Vinylphosphonic Acid Research Articles

Acid stable bi-functional cation exchange membrane based on modified poly(vinylidene fluoride-co-hexafluoropropylene) for electrochemical Bunsen process

Synthesis of 4-(N-isopropylacrylamido)butane-1-sulfonic acid monomer has been achieved by sultone ring opening followed by condensation reaction. Stable and flexible bi-functional cation exchange membranes have been prepared by dehydofluorinated poly(vinylidene fluoride-co-hexafluoropropylene) and 4-(N-isopropylacrylamido)butane-1-sulfonic acid in presence of initiator and vinyl phosphonic acid. Fluorinated carbon chain grafted with bi-functional groups (-SO3H, and –PO3H2) via side chain spacer, are attractive structural features of reported cation exchange membranes. Presence of fluorinated carbon chain grafted with bi-functional charged groups via side chain spacer are responsible for easy accessibility of water. Reported bi-functional PVIP-1.81 cation exchange membrane exhibits 5.84 × 10−2 S cm−1 conductivity and about ~2.5-fold high bound water content, in compare with Nafion 177 membrane due to high molality of charged groups (–SO3H and –PO3H2). Further, PVIP-1.81 cation exchange membrane shows ~100% efficiencies (ηa: 95.8%; and ηc: 96.9%) during electrochemical Bunsen process (water splitting), which rule out side reaction. Further, electrical energy (or equivalent heat energy) (UH2) requirement for producing 1 mol of H2 by electrolysis using PVIP-1.81 membrane (279.46 kJ mol−1-H2) is comparable with that for Nafion117 membrane (280.80 kJ mol−1-H2). These observations confirm the high performance and suitability PVIP-1.81 cation exchange membrane for membrane electrolysis and water splitting (Bunsen process).

Phosphonate mesoporous hybrid thin films: Synthesis of organophosphosilane by thiol-ene click chemistry and applications in formation and stabilization of silver nanoparticles

Abstract The synthesis of hybrid inorganic organic mesoporous films with pores displaying phosphonic acid functions and their use as template for Ag nanoparticles are presented here. The Photochemical radical thiol – ene addition (PRTEA) was used for the synthesis of organophosphonated thiopropyltrimethoxysilanes with either diethyl allylphosphonate (DEAP) and vinylphosphonic acid (VPA) functionalities, which quantitatively lead to two functionalizing agents with differential reactivities. Phosphonated Hybrid Mesoporous Silica Thin Films with different composition were obtained by incorporating variable amounts of the phosphonated silanes by co-condensation strategy. Structural characterization with electron microscopy, X-ray reflectometry (XRR) and small angle X-ray scattering (SAXS) in transmission mode demonstrated the synthesis of ordered mesoporous phases in all tested compositions. The chemical characteristics of the hybrid films were evaluated by Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) showing the quantitative incorporation of the two silanes. The phosphonic groups present in the hybrid mesoporous silica thin films surface improved the adsorption of Ag (I) ion, acting as complexation sites. Silver nanoparticles (NPs) were afterwards obtained by adsorption/reduction cycles using NaBH4 as reduction agent. The obtained nanocomposites presented well distributed Ag NPs, as demonstrated by electronic microscopy and UV–visible spectroscopy. Moreover, the NPs were highly stable against oxidation when included within the functional oxides, in comparison with the pure oxide counterpart. Both phosphonated functions produced a high Ag (I) and Ag NPs loading, but the different chemistry of the phosphonates had an impact on total loading and stability of the NPs. While the free phosphonic acid presented the largest Ag (I) ion adsorption, higher chemical stability of Ag NPs was achieved for the ester protected phosphonate.

Highly efficacious entrapment of Th (IV) and U (VI) from rare earth elements in concentrated nitric acid solution using a phosphonic acid functionalized porous organic polymer adsorbent

It is challenging to extract Th (IV) and U (VI) from rare earth elements (REEs) in concentrated acidic solution. Herein, a nanoporous polymer adsorbent P (DVB-VPA) bearing phosphonic acid groups has been synthesized by solvothermal copolymerization of divinylbenzene (DVB) and vinylphosphonic acid (VPA). The maximum adsorption capacity (qmax) for Th (IV) and U (VI) onto P (DVB-VPA) was estimated to be 354.6 and 216.5 mg g−1 at 298 K in 4 mol L−1 of hydrogen nitrate media, which were much larger than most of the adsorbents reported previously. Besides, P (DVB-VPA) exhibited a good selectivity for Th (IV) and U (VI) from REEs in concentrated nitric acid solution, since the values of the selectivity for Th (IV) and U (VI) over La (III), Ce (III), Eu (III), Nd (III) and Sm (III) were 82.2% and 72.5%, respectively. XPS analysis revealed that the adsorption mechanism was achieved through the complexation of PO ligands anchored onto the polymer skeleton of P (DVB-VPA) with thorium and uranium. Due to P (DVB-VPA) showed a larger binding force toward Th (IV) than U (VI), both q max and selectivity for Th (IV) in concentrated hydrogen nitrate media was larger than those for U (VI) on P (DVB-VPA), which has been confirmed by DFT calculations.

High performance flexible supercapacitors including redox active molybdate incorporated Poly(vinylphosphonic acid) hydrogels

Novel gel polymer electrolyte (hydrogel) was prepared by incorporation of poly (vinylphosphonic acid) (PVPA) as a host matrix and redox active ammonium molybdate, Mo. Supercapacitors including active carbon electrodes were fabricated using hydrogels, PVPA/MoX where X represents the percent fraction of Mo in PVPA. All the electrolytes were in gel form and show excellent bending and stretching properties in a device. The electrochemical performance of the devices was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) experiments. Surprisingly, the specific capacitance (Cs) of the device increased to 1276 F g−1 which is at least 50 times enhancement by introducing Mo as mediator compared to the PVPA based system. The supercapacitor with PVPA/Mo10 has the highest energy density of 180.2 Wh kg−1 at a power density of 500 W kg−1. The device with the same hydrogel structure exhibited higher performance after 2300 charge-discharge cycles and the maintained 85% of its initial capacitance performance. A supercapacitor was fabricated using PVPA/Mo10 and tested under bent and twisted conditions confirming remarkable capacitance retention.

CP MAS kinetics and impedance spectroscopy studies of local disorder in low-dimensional H-bonded proton-conducting materials

The 1H–13C cross-polarization magic angle spinning (CP MAS) kinetics was studied in poly(vinyl phosphonic acid) (pVPA), i.e. material with high degrees of freedom of proton motion along H-bonded chains. It has been shown that the CP kinetic data for the adjacent 1H–13C spin pairs can be described in the frame of the isotropic spin-diffusion approach. The rates of spin diffusion and spin-lattice relaxation as well as the parameters accounting for spin coupling and the effective size of spin clusters have been determined. The local order parameter S ≈ 0.63±0.02, determined as the ratio of the measured dipolar 1H–13C coupling constant and the calculated static dipolar coupling constant, is significantly lower than the values deduced for related sites in other polymers and in series of amino acids. This means that the local disorder of the C–H bonds in pVPA is between those for rather rigid C–H bond configurations having S = 0.8–1.0 and highly disordered –CH3 groups (S ~ 0.4). This effect can be attributed to the presence of the proton transfer path where proton motion is easy to activate. The activation energy for the proton motion Ea = 59±7 kJ/mol was determined from the impedance spectroscopy data analysing the temperature and frequency dependences of the complex dielectric permittivity of pVPA. The rates of proton spin-lattice relaxation and spin diffusion are of the same order and both run in the time scale of milliseconds.

Effect of polyvinylphosphonic acid on resin-dentin bonds and the cytotoxicity of mouse dental papilla cell-23

Statement of problemPolyvinylphosphonic acid (PVPA) could be used as a biomimetic remineralization analog and a matrix metalloproteinases (MMPs) inhibitor. However, studies are lacking regarding the performance of PVPA in dental bonding systems for maintaining the durability of the resin-dentin bond. PurposeThe purpose of this in vitro study was to investigate the effect of PVPA on the durability of resin-dentin bonds and the viability of mouse dental papilla cell-23 (MDPC-23). The mechanical properties of resin-dentin interfaces during long-term storage were analyzed, and the potential application of PVPA as a biomimetic remineralization analog in adhesive dentistry was evaluated. Material and methodsSeventy-five extracted noncarious human third molars were collected and randomly divided into 5 groups, and then the microtensile bond strength (μTBS) data and scanning electron microscope (SEM) images were used to evaluate the preservation condition of resin-dentin bonds after 1 day, 6 months, and 1 year of storage. The cytotoxicity of PVPA was detected by cell proliferation assay and cell apoptosis assay. ResultsCompared with the control and chlorhexidine (CHX) groups, the combined group (treated with both 200-μg/mL PVPA and biomimetic remineralization) had excellent bond durability. The exposed collagen fibril from the PVPA-treated groups (included 200-μg/mL and 500-μg/mL PVPA groups and a combined group) still showed integrity after 1 year of storage when compared with the control group. PVPA up to 500 μg/mL showed no cytotoxicity to MDPC-23 and did not inhibit cell growth. ConclusionsThis study offered evidence that PVPA did not result in cytotoxicity at low concentrations as an MMP inhibitor and a biomimetic remineralization analog. In addition, the application of PVPA improved bond strength and preserved collagen integrity after 1 year of in vitro storage.

Towards High-Performance Proton Exchange Membrane Fuel Cells Using Polymer Coated Heteroatom Doped Partially Unzipped Carbon Nanotubes As Catalyst Support

Enhancing the durability and reducing the cost of Proton Exchange Membrane Fuel Cells (PEMFC) are the bottlenecks for the commercialization. Platinum is reported as the best electrocatalyst for both anode and cathode due to its optimum binding energy towards hydrogen, oxygen atoms and products during the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR). The electrocatalyst loading at the anode and the cathode can be minimized by dispersing Pt nanoparticles (NPs) on high surface area and conductive carbon support material. The durability and performance of PEMFC depend on the interaction between the support and Pt NPs as well as the number of active sites available for the reactions, which can be enhanced by selective coating of proton conducting polymer on the hetroatom doped supporting material. In the present work, we have synthesized highly proton conducting polymer polyvinyl phosphonic acid (PVPA) coated heteroatom doped partially unzipped carbon nanotubes (H-PECNT) and used as the catalyst support material for Pt NPs. The heteroatom doping increases the ORR activity of the support material and the PVPA coating adhere Pt NPs to the support during cycling and also increases the active sites. Moreover, we have coated PVPA on H-PECNT by varying different ratios of PVPA to H-PECNT and to find the optimum PVPA percentage on H-PECNT, which enhances the performance of PEMFC. The single cell measurements deliver a high power density with 6% of PVPA than the commercial Pt/C as well as other PVPA ratios wherein both electronic conductivity of the support material and proton conductivity of PVPA contribute significantly to the performance.

Phosphonic acid vs phosphonate metal organic framework influence on mild steel corrosion protection

Phosphonate metal organic frameworks synthesized starting from a 1:1 ratio of corresponding nitrate and vinylphosphonic acid (VP) in hydrothermal conditions were analyzed by FTIR, X-Ray powder diffraction, elemental analysis and thermogravimetric analysis. The ability Co and Zn vinylphosphonate molecules to anchor on the surface of the iron were investigated. Their binding stability on iron surface in acid saline solution was tested by electrochemical methods (polarization curve- CP and electrochemical impedance spectroscopy -EIS) and ATR-FT-IR.A 2 mM concentration of CoVP allows the formation of a protective layer on the iron surface which provides 96.8% inhibitory efficiency (IE), close to that provided by the corresponding phosphonic acid VP. The low corrosion rate in the presence of CoVP as compared to ZnVP may be due to the lower hydrolytic stability of CoVP. Following the hydrolysis reaction, the phosphonic acid is released. Phosphonic acid released further binds to the metallic surface and thus improves the quality of the protective film.

PKa-Directed Incorporation of Phosphonates into MOF-808 via Ligand Exchange: Stability and Adsorption Properties for Uranium.

We report a class of pKa-directed, precise incorporation of phosphonate ligands into a zirconium-based metal-organic framework (Zr-MOF), MOF-808, via ligand exchange. By replacing of formate ligands with methylphosphonic acid (MPA), ethanephosphonic acid (EPA), and vinylphosphonic acid (VPA), whose pKa values are slightly higher than that of the benzenetricarboxylic acid (BTC) linker in MOF-808, daughter MOFs can be synthesized without controlling the stoichiometric amounts of added MPA. The methylphosphonate MOFs (808-MPAs) demonstrate high porosities, with only small changes in the pore diameter and specific surface area when compared with the parent MOF-808. PXRD patterns and structure refinements indicate the expansion of the lattice for all MOFs after decorating with methylphosphonate ligands. The XPS spectra reveal a charge redistribution of the Zr6 node after ligand exchange. FTIR and 31P MAS NMR spectra, combined with DFT calculation, suggest that the methylphosphonate ligand is connected to the Zr6 node as CH3P(O)(OZr)(OH) species with an accessible acidic P-OH group. Besides, 808-MPAs demonstrate excellent chemical stability in concentrated HCl, concentrated HNO3, hot water, and 0.2 mol/L trifluoroacetic acid solutions. Impressively, 808-MPAs show ultrafast adsorption performance for uranyl ions using the ion-exchange property of P-OH sites in their cavity environment, with an equilibrium time of 10 min, much quicker than the previous adsorbents. The present study demonstrates a series of important proof-of-concept examples of the pKa-directed Zr-MOFs with tunable phosphonate-terminated ligands, which can extend to other phosphonate-functionalized Zr-based framework platforms in the near future.

Effect of vinylphosphonic acid and polymer binders with phosphate groups on performance of high-temperature polymer electrolyte membrane fuel cell

High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are operated between 120 °C and 180 °C. As a result, they cannot employ Nafion® as an electrode ionomer because the proton conductivity of Nafion® is very low without water. In this study, new polymers (poly(phenylene oxide), PPO) with a phosphate group including methyl phosphonic acid (PPO-MPA) or 6-oxohexyl phosphonic acid (PPO-HPA), which show good proton conductivities, are applied as ionomers and binders to form an electrode. In addition, vinylphosphonic acid (VPA) is investigated as an electrode additive. The PPO-MPA electrode shows a lower wetting angle than that of the PPO-HPA electrode. After the addition of VPA, the PPO-MPA electrode becomes more hydrophobic, whereas the PPO-HPA electrode becomes more hydrophilic. In the FT-IR spectra of the PPO-MPA electrode, the peak associated with the PO32− asymmetric stretch is more blue-shifted than the peak of the polyvinylidene difluoride electrode at a high temperature due to increased amounts of released protons from PPO-MPA, indicating that the binder with a phosphate group improved the proton conductivity of the ionomer in the HT-PEMFC. At 0.2 A/cm2, the performance of the membrane electrode assembly (MEA) using the PPO-MPA cathode increases from 0.55 V to 0.59 V by the introduction of VPA, whereas that using the PPO-HPA cathode decreases from 0.61 V to 0.57 V, which exhibits the same propensity as the hydrophobicity change. The value of charge transfer resistance at 0.6 V estimated by fitting of the electrochemical impedance spectra follows the same trend as the MEA performance. This is attributed to a change in catalyst coverage by phosphoric acid in the electrode by the addition of VPA and not a change in proton conductivity. The possibility of new polymer binders for the HT-PEMFC is demonstrated, and the MEA performance is shown to be influenced by the incorporation of VPA, which is accounted for the change in hydrophobicity of the electrode.

Highly Efficient Removal of Thorium in Strong HNO3 Media Using a Novel Polymer Adsorbent Bearing a Phosphonic Acid Ligand: A Combined Experimental and Density Functional Theory Study.

It is an important task to develop the technologies for the extraction of thorium from strong HNO3 media with high efficiency. In this work, solvothermal polymerization of trimethylolpropane trimethacrylate (TRIM) and vinylphosphonic acid (VPA) has been used to synthesize a novel polymer material P (TRIM-VPA) bearing a phosphonic acid ligand for thorium entrapment in strong HNO3 media. Under the current experiment condition, the polymer adsorbents showed a record-breaking maximum adsorption capacity for thorium (403.2 mg g-1) with an excellent selectivity for thorium over Gd(III), Nd(III), Ce(III), Sr(III), Sm(III), and La(III) in 4 mol L-1 HNO3 media at 298 K. The content of P═O ligands existing on P (TRIM-VPA) has an obvious influence on the adsorption capacities for thorium. Increasing the content of P═O ligands would result in higher adsorption capacity of thorium. The isothermal data fitted well the Langmuir model, and the sorption kinetics fitted the pseudo-second-order model. The adsorption behavior was not only spontaneous but also endothermic in reality. Both XPS and FTIR studies revealed that the adsorption interaction for thorium extraction was acquired only via the coordination of P═O groups anchored on P (TRIM-VPA) with thorium. Moreover, P (TRIM-VPA) still had high adsorption capacity after five sorption-desorption cycles in 4 M HNO3 media. DFT calculation suggested that a 1:2 ratio of Th(IV) with the P═O group on the same graft chain validated the experimental findings. Thus, the solvothermal polymerization method might be a promising way for the synthesis of the adsorbents for the highly efficient extraction of thorium from strong HNO3 media.

Influence of monomer reactivity on radiation grafting of phosphorus flame retardants on flax fabrics

Flax fabrics were modified by radiation grafting method to improve their flame retardancy. Several phosphonated monomers with different carbon-carbon double bond reactivity were grafted. According to 1H NMR carried out on irradiated monomers solubilized in water, the reactivity is the highest for (acryloyloxy)methyl phosphonic acid (hPAAPC1), and the lowest for allyl phosphonic acid (APA). Nevertheless, grafting yield on flax, assessed by X-ray fluorescence and scanning electron microscopy showed a different tendency. Especially (methacryloyloxy)methyl phosphonic acid (hPMAPC1) and vinyl phosphonic acid (VPA) appear to be highly grafted. In all cases, diffusion of the molecules into the flax elementary fibers bulk was observed. The choice of the solvent in washing step after the irradiation step showed to be effective to control the final phosphorus content in flax fabrics. The effect of phosphorus grafting on thermal properties and fire behavior was studied using thermogravimetric analysis, pyrolysis combustion flow calorimetry and a preliminary fire test. According to the latter, self-extinguishing and non-flammable fabrics were obtained for phosphorus content of 0.5 wt% and 1.2 wt% respectively. Correlations with flammability at microscale were pointed out. Additional cone calorimeter tests highlight the influence of flame retardant treatment on flammability under forced flaming conditions.

Flame-retardant composite coatings for cotton fabrics fabricated by using oxygen plasma-induced polymerization of vinyl phosphonic acid/cyclotetrasiloxane

Environment-friendly flame-retardant cotton textiles have been receiving considerable interest both in academic and industrial circles for years. Herein, a novel flame-retardant coating for cotton fabrics was reported based on vinyl phosphonic acid and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane through an O2 plasma-induced polymerization process. The coating on cotton fabrics was confirmed by Fourier transform infrared spectrophotometry, scanning electron microscopy and energy dispersive X-ray spectrometry. Excellent flame retardancy and thermal stability properties were found from thermogravimetric analysis, the limiting oxygen index, modified vertical burning tests and pyrolysis combustion flow calorimetry. The results revealed that there was a good synergistic effect between poly(vinyl phosphonic acid) and polysiloxane segments in flame-retardant cotton fibers. The new flame-retardant coating induced an earlier decomposition of cellulose, and enhanced the formation of stable char under thermal oxygen and significantly reduced the heat release capacity.

Proton conductivity and structural properties of nanocomposites based on boehmite incorporated poly(vinlyphosphonic acid)

In this work, novel nanocomposite polymer electrolytes bearing boehmite (Bh) cored polyvinylphosphonic acid (PVPA) were successfully produced and characterized. Nanocomposites based on PVPA(Bh)x were formed where x is the weight percentage of Bh in the PVPA matrix ranging from 2.5 to 20%. The interaction of host polymer and the additive, thermal properties, morphology as well as proton conductivities of the electrolytes were systematically studied. The reaction between PVPA and Bh was confirmed by Raman spectroscopy (RS) and X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) showed that nanocomposites have thermal stability up to around 200 °C. Differential scanning calorimetry (DSC) indicated the shifting of Tg to higher temperatures with rising Bh content. Scanning electron microscopy (SEM) pictures illustrated the wrapping of Bh by PVPA chains forming polymer-coated nanoparticles for both PVPA(Bh)5 and PVPA(Bh)10 and nano-platelet formation for PVPA(Bh)20. In a completely dry state, the proton conductivity of nanocomposite material increased with Bh up to certain content. Anhydrous PVPABh(10) is the optimum combination and conductivity was measured as 0.02 mS/cm at 150 °C. The same electrolyte has conductivity of 0.002 S/cm at ambient temperature in hydrated state (RH = 100%).

Biomineralized Hydrogel with Enhanced Toughness by Chemical Bonding of Alkaline Phosphatase and Vinylphosphonic Acid in Collagen Framework.

Alkaline phosphatase (ALP) and phosphoprotein participation in collagen mineralization is one of the most important physiological processes of bone formation. Simulating the natural mineralization process with the involvement of ALP and phosphoproteins is a powerful tool for the preparation of bone repair scaffolds. Searching for compatible approaches to chemically bond ALP with collagen molecules and introducing phosphoprotein-like molecules into a collagen network is the challenge of the day. Here, we synthesized alkaline phosphatase methacrylamide (ALP-MA) via amidation reaction to enable ALP to be grafted uniformly into the photo-cross-linking collagen gel, achieving homogeneous enzymatic mineralization. Furthermore, vinylphosphonic acid (VAP), a phosphoprotein-like molecule containing phosphonate groups, was successfully introduced on collagen molecules through photo-cross-linking, playing the role of a phosphoprotein for inducing mineralized CaP clusters deposited on the collagen backbone. Hence, a hydrogel termed CAV was synthesized via photochemical reaction among collagen methacrylamide (Col-MA), ALP-MA, and VAP (active mineral bonding site) for in situ mineralization. We found that the binding between the collagen network and CaP clusters would lead to the generation of mechanically enhanced mineralized collagen hydrogel. Encapsulated bone marrow stromal cells (BMSCs) exhibited good growth and proliferation in the in situ enzymatic mineralization process. Additionally, the simulated mineralization system is highly favorable for micropatterned structure construction and 3D bioprinting. In brief, we designed a novel approach to effectively simulate the physiological mineralization process of bone formation. The approach, incorporating great photo-cross-linking performance and enzymatic mineralization activity, was beneficial for in situ cell encapsulation and excellent cell-compatible 3D printing, holding great promise for bone tissue engineering research.

Intumescent fire‐retardant coatings for plastics based on poly(vinylphosphonic acid): Improving water resistance with comonomers

ABSTRACTCoatings based on the in situ photopolymerization of vinyl phosphonic acid (VPA) with triallyl cyanurate as a crosslinking agent are shown to be effective not only for fire‐protecting glass fiber‐reinforced epoxy resin (GRE) composites but also poly(methyl methacrylate) (PMMA), a typical meltable and flammable thermoplastic. Dry adhesion of polyVPA coatings to PMMA surfaces is excellent but, as with coatings on GRE, adhesion following water‐soak tests is poor. Copolymerizing VPA with more hydrophobic monomers improves wet adhesion, albeit with some impairment of fire performance, with copolymers of VPA and acrylonitrile giving the best results. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 47601.

Adsorption of textile dyes using an activated carbon and crosslinked polyvinyl phosphonic acid composite

Activated carbon is one of the most studied materials for the adsorption of textile dyes. The adsorptive properties of this material are a result of its high specific surface area and some of the functional groups acquired during the chemical activation. This work reports the preparation of a composite material using CarZN400 activated carbon and polyelectrolyte poly(VPA-co-TEGDMA). The adsorptive properties of the material obtained are a result of the combination of the high specific surface area of the carbon and the ionic exchange capability of the polyelectrolyte. The covering of the surface of activated carbon with poly(VPA-co-TEGDMA) allowed to obtain a composite material (CarZN400C) with greater adsorption capacity for cationic dyes compared to the carbon. The adsorption isotherms of the dyes fit Langmuir's model, and the adsorptive capacities for cationic dyes for CarZN400C ranged between 222 and 416 mg/g. The kinetic study showed that the adsorption of basic and acid dyes fit the pseudo-second order kinetic model. CarZN400C also exhibited the ability to adsorb textile dyes present in wastewater. It was observed that, when making a previous treatment of the wastewater using coagulation-flocculation followed by adsorption using CarZN400C, it was possible to obtain removal percentages of color close to 100%. The wastewaters treated by coagulation-flocculation and adsorption improved their quality by decreasing the value for COD.

Spontaneous Vesicle Formation of Monododecenyl Phosphonic Acid in Water.

We report the synthesis of amphiphilic dodecenyl phosphonic acid PC12 from vinylphosphonic acid, a reactive phosphonic acid intermediate. The trans-P-C=C moiety enabled PC12 to disperse well in water. Surface tension and dynamic light scattering measurements revealed that PC12 exhibited high surface activity and reduced the surface tension of water from 72.0 to 23.6 mN/m, thereby resulting in the spontaneous formation of aggregates even in a dilute aqueous solution (critical aggregation concentration (CAC) = 4.8 × 10-4 M). In contrast to modern lipids with double-tailed structures, the PC12 of simple singletailed structure spontaneously formed bilayered vesicles, without an external energy supply. Compared with the strength of hydrogen bonds formed by the long, saturated alkyl chain of dodecyl phosphonic acid (DPA), the strength of PC12 intermolecular hydrogen bonds was weaker. The melting point of PC12 was approximately 20°C lower than that of DPA. These results indicate that the trans-P-C=C moiety was considerably important for spontaneous vesicle formation in water. Preliminary modeling of the morphological transitions of the closed bilayer structures in the vesicles was then conducted, by varying the pH and adding an α-helical peptide scaffold.

Enhanced osteogenic activity of phosphorylated polyetheretherketone via surface-initiated grafting polymerization of vinylphosphonic acid.

Polyetheretherketone (PEEK) is considered to be a prime candidate with the potential to replace biomedical metallic materials as an orthopedic and dental implant on account of its elastic modulus similar to that of human cortical bone. Unfortunately, its biomedical application is impeded by the bioinert surface property and inferior osteogenic activity. In this work, phosphate groups were incorporated onto the PEEK surface through a single-step UV-initiated graft polymerization of vinylphosphonic acid. Diffuse reflectance Fourier transform infrared spectroscopy (DRFTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) revealed that phosphate groups were successfully introduced onto the PEEK surface without apparently altering its surface topographical feature and roughness. Water contact angle measurements diclosed the increasing hydrophilia after surface phosphonation. In vitro cell adhesion, spreading, proliferation, alkaline phosphatase activity, extracellular matrix mineralization, and real-time PCR analyses showed enhanced adhesion, spreading, proliferation and osteogenic differentiation of MC3T3-E1 osteoblast on the surface-phosphorylated PEEK. An in vivo biological evaluation in the rabbit tibiae proximal defect model by means of a histological analysis confirmed that the surface-phosphorylated PEEK had improved bone-implant contact. The obtained results indicate that enhanced osteogenic activity to surface-phosphorylated PEEK, which gives positive information of its potential applications in orthopedic and dental implants.

Increasing solubility of metal silicates by mixed polymeric antiscalants

The increase of silicate solubility is a big challenge for both hot and cold water because it reduces the deposition of metal silicates frequently observed in such systems and causes operational obstacles. The deposition of silicate coats the inner surface of the pipelines in an uncontrolled manner and reduces the harvesting of energy from brines. In this work, the solubility performance of two commercial water-soluble polymeric agents (poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA)) of various molecular weights employing dosage from 25 to 100 mg/L was examined. Along with dispersant-type antiscalant, poly(acrylamide) (PAM), poly(vinylsulfonic acid, sodium salt) (PVSA), and poly(vinylphosphonic acid) (PVPA) having chelating acidic groups were employed. Metal silicate deposits were obtained artificially in the lab-scale pressurized reactor. The experimental conditions employed were quite similar to a model power plant located in Çanakkale, Turkey. The concentration of dissolved silica was increased from 130 to 420 mg/L when 100 mg/L PEG 1500 and 25 mg/L PVSA were employed as a mixture. For the atomic-level understanding of the interaction of chelating groups with metal cations, DFT calculations were performed too.