Search

A new series of polymers comprising four terpolymers was synthesized via Mannich polycondensation of benzene-1,4-diamine, formaldehyde and piperazine by varying the benzene-1,4-diamine and piperazine ratio. The new polyamines (labeled Dipip) were characterized using 13C solid-state NMR, FT-IR, TGA, DSC, XRD, SEM and EDX. The adsorptive performances of the synthesized polymers for Erichrome Black T (EBT) uptake from aqueous solution were investigated under batch process. Equilibrium, kinetic, and thermodynamic studies were conducted to determine the influence of different operational parameters of the adsorption process. The two most promising polymers among the series show an excellent EBT removal efficiency of ~100% and ~95% with high adsorption capacities of 775 mg·g−1 and 917 mg·g−1, respectively at a meager dosage of 5 mg. The sorption of EBT on the polymers was well described by Redlich-Peterson & Langmuir model while the kinetic studies indicate that pseudo-second order model was followed. For the thermodynamic studies, the negative ΔG and positive ΔH values obtained suggest a spontaneity of the sorption process which was endothermic in nature. The results of reusability test of the resins were promising even at the fourth cycle, showcasing the potentials of the new polymers in dyes contaminated water treatment.

Oil well acidizing is a common practice used to boost oil well productivity in the industry. This practice, however, exposes the mild steel components of the wells to extremely harsh corrosive environments. Under such conditions, highly efficient inhibitors are used to minimize corrosion attack. In the present study, corrosion inhibition of mild steel in simulated acidic medium saturated with CO2 and H2S gases by a newly synthesized polyurea-based material (PUCorr-1) was investigated. Electrochemical studies supported with quantum chemical density-functional theory calculations and surface characterization revealed that PUCorr-1 adsorbs onto mild steel through a chemisorption mechanism yielding a stable protective film. The polyurea exhibited an excellent efficiency of 99.9% at a temperature of 50 C and a low concentration of 100 ppm, yielding a corrosion current density of 0.3 A/cm2. In the presence of CO2 and H2S gases, PuCorr-1 exhibited a remarkable performance (>93% efficiency) making it a potential corrosion inhibitor in industrial processes that involve the use of acid solutions in the presence of CO2 and H2S gases. The authors would like to acknowledge the financial support provided by the Deanship of Scientific Research (DSR) at the King Fahd University of Petroleum and Minerals (KFUPM) through project no. NUS15107/8. Scopus

A cross-linked microporous organic copolymer, termed KFUPM-2, was synthesized through a Friedel–Crafts alkylation polymerization of phenothiazine, pyrrole, and p-formaldehyde in the presence of iro...

Natural gas sweetening currently requires multistep, complex separation processes to remove the acid gas contaminants, carbon dioxide and hydrogen sulfide. In addition to being widely recognized as energy inefficient and cost-intensive, the effectiveness of this conventional process also suffers considerably because of limitations of the sorbent materials it employs. Herein, we report a new porous organic polymer, termed KFUPM-5, that is demonstrated to be effective in the concurrent separation of both hydrogen sulfide and carbon dioxide from a mixed gas stream at ambient conditions. To understand the ability of KFUPM-5 to selectively capture these gas molecules, we performed both pure-component thermodynamic and mixed gas kinetic adsorption studies and correlated these results with theoretical molecular simulations. Our results show that the underlying polar backbone of KFUPM-5 provides favorable adsorption sites for the selective capture of these gas molecules. The outcome of this work lends credence to the prospect that, for the first time, porous organic polymers can serve as sorbents for industrial natural gas sweetening processes.

This work reports the synthesis of a novel thiophenol-thiophene polymer (termed KFUPM-Hg) and its suitability as an adsorbent for mercury removal from wastewater and liquid hydrocarbons. KFUPM-Hg was synthesized through a Friedel-Crafts polycondensation reaction of thiophenol and thiophene in the presence of p-formaldehyde as a linker. The crosslinked polymer structure was characterized using solid-state 13C-nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis was performed to assess the polymer thermal stability, which indicated that the polymer is thermally stable to over 300 °C. A series of batch adsorption studies were used to investigate the effects of different parameters (pH, temperature, concentration, and time) on the mercury removal from aqueous solution as well as from a model liquid hydrocarbon media (decane/toluene mixture). The batch adsorption studies in aqueous media showed near quantitative removal of inorganic mercury (II) at 100 ppm using the thiophenol-thiophene polymer adsorbent. Furthermore, the thiophenol-thiophene polymer demonstrated excellent removal capabilities of methylmercury in a decane/toluene hydrocarbon mixture. Mercury adsorption onto KFUPM-Hg is an exothermic reversible physical process and follows pseudo-second order adsorption kinetics. Remarkably, these removal capabilities were achieved using polymers that directly incorporated thiophenol and thiophene groups during synthesis without the use of thiol-ene post-synthesis modifications.

The lack of solubility of polyurea materials impedes their application as effective inhibitors against metallic corrosion in aqueous media. Herein, we have synthesized a new piperazine-based polyurea inhibitor (PUCorr) which is readily soluble in water through dispersion in N-methyl-2-pyrrolidone for mild steel corrosion. The inhibitor exhibits a sufficient protection of the surface of mild steel via an intra-molecular keto-enol proton transfer mechanism leading to the formation of the Fe-PUCorr complex. First-principles calculations proposed that the keto-enol tautomerism enhances the adsorption with an increase of adsorption energies of 510, 221, 171 and 211 kJ/mol on {100}, {110}, {111} and {112} surfaces of iron, respectively. The presence of PUCorr at 100 ppm decreases the corrosion current density from 30.3 to 3.05 μA/cm2 in 0.5 M NaCl at room temperature, exhibiting a remarkable inhibition efficiency of 94.5%. Electrochemical measurements revealed that PUCorr functions as a mixed-type inhibitor, suppressing both anodic and cathodic processes. The use of synthetic polyurea materials with a low dosage shall provide a promising approach to reduce mild steel corrosion in harsh environments.

Graphene nanosheet prepared from graphite via a modified Hummers method was used to design a graphene-modified carbon-paste electrode (GCPE). The electrochemical behavior was investigated by studying the electrocatalytic behavior of the ferrocyanide redox couple on its surface by using cyclic voltammetry. The GCPE showed voltammetric responses with a higher level of sensitivity and a lower background current compared to the carbon paste electrode. The analytical applicability of the newly prepared electrodes was demonstrated by the powerful quantitative determination of promazine (PZ). The electrochemical behavior of promazine at the surface of the fabricated electrode was evaluated using cyclic voltammetry and square wave voltammetry. The voltammogram of promazine showed two oxidation peaks at 0.6 V and 0.9 V and one signal of a reduction peak at 0.57 V. A mechanism was proposed to explain the oxidation-reduction process of PZ. Square wave voltammetry (SWV) technique has been successfully applied in this study for the determination of PZ using the prepared graphene-based electrode. A linear dynamic range of 0.1 μM to 8 μM, regression factor (R2) of 0.9979, and a limit of detection (LOD) of 8 nM were obtained. The effective and straightforward method reported here to prepare the GCPE offers a high electrochemical activity and a relatively low background current. The GCPE has an excellent stability and can be recommended for promazine determination in various formulations.

For the first time, a new series of polyamines (TRI series) were synthesized by in situ polymerization of benzene-1,3,5-triamine, paraformaldehyde and various alkydiamines. 1% of acylchloride functionalized carbon nanotubes were added to produce a second series of polyamine/CNT composites (CNT TRI series). The synthesized TRI and CNT TRI Series were characterized using various techniques including Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The functionalized CNTs were characterized by transmission electron microscope (TEM). Both series were evaluated for their efficiency in the removal of lead ions from aqueous solutions. The most efficient adsorbent of both series was evaluated under different controlled conditions, including pH, contact time and initial concentration. The experimental data were subjected to Langmuir, Freundlich, and Temkin isotherm models and found that the adsorption process fit Freundlich isotherm model assuming favorable heterogeneous adsorption process with CNT TRI 1,4 having a higher adsorption capacity toward lead ions than TRI 1,4. Kinetic models including pseudo second-order and intraparticle diffusion model were also employed. The intraparticle diffusion model assumed that the mechanism of the adsorption process is controlled by film diffusion and intraparticle diffusion mechanism. The study provides potential adsorbents for the removal of lead ions from aqueous solutions.

An amine-functionalized, crosslinked porous polymer is synthesized by linking 1,4-benzenediamine and pyrrole with p-formaldehyde in the presence of hydrochloric acid catalyst. The resulting polymer was structurally characterized and proven permanently porous with a surface area of 305 m2 g−1. The high concentration of amines (–NH– and –NH2) within the backbone of the polymer result in exceptional selectivity (141) for CO2 over N2 and dynamic capacity (15.1 cm3 g−1) in the presence of water (20 : 80 v/v CO2 : N2, 91% relative humidity, 1 bar, and 298 K). The performance of this polymer is maintained over 45 cycles without loss of selectivity, capacity, nor recyclability at room temperature; making it stand out among all porous organic materials used for carbon capture.

Graphene nanosheets prepared from graphite via the modified Hummers method were decorated with silver nanoparticles (AgG). The obtained AgG was used to design a silver/graphene-modified carbon-paste electrode (AgGCPE). The prepared material was characterized by using TEM, SEM, UV-vis, Raman, XPS, and FT-IR. The electrochemical behavior of the AgGCPE Electrode was investigated by studying the behavior of the ferrocyanide redox couple on its surface by using cyclic voltammetry (CV). The AgGCPE showed voltammetric responses with a high level of sensitivity and a low background compared to the carbon paste electrode. The analytical applicability of the newly prepared electrodes was demonstrated for the methimazole determination. The electrochemical behavior at the surface of the developed electrodes was evaluated using cyclic voltammetry, amperometry, and square wave voltammetry. Two calibration curves were obtained using amperometry and square wave voltammetry. Square wave voltammetric determination showed a better calibration curve with a R 2 = 0.999 and 1–80 µM dynamic range.

The study reports the synthesis and characterization of phenol–glycol cross-linked polymers for the removal of mercury ions from aqueous solutions at low pH. The cross-linked polymers were synthesized by one pot in-situ polycondensation reaction of phenol, different glycols and paraformaldehyde used as a linker. The cross-linked polymers were characterized by different spectroscopic techniques ( $$^{13}$$ C-NMR, FT-IR). Thermal properties were investigated by thermogravimetric analysis and differential scanning calorimetry. The most efficient cross-linked polymer Ph-TETA was investigated under different controlled conditions (pH, initial concentration, time and temperature). The experimental data were subjected to Langmuir and Freundlich isotherm models and found to fit the Freundlich model with a regression value of $$R^{2}=0.9971$$ . The experimental kinetic data were investigated in pseudo-first-order, second-order and Intraparticle diffusion kinetic models. Thermodynamic parameters revealed that the adsorption is endothermic in nature and spontaneous at low pH values. The outcomes of this study reveal the possible use of Ph-TETA as an adsorbent for mercury ion removal from aqueous solutions.

This work assessed the anticorrosion and antifouling properties of a novel sol-gel derived hybrid coating functionalized with 5 different organic and inorganic biocides. FTIR and NMR analysis of the newly synthesized polymeric base material confirmed the photo-induced organic polymerization of the allyl groups in the allyltrimethoxysilane precursor of the polymer and the inertness of the allyl groups in the allyl glycidyl ether precursor. The parent coating and biocide-embedded coatings were applied on mild steel sheets, cured with UV light, and subjected to thermal, morphological and electrochemical characterization. The cured coatings were thermally stable, and their hydrophobicity increased after immersion in a saline medium, owing to further polymer crosslinking. According to lab-based electrochemical and visual evaluations of the corrosion protection performance of the different formulations, the coating embedded with Irgarol and MOLY-white 101 had an improved performance, compared with the formulations with the other added biocides. Field testing results from the coated samples were consistent with the lab results; i.e., some biocides positively affected the anticorrosion and antifouling behavior of the hybrid coatings, whereas other biocides negatively affected the newly developed hybrid coating. The methodology reported here holds promise for the development of multifunctional hybrid sol-gel coatings for mild steel substrates with interesting anticorrosion and antifouling activities in saline.

This study reports the synthesis of a new series of polydithiocarbamates via polycondensation of pyrrole, alkyldiamines and paraformaldehyde followed by functionalization with carbon disulfide. The polymers where characterized by elemental analyzer, 13 C NMR, FTIR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). The polymers were tested for the removal of cadmium ions from aqueous solutions and spiked wastewater samples. The adsorption experiments revealed the superior efficiency of the synthesized polymers in the removal of cadmium ions from aqueous solutions ( Q m = 14.18 mg/L). Experimental results showed that the data fits Ho second-order kinetic model with R 2 > 0.99, which assumes chemical adsorption. The data showed fitness to Freundlich and Langmuir isotherm models with R 2 ∼ 0.999. PYEDCS 2 cross-linked polymer showed superiority among the synthesized polymers and showed high efficiency with a removal of ∼99.7% of Cd 2+ ions and proven to be a potential adsorbent for treatment of wastewater.

A new series of aniline based polyamines were produced via mannich polycondensation reaction of aniline, formaldehyde and various alkyldiamines. The synthesized polyamines were characterized by solid 13C NMR, FT-IR and elemental analysis. Crystallinity and Surface morphology was investigated by powder X-ray diffraction and SEM-EDX. Thermal stability was tested by thermogravimetric analysis. Adsorption properties toward lead (II) and Arsenic (V) ions was studied by model solutions at controlled conditions (pH, time, temperature and initial concentration). An-Buta polymer showed higher efficacy toward the removal of lead and arsenic ions and was selected to be used in the treatment of wastewater samples and showed efficient removal % of ∼99% and % 85 for lead (II) and Arsenic (V) ions respectively. The results reveal the high potential of the synthesized polyamines to be potential adsorbents for wastewater treatment.

Three novel, highly cross-linked terpolymers were synthesized via Mannich polycondensation reaction. The cross-linked polymers were characterized by different spectroscopic (FT-IR, Solid 13C-NMR) techniques. Thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The adsorption experiments were conducted under various conditions (pH, time, initial concentration of metal ions and temperature) which revealed the efficiency of the synthesized polymers in the removal of lead(II) ions. Adsorption results from model aqueous systems indicated the superiority of BisphenolS–paraformaldehyde–piperazine (BSPF) cross-linked polymer. Further investigation on BSPF proved its efficacy by ∼99% removal of lead ions from a real wastewater sample showing potential as an efficient adsorbent for industrial wastewater treatment.

Adsorption of lead(II) and nickel(II) ions from aqueous solutions was investigated by Bermuda grass biomass. The adsorption process was studied as a function of pH, initial metal concentration, temperature and time. The experimental data obtained were investigated via Langmuir, Freundlich and Temkin isotherms. The kinetic data were examined by pseudo-second-order and intraparticle diffusion models. The biomass was shown to be highly efficient in the removal of lead and nickel ions with the removal of 99% and 54% for lead and nickel ions, respectively. The results showed that Bermuda grass biomass could be utilized as an available, cheap, biodegradable and efficient adsorbent for the removal of toxic metal ions from aqueous solutions.

A series of novel Polydithiocrabamates (DTCP) series were synthesized via Mannich-type polycondensation where Aniline and a series of diaminoalkanes were linked together with paraformaldehyde. The resultant polymer series were converted to dithiocarbamate (DTC) groups by reaction with carbon disulphide in the presence of potassium hydroxide. The size distribution, morphology, molecular structure, and properties of the DTCP series were analysed by FT-IR, 13C NMR, X-ray diffraction, FESEM, AFM, and TGA. A factorial design was created in order to study the effect of the alkyl chain length, pH, contact time and Hg (II) ions initial concentration on the performance of the DTCP towards the removal of Hg (II) ions from aqueous solution. After DTCP screening, further studies were performed on CS2-buta. The adsorption of Hg (II) ions on CS2-buta was spontaneous and endothermic, giving negative and positive values for ΔG and ΔH, respectively. The experimental data fitted the pseudo-second order kinetic model and Langmuir isotherm model (Qm = 0.11 mmol/g). CS2-buta demonstrated high selectivity for the removal of Hg (II) ions (99.87% removal) from wastewater samples. This suggests that CS2-buta demonstrates high potential towards removal of Hg (II) ions as well as other toxic heavy metals from wastewater.

A novel crosslinked microporous polymer was synthesized via a modified acid-catalyzed Friedel-Crafts polycondensation reaction. By virtue of the rigid and polarizable monomers (aniline and pyrrole), the polymer, termed KFUPM-4, was proven permanently porous (Brunauer-Emmett-Teller surface area = 650 m2 g−1) with a high CO2 capacity (33 cm3 g−1 at 760 Torr and 298 K) and selectivity (CO2:CH4 selectivity = 15:1 at 298 K). As a result of these properties, KFUPM-4 was subjected to breakthrough measurements, whereby the material's ability to selectively capture CO2 under dynamic conditions from both dry and wet mixed gas streams was clearly demonstrated.

Novel nanocomposite membranes for application in desalination were fabricated from polysulfone (PSf) and multi-walled carbon nanotubes (MWNTs) functionalized with dodecylamine (DDA) and anti-fouling properties of the membranes were studied during filtration of bovine serum albumin (BSA) solutions. Phase inversion process with dimethylacetamide as solvent and polyvinylpyrrolidone as a porogen was used to prepare flat sheet nanocomposite PSf/DDA-MWNTs membranes. Before embedding MWNTs in the polymer matrix, they were treated with HNO3 for the introduction of carboxylic groups on nanotube surface and then modified with DDA. The prepared DDA-MWNTs were characterized using scanning electron microscope, infrared spectroscopy and thermal gravimetric analysis. The long alkyl chains of DDA functionalized MWNTs seem to enhance the interfacial adhesion and compatibility between inorganic nanotubes and PSf matrix. The changes in surface hydrophilicity, morphology and roughness of fabricated nanocomposite membranes as a function of DDA-MWNTs loading were evaluated by using contact angle goniometry and atomic force microscopy. The prepared nanocomposite membranes possessed significantly higher permeability with improved protein fouling resistance than the pristine PSf membrane during filtration of BSA solutions. The membrane prepared with 0.5 wt.% loading of DDA-MWNTs displayed the highest flux recovery (83%) and lowest total flux loss (29%) with reduced irreversible fouling resistance (17%).

Cross-linked terpolymers made up of phenol, diaminoalkane and formaldehyde monomeric units. The cross-linked terpolymers are synthesized via a Mannich mechanism in n-heptane, characterized with multiple spectroscopic techniques, scanning electron microscopy and powder X-ray diffraction, and are also investigated for their Pb 2+ adsorption capacity and thermodynamic properties. A method of removing Pb 2+ ions from an aqueous solution or a wastewater sample with these cross-linked terpolymers is also described.

The reaction of 4-(diallylammonio)butanoate, H3PO3 and PCl3 in CH3SO3H created water-insoluble 4-diallylamino-1-hydroxybutylidene-1,1-bisphosphonic acid I, a novel monomer that contained residues of the osteoporosis drug alendronic acid. Monomer (±) I, a zwitterionic tetraprotic acid, in the presence of 2 equivs. NaOH(aq) and the initiator ammonium persulfate, underwent cyclopolymerization to yield water-soluble poly(zwitterion–dianion) (± =) II. Under the influence of pH, II was equilibrated to water-soluble poly(zwitterion–trianion) (± ≡) III, polytetraanion (= =) IV, poly(zwitterion–anion) (± −) V, cationic polyelectrolyte (+) VI and water-insoluble polyzwitterion (±) VII. The solution properties of backbone charges were investigated, and protonation constants of several centers in IV were determined. Polymers that contained residues of alendronic acid should have applications in various fields, including the field of medicine.

In this study, polysulfone (PSf)/silver-doped carbon nanotube (Ag-CNT) nanocomposite membranes were prepared by a phase-inversion technique; they were characterized and evaluated for fouling-resistant applications with bovine serum albumin (BSA) solutions. Carbon nanotubes were doped with silver nanoparticles via a wet-impregnation technique. The prepared Ag-CNT nanotubes were characterized with scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The fabricated flat-sheet PSf/Ag-CNT nanocomposite membranes with different Ag-CNT loadings were examined for their surface morphology, roughness, hydrophilicity, and mechanical strength with SEM, atomic force microscopy, contact angle measurement, and tensile testing, respectively. The prepared composite membranes displayed a greater rejection of BSA solution (≥90%) and water flux stability during membrane compaction with a 10% reduction in water flux values (up to 0.4% Ag-CNTs) than the pristine PSf membrane. The PSf nanocomposite membrane with a 0.2% Ag-CNT loading possessed the highest flux recovery of about 80% and the lowest total membrane resistance of 56% with a reduced irreversible fouling resistance of 21%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 134, 44688.

Aqueous two phase systems (ATPS’s) composed of poly(oxyethylene) (POE) and poly[sodium (diallylamino)methylphosphonate-alt-sulfur dioxide], a pH-responsive dianionic polyelectrolytes (DAPE) having aminomethylphosphonate motifs, have been investigated. The effects of HCl and salt (sodium chloride) on the binodal of the phase diagrams have been examined. With the increase in the concentration of sodium chloride, the binodals shifted downward, thus requiring a lower amount of polymers needed to form the ATPS’s. The presence of trivalent nitrogen and negative oxygens in each repeat unit of the DAPE permitted the change of the charge types and their densities in the polymer chain, whose conformations can thus be fine-tuned for potential separation and purification of biomaterials in ATPS’s. The phase separation happened at relatively low total polymer concentrations (below mass fraction of 0.10) which could be useful from the industrial point of view. The solubility behavior of the DAPE makes it a suitable com...

N,N-Diallylammoniomethanesulfonate, a new zwitterionic monomer having a sulfobetaine (SB) motif, has been synthesized by reacting diallylamine with formaldehyde and sodium bisulfite. While the monomer underwent cyclopolymerization to give the unstable polysulfobetaine (PSB) in low yields, copolymerization with sulfur dioxide gave the stable PSB/SO2 copolymer in excellent yields. The polymers, as a consequence of having unquenched nitrogen valency in the repeating units, are pH-responsive. The PSB/SO2 copolymer, upon treatment with sodium hydroxide, was converted into a water-soluble anionic polyelectrolyte (APE). The strong zwitterionic interactions inherent in the PSB/SO2 made it insoluble in salt-free water; the presence of large concentration (>3M) of low molecular weight salts (e.g., NaCl, KI etc,) was required to neutralize the intragroup zwitterionic interactions and promote dissolution. The PSB/SO2 represents the first example of a sulfobetaine polymer having a single methylene spacer separating the charge centers. The stability of the copolymer is explained in terms of electron density on the nitrogens. POLYM. ENG. SCI., 53:2378–2388, 2013. © 2013 Society of Plastics Engineers

A cross-linked polyzwitterionic acid (CPZA) containing aminophosphonic acid motifs was synthesized via cyclocopolymerization of diallylaminomethylphosphonic acid and cross-linker 1,1,4,4-tetraallylpiperazinium dichloride (10 mol%) using tert-butylhydroperoxide as the initiator. The CPZA upon treatment with NaOH was converted to a cross-linked anionic polyelectrolyte (CAPE 5). The adsorption of Zn2+ and Cd2+ on CAPE 5 showed that the experimental data fit the Lagergren second-order kinetic model and Langmuir, as well as Freundlich isotherm models. The adsorption capacity of Zn2+ was found to be higher than that of Cd2+, and the adsorption process was spontaneous and endothermic in nature. The low activation energy of 11.3 and 9.3 kJ/mol for Zn2+ and Cd2+, respectively indicated the adsorptions as a favorable process. The resin demonstrated excellent adsorption efficiency in removing the metal ions from aqueous solution.

A novel cross-linked polyzwitterionic acid (CPZA) was synthesized via cyclopolymerization of diallylaminomethylphosphonic acid (90 mol %) and 1,1,4,4-tetraallylpiperazinium dichloride (10 mol %), a...

A novel cross-linked polyzwitterionic acid (CPZA) was synthesized via cyclocopolymerization of diallylaminomethylphosphonic acid and 1,1,4,4-tetraallylpiperazinium dichloride (10 mol%), a cross-linker, in the presence of tert-butylhydroperoxide in aqueous solution at 85 °C. CPZA, upon treatment with NaOH, was converted into a cross-linked anionic polyelectrolyte (CAPE). The experimental data for the adsorption of Pb 2+ and Cu 2+ on CAPE fitted Lagergren second-order kinetic model and Langmuir as well as Freundlich isotherm models. The adsorption capacity of Pb 2+ was higher than that of Cu 2+ while the rate of adsorption was found to be higher for Cu 2+ . The adsorption process was spontaneous and endothermic in nature with negative and positive values for Δ G and Δ H , respectively. The low activation energies of 12.8 and 17.9 kJ/mol for Cu 2+ and Pb 2+ , respectively, indicated the adsorption as a favorable process. The excellent adsorption and very good desorption efficiencies implied the efficacy of the resin in removing as well as recovering the metal ions from aqueous solution. An efficient synthetic access to the resin would enable its use in the treatment of contaminated waste water.

A new class of ionic copolymers containing amine and phosphonate functionalities has been prepared for the first time. N,N-Diallyl-3-(Diethylphosphonato)-methylammonium chloride underwent cyclocopolymerization with SO2 to give a cationic polyelectrolyte (CPE) in very good yields. Likewise, ethyl 3-(N,N-diallylammonio)methanephosphonate/SO2 cyclopolymerization afforded the corresponding polyzwitterion-ester (PZE), which on neutralization with NaOH gave the anionic polyelectrolyte (APE). Both CPE and PZE on hydrolysis of the phosphonate ester functionalities gave the same polyzwitterionic acid (PZA). The pH-responsive PZA on treatment with excess NaOH was converted to dianionic polyelectrolyte (DAPE) which on treatment with 1 equivalent HCl afforded the zwitterionic-anionic polyelectrolyte (ZAPE). Solution properties of the CPE, PZE, DAPE, APE and ZAPE having similar degree of polymerization have been studied in some detail. The apparent basicity constants of the amine group in APE have been determined. An aqueous two-phase system of polyethylene glycol-DAPE-H2O (0.4 N NaCl) has been constructed for its potential application in selective separation of toxic metal ions since polyphosphonates are expected to be effective chelators.

The cationic monomer, N,N-diallyl-(diethylphospho- nato)methylammonium chloride, and zwitterionic monomer, ethyl 3-(N,N-diallylammonio)methanephosphonate, were cyclo- polymerized in aqueous solutions using ammonium persulfate or t-butylhydroperoxide as initiators to afford a cationic polyelectro- lyte (CPE) and a polyzwitterion ester (PZE), respectively. The CPE and PZE on acidic hydrolysis of the ester functionalities afforded the same polyzwitterionic acid (PZA): poly(3-(N,N-diallylammo- nio)methanephosphonic acid). The solution properties of the CPE, pH-responsive PZE, and PZA were studied in detail by poten- tiometric and viscometric techniques. Basicity constants of the phosphonate (P¼O(OEt)O � ) and amine groups in the PZE and in the conjugate base of the PZE, respectively, were found to be ''apparent'' and as such follow the modified Henderson-Hassel- balch equation. In contrast to many polycarbobetaines and sulfo- betaines, PZE was found to be soluble in salt-free water as well as salt (including Ca 2þ ,L i þ )-added solutions, and demonstrated ''antipolyelectrolyte'' solution behavior. The PZA, on the other hand, was found to be insoluble in salt-free water, and on treat- ment with NaOH gave dianionic polyelectrolyte (DAPE) contain- ing trivalent nitrogen and (P¼ ¼O(O)2 2� ) groups. For the first time, several new phase diagrams of polyethylene glycol-DAPE aque- ous two-phase systems (ATPSs) have been constructed in the presence of varying proportions of HCl. The ATPSs may find application in affinity partitioning of metal ions because DAPE is expected to be an effective chelator. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 000: 000-000, 2012

A new cross-linked polyzwitterion (CPZ) was synthesized through cyclocopolymerization of 3-[diallyl(carboxymethyl)ammonio]propane-1-sulfonate (92.5 mol%), and a cross-linker 1,1,4,4-tetraallylpiperazine-1,4-diium chloride (7.5 mol%) in the presence of tert-butylhydroperoxide. The cross-linked polyzwitterion/anion (CPZA) was obtained by the basification of CPZ with NaOH. The adsorption data fit both Temkin and Freundlich isotherm models. The adsorption trend on CPZA is as Cu2+ > Cd2+ and both followed pseudo-second-order kinetic model. The negative ΔG and positive ΔH values ascertained the spontaneous and endothermic nature of the adsorption process. The effectiveness of a zwitterionic–anionic motif consisting of quaternary nitrogen, sulfonate and carboxylate groups has been tested for the first time for capturing Cd2+ and Cu2+ ions at low concentrations. Keywords: Adsorption, Cross-linked resin, Cadmium, Copper, Metal ion removal

Alkylene and arylene diphenyl dicarbonates were used as monomers for the preparation of polycarbonate polymers. The diphenyl dicarbonates were first prepared from dihydroxy compounds and phenyl chloroformate. The polycarbonates were then prepared by the melt-phase polycondensation of these diphenyl dicarbonates with dihydroxy compounds as monomers. The same polycarbonates were also synthesized by a different route involving the polycondensation of a different arylene or alkylene diphenyl dicarbonates with bisphenol A diphenyl dicarbonate to give another series of polycarbonates. The process involved precondensation under a stream of nitrogen and then melt polycondensation at a high temperature and low pressure. The prepared polycarbonates were characterized by inherent viscosity measurement, Fourier transform infrared spectroscopy, 1H-NMR and 13C-NMR spectroscopy, and powder X-ray diffraction. The thermal properties of the polycarbonates were studied with differential scanning calorimetry and thermogravimetric analysis. With alkylene or arylene diphenyl dicarbonates as monomers, the polycondensation reactions led to the formation of polycarbonates with inherent viscosities of up to 0.68 dL/g and with high thermal stability. The glass-transition temperature values of the polycarbonates were in the range 24–130°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3597–3609, 2006

Two novel cross-linked anionic polyelectrolytes (CAPE) I and II containing pH-responsive amino acid residues have been synthesized via cycloco- and ter-polymerization of a monomer having diallylammonioethanoate motif (90 mol%) and a cross-linker 1,1,4,4-tetraallylpiperazinium dichloride (10 mol%) in the absence and presence of SO2 (100 mol%), respectively. The experimental data for the adsorption of Cu2+ on the CAPES fitted Lagergren second-order kinetic model thereby indicating the chemical nature of the adsorption process. The fitness order of Freundlich > Langmuir > Temkin for the isotherm models for CAPE I showed the favorability of adsorption on a heterogeneous surface, whereas for CAPE II the fitness order of Langmuir > Freundlich > Temkin certified the favorability toward monolayer adsorption. The adsorption process was spontaneous and endothermic in nature with negative and positive values for ΔG and ΔH, respectively. For the sorbents CAPE I and CAPE II, the efficiency of Cu2+ removal at an initial metal concentration of 200 ppb was found to be 77.5 and 99.4%, respectively. Desorption efficiencies were found to be 88 and 93% for CAPE I and CAPE II, respectively. Treatment of real wastewater samples spiked with Cu2+ ions showed the excellent ability of the resins to adsorb metal ions.