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Cellulose acetate (CA) was used for the preparation of food packaging film. Glycerol and n-propanol were introduced, as plasticizer and transparent agent, respectively for evaluating the possible changes of the film functional properties of tensile strength and transparency. The transmittance, haze value, tensile strength and flexibility were acquired by using optical and mechanical analyses, respectively. The presence of glycerol improved the functional properties of films by increasing their extensibility, flexibility, and elasticity; however transparency of the films deteriorated with the inclusion of plasticizer. Therefore, the addition of n-propanol as transparent agent into the films enhanced the transparency. Moreover, morphological changes and gas barrier property were confirmed by SEM and WVTR analyses. The results suggest that CA films incorporated with plasticizer and transparent agent have good functional properties in isolating water vapor, mechanical performance and optical properties, demonstrating that the optimal film has a potential in the application for food packaging.

This review summarises the advancements of stimuli-responsive membranes, focusing on stimuli-responsive chemistry, controllable membrane properties, membrane preparation, and advanced applications.

Hydrophilic modification is a promising method to inhibit fouling formation on ultrafiltration membrane. In this work, different mass concentrations (1%–16%) of hydrophilic polyvinylpyrrolidone were incorporated into polyethersulfone (PES) membranes fabricated by none-solvent induced phase separation. Then, polydopamine (PDA) coating on the surface of prepared membrane was carried out at pH 8.5. The morphology and structure, surface hydrophilicity, permeation flux, BSA rejection, antifouling and stability performances of PES and PDA/PES modified membranes were investigated in detail. The results indicated that PDA was successfully attached onto the membranes. Membrane hydrophilicity was evaluated by water contact angle measurement. The contact angles of modified membranes reduced remarkably, suggesting that the membrane hydrophilicities were significantly increased. The results of filtration tests, which were done by dead-end filtration of bovine serum albumin solution, showed that the properties of permeability and fouling resistance were obviously improved by PDA modification. When polyvinylpyrrolidone mass content reached 10%, flux recovery ratio of modified membrane was up to 91.23%, and its BSA rejection were over 70%. The results of stability tests showed that the modified membranes had good mechanical stability and chemical stability. This facile fabrication procedure and outstanding performances suggested that the modified membranes had a potential in treating fouling.

Two-phase Ca2+-doped LaVO4:Eu3+ nanocrystals were prepared through a hydrothermal method with the help of SOD CITR and EDTA surfactants. The phase and morphology of the products were characterized by XRD and TEM, and the fluorescence performances were also recorded. The results indicated that Ca2+ ions were doped into the LaVO4:Eu3+ host lattice, impeding the aggregation of the nanocrystals and enhancing the luminescence intensity. The morphology transformation process and luminescence enhancement were systematacially investigated. The fluorescence intensity of the two selected samples could be completely quenched by Fe3+ ions without the disturbance of other ions, with the mechanism being due to the adsorption of Fe3+ ions onto the grains and a subsequent energy transfer from Eu3+ to Fe3+. Therefore, the present two Ca2+-doped LaVO4:Eu3+ samples can be applied as appropriate candidates for detecting Fe3+ ions with agility and sensitivity in aqueous solution.

In this work, various photocatalysts were synthesized with an impregnation-precipitation process to in situ decorate Ag-based nanoparticles (NPs, including Ag3PO4, AgCl, Ag2O, and Ag2CO3) on the cellulosic paper. The structure and properties of the Ag-based composites were characterized by scanning electron microscopy, X-ray diffraction, transmitting electron microscopy, UV-vis diffuse reflectance spectra, and photocatalysis testing. The results showed that cellulosic paper is an efficient carrier which is feasible to grasp NPs due to the cellulosic nanofiber-network microstructure. Among the obtained samples, Ag2CO3 and AgCl NPs on cellulosic paper displayed high photocatalytic activity for the degradation of methyl orange under ultraviolet and visible light. However, photo lability of Ag2CO3 limits its recyclable. AgCl showed a better reutilization with the assistance of a surface plasmon resonance effect by Ag NPs that were grown in situ on the AgCl NPs, which formed Ag@AgCl nanocomposite structure. The photocatalytic activity of the AgCl/cellulosic paper decreased only slightly after three runs of photodegradation of methyl orange. The possible mechanism for photocatalysis was proposed. This work may provide a new method for the design of silver-based NPs/cellulosic paper nanocomposite photoreactors with favorable photocatalytic activities for industrial applications.

In this paper, non-solvent-induced phase separation and in situ deposition are applied to prepare a multifunctional Ag@AgCl-cellulose acetate/silk fibroin (Ag@AgCl-CA/SF) composite film. The CA/SF film is employed as an eco-friendly substrate that provides sites for Ag@AgCl nanoparticle (NP) in situ deposition. The films are characterized using various analytical methods. The photocatalytic activity of the films is evaluated via the decomposition of methyl orange (MO) under visible light. The results indicate that the Ag@AgCl-CA/SF film exhibits higher photocatalytic activity than the Ag-CA/SF film and that the reaction rate constant of MO decomposition photocatalyzed by Ag@AgCl-CA/SF is approximately 10.3 times that of Ag-CA/SF. Meanwhile, a possible photocatalytic mechanism over the Ag@Ag-CA/SF film is presented based on theoretical analysis and active species trapping experiments. Furthermore, films with silver atom and silver ion deposition exhibit good antibacterial activity against E. coli and S. aureus. This research may provide new insight into the construction of a multifunctional film reactor for organic pollutant degradation and bacterial inactivation.

An ion-imprinted sorbent (IIP) was prepared by using Ni2+ as template, 3-[2-(2-aminoethylamino) ethylamino] propyl-trimethoxysilane as functional monomer, and silica gel as carrier. The adsorption performance of IIP towards Ni2+ was investigated. IIP showed a higher adsorption capacity than that of non-imprinted sorbent, and it also exhibited high selectivity for Ni2+ in the presence of Cu2+ and Zn2+ ions. Then, IIP was used to form a dynamic membrane onto the surface of ceramic membrane for treatment of electroplating wastewater containing Ni2+. Compared with ceramic membrane, IIP dynamic membrane had much higher steady membrane flux, and also rejected Ni2+ to obtain a lower concentration of Ni2+ in the permeate fluid. Perhaps it is suitable for future practice applications.

A series of polyurethane hydrogel and polyurethane thermoplastic elastomer composite based separation membranes were successfully prepared via wet phase inversion method. The morphology, chemical structure, phase transition temperature and crystallinity of the polyurethane (PU) membranes were characterized by SEM, FTIR, DSC, and XRD, respectively. The SEM observation showed that the PU membranes exhibited irregular porous structure on the surface and path of the hole was flexural and asymmetrical in cross-section. The FTIR analysis demonstrated that thermalsensitive groups and pH-sensitive components (-N(CH₃)-) were incorporated into the PU network. The DSC experiment and XRD experiment showed that the regular arrangement of PU network was destroyed partly due to the introduction of polyurethane thermoplastic elastomer. The equilibrium swelling ratio (ESR) and water flux (J) for PU membranes clearly decreased and increased with functional groups and sophisticated structure of PU membranes, respectively. In addition, the permeation experiments indicated that the permeation percentage (P) of the glycine was strongly affected by the external temperature and pH value.

Lignocellulosic biomass is the most abundant renewable carbon resource on earth, for which many efforts have been made to convert it using various chemocatalytic processes. Heterogeneously chemocatalytic conversion conducted based on reusable solid catalysts is the process with the greatest potential studied presently. This review provides insights into the representative achievements in the research area of heterogeneous chemical catalysis technologies for the production of value-added chemicals from lignocellulosic polysaccharides (cellulose and hemicellulose). Popular approaches for the conversion of lignocellulosic polysaccharides into chemicals, including hydrolyzation (glucose, xylose and arabinose), dehydration (5-hydroxymethylfurfuran, furfural and levulinic acid), hydrogenation/hydrogenolysis (sorbitol, mannitol, xylitol, 1,2-propylene glycol, ethlyene glycol and ethanol), selective oxidation (gluconic acid and lactic acid), have been comprehensively reviewed. However, technological barriers still exist, which have to be overcome to further integrate hydrolysis with the refinery processes based on multifunctional solid catalysts, and convert ligncellulosic polysaccharides into value-added fine chemicals. In general, the approaches and technologies are discussed and critically evaluated in terms of the possibilities and potential for further industrial implementation.

Two-phase Ca

An efficient Ag@AgCl-polyurethane/silk fibroin (Ag@AgCl-PU/SF) composite photocatalyst was synthesized by an eco-friendly and practical multistep route, including a wet phase inversion technique, to prepare polyurethane/silk fibroin (PU/SF) composite porous films as a substrate. An impregnation-precipitation-photoreduction process was used to decorate Ag@AgCl nanoparticles in situ on the PU/SF composite porous films. The obtained samples exhibited high photocatalytic activity for the degradation of Rhodamine B (RhB) under ultraviolet and visible light. Meanwhile, the photocatalytic activity of the samples decreased only slightly after 4 runs of photodegradation of RhB. Importantly, the Ag@AgCl-PU/SF films could be recycled without centrifugation and filtration. The Ag@AgCl-PU/SF films also exhibited excellent antibacterial activity. Possible mechanisms for photocatalysis were proposed. This work may provide a new approach for the design of novel porous polyurethane film photoreactors that possess excellent photocatalytic and antibacterial activities for multifunctional applications.

A novel ion-imprinted blend membrane was fabricated to separate selectively platinum(IV) from aqueous media. An amphiphilic copolymer poly(methyl methacrylate)-b-poly(4-vinylpyridine) (PMMA-b-P4VP) was firstly synthesized via the reversible addition fragmentation chain transfer polymerization, and characterized by 1H NMR, FT-IR and GPC. Subsequently, poly(vinylidene fluoride) (PVDF) blend membranes were prepared using PMMA-b-P4VP as a blending additive. Effects of the following factors on performance of blend membranes were systematically examined: P4VP content of PMMA-b-P4VP, solvent type, and PMMA-b-P4VP/PVDF ratio. Further, platinum(IV) ion-imprinted membrane (Pt(IV)-IIM) was fabricated by blending polymer-Pt(IV) complexes with PVDF. SEM, FTIR-ATR, contact angle, water flux and adsorption capacity were employed to characterize all membranes. Results indicated that the membrane, which was prepared using the copolymer with high P4VP content (polymerization time 10 h) as a functional polymer, N,N-dimethylacetamide as a solvent and PMMA-b-P4VP/PVDF ratio of 30 wt%, exhibited an intriguing morphology and much higher performance. Pt(IV)-IIM showed higher adsorption and selectivity for Pt(IV) (selectivity coefficients of 27.66 ± 1.38 and 77.16 ± 3.86 for Pt(IV)/Cu(II) and Pt(IV)/Ni(II), respectively) compared with a non-imprinted membrane. During membrane filtration, Pt(IV)-IIM was effective and selective for separation of Pt(IV) in the presence of Cu(II) and Ni(II) ions. Also, Pt(IV)-IIM was chemical stable, and had a good regeneration performance.

The flotation performance and hydrophobic mechanism of O-ethyl-N-benzoyl thionocarbamate (EBZTC) on chalcopyrite were first estimated by single flotation experiments, batch adsorption experiments, contact angle measurements, DFT calculation and FTIR analysis. Single flotation experiments illustrated that a flotation recovery of 96.7% was achieved to chalcopyrite when EBZTC was used compared to 90% with SIBX at pH 6.5. Adsorption experiments indicated that the adsorption process of EBZTC on chalcopyrite surface was an exothermic monolayer chemisorption process. Hydrophobic mechanism demonstrated that EBZTC chemisorbed onto the chalcopyrite surface through the chemical reactions of C O and C S groups to the copper species with the formation of C O Cu and C S Cu bonds, which resulted in the coverage of the hydrophobic groups of EBZTC onto the chalcopyrite surface to enhance its hydrophobicity.

Novel rod-like Bi3+/Ln3+:GdVO4 phosphor have been successfully fabricated via a mixed solvothermal route. X-ray diffraction, transmission electron microscopy, inductively coupled plasma and spectrofluorimeter equipments are used to characterize the samples. By introducing Bi3+ into Ln3+:GdVO4, efficient energy transfer occurs from Bi3+–V5+ charge transfer state to Ln3+, these phosphors can efficiently absorb near-ultraviolet light through the Bi3+–V5+ metal–metal couple charge transfer and exhibit intense multifarious luminescent colors by modulating the doping content of Ln3+ ions. Therefore they have potential applications in color display field.

Nanofiltration membrane with good separation performance can effectively remove dyes from wastewater. A new type of composite membrane (TiO2/PEI/PDA-SMA/PES), which possesses excellent dye/salt separation property, was facilely manufactured by a combined strategy of mixing styrene-maleic anhydride (SMA) with polyethersulfone (PES), polydopamine (PDA) coating, titanium dioxide (TiO2)/polyethylenimine (PEI) co-deposition and cross-linking. The as-prepared membranes were characterized using SEM, AFM, FTIR, surface zeta potential, water permeability and contact angle measurement. The effect of TiO2 content on permeability and retention of membrane was discussed. Results demonstrate that TiO2/PEI/PDA-SMA/PES membrane is hydrophilic and positively charged, and it exhibits high permeability for pure water (73.2 L·m−2·h−1·bar−1), reasonable retention to dyes (98.6%, 92.3% and 90.4% for Congo Red, Rhodamine B and Crystal violet, respectively) and satisfactory transport to salts (39.5, 36.4, 30.6 and 29.4 L·m−2·h−1·bar−1 for Na2SO4, NaCl, MgSO4 and MgCl2, respectively). In addition, the membrane shows a great antifouling performance and long-term stability during the filtration of dye/salt simulated wastewaters. Further, the membrane is used to treat actual textile wastewater. It also shows good separation performance (permeability 10.6 L·m−2·h−1·bar−1, COD retention 98.2%, and color retention 99.7%). Perhaps it is fit for potential treatment of textile wastewater.

Flotation collectors with strong collecting ability and superior selectivity have important application prospects for recovering complex and refractory copper sulfide resources. Herein, a novel surfactant of N-benzoyl-N’,N’-diethyl thiourea (BDETU) with C O and C S groups is synthesized for separation of chalcopyrite and pyrite. The flotation performance and adsorption mechanism of BDETU to chalcopyrite and pyrite were evaluated by flotation experimental, adsorption experimental, contact angle measurements, UV–vis spectroscopy, as well as FTIR analyses and DFT calculation. By comparing the flotation performances with the traditional flotation collector of O-isopropyl-N-ethyl thionocarbamate (IPETC), it becomes evident that BDETU exhibit stronger collecting ability and excellent selectivity for chalcopyrite against pyrite. These results might be attributed to the facts that BDETU can selectively adsorb on the surface of chalcopyrite and strengthen its surface hydrophobicity, while the hydrophobicity of pyrite surface is not improved with the weak adsorption of BDETU on its surface. The analyses of adsorption mechanism reveal that BDETU is chemically adsorbed on the surface of chalcopyrite by the reactions of the functional groups (C O and C S) to the copper species with the formation of C O Cu and C S Cu structures.

A surface-grafted imprinted ceramic membrane (IIP-PVI/CM) for recognizing molybdate (Mo(VI)) anion was prepared by surface-initiated graft-polymerization. Firstly, raw alumina ceramic membrane (CM) was deposited with SiO2 active layer by situ hydrolysis deposition method. Subsequently, γ-methacryloxy propyl trimethoxyl silane (MPS) was used as a coupling agent to introduce double bonds onto the SiO2 layer (MPS-CM). Then, 1-vinylimidazole (VI) was employed as a functional monomer to graft-polymerization onto the MPS-CM (PVI-CM). During the graft-polymerization, the influence factors of grafting degree of PVI were investigated in detail. Under optimum conditions (monomer concentration 20 wt%, temperature 70 °C, initiator amount 1.1 wt% and reaction time 8 h), the grafting degree of 20.39 g/100 g was obtained. Further, Mo(VI) anion was used as a template to imprint in the PVI-CM by employing 1,6-dibromohexane as a cross-linking agent, and then Mo(VI) was removed, obtaining the IIP-PVI/CM with many imprinted cavities for Mo(VI). Thereafter, static adsorption and dynamic separation properties of IIP-PVI/CM for Mo(VI) were studied. Results indicate that IIP-PVI/CM shows a specific selectivity for Mo(VI) with the adsorption capacity of 0.69 mmol/100 g, and the selectivity coefficient of IIP-PVI/CM is 7.48 for molybdate to tungstate anions. During the dynamic separation, IIP-PVI/CM has also good selectivity for separation of Mo(VI) and W(VI) anions.

An ion-imprinted blend membrane (Ru(III)-IIM) for selectively adsorbing ruthenium(III) from aqueous solutions was fabricated by blending poly(methyl methacrylate- co -2-hydroxyethyl methacrylate) P(MMA-HEMA) with polyvinylidene fluoride (PVDF). Firstly, P(MMA-HEMA) was successfully synthesized and characterized. Subsequently, combining with the ion-imprinting technology, a series of Ru(III)-IIMs were fabricated via the non-solvent induced phase inversion method. The results indicated that increasing the polymer concentration and extending the evaporation time led to transform the cross-section of membranes from macrovoid structure to a finger-like or tear-like even sponge structure, and also decreased the water flux. The contact angle tests showed the hydrophilicity of Ru(III)-IIMs were effectively improved by blending with P(MMA-HEMA), compared with the PVDF membrane. The adsorption experiments showed that the adsorption capacity of ruthenium(III) onto the Ru(III)-IIM was pH-dependent, and the maximum adsorption capacity reached 42.31 mg g − 1 at pH 2.0. The adsorption process was well described by the pseudo-second-order kinetic model and the Langmuir isotherm model. The selective adsorption was studied by using Ni(II) as an interfering ion. Compared with the non-imprinted membrane, the Ru(III)-IIM showed a higher selectivity for Ru(III), with a selectivity coefficient of 6.0 for Ru(III)/Ni(II). In addition, the Ru(III)-IIM had a high reusability and still maintained about 95% of its initial adsorption capacity for Ru(III) after eight cycles.

In order to separate palladium (II) from electroplating wastewaters, poly(4-vinylpyridine)-b-polysulfone-b-poly(4-vinylpyridine) (P4VP-PSF-P4VP) / polysulfone blend membranes were fabricated by combining non-solvent induced phase separation, surface segregation and self-assembly of block copolymer. Amphiphilic P4VP-PSF-P4VP was used as the membrane base material, which was synthesized by introducing the functional monomer of 4-vinylpyridine (4-VP), and polysulfone as the additive. Effects of blend ratio and 4-VP content on membrane performance, such as structure, hydrophilicity, pure water flux and adsorption capacity towards Pd (II), were investigated. The membranes exhibited dense surface structure and low roughness due to surface segregation and self-assembly of P4VP-PSF-P4VP. The presence of 4-VP increased hydrophilicity and water flux of membrane, and it also provided good adsorption capacity towards Pd (II) (up to 103.1 ± 5.15 mg/g). Further, the membrane was used to separate Pd (II) from simulated wastewaters during filtration. It showed good rejection ability and high selectivity towards Pd (II) in co-existence of Cu (II) and Ni (II), and selectivity coefficients of Pd/Cu and Pd/Ni are 41.9 ± 1.88 and 97.8 ± 4.32, respectively. In filtration process of actual electroplating wastewater, the membrane also exhibited excellent rejection performance (Pd (II) rejection reached up to 96.8 ± 2.71%). Perhaps it is suitable for future practice applications.

Highly dispersed Co/SBA-15 mesoporous materials as an efficient and stable catalyst for partial oxidation of cyclohexane has been studied in present work. The physico-chemical properties of Co/SBA-15 catalysts were systematically characterized by XRD, XPS, H2-TPR, UV–vis DRS, FT-IR, BET, SEM and TEM-EDX. The characterization results indicated that the nanoscale cobalt oxide particles were highly dispersed on SBA-15 support surface, and part of cobalt ions were incorporated into the silica framework to formed very stable structure. For partial oxidation of cyclohexane with molecular oxygen, Co/SBA-15 displayed a good catalytic performance for 9.6% of cyclohexane conversion and 81.1% of selectivity toward KA oil among the Co-containing molecular sieves catalysts, and it also showed highly stability and reusability in this oxidation reaction. The influences of reaction parameters such as initial oxygen pressure, reaction temperature, catalyst dosage and reaction time on the cyclohexane oxidation with Co/SBA-15 as catalys were also investigated. Maybe this work employing Co/SBA-15 as highly efficient and stable catalyst for the preparation of KA oil from cyclohexane has potential industrial application prospects.

A multifunctional Ag3PO4@AgBr-polyurethane/negative ion powder (Ag3PO4@AgBr-PU/NI) composite film is obtained by a combination of nonsolvent induced phase separation (NIPS) and an impregnation-precipitation-ion exchange method. The PU/NI composite film has an asymmetric porous structure and is used as a support to provide sites for the in situ loading of Ag3PO4@AgBr particles. Various analytical techniques are applied to explore the characteristic properties of the films. The photocatalytic activity and recyclability of the films are assessed by the decomposition of methyl orange (MO) in recycling processes under visible light irradiation. The Ag3PO4@AgBr-PU/NI composite film exhibits higher photocatalytic activity than the Ag3PO4 -PU/NI and AgBr-PU/NI composite films. Moreover, up to approximately 85% of the photocatalytic efficiency of the Ag3PO4@AgBr-PU/NI composite film is retained after three-cycle testing. A possible photocatalytic mechanism for the Ag3PO4@AgBr-PU/NI film is proposed based on active species trapping experiments and a theoretical analysis. The composite films display a broad-spectrum antibacterial property against Gram-negative E. coli and Gram-positive S. aureus. This work may provide a simple pathway to construct a highly efficient polyurethane composite film reactor for organic pollutants degradation and bacterial inactivation.

To promote the utilization of collagen fiber, silver salts/collagen fiber hybrid composites with photocatalytic and antibacterial activities were successfully prepared in this study via the in-situ organic-inorganic process. The surface morphology, chemical composition and structure were discussed. Scanning electron microscopy (SEM) observation showed that the silver salts/collagen fiber hybrid composites were successfully prepared with silver salt particles (300–500 nm) distributing evenly on the surface of collagen fiber. X-ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FTIR) analysis provided strong evidence for the successful coating of silver salts on the surface of collagen fiber and the hybrid mechanism was subsequently discussed. The photocatalytic activity was evaluated by degrading methyl orange (MO) under ultraviolet (UV) light and visible light, respectively. The results indicated that AgCl/Collagen Fiber showed the most efficient photocatalytic activity under UV and visible light irradiation. Furthermore, the introduction of Ag+ endowed the photocatalysts with antibacterial performance, which was investigated by measuring the width of the bacteriostatic belts. The results indicated the antibacterial activity of the composites, proving that the photocatalysts were durable and reusable.

A novel modified ceramic membrane (CM-SiO2-A) has been prepared with the depositing and grafting technologies for removal of Ni2+ from aqueous solutions. Firstly, the silica was deposited onto the surface of initial ceramic membrane (CM) by using the in situ hydrolysis deposition method and activated to obtain the silanol groups. Then, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane was grafted onto the silica layer to obtain the CM-SiO2-A. The CM-SiO2-A was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, and thermogravimetric analysis. Further, the change of water flux and separation of Ni2+ were studied by using the modified membrane. Results showed that the water flux of CM-SiO2-A was decreased by 84.79% compared with the CM. The CM-SiO2-A had a much higher total rejection rate of Ni2+ (77.24%) than that of the un-grafted membrane (1.02%) at initial Ni2+concentration of 10 mg/L and exhibits the potential for separation of low concentration of Ni2+ from aqueous solutions. Copyright © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.

A novel copper(II) ion-imprinted chitosan/aluminum oxide (IIP/Al2O3) has been prepared with the surface-grafted and surface imprinting technologies for selective adsorption of Cu(II) from aqueous solutions. Al2O3 powder, modified with tetraethyl orthosilicate, was used as the carrier material. Chitosan was employed as the functional monomer. The prepared IIP/Al2O3 was characterized by using the infrared spectra, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Effects of pH and initial concentration of Cu(II) on the adsorption capacity of IIP/Al2O3 were investigated, and the adsorption kinetics and thermodynamics were also studied. Results showed that, the kinetic data were fitted well by the pseudo-second-order model. The adsorption equilibrium data were fitted well by the Langmuir isotherm model. The thermodynamic parameters indicated that the adsorption of Cu(II) on IIP/Al2O3 was an endothermic and spontaneous process. Further, the selectivity experiment was done for the ...

Hexagonal Yb3+/Er3+:NaGdF4 nanocrystals codoped with Sn4+ ions were produced via an adjustive solvothermal approach. Simultaneous morphology regulation and intensified upconversion (UC) luminescence of Yb3+/Er3+:NaGdF4 nanocrystals were achieved through Sn4+ ions doping. Upon introducing Sn4+ ions into the NaGdF4 host, a part of the nanocrystals were converted to nanocubes. By optimizing the Sn4+ ions doping content to 40 mol%, UC luminescence intensity of the green and red emissions were intensified by 21 and 31 times, respectively. Moreover, the possible mechanisms for morphology transformation and UC luminescence enhancement of Sn4+-doped Yb3+/Er3+:NaGdF4 nanocrystals were discussed elaborately. Additionally, in contrast to the sample fabricated by co-precipitation method, the result indicated that the UC luminescence intensity with 40 mol% Sn4+ ions doping was about 2.5 times higher than the former one. This research could be helpful for designing high-performance UC materials and fulfilling their practical applications.

Polyelectrolyte-enhanced ultrafiltration was investigated for the removal of chromium(VI) anion from aqueous solutions with the help of cationic polyquaternium-6 (PQ6). The ultrafiltration behavior of Cr(VI) aqueous solutions was studied at pH 6. Owing to an effect of electrostatic repulsion, the membrane with a molecular weight cutoff (MWCO) of 10 000 Da rejected about 30% of Cr(VI). Then, ultrafiltration of aqueous solutions of a Cr(VI)–PQ6 complex was further studied. Factors affecting Cr(VI) rejection coefficient (RCr) and permeate flux (J) such as pH, polymer metal ratio (PMR), the added salts, temperature, operating pressure and MWCO were investigated. The best operating parameters, such as pH 9 and PMR 10, were obtained in order to achieve high RCr (>0.97). By increasing the concentrations of the added salts (KCl, KNO3 and K2SO4), RCr was found to decrease significantly. J decreases slightly in the pH range of 2–5. Cl− or SO42− does not affect J, whereas NO3− results in the decrease of J. The binding mechanisms of dichromate, chromate and nitrate with PQ6 were proposed. Finally, the concentration experiment was carried out under the optimal conditions. RCr was close to 1, and J decreases slightly. Chromium was effectively concentrated by the membrane. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

Polyquaternium-6 (PQ6) as the water-soluble polymer was used for complexing the anion forms of tungsten (VI) before ultrafiltration. Tungsten (VI)-PQ6 complex was retained by polysulfone hollow fiber ultrafiltration membrane in the complexation-ultrafiltration process. Effects of various operating parameters such as polymer metal ratio(PMR), pH and chloride ion concentration on permeate flux ( J ) and tungsten rejection coefficient ( R ) were investigated. The integration of four experiments including concentration, decomplexation, diafiltration and reuse of regenerated polymer was carried out. In the process of concentration, J declines slowly and R is about 1 at PMR of 3 and pH of 7. Tungsten concentration in the retentate increases linearly with volume concentration factor. Tungsten is concentrated efficiently with the membrane. The concentrated retentate was used further for the decomplexation. It takes about 6 min to reach the decomplexation equilibrium at chloride ion concentration of 50 mgL −1 . The decomplexation percentage of tungsten (VI)-PQ6 complex reaches 56.1%. In the diafiltration process, tungsten (VI) can be extracted effectively by using 50 mgL −1 chloride ion solution, and the purification of the regenerated PQ6 is acceptably satisfactory. The regenerated PQ6 was used to bind tungsten (VI) at various pH values. The binding capacity of the regenerated PQ6 is close to that of fresh PQ6, and the recovery percentage of binding capacity is higher than 90%.

Complexation–ultrafiltration process was investigated for cerium(III) recovery from aqueous solutions by using poly (acrylic acid) sodium salt (PAASS) as a complexing agent. The adsorption of cerium(III) on PAASS was preliminarily studied at different pH values. Next, effects of pH, polymer metal ratio (PMR), calcium(II) and competitive complexing agents on permeate flux (J) and cerium rejection coefficient (R) were investigated in the total recirculation mode. Finally, the integrations of four experiments including concentration, decomplexation, regeneration of PAASS and reuse of regenerated PAASS were carried out. Obtained results show that the adsorption can be described well using the Langmuir equation. If pH is reduced below 4, J decreases rapidly. PMR has negligible effect on J. R increases with increasing pH or PMR. Calcium(II) and ethylenediaminetetraacetic acid disodium salt have the effects on R, but these effects can decrease by increasing pH. Tartrate sodium does not influence R. In the process of concentration, J declines slowly, and R is about 1. It takes 40 min to reach the decomplexation equilibrium at pH 3. The decomplexation percentage of cerium(III)–PAASS complex is about 70%. In the regeneration of PAASS, cerium(III) can be removed effectively, and the purification of regenerated PAASS is acceptably satisfactory. The binding capacity of regenerated PAASS is close to that of fresh PAASS, and the recovery percentage of binding capacity is higher than 90%. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.