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An efficient and profitable separation process was proposed to prepare 5N (the purity of the metal solution reaches 99.999%) high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions, was explored quantitatively. The maximum adsorption capacity for copper was 2.286mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing 5N-level high-purity nickel solutions, which was further verified using the 800BV (bed volume) effluent in the column dynamic process. According to the cost-benefit analysis, purification contributed to a profit of approximately 60,000USD per cycle, and the investment return period was less than 1/3years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms, implying a coordination ratio of approximately 1:1., (Copyright © 2016. Published by Elsevier B.V.)

Cu removal by a novel multi-amines decorated resin (PAMD) from wastewater in the absence or presence of citric acid (CA) was examined. Adsorption capacity of Cu onto PAMD markedly increased by 186% to 5.07 mmol/g in the presence of CA, up to 7 times of that onto four commercial resins under the same conditions. Preloaded and kinetic studies demonstrated adsorption of [Cu-CA] complex instead of CA site-bridging and variations of adsorbate species were qualitatively illustrated. The interaction configuration was further studied with ESI-MS, FTIR, XPS and XANES characterizations. The large enhancement of Cu adsorption in Cu-CA bi-solutes systems was attributed to mechanism change from single-site to dual-sites interaction in which cationic or neutral Cu species (Cu(2+) and CuHL(0)) coordinated with neutral amine sites and anionic complex species (CuL(-) and Cu2L2(2-)) directly interacted with protonated amine sites via electrostatic attraction, and the ratio of the two interactions was approximately 0.5 for the equimolar bi-solutes system. Moreover, commonly coexisting ions in wastewaters had no obvious effect on the superior performance of PAMD. Also, Cu and CA could be recovered completely with HCl. Therefore, PAMD has a great potential to efficiently remove heavy metal ions from wastewaters in the presence of organic acids.

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., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel magnetic weak acid resin NDMC was self-synthesized for the removal of Cu(2+) from aqueous solutions. NDMC showed superior properties on the removal of Cu(2+) compared to commercial resins C106 and IRC-748, which was deeply investigated by adsorption isotherms and kinetic tests. The equilibrium adsorption amount of Cu(2+) onto NDMC (267.2mg/g) was almost twice as large as that onto IRC-748 (120.0mg/g). The adsorption kinetics of Cu(2+) onto the three resins fitted well with the pseudo-second-order equation. The initial adsorption rate h of NDMC was about 4 times that of C106 and nearly 8 times that of IRC-748 at the initial concentration of 500mg/L. External surface area was determined to be the key factor in rate-controlling by further analyzing the adsorption thermodynamics, kinetics parameters and physicochemical properties of the resins. NDMC resin with the smallest bead radius possessed the largest external surface and therefore exhibited the fastest kinetics. The adsorption amount of Cu(2+) onto NDMC was not influenced as the concentration of Na(+) increased from 1.0 to 10.0mM/L. Dilute HCl solution could effectively desorb Cu(2+). NDMC demonstrated high stability during 10 adsorption/desorption cycles, showing great potential in the rapid removal of Cu(2+) from wastewater., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The adsorption of Cu(II) on oxidized multi-walled carbon nanotubes (oMWCNTs) as a function of contact time, pH, ionic strength, temperature, and hydroxylated fullerene (C60(OH)n) and carboxylated fullerene (C60(C(COOH)2)n) were studied under ambient conditions using batch techniques. The results showed that the adsorption of Cu(II) had rapidly reached equilibrium and the kinetic process was well described by a pseudo-second-order rate model. Cu(II) adsorption on oMWCNTs was dependent on pH but independent of ionic strength. Compared with the Freundlich model, the Langmuir model was more suitable for analyzing the adsorption isotherms. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Cu(II) adsorption on oMWCNTs was spontaneous and endothermic. The effect of C60(OH)n on Cu(II) adsorption of oMWCNTs was not significant at low C60(OH)n concentration, whereas a negative effect was observed at higher concentration. The adsorption of Cu(II) on oMWCNTs was enhanced with increasing pH values at pH < 5, but decreased at pH ≥ 5. The presence of C60(C(COOH)2)n inhibited the adsorption of Cu(II) onto oMWCNTs at pH 4-6. The double sorption site model was applied to simulate the adsorption isotherms of Cu(II) in the presence of C60(OH)n and fitted the experimental data well.

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.

Au-PtCu core-shell nanoparticles were successfully synthesized via galvanic replacement of Cu by Pt on hollow Au nano-spheres. Characterizations of the nanoparticles were conducted by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical measurements. Results indicate 2-2.5 times higher specific activity and mass activity of the Au-PtCu catalysts than commercial Pt black and Pt/C in oxygen reduction reaction (ORR), measured in a rotating disk electrode system. Besides, thinner PtCu coating (25 nm thick, deposition time of 20 min) on the hollow Au nano-spheres demonstrated a pronounced CO oxidation peak shift (by 0.13 V) and long-term durability probably due to the unique core-shell structure and strong electronic coupling between the Au core and the PtCu shell.

Kaolin has been widely used as an adsorbent to remove heavy metal ions from aqueous solutions. However, the lower heavy metal adsorption capacity of kaolin limits its practical application. A novel environmental friendly material, calcium alginate immobilized kaolin (kaolin/CA), was prepared using a sol-gel method. The effects of contact time, pH, adsorbent dose, and temperature on Cu2+ adsorption by kaolin/CA were investigated. The Langmuir isotherm was used to describe the experimental adsorption, the maximum Cu2+ adsorption capacity of the kaolin/CA reached up to 53.63 mg/g. The thermodynamic studies showed that the adsorption reaction was a spontaneous and endothermic process.

With bulk production and increasing application of carbon nanotubes (CNTs) as adsorbents in wastewater treatment, they will eventually be discharged into water environment and result in human contact risk to these toxic materials. However, so far few attentions have been paid to resolve the environmental micro-pollution caused by these micro-sized CNTs. In this research, an environmental friendly adsorbent, CNTs immobilized by calcium alginate (CNTs/CA) was prepared. Its copper adsorption properties were investigated via equilibrium studies. Experimental results showed that copper removal efficiency of CNTs/CA is high and reaches 69.9% even at a lower pH of 2.1. The copper adsorption capacity of CNTs/CA can attain 67.9 mg/g at copper equilibrium concentration of 5mg/L., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

Magnetic strongly basic anion exchange resin (MAEX) and weakly acidic cation exchange resin (MCEX) and their combined processes were employed to simultaneously remove such heavy metals (HMs) as Cu(II), Ni(II) and tannic acid (TA). Both MAEX and MCEX resins exhibited co-removal capability for Cu(II) and TA in binary solutions. Complexing-bridging was ascribed as the primary mechanism for the co-removal of TA and Cu(II) based on Density-Functional-Theory (DFT) calculation, fluorescence spectra, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) characterization. Moreover, an interesting discovery was found that hydrogen bond interaction between both nitrogen atom of the secondary amine ( NH ) and oxygen atom of carbonyl (C O) with un-ionized TA, and quaternary ammonium ( N + (CH 3 ) 3 ) ion exchange with ionized TA were ascribed to the mechanism of TA adsorption onto MAEX. The novel integrative technique based on MAEX and MCEX mixed completely in the same reactor could simultaneously remove Cu(II), Ni(II) and TA with high efficiencies of 92.1%, 94.8% and 88.4%, respectively. Three adsorbates could be successfully recovered with 0.1 M NaOH followed by 0.01 M HCl solution. Given the stable application for five cycles, combined magnetic resin treatment showed great potential in simultaneous removal of Cu(II), Ni(II) and TA. [ABSTRACT FROM AUTHOR]

Simultaneous recovery of heavy metal ions (HMIs) such as Cu(II) and Cr(VI) from strong-acid media was a great challenge due to the inhibition of protons. Herein, a novel biomass hydrogel (CMC/PEI-PD) containing various groups (bis-picolylamine, amino, and hydroxyl groups) was newly prepared by a facile two-step process. The static experiments relating pH, kinetics and isothermal co-adsorption confirmed the synergistic effect towards Cu(II) and Cr(VI) consistently. Specifically, the adsorption capacities of Cu(II) and Cr(VI) at pH 2.0 increased by 23.73% and 40.18% in comparison with the single systems. Moreover, coexistence of inorganic anions and cations could further increase the adsorption of Cu(II) and Cr(VI) by 59.90% and 43.39%, respectively. At the same time, the adsorption and desorption ratios for both HMIs remained stable. The superior performance came from the two dominant mechanisms of co-removal. On the one hand, Cu(II) chelated by bis-picolylamine group attracted Cr(VI) in the form of cation bridge, thus promoting Cr(VI) adsorption. On the other hand, the protonated amine group attracted Cr(VI) by electrostatic interaction and weakened the inter-cationic repulsion by electrostatic shielding, thus promoting Cu(II) adsorption. In addition, the dynamic column experiment towards simulated acidic electroplating wastewater involving Cu(II)–Cr(VI)–Ni(II) certified the high efficiency and feasibility of the co-removal. Therefore, CMC/PEI-PD owned great potential in the separation of typical HMIs even directly from strong-acid media. [Display omitted] • Biomass hydrogel with three functional groups was made in facile two-step process. • Cu(II) and Cr(VI) mutual adsorption was enhanced in strong-acid media. • Co-removal capacities were boosted by common inorganic salts. • Protonated amino group attracted Cr(VI) and electrostatically shielded Cu(II). • Cation bridge of Cu(II) with bis-picolylamine group enhanced Cr(VI) reduction. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cu(II) and SMZ were synergistically adsorbed by PSA at low concentrations. • Cu(II) could serve as new adsorption sites for SMZ as proved by FTIR and XPS. • SMZ− could help Cu(II) adsorption through electrostatic shielding effects. • The interface interactions were proposed by DFT calculations and column tests. Abstract In this study, the coadsorption behaviors of Cu(II) and sulfamethoxazole (SMZ) onto a polyamine-modified resin (PSA) have been systematically investigated. The synergistic adsorption of Cu(II) and SMZ by PSA has been observed, especially at low concentrations. The adsorption amount increased by 9.1% for SMZ and 20.9% for Cu(II) when they coexisted. Herein, two bridging mechanisms were revealed using sequential adsorption tests and characterizations (Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, pH monitoring, and Density-Functional-Theory calculations). Cu(II) preloaded in the resin phase could serve as new sites for SMZ, thereby forming surface ternary complexes ([ N Cu]–SMZ), in which Cu(II) may coordinate with both the heterocyclic N and sulfonamide N groups in SMZ. Meanwhile, the adsorption of anionic SMZ onto the surface NH 3 + sites facilitates more Cu N coordination binding due to the electrostatic shielding effect. Furthermore, we have quantitatively estimated the adsorbate distribution in the resin phase during coadsorption. In addition, approximately 96.7% SMZ and 99.8% Cu(II) could be successively recovered with NaClO 3 followed by HCl. Cu(II) could also enhance the adsorption of other sulfonamides onto PSA by a maximum of 61.4%. These results supply more understanding of the mutual interaction between heavy metals and sulfonamides in amine-containing adsorbents and demonstrate the potential application of these adsorbents for controlling the combined pollution. [ABSTRACT FROM AUTHOR]

Strong acidic heavy metal ions (HMIs) wastewater (pH < 3.0) is characterized by widespread source, mixed composition and high toxicity, which is extremely difficult to control and meet the requirements of HMIs separation and resource recovery. Herein, a novel aminophosphonic acid-functionalized hydrogel (CMC/PEI-P) was prepared successfully and applied to highly-selective separate Cu(II) from strong acidic media (SAM) (pH = 2.0). Thanks to the abundant and outward amino phosphonic acid groups, the maximum adsorption capacity and the initial adsorption rate constant were 119.41% and 116.64% higher than those of the precursor CMC/PEI. Most importantly, the exclusive separation with the super-high selectivity coefficients (+∞) could unexpectedly achieve with CMC/PEI-P even from the mixed polymetallic SAM. Furthermore, the purity of Co(II) in strong acidic cobalt-rich solution could be increased to more than 99.50%, with the benefit of about 200 times higher than the cost. The predominant mechanisms existed in the coordination with various active groups such as phosphonate, amine and hydroxyl. According to Density Functional Theory (DFT) calculations, the tetradentate coordination configuration with the best stability could be formed involving CMC/PEI-P and Cu(II). Therefore, this work explored a new pathway for the cost-effective separation and purification toward Cu(II) directly especially from SAM. [Display omitted] • Aminophosphonic acid-functionalized hydrogel was constructed by two-step procedure. • Exclusive separation for Cu(II) with high selectivity coefficient tending to +∞. • The abundant and outward groups contributed to the rapid adsorption of Cu(II). • Tetradentate coordination configuration was the most stable complex for Cu(II). [ABSTRACT FROM AUTHOR]

[Display omitted] • A γ-Fe 2 O 3 -based magnetic nanomaterial was synthesized for Au(III) recovery. • The maximum sorption capacity of Au(III) by γ-Fe 2 O 3 @PDA-NAM reached 2910 mg/g. • Superior Au(III) sorption selectivity by γ-Fe 2 O 3 @PDA-NAM at pH 4 is evident. • 78.03% of Au(III) was directly reduced to Au(0) during sorption on γ-Fe 2 O 3 @PDA-NAM. • The magnetic γ-Fe 2 O 3 @PDA-NAM can be readily separated after sorbing Au(III). To synthesize a novel magnetic nanomaterial for effective Au(III) recovery from the aqueous phase with excellent capability, superior selectivity, one-step reduction and ease of separation after loading Au(III) still remains a huge challenge. In this study, a magnetic nanomaterial (γ-Fe 2 O 3 @PDA-NAM) with a core–shell structure was synthesized for effective Au(III) recovery by sorption. The maximum Au(III) sorption capacity by γ-Fe 2 O 3 @PDA-NAM reached 2910 mg/g at pH = 6.10 ± 0.15, 44.29 times that by γ-Fe 2 O 3 (65.7 mg/g). Its Au(III) sorption efficiency was over 97.75% at very low concentrations (i.e., 5.5 × 10-4 and 5.5 × 10-5 mg/mL). TEM, XPS and FTIR analysis verified that excellent Au(III) recovery by γ-Fe 2 O 3 @PDA-NAM resulted from N/S-containing soft base moieties introduced to different layers. N and/or S elements at these sites provided lone pair electrons to Au(III) to form stable coordination bond. Meanwhile, the hydrogen bond between O-containing (–OH, -C=O) and N-containing (-C-N, -N(-C)-N-, -C=N) moieties on γ-Fe 2 O 3 @PDA-NAM and –OH on the main speciations of Au(III) (AuCl 3 (OH)-, AuCl 2 (OH) 2 -, and AuCl(OH) 3 -) also greatly enhanced Au(III) recovery. About 78.03% of Au(III) was directly reduced to elemental gold by -C-S- and -N(-C)-N- group on the tertiary amine structure during sorption. More than 98.84% of Au(III) was selectively sorbed on γ-Fe 2 O 3 @PDA-NAM at pH 4.0 even though Pt(IV), Cu(II), Zn(II), Pb(II), and Ni(II) were co-present at the same concentration as that for Au(III) (0.01 mg/mL). In contrast, sorption efficiency of other interfering ions was within 1.75–26.05%. A relatively poor sorption selectivity for Pt(IV) could be acceptable because it is also a noble metal. [ABSTRACT FROM AUTHOR]