Diethylenetriamine-grafted poly(glycidyl methacrylate) adsorbent for effective copper ion adsorption

Silicone-modified black peanut shell (BPS) biochar adsorbents: Preparation and their adsorptions for copper(II) from water

Novel silicone-modified biochar adsorbents (BPS-MBCs) were prepared by utilizing waste black peanut shell (BPS) as a raw biochar and gamma-amino-propyl triethoxysilane (silicone) as an inorganic modifier. The novelty of this work is that the incorporation of silicone into BPS can rise the specific surface area and porosity of BPS-MBCs and elevate their adsorptions for copper (II). Sorption kinetics data for copper (II) were molded using five kinetic equations [i.e. Lagergren 1st-order and 2nd-order, intraparticle diffusion (IN-D), Elovich, and Diffusion-chemisorption]. The equilibrium adsorption data for copper (II) were analyzed using two-parameter isotherm equations [i.e. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin] and three-parameter Sips, Redlich-Peterson and Toth isotherm models. It was validated that copper (II) sorption on BPS-MBCs matched better with pseudo-2nd-order kinetic, Diffusion-chemisorption and Langmuir isotherm models. The maximal qmLan of BPS-MBC-400 was near 284 mg/g at 45 °C. By multi-phase fitting of IN-D modelling, intra-particle diffusion coefficient (kin-d) and diffusion coefficient of external mass-transfer (DEx-Di) for copper (II) were calculated. The low sorption energy from Temkin and mean free energy from D-R modellings implied that copper (II) sorption was initiated by weak non-covalent bond interactions. Thermodynamic parameters indicated that copper (II) on BPS-MBCs was an endothermic and spontaneous process. Recycling of BPS-MBC-400 for copper (II) suggested it has excellent reusability. The major mechanism of copper (II) on BPS-MBCs is possibly comprised of multiple processes, such as physical adsorption (electrostatic attraction), chemical adsorption (adsorption from functional groups, chelation, and ion exchange) and diffusion-chemisorption. Based on these findings, it is expects that BPS-MBCs are promising sorbents for copper (II) eradication from Cu(II)-including wastewater.

Studies on adsorption properties of magnetic composite prepared by one-pot method for Cd(II), Pb(II), Hg(II), and As(III): Mechanism and practical application in food

A one-pot synthesis afforded a magnetic, crosslinked polymer adsorbent (m-P6) with a variety of functional groups to realize simultaneous adsorption of Cd2+, Pb2+, Hg2+, and As3+. The material was characterized by TEM-EDS, XRD, FT-IR, VSM, and XPS. Kinetic and isothermal analyses suggested mainly chemisorption processes of heavy metal ions that form multiple layers on heterogeneous surfaces. Theoretical adsorption capacities calculated by a pseudo-2nd-order kinetic model and the Sips isothermal model were 282.88 mg/g for Cd2+, 326.18 mg/g for Pb2+, 117.85 mg/g for Hg2+, and 320.29 mg/g for As3+. m-P6 not only can efficiently adsorb divalent heavy metals (Cd2+, Pb2+, Hg2+), but also demonstrate a process of adsorption-driven catalytic oxidation by single-electron transfer (SET) from As3+ to As5+. In application, in addition to adsorption in water, m-P6 is capable of minimizing matrix interference, and extracting trace heavy metals in a complex environment (cereal) through easy operations for improving the detection accuracy, as well as it is potential for application in detection of trace heavy metals in foodstuffs. m-P6 can be readily regenerated and efficiently recycled for 5 cycles using eluent E12 and dilute acid.

Multilayer Graphene Oxide Supported ZIF-8 for Efficient Removal of Copper Ions

To address the performance deterioration of ZIF-8 for the adsorption of copper ions caused by powder volume pressure and particle aggregation, we employed multilayer graphene oxide (MGO) as a support to prepare composite adsorbents (MGO@ZIF-8) by using the in situ growth of ZIF-8 on MGO. Due to a good interfacial compatibility and affinity between ZIF-8 and graphene nanosheets, the MGO@ZIF-8 was successfully prepared. The optimal Cu²⁺ adsorption conditions of MGO@ZIF-8 were obtained through single factor experiments and orthogonal experiments. Surprisingly, the Cu²⁺ adsorption capacity was significantly improved by the integration of MGO and ZIF-8, and the maximum Cu²⁺ adsorption capacity of MGO@ZIF-8 reached 431.63 mg/g under the optimal adsorption conditions. Furthermore, the kinetic fitting and isotherm curve fitting confirmed that the adsorption law of Cu²⁺ by MGO@ZIF-8 was the pseudo-second-order kinetic model and the Langmuir isotherm model, which indicated that the process of Cu²⁺ adsorption was monolayer chemisorption. This work provides a new approach for designing and constructing ZIF-8 composites, and also offers an efficient means for the removal of heavy metals.

Effects of Fe(III) and Cu(II) on the sorption of s-triazine herbicides on clay minerals

The effects of Fe(III) and Cu(II) on the sorption of atrazine (AT) and prometryn (PY) on clay minerals were investigated both preloaded and in solution. For smectite, Fe(III) preloading greatly enhanced AT and PY sorption at pH 4.0 and 6.0 but diminished AT sorption at pH 8.0. Cu(II) preloading promoted AT and PY sorption under alkaline conditions but suppressed AT sorption at pH 4.0. The adverse effects were not obvious for PY. While for illite and kaolinite, Fe(III) and Cu(II) had little or promotion effects due to the lower contents of them in these two minerals. In the co-sorption studies, for smectite, AT sorption remained at pH 4.0 and increased at pH 6.0 and 8.0, while PY sorption was inhabited over the pH range of 4.0-8.0 in the presence of Fe(III). AT and PY sorption were not affected by Cu(II) except for PY at pH 8.0, in which case, the sorption was promoted. For illite and kaolinite, Fe(III) and Cu(II) generally enhanced AT and PY sorption.

Polymer brush-grafted cotton fiber for the efficient removal of aromatic halogenated disinfection by-products in drinking water

Apart from the activated carbon, other functional adsorbents are usually not frequently reported for the removal of disinfection by-products (DBPs) in drinking water. In this study, a novel polymer brush-grafted cotton fiber was prepared and for the first time used as adsorbents for the efficient removal of aromatic halogenated DBPs in drinking water in the column adsorption mode. Poly (glycidyl methacrylate) (PGMA) was grafted onto the surface of cotton fibers via UV irradiation, and then diethylenetriamine was immobilized on the PGMA polymer brush through amination reaction to obtain the aminated cotton fibers (ACFs). The adsorption performance of the prepared ACF was investigated with eight aromatic halogenated DBPs via dynamic adsorption experiments. The results revealed that ACF showed significantly longer breakthrough point (38,500-225,500 BV) for aromatic halogenated DBPs compared with the granular activated carbon (150-500 BV). Thomas model was used to fit the breakthrough curves, and the theoretical value of the maximum adsorption capacity ranged from 14.76 to 89.47 mg/g. The enhanced adsorption performance of the ACF for aromatic halogenated DBPs was mainly due to the formation of hydrogen bonds. Additionally, the partially protonated amine groups also improved the adsorption performance. Furthermore, the ACF also showed remarkable stability and reusability.

Lead removal from water using organic acrylic amine fiber (AAF) and inorganic-organic P-AAF, fixed bed filtration and surface-induced precipitation

Granular porous sorbents were normally used for heavy metals removal from water. To search for the new commercial sorbent and treatment strategy, an organic acrylic amine fiber (AAF) and phosphorus loading inorganic-organic AAF (P-AAF) were prepared and used for lead (Pb) removal from water. A new strategy of inorganic-organic coupling technology was proposed for Pb removal, based on the hypothesis of surface-induced precipitation mechanism. The AAF showed a Pb adsorption capacity of 417 mg/g from the Langmuir fitting, while the column filtration technology was further applied to measure the adsorption edge and applications. Effects of different initial Pb concentrations, hydraulic retention time, and co-existing P were considered in the filtration experiments. The presence of 0.8 mg/L P in water significantly improved the Pb breakthrough point from 15,000 to 41,000 bed volumes of water spiked with 85 µg/L Pb, while the P-AAF fixed bed showed better removal of Pb than AAF SEM/EDX and XRD spectra were employed for determining the surface functional groups and the formation of surface-induced precipitation of pyromorphite (Pb₅(PO₄)₃OH) on AAF. This study verified the application of AAF sorbent for Pb removal and the enhanced effect of coating P on AAF, thus improved our fundamental understanding and application of the surface chemistry process of Pb with P.

A new route for manufacturing poly(aminophosphonic)-functionalized poly(glycidyl methacrylate)-magnetic nanocomposite - Application to uranium sorption from ore leachate

A high-energy ball milling of magnetite nanoparticles with amino-phosphonic functionalized poly(glycidyl methacrylate) polymer is used for manufacturing a highly efficient magnetic sorbent for U(VI) sorption from aqueous solutions. The Uranyl ions were adsorbed through the binding with amine and phosphonic groups as confirmed by Fourier Transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The maximum sorption capacity (up to 270 mg U g^-1) occurred at pH = 3-4; Langmuir isotherm well describes the sorption process. Small-size particles allow achieving fast uptake (within ≈90 min of contact); and the kinetic profiles are modeled by the pseudo-second order rate equation. Uranium is successfully desorbed from loaded sorbent using 0.25 M NaHCO₃ solution: Sorbent can be recycled with minimal decrease in sorption and desorption efficiency for at least 6 cycles. The sorbent is efficiently used for U(VI) recovery from the acidic leachates of U-bearing ores (after precipitation pre-treatment). Sorption capacity approaches 190 mg U g^-1 despite the presence of high concentrations of Fe and Si: the sorbent has a marked preference for U(VI) (confirmed by distribution ratios and selectivity coefficients).

Highly efficient removal of Cu(ii) by novel dendritic polyamine–pyridine-grafted chitosan beads from complicated salty and acidic wastewaters

In this study, dendritic polyamine chitosan beads with and without 2-aminomethyl pyridine were facilely prepared and characterized. Compared to CN (without the pyridine function), more adsorption active sites, larger pores, higher nitrogen content, higher specific surface area, and higher strength could be obtained for CNP (with the pyridine function). CNP microspheres afforded a larger adsorption capacity than those obtained by CN for different pH values; further, the uptake amounts of Cu(ii) were 0.84 and 1.12 mmol g⁻¹ for CN and CNP beads, respectively, at pH 5. The CNP microspheres could scavenge Cu(ii) from highly acidic and salty solutions: the maximum simulated uptake amount of 1.93 mmol g⁻¹ at pH 5 could be achieved. Due to the strong bonding ability and weakly basic property of pyridine groups, the adsorption capacity of Cu(ii) at pH 1 was 0.75 mmol g⁻¹ in highly salty solutions, which was comparative to those obtained from the commercial pyridine chelating resin M4195 (Q_Cu(II) = 0.78 mmol g⁻¹ at pH 1). In addition, a distinct salt-promotion effect could be observed for CNP beads at both pH 5 and 1. Therefore, the prepared adsorbent CNP beads can have promising potential applications in the selective capturing of heavy metals in complex solutions with higher concentrations of H⁺ and inorganic salts, such as wastewaters from electroplating liquid and battery industries.

Dendritic polyamine chitosan (CNP) beads containing 2-aminomethyl pyridine were facilely prepared for the efficient removal of Cu(ii) ions from highly acidic and salty solutions.

Facile synthesis of functionalized polyglycidyl methacrylate-magnetic nanocomposites for enhanced uranium sorption

Designing and fabricating nanocomposite magnetic sorbents (with more accessible active sites for achieving high sorption capacities, selectivity and rapid kinetics) has become an impending challenge in the removal of radionuclides. Two core-shell multifunctional magnetic-nanocomposites have been prepared suitably to be used as sorbents using facile two-step processes. In the first step, after synthesis of parent PGMA microparticles (by a dispersion polymerization method), the grafting of aminoalkylcarboxylate and aminoalkylphosphonic ligands (via an intermediary amination step of PGMA) allows increasing sorption capacities due to the specific reactivity of carboxylate and phosphonate groups, giving iminodiacetate (IDA-PGMA) and iminodiphosphonate (IDP-PGMA), respectively. In the second step, functionalized-PGMA was ball-milled with pre-formed magnetic nanoparticles using high-energy planetary milling, resulting in a magnetic nanocomposite structure (M-IDA-PGMA and M-IDP-PGMA). These sorbents were characterized by elemental analysis, FTIR, XRD, pHZPC, TEM, and VSM. The magnetic nanocomposite sizes were around 10.0 nm. The super paramagnetic properties of the hybrid materials make their solid/liquid separation quite easy using an external magnetic field. These materials were investigated for uranium sorption. Optimum pH was found to be close to 4.0; the maximum monolayer chemisorption capacities reach 122.9 and 147.0 mg g-1 for M-IDA- and M-IDP-PGMA, respectively. The adsorption activation energies were calculated from the Arrhenius equation. The sorption is spontaneous, endothermic and controlled by entropic change. Sorbents were tested for U(vi) removal from a real acidic leachate of ores collected in the El-Sella mining area. Finally, sodium bicarbonate revealed efficiency for uranium desorption and the re-use of sorbents was successfully tested for five cycles.

Kinetic and equilibrium study of the removal of reactive dye using modified walnut shell

Modified walnut shell (EAWNS) was prepared by reaction with epichlorohydrin and alkaline solution of aspartic acid and used to remove reactive dye (Reactive Brilliant Blue (KN-R)) from aqueous media. The isotherms, kinetics and thermodynamics of KN-R adsorption onto EAWNS were studied at 298-318 K. The isotherm data of KN-R adsorption onto EAWNS agreed closely with the Langmuir model. The theoretical monolayer adsorption capacity for KN-R was 224.42 mg/g at 318 K. The result from the Dubinin-Radushkevich model showed that the KN-R adsorption onto EAWNS is chemisorption. The adsorption rate of KN-R onto EAWNS conformed to the pseudo-second-order model. The diffusion mechanism was investigated by the intraparticle diffusion model. The mass-transfer coefficient calculated by the surface mass-transfer coefficient model was in range of 2.95 × 10^-5 to 2.93 × 10^-4cm/s. The thermodynamic results suggested that the adsorption of KN-R onto EAWNS is spontaneous and endothermic in nature. The design of a single-stage batch adsorption process based on EAWNS adsorbent was carried out. Furthermore, the recycled EAWNS maintains high adsorption capacity despite four cycles.

Ambient Temperature NO Adsorber Derived from Pyrolysis of Co-MOF(ZIF-67)

Co-, Ni-, and Zn-containing MOFs are prepared and then pyrolyzed to generate materials for ambient temperature NO adsorption. Materials containing Co are much more efficient for NO adsorption than those containing Ni and Zn; therefore, Co is identified as the active phase. The best performing material studied here achieves 100% low concentration (10 ppm) NO adsorption for more than 15 h under a weight hourly space velocity of 120 000 mL g^-1 h^-1. Powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopies, along with scanning electron microscopy and TEM, are used to probe the physicochemical properties of the materials, particularly the Co active phase, and chemistries involved in NO adsorption-desorption. NO adsorbs on oxygen-covered Co nanoparticle surfaces in the form of nitrates and desorbs as NO at higher temperatures as a result of surface nitrate decomposition. NO storage capacity decreases gradually upon repeated NO adsorption-desorption cycles, likely because of Co₃O₄ formation during these processes.

Facile Fabrication of Self-Healable and Antibacterial Soy Protein-Based Films with High Mechanical Strength

Soy protein isolate (SPI), a ubiquitous and readily available biopolymer, has drawn increasing attention because of its sustainability, abundance, and low price. However, the poor mechanical properties, tedious performance adjustments, irreversible damage, and weak microorganism resistance have limited its applications. In this study, a facile but delicate strategy is proposed to fabricate an excellently self-healable and remarkably antibacterial SPI-based material with high mechanical strength by integrating polyethyleneimine (PEI) and metal ions (Cu(II) or Zn(II)). The tensile strengths of the SPI/PEI-Cu-0.750 and SPI/PEI-Zn-0.750 films reach up to 10.46 ± 0.50 and 9.06 ± 0.62 MPa, which is 367.06 and 306.28% strength increase compared to that of neat SPI film, respectively. Due to abundant non-covalent bonds and low glass transition temperature of the network, both SPI/PEI-Cu and SPI/PEI-Zn films exhibit a satisfactory self-healing behavior even at room temperature. Furthermore, SPI/PEI-Cu and SPI/PEI-Zn films demonstrate high bacterial resistance against Escherichia coli and Staphylococcus aureus. This facile strategy of establishing dynamic networks in a biomaterial with numerous excellent properties will enormously expand the scope of its applications, especially in the field of recyclable and durable materials.

A Surface-Functionalized Ionovoltaic Device for Probing Ion-Specific Adsorption at the Solid-Liquid Interface

Aqueous ion-solid interfacial interactions at an electric double layer (EDL) are studied in various research fields. However, details of the interactions at the EDL are still not fully understood due to complexity induced from the specific conditions of the solid and liquid parts. Several technical tools for ion-solid interfacial probing are experimentally and practically proposed, but they still show limitations in applicability due to the complicated measurements. Recently, an energy conversion device based on ion dynamics (called ionovoltaic device) was also introduced as another monitoring tool for the EDL, showing applicability as a novel probing method for interfacial interactions. Herein, a monitoring technique for specific ion adsorption (Cu²⁺ and Pb²⁺ in the range of 5 × 10^-6 -1000 × 10^-6 m) in the solid-liquid interface based on the ionovoltaic device is newly demonstrated. The specific ion adsorption and the corresponding interfacial potentials profiles are also investigated to elucidate a working mechanism of the device. The results give the insight of molecular-level ion adsorption through macroscopic water-motion-induced electricity generation. The simple and cost-effective detection of the device provides an innovative route for monitoring specific adsorption and expandability as a monitoring tool for various solid-liquid interfacial phenomena that are unrevealed.

Kinetic, Isotherm, and Thermodynamic Studies for Ag(I) Adsorption Using Carboxymethyl Functionalized Poly(glycidyl methacrylate)

Industrial wastewater contains large amounts of silver ions. Here, a new adsorbent was synthesized by functionalizing poly(glycidyl methacrylate) with carboxymethyl groups. The adsorbent was used to recover Ag(I) in wastewater. Fourier transform infrared spectroscopy, zeta potential, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the adsorbent. The experimental parameters affecting the adsorption are solution pH, contact time, and initial silver ion concentration. The optimum pH for adsorption of Ag(I) is pH 4. The maximum adsorption capacity at pH 4 is 157.05 mg/g, and the adsorption reaches equilibrium at 300 min. The kinetics and isotherms of the adsorption process were described by pseudo second-order, Langmuir and D-R models, respectively. The adsorption process was a single layer chemical adsorption, exothermic, feasible, and spontaneous. The adsorption mechanism is electrostatic or chelation. The adsorbent selectively absorbed Ag(I) from coexisting ions (Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺). Finally, the removal rate of silver ions decreased from 79.29% to 65.01% after four repetitive experiments, which proved that the adsorbent had good reusability. The adsorbent has great potential benefit in removing Ag(I).

Adsorption of Cu (II) and Ni (II) from aqueous solutions by taro stalks chemically modified with diethylenetriamine

Taro stalks (TS) were modified by diethylenetriamine (DETA) to obtain the modified taro stalks adsorbents (recorded as MTSA). This kind of raw material is unprecedented and the method of modification is relatively simple. The physicochemical properties of MTSA were characterized by scanning electron microscope (SEM), FTIR, and zeta potential analyzer. The capacity of MTSA for adsorbing heavy metals under different influencing factors was tested by UV-visible spectrophotometer. The results indicated that the gaps between the microspheres of MTSA are more, which are conducive to adsorption. The MTSA might have increased the amino-functional groups which are beneficial for adsorption, resulting in an increase in the adsorption capacity of copper and nickel ions (35.71 and 31.06 mg/g) of about 5-7 times compared to bare taro stalks (5.27 mg/g and 6.08 mg/g). High Cu²⁺ uptake on MTSA was observed over the pH range of 5.5-7.0, while for Ni²⁺ the range was 7.0-8.5, and the optimum dosage of adsorbent were both about 0.80 g for Cu²⁺ and Ni²⁺. The adsorption kinetics of Cu²⁺ and Ni²⁺ on MTSA could be interpreted with a pseudo-second order and the equilibrium data were best described by the Langmuir isotherm model. Graphical abstract ᅟ.

Modification of chitosan/calcium alginate/Fe3O4 hydrogel microsphere for enhancement of Cu(II) adsorption

Copper in drinking water causes a significant environmental problem. Composite material based on alginate hydrogel has been gaining attention in the field of Cu(II) adsorption. However, alginate-based hydrogel exhibits poor mechanical property and relative low adsorption capacity which limit their application. The present study is devoted to the modification of chitosan/calcium alginate/Fe₃O₄ (CAF) hydrogel microsphere by NaOH solution for enhancement of Cu(II) adsorption. Results reveal that modification of CAF via NaOH solution significantly improves the mechanical strength and Cu²⁺ adsorption capacity of pristine materials. FTIR and XRD analysis confirms that CAF and newly prepared materials (NACAF) are successfully prepared. SEM and EDX are employed to analyze the surface morphology and elemental composition, respectively, both before and after their loading with Cu²⁺. XPS study demonstrates adsorption mechanism is based on chelation and ion-exchange. Compressive stress-strain curves demonstrate NACAF has better mechanical performance than CAF. The adsorption kinetics of the two adsorbents follow a pseudo-second-order model. The equilibrium data were best described by Langmuir isotherm model, and the estimated maximum equilibrium sorption capacity, q _m,is 261.31 mg/g for the NACAF, which is larger than that of CAF (145.39 mg/g). Hence, NACAF shows excellent mechanical strength and high sorption capacity for Cu²⁺. It has great potential for Cu(II) removal in aqueous solutions.

Novel recyclable adsorbent for the removal of copper(II) and lead(II) from aqueous solution

Adsorbents synthesized with biopolymer have been widely used in the removal of toxic metal ions. Novel high-efficiency, recyclable, and low-cost adsorbents have received more and more attention. Chitosan and cellulose are the most abundant biopolymers in nature. Composite modified adsorbent (CSTEC) was synthesized as novel fibrous materials for the adsorption of Cu²⁺ and Pb²⁺ ions from water in this study. The functional fiber was characterized to investigate the surface appearance, functional groups, crystallinity, and thermal stability. The kinetics study revealed that adsorption processes of Cu²⁺ and Pb²⁺ ions on the CSTEC followed the second-order kinetics model. CSTEC showed better performance (Cu²⁺, 95.24; Pb²⁺, 144.93mgg^-1) than most of other adsorbents. The co-existing ions (K⁺, Na⁺, Mg²⁺) had no significant influence on the removal of target ions by the CSTEC. The excellent reusability indicated that CSTEC had the promising application in the treatment of toxic metal pollution.

Visible sequestration of Cu2+ions using amino-functionalized cotton fiber

In this study, an amino functionalized cotton fiber, which was used to adsorb Cu²⁺ionsviavisible sequestration, was prepared and investigated.

New insight into adsorption characteristics and mechanisms of the biosorbent from waste activated sludge for heavy metals

The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb(2+) and Zn(2+) in aqueous single-metal solutions. A pH value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients (above 0.99 for both metal ions) and insignificant lack of fit (p=0.0838 and 0.0782 for Pb(2+) and Zn(2+), respectively). Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation (between -NH2, -CN and metal ions) and ion-exchange (between -COOH and metal ions). The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.

Scalable Fabrication of Electrospun Nanofibrous Membranes Functionalized with Citric Acid for High-Performance Protein Adsorption

Fabricating protein adsorbents with high adsorption capacity and appreciable throughput is extremely important and highly desired for the separation and purification of protein products in the biomedical and pharmaceutical industries, yet still remains a great challenge. Herein, we demonstrate the synthesis of a novel protein adsorbent by in situ functionalizing eletrospun ethylene-vinyl alcohol (EVOH) nanofibrous membranes (NFM) with critic acid (CCA). Taking advantage of the merits of large specific surface area, highly tortuous open-porous structure, abundant active carboxyl groups introduced by CCA, superior chemical stability, and robust mechanical strength, the obtained CCA-grafted EVOH NFM (EVOH-CCA NFM) present an excellent integrated protein (take lysozyme as the model protein) adsorption performance with a high capacity of 284 mg g(-1), short equilibrium time of 6 h, ease of elution, and good reusability. Meanwhile, the adsorption performance of EVOH-CCA NFM can be optimized by regulating buffer pH, ionic strength, and initial concentration of protein solutions. More importantly, a dynamic binding efficiency of 250 mg g(-1) can be achieved driven solely by the gravity of protein solution, which matches well with the demands of the high yield and energy conservation in the actual protein purification process. Furthermore, the resultant EVOH-CCA NFM also possess unique selectivity for positively charged proteins which was confirmed by the method of sodium dodecyl sulfate polyacrylamide gel electrophoresis. Significantly, the successful synthesis of such intriguing and economic EVOH-CCA NFM may provide a promising candidate for the next generation of protein adsorbents for rapid, massive, and cost-effective separation and purification of proteins.

Surface-Initiated ARGET ATRP of Poly(Glycidyl Methacrylate) from Carbon Nanotubes via Bioinspired Catechol Chemistry for Efficient Adsorption of Uranium Ions

Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) integrated with mussel-inspired polydopamine (PDA) chemistry was, for the first time, employed for controlled grafting of poly(glycidyl methacrylate) (PGMA) brushes from carbon nanotubes (CNTs). The strategy initially involved deposition of a PDA layer by spontaneous self-polymerization, which is a benign and nonsurface specific way for anchoring 2-bromoisobutyryl bromide to form initiators on the CNTs. Dense and uniform PGMA brushes were then grown via ARGET ATRP using low concentration of Cu catalyst in different solvents. With abundant highly reactive epoxy groups, the PGMA-grafted CNTs could serve as a versatile platform for further modification or functionalization. Ethylenediamine ligands were facilely introduced, imparting the functionalized CNTs with record-high adsorption ability toward uranium ions among CNTs composites. The integrated strategy combining surface-initiated ARGET ATRP technique and PDA chemistry would provide new opportunities for surface engineering of nanomaterials for advanced applications.

A rheological study of reverse vesicles formed by oleic acid and diethylenetriamine in cyclohexane

A reverse aggregate system composed of oleic acid and diethylenetriamine in cyclohexane has been studied.

Adsorption of toxic acidic dye from aqueous solution onto diethylenetriamine functionalized magnetic glycidyl methacrylate-N,N′-methylenebisacrylamide

Magnetic sorbent microgranules with magnetite (Fe₃O₄) core and glycidyl methacrylate/N,N′​-methylenebisacrylamide shell were prepared. The sorbent was tested for Acid Yellow 99 dye removal from aqueous solution.

Induced application of biological waste Escherichia coli functionalized with an amine-based polymer for CO2capture

Amine-based polymer (polyethylenimine) functionalized biological waste (Escherichia coli) could open up its new application as a reusable waste source for CO₂capture.

Enhanced selective removal of Cu(II) from aqueous solution by novel polyethylenimine-functionalized ion imprinted hydrogel: Behaviors and mechanisms

A novel polyethylenimine-functionalized ion-imprinted hydrogel (Cu(II)-p(PEI/HEA)) was newly synthesized by (60)Co-γ-induced polymerization for the selective removal of Cu(II) from aqueous solution. The adsorption performances including the adsorption capacity and selectivity of the novel hydrogel were much better than those of similar adsorbents reported. The hydrogel was characterized via scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectra, thermal gravimetric analysis and X-ray photoelectron spectroscopy to determine the structure and mechanisms. The adsorption process was pH and temperature sensitive, better fitted to pseudo-second-order equation, and was Langmuir monolayer adsorption. The maximum adsorption capacity for Cu(II) was 40.00 mg/g. The selectivity coefficients of ion-imprinted hydrogel for Cu(II)/Pb(II), Cu(II)/Cd(II) and Cu(II)/Ni(II) were 55.09, 107.47 and 63.12, respectively, which were 3.93, 4.25 and 3.53 times greater than those of non-imprinted hydrogel, respectively. Moreover, the adsorption capacity of Cu(II)-p(PEI/HEA) could still keep more than 85% after four adsorption-desorption cycles. Because of such enhanced selective removal performance and excellent regeneration property, Cu(II)-p(PEI/HEA) is a promising adsorbent for the selective removal of copper ions from wastewater.

Selective recovery of Pd(II) from extremely acidic solution using ion-imprinted chitosan fiber: Adsorption performance and mechanisms

A novel, selective and acid-resisting chitosan fiber adsorbent was prepared by the ion-imprinting technique using Pd(II) and epichlorohydrin as the template and two-step crosslinking agent, respectively. The resulting ion-imprinted chitosan fibers (IIF) were used to selectively adsorb Pd(II) under extremely acidic synthetic metal solutions. The adsorption and selectivity performances of IIF including kinetics, isotherms, pH effects, and regeneration were investigated. Pd(II) rapidly adsorbed on the IIF within 100 min, achieving the adsorption equilibrium. The isotherm results showed that the maximum Pd(II) uptake on the IIF was maintained as 324.6-326.4 mg g(-1) in solutions containing single and multiple metals, whereas the Pd(II) uptake on non-imprinted fibers (NIF) decreased from 313.7 to 235.3 mg g(-1) in solution containing multiple metals. Higher selectivity coefficients values were obtained from the adsorption on the IIF, indicating a better Pd(II) selectivity. The amine group, supposedly the predominant adsorption site for Pd(II), was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The pH value played a significant role on the mechanism of the selective adsorption in the extremely acidic conditions. Furthermore, the stabilized performance for three cycles of sorption/desorption shows a potential for further large-scale applications.

Amine-functionalized mesoporous polymer as potential sorbent for nickel preconcentration from electroplating wastewater

In this study, mesoporous glycidyl methacrylate-divinylbenzene-based chelating resin was synthesized and grafted with diethylenetriamine through epoxy ring-opening reaction. The synthesized resin was characterized by elemental analysis, infrared spectroscopy, surface area and pore size analysis, scanning electron microscopy, energy-dispersive spectroscopy, and thermogravimetry. The resin was used for the first time as an effective sorbent for the preconcentration of nickel in electroplating wastewater samples. The analytical variables like pH, flow rate for sorption/desorption, and eluate selection were systematically investigated and optimized. The uniform and monolayer sorption behavior of resin for nickel was proved by an evident fit of the equilibrium data to a Langmuir isotherm model. Under optimized conditions, the resin was observed to show a good sorption capacity of 20.25 mg g(-1) and >96% recovery of nickel even in the presence of a large number of competitive matrix ions. Its ability to extract trace amount of nickel was exhibited by low preconcentration limit (5.9 μg L(-1)). The calibration curve was found to be linear (R(2) = 0.998) in the concentration range of 6.0-400.0 μg L(-1). Coefficient of variation of less than 5 for all the analysis indicated good reproducibility. The reliability was evaluated by the analysis of standard reference material (SRM) and recovery experiments. The applicability of the resin for the systematic preconcentration of nickel is substantiated by the analysis of electroplating wastewater and river water samples. Graphical abstract ᅟ.

Enhanced removal of Cu(II) and Ni(II) from saline solution by novel dual-primary-amine chelating resin based on anion-synergism

A novel dual-primary-amine chelating resin (EDTB) was newly synthesized for the effective removal of Cu(II) and Ni(II) from saline solutions. NaNO3 as well as Ca(NO3)2, NaCl and CaCl2 unexpectedly promoted the adsorption of Cu(II) or Ni(II) by up to 63.42% or 133.49% in single heavy-metal species systems. Meanwhile, inorganic salts enhanced both Cu(II) and Ni(II) uptake capacities in binary heavy-metal species systems. Anions significantly increased the amount of adsorption sites by condensing the double electric layer. Interestingly, increasing Ni(NO3)2 concentrations elevated the adsorption capacity of EDTB for Cu(II) by 2.10-11.69% in aqueous media without salts while in the presence of salts, rising Ni(NO3)2 concentrations suppressed Cu(II)-adsorption by 2.42-7.68%. The marginal analysis of anion-synergism depending on salt concentrations quantitatively explained such opposite effects using a promotion index. Furthermore, the solid characterizations and a newly-proposed metastable-state model based on pre-loading experiments conformably indicated the reciprocal relationships between cations and anions involving site competition, displacement effect and anion enhancement. Because of such salt-enhanced removal performance and excellent regeneration efficiency higher than 99%, EDTB is potentially eligible for reusing heavy-metals from actual wastewaters especially containing high-concentration salts.

Preparation and evaluation of aminopropyl-functionalized manganese-loaded SBA-15 for copper removal from aqueous solution

A novel material, aminopropyl-functionalized manganese-loaded SBA-15 (NH2-Mn-SBA-15), was synthesized by bonding 3-aminopropyl trimethoxysilane (APTMS) onto manganese-loaded SBA-15 (Mn-SBA-15) and used as a Cu2+ adsorbent in aqueous solution. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectra (XRD), N2 adsorption/desorption isotherms, high resolution field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the NH2-Mn-SBA-15. The ordered mesoporous structure of SBA-15 was remained after modification. The manganese oxides were mainly loaded on the internal surface of the pore channels while the aminopropyl groups were mainly anchored on the external surface of SBA-15. The adsorption of Cu2+ on NH2-Mn-SBA-15 was fitted well by the Langmuir equation and the maximum adsorption capacity of NH2-Mn-SBA-15 for Cu2+ was over two times higher than that of Mn-SBA-15 under the same conditions. The Elovich equation gave a good fit for the adsorption process of Cu2+ by NH2-Mn-SBA-15 and Mn-SBA-15. Both the loaded manganese oxides and the anchored aminopropyl groups were found to contribute to the uptake of Cu2+. The NH2-Mn-SBA-15 showed high selectivity for copper ions. Consecutive adsorption-desorption experiments showed that the NH2-Mn-SBA-15 could be regenerated by acid treatment without altering its properties.

A novel tetraethylenepentamine functionalized polymeric adsorbent for enhanced removal and selective recovery of heavy metal ions from saline solutions

A novel tetraethylenepentamine functionalized polymeric adsorbent with polymethacrylate–divinylbenzene as the substrate was facilely prepared for the enhanced removal and selective recovery of Cu(ii) and Ni(ii) from saline solutions.

Magnetic Co–Fe bimetallic nanoparticle containing modifiable microgels for the removal of heavy metal ions, organic dyes and herbicides from aqueous media

Poly(methacrylic-co-acrylonitrile) (p(MAc-co-AN)) microgels were prepared and nitrile groups were converted to amidoxime groups by chemical modification.

Enhancement mechanisms behind exclusive removal and selective recovery of copper from salt solutions with an aminothiazole-functionalized adsorbent

The aminothiazole-functionalized adsorbent (CEAD) could exclusively remove and to selectively recover copper. The adsorption and separation properties of Cu(II) onto CEAD from aqueous media, with or without salts such as NaNO3, Ca(NO3)2 and Ni(NO3)2, were systematically compared by carrying out single, binary and multiple component static and dynamic experiments. In binary systems, the adsorption capacities of Cu(II) were obviously increased by 39.47%, 47.37% and 57.89% with Ni(NO3)2, NaNO3 and Ca(NO3)2, respectively. Besides, simulation study was performed to selectively recover Cu(II) from multi-component aqueous media, with the separation factor of only 54.91 in aqueous media without salts. The separation factor became infinite in the presence of NaNO3 and the enhancement ratio for Cu(II) was raised by 126.31%. Dynamic adsorption could separate Cu(II) and Ni(II) completely and the amount of effluent for pure Ni(II) increased to 127 BV with the help of NaNO3. In the predominant chelating mode simulated by density functional theory calculation, a metal ion coordinated with three nitrogen atoms and formed a chelating complex with two five-membered rings, and Cu(II) showed stronger coordinating ability than Ni(II) did. Meanwhile, anions exerted significant beneficial effects by electrostatic screening, and thus strengthened the exclusive removal and selective recovery of Cu(II).

A new absorbent by modifying walnut shell for the removal of anionic dye: kinetic and thermodynamic studies

A novel, low cost and easy regeneration biosorbent, chem-modified walnut shell (MWNS), was studied to investigate its potential for removal of an anionic dye, reactive brilliant red K-2BP. The MWNS was synthesized with epichlorohydrin and diethylenetriamine as etherifying agent and crosslinking agent, respectively, and its characteristics were performed with Fourier transform infrared spectroscopy, scanning electron microscope, electron dispersive spectroscopy and thermogravimetric analysis. The influences of pH (0.5-11) and adsorbent dosage (0.1-6g/L) on adsorption capacity of MWNS were evaluated. The maximum K-2BP adsorption capacities (Qm) calculated by best fitting model (Langmuir) were 568.18 mg/g at 313 K, which was almost 10 times than that of raw material. The adsorption kinetic was well confirmed with pseudo-second-order equation. Thermodynamic studies demonstrated adsorption process by MWNS was spontaneous and endothermic. Furthermore, the regeneration capability of MWNS implied MWNS was a cheap, excellent and promising biosorbent for K-2BP removal in azo dye wastewater treatment.

An integrative technique based on synergistic coremoval and sequential recovery of copper and tetracycline with dual-functional chelating resin: roles of amine and carboxyl groups

A novel chelating resin (R-AC) bearing dual-functional groups (amino and carboxyl groups) was self-synthesized and it showed superior properties on synergistic coremoval of Cu(II) and tetracycline (TC) to commercial resins (amine, carboxyl, and hydrophobic types), which was deeply investigated by equilibrium and kinetic tests in binary, preloading, and saline systems. The adsorption of TC on R-AC was markedly enhanced when coexisted with Cu(II), up to 13 times of that in sole system, whereas Cu(II) uptake seldom decreased in the copresence of TC. Decomplexing-bridging, which included [Cu-TC] decomplexing and [R-Cu] bridging for TC, was demonstrated as the leading mechanism for the synergistic coremoval of Cu(II) and TC. Carboxyl groups of R-AC played a dominant role in decomplexing of [Cu-TC] complex and releasing free TC. Cu(II) coordinated with amine groups of R-AC was further proved to participate in bridging interaction with free TC, and the bridging stoichiometric ratio ([NH-Cu]: TC) possibly was 2:1. About 96.9% of TC and 99.3% of Cu could be sequentially recovered with dilute NaOH followed by HCl. Considering stable application for five cycles in simulated and practical wastewater, R-AC shows great potential in green and simple coremoval of antibiotic and heavy metal ions.

Insight into highly efficient coremoval of copper and p-nitrophenol by a newly synthesized polyamine chelating resin from aqueous media: competition and enhancement effect upon site recognition

Highly efficient coremoval of Cu(II) and p-nitrophenol (PNP) was accomplished using a newly synthesized polyamine chelating resin (CEAD) as compared to three other commercial resins. The mutual effects and inner mechanisms of their adsorption onto CEAD were systematically investigated by binary, preloading, thermodynamic, and dynamic adsorption procedures. PNP was adsorbed onto both hydrophobic and hydrophilic sites, while Cu(II) only interacted with hydrophilic amine group sites. In both preloading and binary systems, the adsorption of PNP was inhibited to the same degree by the presence of Cu(II) because of selective recognition and direct competition. On the other hand, the presence of PNP obviously enhanced the adsorption of Cu(II) by more than 7%, which was related to PNP loading on the hydrophobic surface. As proved by structural characterization, hydroxyl groups facing outward create new sites for coordination with Cu(II). Moreover, ionic strength exerted some positive influence on the properties of CEAD. Finally, more than 98% of PNP and 99% of Cu(II) could be sequentially recovered with dilute NaClO3 and HCl. These superior properties demonstrated with CEAD indicate that it could be applied to wastewaters containing both heavy metals and PNP, even for high saline aqueous media.