高效去除水溶液中重金属离子的氧化石墨烯基材料的综述

综述了氧化石墨烯(graphene oxide,GO)基纳米材料对水溶液中各种重金属离子的优异去除能力的最新研究成果。重点论述了吸附剂的合成,吸附过程特征及相互作用机理,概述了各种环境条件的影响。综述旨在为设计和制造GO基纳米材料提供有用的信息,以消除环境污染管理中废水中的重金属离子。此外,简要概述,并提出了这一鼓舞人心的领域所面临的挑战和前景。     

Adsorption from aqueous solution by δ-manganese dioxide II. Adsorption of some heavy metal cations

The adsorption isotherms of M²⁺ ions (M²⁺ = Ni²⁺, Co²⁺, Cd²⁺, Zn²⁺ and Mn²⁺) on the K⁺-form of δ-MnO₂, at pH 6 and at different temperatures, fitted the Langmuir equation and an apparent heat of adsorption, Q, was found to be - 78, - 33, - 34, - 19 and - 15 kJ mol^?1 respectively. The adsorption capacity of δ-MnO₂ increased in the series: Ni²⁺ < Co²⁺ < Cd²⁺ ± Zn²⁺ < Mn²⁺. This was nearly the order of decrease in the radii, r′, of the hydrated ions, estimated from hydration enthalpies. An ionexchange mechanism between hydrated K⁺ ions in the outer Helmholtz layer and hydrated M²⁺ ions in the solution, suggests positive entropy contributions which offset the endothermic Q. The proposed mechanism is in agreement with the observed sequence of adsorption capacity and with the decrease in Q in the above series, except for Co²⁺ adsorption (possibly complicated by the oxidation of Co²⁺ by δ-MnO²). The adsorption of the cations is probably accompanied by the exchange with Mn ions from the solid. There was evidence of specific adsorption below the point of zero charge (pH 3.3). The adsorption isotherms of Mn²⁺ ions at pH 7 were higher than those at pH 6 and Q was found to be - 19 kJ mol^?1. As the ionic strength increased, the adsorption isotherm of Mn²⁺ ions at pH 7 and 298 K shifted to lower values. Adsorption isotherms of Cu(II)ions at pH 3.5 and of Fe(III) at pH 2 represent specific adsorption and Q was found to be - 74 and - 13 kJ mol^?1 respectively.     

Synthesis of α‐cellulose/polypyrrole composite for the removal of reactive red dye from aqueous solution: Kinetics and equilibrium modeling

In this work, a composite from α‐cellulose coated with conducting polypyrrole by in situ polymerization using potassium persulfate as oxidant was obtained. The composite was characterized by fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry, UV/Vis spectroscopy, and scanning electron microscopy (SEM) analysis showed homogeneous coating of α‐cellulose with polypyrrole (PPy) to produce a composite with a conductivity of 3.5 × 10⁻⁵ S/m. Batch aqueous adsorption experiments of the reactive red 120 (RR120) dye onto the synthesized material were conducted. The results showed that this composite is an efficient adsorbent for RR120 dye removal. For the adsorption experiments set to an initial pH of 3.9, the adsorption capacity was 15.6 mg of dye/g of composite for an equilibrium concentration (in the liquid) of RR120 dye equal to 1,000 mg/L, whereas a value of 96.1 mg of dye/g of composite was obtained when the solution pH was set to 2.0 for the same equilibrium concentration. When performing adsorption experiments using pure α‐cellulose, dye adsorption was insignificant at any pH value. Adsorption isotherm for RR120 was described by a typical Freundlich model. The transient adsorption of RR120 on the synthesized composite was described by a general three‐resistance model that includes the transport on the film that surrounds the composite particles, diffusion inside the particles, and adsorption on the surface of the particles. A fitting of the uptake curves was performed allowing the estimation of values for the effective diffusivity, D₀, and the adsorption rate coefficient, k₁. For the adsorption experiments with an initial pH value set to 3.9, D₀ was estimated as 1.05 × 10⁻¹⁰ m²/s, whereas k₁ was 1.65 × 10⁻⁴ Lⁿ/g mg^{n − 1} s; the corresponding values of k₁ at pH = 2 and 9.0 were 3.18 × 10⁻⁴ and 5.16 × 10⁻⁵, respectively. POLYM. COMPOS., 36:312–321, 2015. © 2014 Society of Plastics Engineers     

Synthesis of γ‐Fluoro‐α, β‐unsaturated Carboxylic Esters from Saturated α‐Fluoro Aldehydes

γ‐Fluoro‐α, β‐unsaturated carboxylic esters 7a, 7b and 7d and 4‐fluoro‐4‐phenylbut‐3‐enoic ester ( 8 ) are obtained by two alternative pathways from 2‐fluoro aldehydes 5a—d , either by Horner—Wadsworth—Emmons reaction or by Wittig reaction. The aldehydes 5a—d are prepared by Swern oxidation of the corresponding fluorohydrins 4a—d . These are available from α‐olefins by bromofluorination, bromineby‐acetate replacement and subsequent hydrolysis.     

Thiourea modified hyper‐crosslinked polystyrene resin for heavy metal ions removal from aqueous solutions

A hyper‐crosslinked resin chemically modified with thiourea (TM‐HPS) was synthesized, characterized, and evaluated for the removal of heavy metal ions (Pb²⁺, Cd²⁺, and Cu²⁺) from aqueous solutions. The structural characterization results showed that a few thiourea groups were grafted on the surface of the resin with a big BET surface area and a large number of narrow micropores. Various experimental conditions such as pH, contact time, temperature, and initial metal concentration of the three heavy metal ions onto TM‐HPS were investigated systematically. The results indicated that the prepared resin was effective for the removal of the heavy metal ions from aqueous solutions. The isotherm data could be better fitted by Langmuir model, yielding maximum adsorption capacities of 689.65, 432.90, and 290.69 mg/g for Pd²⁺, Cd²⁺, and Cu²⁺, respectively. And the adsorption kinetics of the three metal ions followed the pseudo‐second‐order equation. FTIR and XPS analysis of TM‐HPS before and after adsorption further revealed that the adsorption mechanism could be a synergistic effect between functional groups and metal ions and electrostatic attraction, which may provide a new insight into the design of highly effective adsorbents and their potential technological applications for the removal of heavy metal ions from aqueous solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45568.     

Adsorption of γ-aminopropyltriethoxysilane onto bulk iron from aqueous solutions

The adsorption of γ-aminopropyltriethoxysilane (γ-APS) onto mechanically polished iron coupons from 1% aqueous solutions has been investigated using reflection–absorption infrared spectroscopy. Thick films were formed on the coupons during 1-hr exposures to the γ-APS solutions. The outermost portion of these films consisted of highly hydrolyzed polysiloxanes that were weakly bound and easily desorbed by cold water. This fraction of the films was characterized by an infrared band near 1575 cm^?1 that was tentatively assigned to the NH₂ deformation of acceptor amine groups in strong hydrogen bonds or to coordination of the amino nitrogen atoms to silicon atoms. Removal of the weakly bound outermost portion of the films with water revealed an incompletely hydrolyzed, strongly bound film approximately 60 Å in thickness characterized by a band near 1510 cm^?1 that was assigned to NH groups. Formation of NH₃⁺ groups indicated that γ-APS may have been adsorbed initially as cyclic, internal zwitterions.     

Water‐soluble chitosan intercalated montmorillonite nanocomposites for removal of basic blue 66 and basic yellow 1 from aqueous solution

Water‐soluble chitosan intercalated montmorillonite (wCTS/MMT) nanocomposites were modified and characterized by using Fourier transform infrared, thermogravimetric analysis, and X‐ray diffractometer techniques. Two types of wCTS, namely, low molecular‐weight chitosan (L‐wCTS) and hydroxyethylacryl chitosan (H‐wCTS) were synthesized and applied. The batch adsorption experiments on these nanocomposites were conducted by using basic dyes, that is, Basic Blue 66 and Basic Yellow 1 (BY1). The adsorption capacities of sodium montmorillonite (Na‐MMT), chitosan, L‐wCTS/MMT, and H‐wCTS/MMT were measured and compared. The results showed that the adsorption capacities of wCTS/MMT nanocomposites were higher than those values of Na‐MMT and chitosan. The adsorption kinetics of wCTS/MMT nanocomposites for BY1 were studied. It was described that the adsorption processes were better fitted by pseudo‐second‐order equation. The Langmuir and the Freundlich models were used to fit the adsorption isotherm. It was indicated that the adsorption isotherms followed the Langmuir model. The values of the maximum adsorption capacity of L‐wCTS/MMT and H‐wCTS/MMT adsorbents were at 188.7 and 294.1 mg/g, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Calixarene-based extractants for heavy metal ions removal from aqueous solutions

The article reviews the literature on the possibility of application of the calixarene-based compounds for selective separation of toxic heavy metals from aqueous solutions by the solvent extraction and transport across liquid membranes. The specific three-dimensional structure of calixarenes and their derivatives, simple and low-cost synthesis, and ease of chemical transformation qualify these compounds for the role of selective chemical extractants of toxic heavy metal ions present in industrial wastewater. This article analyses the influence of various process factors, with the greatest emphasis on the structure of the extractants/carriers, on efficient separation of heavy metal ions, primarily those most commonly found in galvanic wastewater.     

Poly(benzoxazine‐co‐sulfur): An efficient sorbent for mercury removal from aqueous solution

A novel sulfur‐rich adsorbent, poly(BA‐ala‐co ‐sulfur), was synthesized by reacting allyl functional benzoxazine (BA‐ala) and elemental sulfur. Simultaneous inverse vulcanization and ring‐opening reactions of benzoxazine generated copolymers in several feed ratios. The adsorption behavior of these copolymers was investigated in aqueous solutions containing Hg²⁺. A three level Box–Behnken design with four factors was applied in order to examine the interactive effect of Hg²⁺ concentration (ppm), S % in adsorbent, temperature, and pH. The optimum adsorption conditions were determined as: 10.33 ppm Hg²⁺, 68% S content, 329 K, and pH 6.3. Common isotherm and kinetic models were applied to the experimental data, where the Langmuir isotherm provided the better fit (q _max = 79.36 mg g^?1) and the pseudo‐second order fit indicated chemisorption as the process‐controlling step. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45306.     

A cost‐effective crosslinked β‐cyclodextrin polymer for the rapid and efficient removal of micropollutants from wastewater

Water pollution problems pose a serious threat to the health of humans and other living organisms due to the increasing global contamination of various water resources by organic micropollutants, such as plastic components, dyes and pesticide intermediates. It has been a challenging problem to remove these organic micropollutants, despite various attempts. Here, we report a novel, cost‐effective and water‐insoluble crosslinked β‐cyclodextrin polymer for the efficient removal of various organic micropollutants from wastewaters with excellent adsorption capacity, large removal rate, robust performance and reusability. This polymer can remove 93% of bisphenol A within 1 min with an equilibrium uptake of 38 mg g^?1 and a maximum adsorption capacity at equilibrium of 139 mg g^?1. This is the fastest removal performance that has been reported so far, showing a bright future towards practical applications. © 2019 Society of Chemical Industry     

Highly porous,water-swellable,and reusable chelating polymeric gels for heavy metal ion removal from aqueous waste

Sequestration and removal of heavy metal ions from aqueous solutions pose multiple challenges. Ease of synthesis, high adsorption capacity and ease of regeneration are important considerations in the design of polymeric adsorbent materials developed for this purpose. To meet this objective, a new approach was used to design and synthesize a highly porous polystyrene-based resin (IDASR15) bearing iminodiacetate functional groups in every repeat unit by free radical polymerization with N, N'-methylenebisacrylamide as crosslinker followed by base hydrolysis. The physiochemical chemical properties of the resin were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, equilibrium swelling value (ESV) and thermogravimetric analysis. Metal uptake capacity of IDASR15 towards low concentrations of various toxic heavy metal ions such as Cu²⁺, Cd²⁺, Mn²⁺, Zn²⁺, Pb²⁺, Ni²⁺, Co²⁺, Co³⁺, Cr³⁺, Fe²⁺, Fe³⁺, and Al³⁺ were investigated from their aqueous solution by batch method and found to be 0.943–2.802 mmol/g. The maximum capacity was 2.802 mmol/g obtained for Cu²⁺ ion at pH 5. The potential for regeneration and reuse has been demonstrated with Cu²⁺ ion by batch and column methods. The reported results suggest that IDASR15 is a highly efficient and porous complexing agent for commonly found toxic metal ions in aqueous streams with a high ESV of 68.55 g of water/1.0 g of IDASR15. It could also be reused ~99.5% of adsorption efficiency which is very promising and holds significant potential for waste-water treatment applications.     

Melamine‐based microporous polymer for highly efficient removal of copper(II) from aqueous solution

In this study, we investigated the ability of a melamine‐based microporous polymer network as an adsorbent for removal of copper(II) species from aqueous solutions. A designed Schiff based network (SNW) with high specific surface area was synthesized using melamine and terephthalaldehyde monomers at 180 °C for 3 days followed by a freeze‐drying process. The porous structure of the material was confirmed by SEM analysis and CO₂ adsorption/desorption studies at 77.3 K. The adsorption character of the SNW polymer for various metal salts, namely Pb(II), Fe(II), Hg(II), Zn(II), Ni(II) and Cd(II), was investigated and a specific sorption behaviour against Cu(II) salts was observed. The role of pH and contact time was examined and the highest adsorption capacity for Cu(II) was found as 92% with pH 3.5 at the end of 300 min. As evidenced by XRD and Fourier transform infrared spectral analysis, the sorption mechanism is attributed to the coordination system formed between amino groups in the porous structure and Cu(II) ions. Reusability of the system was also demonstrated by applying four cycles without any significant loss of activity. © 2016 Society of Chemical Industry     

Synthesis of α‐Arylphosphonates using Copper‐Catalyzed α‐Arylation and Deacylative α‐Arylation of β‐Ketophosphonates

Efficient methods for the direct arylation and deacylative arylation of β‐ketophosphonates with iodoarenes in presence of a copper(I) or a copper(II) salt as the catalysts have been developed. The corresponding α‐arylphosphonates were obtained in high yields. A tentative mechanism for the deacylative arylation reaction was proposed on the basis of the experimental data.     

One‐Pot Quinine‐Catalyzed Synthesis of α‐Chiral γ‐Keto Esters: Enantioenriched Precursors of cis‐α,γ‐Substituted‐γ‐Butyrolactones

A highly enantioselective one‐pot synthesis of important building blocks, α‐chiral γ‐keto esters, has been developed by combining a quinine‐catalyzed Michael addition of malononitrile to trans‐enones followed by magnesium monoperoxyphthalate (MMPP) oxidation. These synthons proved to be useful reagents for a simple access to challenging cis‐α,γ‐disubstituted γ‐butyrolactones in good diastereoselectivity and high enantiocontrol.

     

Enantioselective Phase‐Transfer Catalytic α‐Benzylation and α‐Allylation of α‐tert‐Butoxycarbonyllactones

A new enantioselective α‐benzylation and α‐allylation of α‐tert‐butoxycarbonyllactones was devloped. α‐Benzylation and α‐allylation of α‐tert‐butoxycarbonylbutyrolactone and α‐tert‐butoxycarbonylvalerolactone under phase‐transfer catalytic conditions (50% cesium hydroxide, toluene, −60 °C) in the presence of (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide (1 mol%) afforded the corresponding α‐substituted α‐tert‐butoxycarbonyllactones in very high chemical yields (up to 99%) and optical yields (up to 99% ee). The synthetic potential of this method has been successfully demonstrated by the asymmetric synthesis of unnatural α‐quaternary homoserines, 3‐alkyl‐3‐carboxypyrrolidine and 3‐alkyl‐3‐carboxypiperidine.     

Catalytic Asymmetric Synthesis of Functionalized α,α‐Disubstituted α‐Amino Acid Derivatives from Racemic Unprotected α‐Amino Acids via in‐situ Generated Azlactones

Masked and activated highly enantioenriched α,α‐disubstituted α‐amino acids with an additional adjacent stereocenter were formed by a tandem reaction involving five steps using racemic unprotected amino acid substrates. Key step is the 1,4‐addition of in‐situ generated azlactones to a broad number of enones. The products of this step‐economic route can, e.g., be useful for a divergent and rapid access to biologically interesting unnatural glutamic acid derivatives.     

Cross‐linked chitosan beads for phosphate removal from aqueous solution

Chitosan beads were cross‐linked with glutaraldehyde (GA) and epichlorohydrin (EP), respectively, at variable composition. The general features of the adsorptive and textural properties of the bead systems were characterized using p‐nitrophenolate (PNP) at pH 8.5. As well, a systematic adsorption study of phosphate dianion (phosphate ( ) species was carried out in aqueous solution at pH 8.5 and 295 K. The Sips isotherm model yielded adsorption parameters for the chitosan bead systems: (i) monolayer adsorption capacity (Q_m) for PNP ranged from 0.30 to 0.52 mmol g^?1 and (ii) Q_m values for the bead systems with ranged from 22.4–52.1 mg g^?1 for these conditions. GA cross‐linked beads reveal greater Q_m values for PNP while EP cross‐linked beads showed greater Q_m values for , in accordance with the surface chemistry and the materials design described herein. The EP cross‐linked beads show favorable adsorption–desorption properties and represents a promising tunable adsorbent system for the effective removal of phosphate dianion species in aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42949.     

The effect of β-dicalcium silicate, α-monocalcium silicate and calcium hydroxide upon the removal of lead (pb2+) ions from aqueous solution

A study was conducted of the influence of pH, initial reactant concentration and reaction time upon the rate of removal of lead ions from solutions of lead nitrate. Three different reactants were used: β-dicalcium silicate (β-C₂S)*, α-monocalcium silicate (α-CS), in the form of finely ground clinkers, and commercial calcium hydroxide. The initial concentration of lead in solution was varied between 5 and 1000 mg cm^-3 Pb²⁺ for different additions of reactant. For each concentration of lead ion the effect of time of shaking on the removal of lead was followed by the determination of residual lead concentration in the filtrate. Lead was reduced to low levels by all the precipitants. The precipitated reaction products were identified by X-ray diffraction techniques, electron diffraction analysis and infrared spectroscopy. The analysis characterised the products of the precipitation reactions as basic lead carbonate, basic lead nitrates and lead hydroxide.