Eu–ciprofloxacin complex by different concentrations of tyrosine was successfully used as an optical sensor in acetonitrile at 617 nm. The effects of different analytical parameters, e.g. pH, solvent, tyrosine concentration and foreign ion concentrations, were fully analysed. A calibration plot was achieved over the tyrosine concentration range 1.2 × 10−6 to 1.0 × 10−9 mol L−1, with a correlation coefficient of 0.997 and a detection limit of 1.0 × 10−10 mol L−1. The developed method is simple and proceeds without practical artifacts compared to other published methods.

Hexavalent chromium, Cr(VI), is a highly toxic species, while trivalent chromium, Cr(III), is an essential trace element for humans and other organisms. In the present work, a simple, rapid, and efficient procedure for water treatment of Cr(VI) is described. Active carbon (AC) was chemically treated with HCl and NaOH for the formation of surface modified Acidic-AC and Basic-AC sorbents, respectively. In addition, AC sorbent was treated with HNO$_{3}$ as an oxidizing agent and sodium sulfite as a reducing agent for the formation of Ox-AC and Rd-AC sorbents, respectively. The modified AC sorbents were tested to identify their potential applications in removal of Cr(VI) under various controlling factors using the batch technique. The results indicated that these sorbents can be used in water treatment due to their excellent and efficient reduction of Cr(VI) into Cr(III) with percentage transformation values in the range of 90%-100%. Acidic-AC was found to be the superior sorbent in the reduction process of Cr(VI). The produced Cr(III) was removed from aqueous solutions via adsorption on the surface of these sorbents. The reduction and adsorption processes of Cr(VI)-Cr(III) were evaluated and optimized under different experimental parameters. The potential applications of these sorbents in real water treatment were also explored.

We have studied the extraction of Cu(II) and Pb(II) ions from different types of aqueous solution by novel cross-linked graphene oxide sheets by modified extracted cellulose. The novel sorbent cellulose was extracted from the mangrove trees (Avicennia marina) and it was then grafted with acrylamide and immobilized by ethylenediamine for cross-linking process. The cross-linked graphene oxide sheets were identified by means of FT-IR, SEM and XRD. The adsorption studies of synthesized sorbent was optimized. Langmuir and Freundlich models were used for establish sorption equilibria. The cross-linked graphene oxide sheets showed maximum adsorption capacity 46.39 and 186.48 mg g−1 for Cu(II) and Pb(II), respectively. The potential applications of this sorbent was applied to remove Cu(II) and Pb(II) metal ions from hard water samples by using a multi-stage micro-column technique.