Poly(itaconic acid)-assisted ultrafiltration of heavy metal ions’ removal from wastewater

The complexation–ultrafiltration technique has been introduced as a capable system to remove heavy metals ions from wastewater. This method needs a water-soluble polymer; therefore, in this paper we synthesized super water-soluble poly(itaconic acid) (PITA) and employed it in polymer-assisted ultrafiltration process to remove Pb(II) ions from synthetic wastewater solutions. The itaconic acid can be produced from different agricultural products and is a green and eco-friendly material. Factors influencing the removal of the metals ions including poly(itaconic acid) concentration, pH and permeate flux were investigated. The results showed that the maximum percentage of metal ion removal was obtained in the basic pH (pH > 7). The flux test was performed by 200 mg/L of poly(itaconic acid) and after 60 min, the flux of membrane was 33.4 L/m²h. The simultaneously selective removal ability of the poly(itaconic acid) for adsorption of different metal ions (Pb²⁺, Sn²⁺, Cu²⁺, Zn²⁺, and Cd²⁺) was also studied. The trend of rejection was Pb²⁺ > Cu²⁺ > Sn²⁺ > Zn²⁺ > Cd²⁺. The highest rejection of Pb(II) ions was achieved as 86%. Generally, the results of this research demonstrated that poly(itaconic acid) (with two carboxyl groups on its repeating unit) is more effective in removing heavy metals ions from wastewater in comparison with customary polymers.

     

Synthesis of zinc oxide nanoparticles reinforced clay and their applications for removal of Pb (Ⅱ) ions from aqueous media

The aim of the study was to synthesize zinc oxide nanoparticles (ZnONPs) composite with clay by a novel route and then to explore the capability of composite of ZnONPs and silty clay (SC) as adsorbents for Pb (Ⅱ) eradication from aqueous media by batch adsorption method. The effect of different operating factors like temperature, pH, dose and time of contact on the adsorption process were studied to optimize the conditions. Langmuir, Freundlich, Dubinin–Radushkevich (D-R) and Temkin isotherms were applied for the interpretation of the process. The R2 and q values obtained from Langmuir model suggested that the process is best interpreted by this model. The values of adsorption capacity (qm) noted were 12.43 mg·g-1 and 14.54 mg·g-1 on SC and ZnONPs-SC respectively. The kinetic studies exposed that pseudo second order (PSO) kinetics is followed by the processes suggesting that more than one steps are involved to control the rate of reactions. Various thermodynamic variables such as change in free energy (ΔGΘ), change in enthalpy (ΔHΘ) and change in entropy (ΔSΘ) were calculated. Thermodynamic data suggested that Pb (Ⅱ) adsorption on SC and ZnONPs-SC are spontaneous, endothermic and feasible processes.     

Synthesis and properties of poly(ester imide) copolymers from 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′-bis(trifluoromethyl)benzidine,and 4-aminophenyl-4′-aminobenzoate

A series of poly(ester imide) (PEsI) copolymers were synthesized using 3,3′,4,4′-biphenyltetracarboxylic dianhydride (4,4′-BPDA), 2,2′-bis(trifluoromethyl)benzidine (TFMB), and 4-aminophenyl-4′-aminobenzoate (APAB) as the monomers. Wide-angle x-ray diffraction results revealed that the average interchain distances of these polymers ranged from 4.6 to 5.7 Å, increasing with the increase of TFMB contents. PEsI-0.3 and PEsI-0.4 exhibited a glass transition temperature (T_g) of 445 and 455°C, respectively, while no distinctive T_g was observed for the PEsI copolymers when the APAB content was >50 mol%. The coefficients of thermal expansion (CTE) of these PEsI copolymers ranged from 3.8 to 24.2 ppm K⁻¹, increasing with the increase of TFMB contents. The PEsI copolymers exhibited a modulus of 5.7–7.8 GPa, a tensile strength of 282–332 MPa, and an elongation-at-break of 10.2%–23.3%. Furthermore, these copolymers exhibited a dielectric constant of 2.53–2.76, and a low dissipation factor (D_f) of 0.0026–0.0032 at 10 GHz in dry state. Because of their excellent combined properties, these PEsI copolymers are promising candidates as dielectric substrate materials for the applications in next generation flexible printed circuit boards operating at high frequencies.     

Synthesis and characterization of poly(11-(4′-cyano-trans-4-stilbenyloxy)undecanyl vinyl ether)

Summary Polymers based on 11-(4-cyano-trans-4-stilbenyloxy)undecanyl vinyl ether have been synthesized by living cationic polymerization, photo-initiated cationic polymerization using onium salts and thermal initiated cationic polymerization using onium salts. The polymers have been characterized by size exclusion chromatography, nuclear magnetic resonance spectroscopy, differential scanning calorimetry and polarized light microscopy. Living cationic polymerization resulted in a polymer of low molecular mass M_n3 600, with a uniformity index (D) of 1.2 displaying a focal conic texture indicative of smectic A (s_A) phase with preserved cyanogroup and trans-configuration. Photo-initiation using 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide and diphenyliodonium hexafluorophosphate resulted in an insoluble polymer exhibiting only vague liquid crystalline textures. Initiation with phenothiazine and phenacyltetramethylenesulfonium hexafluoroantimonate also yielded a partly insoluble polymer with a disturbed s_A phase. It is suggested that the monomer and polymer are sensitive towards radicals leading to cross-linking and branching. The thermal initiation on systems with -methylbenzyltetramethylenesulfonium hexafluorophosphate and p-methoxybenzyltetramethylenesulfonium hexafluorophosphate resulted in completely soluble mesomorphic polymers of M_n13 000, D=1.7 and M_n26 000, D=2.8 respectively, in both cases with a preserved cyanogroup and a transconfiguration. Polarized light microscopy revealed a distinct focal conic structure indicative of s_A in both cases.     

Air–water interfacial synthesis of metal–organic framework hollow fiber membranes for water purification

In this study, we report a novel air–water interfacial self-crystallization (AWISC) method for scalable depositing continuous metal–organic framework (MOF) layers on modification-free polyvinylidene fluoride (PVDF) hollow fibers. Through importing MOF precursors into porous hollow fiber substrates with outer diameters of 1.2 mm and evaporating aqueous solutions under mild conditions, the metal ions and linkers close to solution surface can be concentrated firstly, thus the crystallization of MOFs will preferentially occur at interface of air and liquid precursors. The formed crystals can block off the pores of substrates to form defect-free MOF membranes. The prepared ZIF-8 membranes exhibit superior performance in molecular separation, with high rejections of 94.1 ∼ 99.5% for small molecules (molecular weight: 320 ∼ 800 Da) and large permeance up to 50 L m⁻² h⁻¹ bar⁻¹. Moreover, by combining AWISC and microfluidic processing, the high-performance ZIF-8 hollow fiber membranes with long length of 30 cm can be easily fabricated in scalability.     

Compatibilizing capability of poly(β-hydroxybutyrate-,co-ε-caprolactone) in the blend of poly(β-hydroxybutyrate) and poly(ε-caprolactone)

In order to increase the miscibility in the blend of poly(β-hydroxybutyrate) [PHB] and poly(ε-caprolactone) [PCL], PHB/PCL copolyesters were used as compatibilizers. These PHB/PCL copolyesters were synthesized by transesterification in solution phase. The melting point [T_m] depression, which was not observed in PHB/PCL blend without compatibilizer, was observed when PHB/PCL copolyesters as compatibilizers were added to the PHB/PCL blend system. As the amount of compatibilizer added to the blend increased, the crystallization temperature [T_c] of PCL in the blend increased and T_c of PHB in the blend decreased. The difference in T_c between PHB and PCL was gradually reduced. When the sequence length of PHB block and PCL block in the PHB/PCL copolyester increased, the miscibility of the blend increased. This is evidenced by the depression in the T_m of PHB and PCL in the blend and by the decrease in the difference of T_c between PHB and PCL. From the polarizing optical micrographs, the phase separation in PHB/PCL blend was observed. However, in the presence of PHB/PCL copolyester, the spherulite of PHB grows in equilibrium with one phase melt. Received: 27 July 1998/Revised version: 12 October 1998/Accepted: 4 November 1998     

Unravel the potential of zinc oxide nanoparticle-carbonized sawdust matrix for removal of lead(Ⅱ) ions from aqueous solution

Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained from a local wood mill.The matrix of both provides a better material as an adsorbent.The present study applied the functionality of ZnOnp,CSD,and ZnOnp-CSD matrix as adsorbent materials for the removal of Pb(Ⅱ) ions from aqueous solution.The method of batch process was employed to investigate the potential of the adsorbents.The influence of pH,contact time,initial concentration of adsorbate,the dosage of adsorbents,and the temperature of adsorbate-adsorbent mixture on the adsorption capacity were revealed.The adsorption isotherm studies indicate that both Freundlich and Langmuir isotherms were suitable to express the experimental data obtained with theoretical maximum adsorption capacities(q_m) of 70.42,87.72,and 92.59 mg·g~(-1) for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix,respectively.The separation factors(R_L) calculated showed that the use of the adsorbents for the removal of Pb(Ⅱ) ions is a feasible process with R_L 1.The thermodynamic parameters obtained revealed that the processes are endothermic,feasible,and spontaneous in nature at 25-50℃.Evaluation of the kinetic model elected that the processes agreed better with pseudo-second order where the values of rate constant(k_2) obtained for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix are 0.00149,0.00188,and 0.00315 g·mg~(-1)·min~(-1),respectively.The reusability potential examined for four cycles indicated that the adsorbents have better potential and economic value of reuse and the ZnOnp-CSD matrix indicates improved adsorbent material to remove Pb(Ⅱ) ions from aqueous solution.     

Synthesis and characterization of multiblock semi-crystalline hydrophobic poly(ether ether ketone)–hydrophilic disulfonated poly(arylene ether sulfone) copolymers for proton exchange membranes

Multiblock copolymers based on alternating segments of telechelic phenoxide terminated hydrophilic fully disulfonated poly(arylene ether sulfone) (BPS100) and decafluorobiphenyl (DFBP) terminated hydrophobic poly(arylene ether ketimine) (PEEKt), were synthesized from the hydrophilic and ketimine-protected amorphous hydrophobic telechelic oligomers by nucleophilic coupling reactions. After film formation from DMSO, the copolymer was acidified, which converted the ketimine to semi-crystalline ketone segments and the sulfonate salts to disulfonic acids. A semi-crystalline phase with a T_m of 325 °C was confirmed. The semi-crystalline multiblock copolymer membranes were tough, ductile and solvent resistant. Fundamental properties as proton exchange membranes (PEMs) showed enhanced conductivities under fully hydrated and reduced humidity conditions. These multiblock copolymers exhibited low in-plane anisotropic swelling behavior, in contrast to the random copolymers.     

Ionic liquids as co-solvents for zwitterionic copolymers and the preparation of poly(vinylidene fluoride) blend membranes with dominated β-phase crystals

A new series of green solvents that constituted with ionic liquids (ILs) and dimethyl acetamide (DMAc) were developed as good solvents for zwitterionic copolymers, and the dissolutions of amphiphilic copolymers carrying carboxylbetaine and sulfonatebetaine in these new solvents were studied. It was determined that the commonly found ILs such as 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF₄), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF₆) and many others were all effective co-solvents for zwitterionic copolymer with carboxylbetaine groups. However, the 1-methylimidazolium trifluoromethanesulfonic ([MIM]CF₃SO₃) instead of the [BMIM]BF₄ was proved as an effective co-solvent for the copolymer carrying sulfonatebetaine units. These newly designed mix-solvents were also good solvents for poly(vinylidene fluoride) (PVDF) and their influences on the crystallization as well as the formation of PVDF membranes were investigated. Our results had demonstrated that blend membranes with zwitterionic additives could be facilely prepared with many new solvent candidates.     

Selective removal of Cu(Ⅱ) from contaminated water using molecularly imprinted polymer

A synthetic molecularly imprinted polymer (MIP) was prepared by noncovalent imprinting technique for the selective removal of Cu²⁺ from aqueous solutions. In the preparation of imprinted polymer, Cu²⁺ was used as the template, oleic acid as the functional monomer and divinylbenzene as the cross-linker. The surface morphologies and characteristics of the MIP were determined by BET, scanning electron microscopy (SEM), FTIR and energy dispersive X-ray spectrometer (EDS). The proper adsorption and selective recognition ability of the MIP were studied by an equilibrium-adsorption method. In general, the removal efficiency of Cu²⁺ increased rapidly with pH from 2 to 7 and decreased at a pH 8. The removal efficiency of Cu²⁺ increased with temperature from 25°C to 50°C. Competitive adsorption studies showed that the coexisting cations have no obvious influence on the adsorption of Cu²⁺. In addition, the variation in the adsorption ability of the MIP that was repeatedly used was investigated, and it showed excellent reproducibility.     

Modification of poly(vinylidene fluoride) membranes with aluminum oxide nanowires and graphene oxide nanosheets for oil–water separation

To improve the hydrophilic and oleophobic properties of membrane, we adopted aluminum oxide (Al₂O₃) nanowires and graphene oxide (GO) nanosheets to modify poly(vinylidene fluoride) (PVDF) membranes. The experimental results show that the intercalation of Al₂O₃ nanowires between GO nanosheets effectively improved the roughness of the GO–Al₂O₃–PVDF membrane, and the permeability of the membrane with an optimal mass ratio of Al₂O₃ to GO of 7.5 was 31 times that of the GO–PVDF membrane. Furthermore, the addition of Al₂O₃ nanowires significantly enhanced both the hydrophilic and oleophobic properties of the GO–Al₂O₃–PVDF membrane. On the basis of the extended Derjaguin–Landau–Verwey–Overbeek theory, the energy barriers between the oil droplets and GO–PVDF and GO–Al₂O₃–PVDF membranes were 0.63 and 0.9 KT, respectively; this indicated improvements in the anti-oil-fouling ability of the GO–Al₂O₃–PVDF membranes. We also found that both the GO–PVDF and GO–Al₂O₃–PVDF membranes had great oil–water separation rates (97.9 and 99.4%, respectively) with an initial oil concentration of 200 mg/L. The findings of this study show that the GO–Al₂O₃–PVDF membrane is a promising oil–water separation membrane, and further investigation of the cleaning procedure is needed to promote its practical application in oil–water separation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47493.     

Preparation and thermotropic properties of copoly(4,4′-biphenylene sebacate-co-eicosanedioate)s

Summary A series of thermotropic copoly(4,4-biphenylene sebacate-co-eicosanedioate)s were prepared by melt polycondensation of 4,4-biphenylene diacetate, sebacic acid and eicosanedioic acid. Their thermal transitions and liquid crystalline properties were investigated by DSC and polarized micrrocope. The copolyesters were found to exhibit a smectic phase, but no nematic phase was observed upon cooling. The smectic-isotropic transition temperature decreased as the content of eicosanedioate unit increased, and the corresponding transition heat did not change to a great extent. However, the crystalline-smectic transition temperature showed an eutectic behavior, and the crystalline-smectic transition heat was depressed considerably after copolymerization. The X-ray diffraction data of the copolyesters after thermal treatment were measured and compared with the thermal properties measured by DSC.     

Synthesis of poly(1-β-naphthyl-2-phenylacetylene) membranes through desilylation and their properties

The polymerization of 1-β-naphthyl-2-[(p-trimethylsilyl)phenyl]acetylene (8a) with TaCl₅-n-Bu₄Sn in cyclohexane provided a high molecular weight polymer (9a) (M_w=3.4×10⁶). The corresponding monomers having p-dimethyl-t-butylsilyl and p-dimethyl(10-pinanyl)silyl groups in place of p-trimethylsilyl group in 8a also polymerized in a similar way to give high molecular weight polymers (9b, 9c, respectively; M_w>1×10⁶). All these polymers were soluble in many common solvents such as toluene and chloroform, and provided free-standing membranes by casting from toluene solution. The oxygen permeability coefficients (P_O2) of 9a at 25 °C was as high as 3500 barrers. The membrane of poly(1-β-naphthyl-2-phenylacetylene) (10a) was prepared by desilylation of the membrane of 9a with trifluoroacetic acid. Polymer 10a was insoluble in any solvents, and showed high thermal stability (the onset temperature of weight loss in air ∼470 °C). The P_O2 value of 10a reached 4300 barrers. Not only the membrane of 9c but also its desilylation product 10c exhibited large optical rotations ([α]_D=+2924 and +9800°, respectively) and strong CD signals. This indicates that the membrane of 10c maintains the helical main chain conformation of 9c with a large excess one-handed helix sense.     

Synthesis and thermal properties of block copolyetheresters with poly(pentamethylene p,p′-bibenzoate) segments

The block copolyetheresters with hard segments of poly(pentamethylene p,p-bibenzoate) and soft segments of poly (tetramethylene ether) were prepared by melt polycondensation of dimethyl-p,p-bibenzoate, 1,5-pentanediol and poly (tetramethyene ether) glycol (PTMEG) with molecular weights of 650, 1000 and 2000. The results by NMR indicate that the polymer composition is determined by the charge molar ratio (x) of PTMEG to dimethyl-p,p-bibenzoate. The thermal transitions of the block copolyetheresters were investigated by DSC in combination with X-ray diffraction and polarized microscopy. Some block copolyetheresters exhibit a monotropic smectic phase due to the presence of the poly (pentamethylene p,p-bibenzoate) segments. As the molar content of PTMEG increases, the average sequence length of the polyester segments decreases, the isotropic-smectic transition temperature and the smectic order decrease accordingly. When x is as high as 0.3, the block copolyetheresters exhibit no liquid crystallinity.     

Synthesis,and characterization folate-conjugated photocleavable poly(4-substituted-ε-caprolactone) polymers for drug delivery

Abstract

Photo-cleavable polymers containing 5-hydroxy-2-nitrobenzyl alcohol (ONB) junction point between the target molecule of folic acid (FA) and the hydrophobic poly(4-substituted-?-caprolactone) (PXCL_n) chain were synthesized. FA –terminated ONB-PXCL_n polymers formed micelles with critical micelle concentration (CMC) 1.2 – 64.3?mg L^?1. Fluorescence emission spectroscopy indicated the release of Nile red encapsulated FA-ONB-PXCL_n micelles in response to irradiation. Light-triggered bursts released were observed for drug-loaded FA-ONB-PXCL_n micelles. The nanoparticles exhibited nonsignificant toxicity at concentrations up to 300?µg mL^?1. Flow cytometry revealed that the uptake of folate-targeted doxorubicin (DOX) -encapsulated micelles by HeLa cells was faster than that of free DOX.     

Synthesis and Polymerization of Bismaleimide Derived from 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane

The acid-catalyzed dimerization of α-methyl styrene led to the formation of trimethyl phenyl indane, which on nitration followed by reduction using hydrazine hydrate gave 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane. This aromatic diamine was used to synthesize bismaleamic acid and imidized to yield bismaleimide. The bismaleamic acid was converted to prepolymer directly by imidizing it in refluxing toluene. All the materials synthesized were characterized using FTIR, ¹H and ¹³C NMR. The direct inlet mass spectral characterizations were carried out for bismaleamic acid, bismaleimide and bismaleimide prepolymer. The fragmentation pattern was discussed in detail and the structure proposed was confirmed. The thermogravimetric studies were done for all the materials and kinetic parameters (energy of activation and frequency factor) were calculated using Dharwadkar and Kharkhanavala method. The structural changes occurring in the thermally polymerized bismaleimide and bismaleimide prepolymer were discussed.     

Core–sheath nanofibrous membranes based on poly(acrylonitrile-butadiene-styrene), polyacrylonitrile,and zinc oxide nanoparticles for photoreduction of Cr(VI) ions in aqueous solutions

This investigation addresses the design of a series of poly(acrylonitrile-butadiene-styrene)/polyacrylonitrile–zinc oxide(ABS/PAN–ZnO) membranes by coaxial electrospinning. In the first instance, an optimization of ABS and PAN electrospinning was performed, thus establishing suitable compositional and processing parameters for obtaining homogenous fibers. Then, coaxial electrospinning of ABS and PAN solutions containing different amount of ZnO nanoparticles was carried out. The coaxial morphology of the nanofibers and ZnO distribution/dispersion were studied by the combination of several techniques such as scanning electron microscopy, X-ray energy dispersive analysis, contact angle, and thermogravimetric analysis. The performance of the obtained membranes for chromium (VI) ions removal from aqueous solutions was assessed by photoreduction using ultraviolet–visible spectroscopy. Electrospun mats composed of ABS (core)/PAN (sheath) embedded with 30 wt % of ZnO nanoparticles exhibited the highest chromium photoreduction (about 80%), suggesting the potential use of these membranes as filters for water purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48429.     

Synthesis and application of nanocomposite Fe3O4@SiO2@CTAB–SiO2 as a novel adsorbent for removal of cyclophosphamide from water samples

ABSTRACT

We present a way of synthesizing nanocomposite Fe₃O₄@SiO₂@CTAB–SiO₂ by employing simple sol–gel technique with selective etching for extreme selectivity adsorption of cyclophosphamide (CP). The transmission electron microscopy (TEM); scanning electron microscopy (SEM); X-ray diffraction (XRD); Fourier transform infrared (FT-IR); vibrating sample magnetometer (VSM); pH_PZC; and Brunauer, Emmett and Teller (BET) techniques were used for nanocomposite characterization. These nanoparticles have an S_BET of 157.8 m² g^?1 and a high saturation magnetization of 67.5 emu g^?1. First, the adsorption system was examined as a function of contact time under various initial CP contents, ionic strength, initial solution pH, adsorbent dose and temperature in batch test. The optimum dose, pH and contact time were obtained to be 0.01 g, 7.0 and 30 min, respectively. Ultimately, experimental isotherm and kinetics data of adsorption of CP onto nanocomposite Fe₃O₄@SiO₂@CTAB–SiO₂ were fitted to classical models. Additionally, it was found that the maximum adsorption process capacity of CP on adsorbent was 342.8 mg g^?1.     

Synthesis,characterization, and drug release properties of poly(N-isopropylacrylamide) gels prepared in methanol–water cononsolvent medium

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels were simply prepared by free radical polymerization in different methanol–water mixture. A scanning electron microscopy study revealed that the freeze-dried hydrogels were macroporous. The swelling ratios in water at 20°C of the resulting hydrogels followed the order: X_0.43>X_0.21>X_0.76 ≈ X_0.57>X_0.31>X_0.13>X_0.06>X₀, where X_m denotes a gel prepared in a methanol–water mixture with m mole fraction of methanol (x_m). Below the lower critical solution temperature, the swelling ratio values of all of the hydrogels gradually decreased with the increase in the temperature. The complete collapse of the PNIPAM chain of all the gels occurred at about 38°C, whereas the same was observed at about 35°C for the conventional gel prepared in water. The swelling ratio values of all the PNIPAM gels in the methanol–water mixtures with different x_m values at 20°C passed through a minimum in the cononsolvency zone. The deswelling rates of the hydrogels decreased in the following order: X_0.43> X_0.31> X_0.21> X_0.57> X_0.76 ≈ X_0.13> X_0.06> X₀. The reswelling rates of these hydrogels decreased in the following order: X₀> X_0.31> X_0.06 ≈ X_0.13 > X_0.76> X_0.57> X_0.21> X_0.43. The release rates of the Tramadol Hydrochloride drug at 37°C from the drug-loaded hydrogels were almost same for all of the hydrogels. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012