Competitive removal of nickel (II), cobalt (II), and zinc (II) ions from aqueous solutions by starch‐graft‐acrylic acid copolymers

Graft copolymerization of acrylic acid (AA) onto starch was carried out with ceric ammonium nitrate as initiator under nitrogen atmosphere. The grafting percentages (GP%) of starch‐graft‐acrylic acid (St‐g‐AA) copolymers were determined. The effect of GP% of St‐g‐AA copolymers on the competitive removal of Co²⁺, Ni²⁺, Zn²⁺ ions from aqueous solution was investigated at different pH (2, 4, 6). The concentrations of each ion in aqueous solution 5 mmol/L. Effects of various parameters such as treatment time, initial pH of the solution and grafting percentage of starch graft copolymers were investigated. Metal ion removal capacities of St‐g‐AA copolymers increased with GP% of the copolymers and pH. The results show that the removal of metal ions followed as given in the order Co²⁺ > Ni²⁺ > Zn²⁺. In this study, metal ion removal capacities were determined by atomic absorption spectrophotometer (AAS). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Novel grafted nafion membranes for proton‐exchange membrane fuel cell applications

Novel poly(glycidyl methacrylate)‐grafted Nafion–phosphoric acid membranes for direct‐oxidation methanol fuel cells were prepared with a potassium persulfate chemical initiation system for the first time. The introduced epoxy groups were converted to amine groups through a reaction with ethylenediamine, which consequently doped with phosphoric acid ( PO₃H) groups. The latter significantly contributed to enhancing the ion‐exchange capacity, mechanical properties, and thermal stability. Factors affecting the modification steps were studied. Changes in the chemical and morphological structure were verified through Fourier transform infrared spectroscopy, TGA, and scanning electron microscopy characterization. Various grafting percentages (GP%'s) up to 32.31% were obtained. As a result, the thickness of the grafted membranes increased. Furthermore, the methanol permeability of the modified membranes was reduced with increasing grafted polymer content compared with that of the Nafion membrane. An 83.64% reduction in the methanol permeability was obtained with a polymer grafted content of 18.27%. Finally, the efficiency factor for all of the modified Nafion membranes was enhanced compared with that of Nafion. A fourfold improvement was obtained with membranes with a GP% of 18.27% as a maximum value. Such promising results nominate the used technique as a one for the improvement of Nafion membrane efficiency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Alkaline hydrolysis of methyl acrylate grafted cellulose fibers

In this work, methyl acrylate grafted cellulose fibers were hydrolyzed in an aqueous NaOH solution to obtain a superabsorbent hydrogel. The effect of process variables, such as the hydrolysis reaction time, temperature, and NaOH concentration, during alkaline hydrolysis were carefully determined and optimized. The degree of hydrolysis was estimated on the basis of the determination of the carboxylate group contents. The material loss during hydrolysis followed a first‐order reaction mechanism. The differences in the behavior of the grafted fibers during hydrolysis could be explained by their structural differences. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Removal of heavy‐metal ions from aqueous solution with nanochelating resins based on poly(styrene‐alt‐maleic anhydride)

Chelating resins have been considered to be suitable materials for the recovery of heavy metals in water treatments. A chelating resin based on modified poly(styrene‐alt‐maleic anhydride) with 2‐aminopyridine was synthesized. This modified resin was further reacted with 1,2‐diaminoethan or 1,3‐diaminopropane in the presence of ultrasonic irradiation for the preparation of a tridimensional chelating resin on the nanoscale for the recovery of heavy metals from aqueous solutions. The adsorption behavior of Fe²⁺, Cu²⁺, Zn²⁺, and Pb²⁺ ions were investigated by the synthesis of chelating resins at various pH's. The prepared resins showed a good tendency for removing the selected metal ions from aqueous solution, even at acidic pH. Also, the prepared resins were examined for the removal of metal ions from industrial wastewater and were shown to be very efficient at adsorption in the cases of Cu²⁺, Fe²⁺, and Pb²⁺. However; the adsorption of Zn²⁺ was lower than those of the others. The resin was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction analysis, and differential scanning calorimetry analysis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of acrylic acid grafted polypropylene nonwoven fabric by photoinduced graft polymerization with preabsorption of monomer solution

We improved photoinduced graft polymerization by absorbing the monomer solution onto the substrate (Ab‐type) instead of immersing the substrate in the monomer solution (Im‐type) before photoirradiation to yield a more practical and effective grafting system. With this system, acrylic acid (AA) was effectively grafted onto polypropylene (PP) nonwoven fabric. The maximum degree of grafting obtainable was restricted by the amount of monomer preabsorbed onto the PP fabric. However, we effectively enhanced the degree of grafting by increasing the monomer concentration, adding trimethylolpropane triacrylate (TMPTA) to the monomer solution, and repeating the photoirradiation with supplementation of the monomer solution. The net availability of the monomer for graft polymerization was 50% or greater; this increased to 90% or greater with the addition of TMPTA and was much higher than for conventional Im‐type photografting (≤13%). Fourier transform infrared spectra, scanning electron microscopy morphology observations, and the adsorption–regeneration properties confirmed that the PP‐g‐AA fabric prepared by the improved Ab‐type photografting method had comparable qualities to those of fabric prepared by conventional Im‐type photografting. Thus, the improved Ab‐type photografting system provides potential for the preparation of graft adsorbents on a large scale at a competitive cost with a continuous reactor, such as a conveyer belt system, instead of a batch reactor. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Adsorption of Hg2+ on a novel chelating fiber prepared by preirradiation grafting and amination

A novel chelating fiber was prepared by the irradiation‐induced grafting copolymerization of glycidyl methacrylate on polypropylene fiber and consequent amination with diethylenetriamine. The effects of the reaction conditions, such as reaction time, temperature, and monomer concentration, on the degree of grafting were investigated. The optimal conditions for grafting were found to be 3 h, 100°C, and a 50% (v/v) glycidyl methacrylate concentration in tetrahydrofuran solution. This fiber showed good adsorption performance at different concentrations of Hg²⁺, in particular for trace Hg²⁺. Under the adsorption conditions of pH = 4, initial concentration = 1000 mg/L, and time = 20 h, the adsorption capacity of the chelating fiber for Hg²⁺ reached 785.28 mg/g. It completely adsorbed the Hg²⁺ ions in solution within a short contact time, showing a very high adsorption rate for Hg²⁺. Furthermore, the chelating fiber also had a high selectivity for mercury, whereas Cu²⁺ coexisted in different concentrations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of an anion‐exchange adsorbent by the radiation‐induced grafting of vinylbenzyltrimethylammonium chloride onto cotton cellulose and its application for protein adsorption

Poly(vinylbenzyltrimethylammonium chloride)‐graft‐cotton cellulose, an anion‐exchange matrix, was synthesized by a mutual radiation‐induced grafting technique with a ⁶⁰Co γ‐radiation source. The grafted matrix was characterized by grafting yield estimation, elemental analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The grafting yield decreased with the increase in the dose rate. However, the grafting yield and nitrogen content of grafted samples increased almost linearly with an increase in the total irradiation dose. To evaluate the performance of the grafted anion‐exchange matrix, the protein adsorption and elution behavior were investigated in a continuous column process under various experimental conditions, with bovine serum albumin used as a model protein. The binding and elution behavior of the anion‐exchange matrix depended on different experimental parameters, such as the grafting yield, ionic strength, pH of the medium, and amount of protein loaded. From a breakthrough curve, the equilibrium binding capacity and elution percentage of the grafted anion‐exchange matrix were estimated to be 40 mg/g and 94%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5512–5521, 2006     

Preparation of poly(vinyl amine)‐grafted crosslinked poly(vinyl alcohol) microspheres

Crosslinked poly(vinyl alcohol) (CPVA) microspheres were first prepared via the suspension polymerization of vinyl acetate and the alcoholysis of poly(vinyl acetate). Afterwards, a two‐step method involving graft polymerization and Hofmann degradation was used to prepare functional poly(vinyl amine)‐grafted crosslinked poly(vinyl alcohol) (PVAm–CPVA) microspheres, onto which poly(vinyl amine) (PVAm) macromolecules were grafted. The graft polymerization of acrylamide (AM) on CPVA microspheres was performed with cerium salt as the initiator in an acidic aqueous medium, resulting in polyacrylamide (PAM)‐grafted CPVA microspheres. Subsequently, the grafted PAM was transformed into PVAm via the Hofmann degradation reaction, and PVAm–CPVA microspheres were prepared. The effects of the main factors on the graft polymerization and Hofmann degradation were examined, and the reaction mechanisms were researched in depth. The experimental results showed that for the graft polymerization of AM on CPVA microspheres initiated by cerium salt, the acid concentration and the amount of cerium salt affected the grafting degree of PAM greatly. For the Hofmann degradation reaction of the grafted PAM, the amination degree of PVAm–CPVA microspheres was obviously affected by the amount of sodium hypochlorite in the presence of sodium hydroxide. The preliminary adsorption tests showed that PVAm–CPVA microspheres were multifunctional and had strong adsorption ability for Fe(III) ions by chelation action and for chromate ions (CrO) by strong electrostatic interactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

UV‐radiation–induced preirradiation grafting of methyl methacrylate onto lignocellulose fiber in an aqueous medium and characterization

The preirradiation method of grafting has been established by ultraviolet radiation. Methyl methacrylate (MMA) was grafted onto jute fiber in an aqueous medium. The variation of graft weight with UV‐radiation time, monomer concentration, and reaction time was investigated. The conversion of monomer into homopolymer and graft copolymer was evaluated. The graft weight passes through a maximum value (～ 122%) with UV‐radiation time. The optimum value of the monomer concentration was evaluated for maximum degree of grafting. Graft copolymerization of MMA onto lignocellulose fiber significantly increases the elongation at break (～ 65%) compared to that of the “as‐received” sample. However, a linear decrease on breaking load was observed with the increase of graft weight. The estimation of degree of grafting was achieved using an IR technique by correlating band intensities with the degree of grafting. Considering the water‐absorption property, the grafted sample showed a maximum up to 61% decrease in hydrophilicity compared to that of the as‐received sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1667–1675, 2004     

Chemically induced graft copolymerization of acrylonitrile onto lignocellulosic fibers

The grafting of vinyl monomers is an important method for replacing hydrophilic hydroxyl groups present on the surface of natural fibers by hydrophobic polymer chains. It improves the compatibility of natural fibers with polymer matrixes during the fabrication of natural‐fiber‐reinforced polymer composites. This article deals with the graft copolymerization of acrylonitrile onto Agave americana fibers in air in the presence of ceric ammonium nitrate as a redox initiator. A maximum percentage grafting of 24% was obtained after the optimization of various reaction parameters, including the reaction time, temperature, and concentrations of nitric acid, initiator, and monomer. The graft copolymers obtained under the optimum conditions were then subjected to the evaluation of different physicochemical properties, including swelling behavior in different solvents, moisture absorption behavior under different humidity levels, and chemical resistance. The graft copolymers were further characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analysis (thermogravimetric analysis/differential thermal analysis), and X‐ray diffraction techniques. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Characterization of polyacrylonitrile,poly(acrylonitrile‐co‐vinyl acetate), and poly(acrylonitrile‐co‐itaconic acid) based activated carbon nanofibers

In this study, three different acrylonitrile (AN)‐based polymers, including polyacrylonitrile (PAN), poly(acrylonitrile‐co‐vinyl acetate) [P(AN‐co‐VAc)], and poly(acrylonitrile‐co‐itaconic acid) [P(AN‐co‐IA)], were used as precursors to synthesize activated carbon nanofibers (ACNFs). An electrospinning method was used to produce nanofibers. Oxidative stabilization, carbonization, and finally, activation through a specific heating regimen were applied to the electrospun fibers to produce ACNFs. Stabilization, carbonization, and activation were carried out at 230, 600, and 750 °C, respectively. Scanning electron microscopy, thermogravimetric analysis (TGA), and porosimetry were used to characterize the fibers in each step. According to the fiber diameter variation measurements, the pore extension procedure overcame the shrinkage of the fibers with copolymer precursors. However, the shrinkage process dominated the scene for the PAN homopolymer, and this led to an increase in the fiber diameter. The 328 m²/g Brunauer–Emmett–Teller surface area for ACNFs with PAN precursor were augmented to 614 and 564 m²/g for P(AN‐co‐VAc) and P(AN‐co‐IA), respectively. The TGA results show that the P(AN‐co‐IA)‐based ACNFs exhibited a higher thermal durability in comparison to the fibers of PAN and P(AN‐co‐VAc). The application of these copolymers instead of AN homopolymer enhanced the thermal stability and increased the surface area of the ACNFs even in low‐temperature carbonization and activation processes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44381.     

Preparation and application of glycidyl methacrylate and methacrylic acid monomer mixture‐grafted poly(ethylene terephthalate) fibers for removal of methylene blue from aqueous solution

A novel fibrous adsorbent that grafts glycidyl methacrylate (GMA) and methacrylic acid (MAA) monomer mixture onto poly(ethylene terephthalate) (PET) fibers was used for removal of methylene blue (MB) in aqueous solutions by a batch equilibration technique. The operation parameters investigated included, pH of solution, removal time, graft yield, dye concentration, and reaction temperature. The adsorption rate of MB is much higher on the MAA/GMA‐grafted PET fibers than on the ungrafted PET fibers. MB was removed 99% the initial dye concentration at 10 mg L⁻¹ and 93% at 200 mg L⁻¹ by monomers mixture‐grafted PET fibers. Pseudofirst order and pseudosecond order kinetic equations were used to examine the experimental data of different graft yield. It was found that the pseudosecond order kinetic equation described the data of dye adsorption on fibrous adsorbent very well. The experimental isotherms data were analyzed using Langmuir and Freundlich isotherm models. The data was that Freundlich isotherm model fits the data very well for the dyes on the fibers adsorbent. The dye adsorbed was easily desorbed by treating with acetic acid/methanol mixture (50% V/V) at room temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Absorption and release of zinc and copper ions by chitosan fibers

Chitosan fibers were treated with aqueous solutions of ZnCl₂ and CuSO₄·5H₂O to prepare zinc and copper containing fibers, respectively. Significant weight gains were obtained as the zinc and copper ions were absorbed onto the fibers through chelation with the primary amine groups. The fibers were then placed in contact with aqueous solutions containing NaCl and water soluble proteins, respectively, to assess the release of zinc and copper ions. Results showed that the release of zinc and copper ions were affected by the treatment temperature, time, and the composition of the contacting media. More metal ions were released when the fibers were in contact with aqueous protein solutions than in NaCl solution, indicating the binding abilities of the protein molecules for zinc and copper ions. The zinc and copper containing fibers were tested for their antimicrobial effects against several species of bacteria commonly found in wound and skin. Results showed that these metal containing chitosan fibers had much stronger antimicrobial properties than the original chitosan fiber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Syntheses and the Main Properties of Fiban Fibrous Ion Exchangers

The works on synthesis and main properties of fibrous ion exchangers are reviewed in the paper. The main attention is paid to the FIBAN materials found practical applications in water treatment and air purification processes. The following methods for preparation of ion exchange fibers have been considered: mechanical mixing of inert fiber‐forming polymer solutions or melts with finely dispersed ion‐exchangers with their following spinning into fibers; preparation of composite fibers containing polymeric reinforcement in the polyelectrolyte body; spinning of specially prepared polymers containing ionizable groups and having fiber‐forming properties; grafting of ionogenic polymers (or polymers in which ionogenic groups can be introduced after grafting) onto polymer chains of the existing polymer fiber; polymer analogues conversion of existing polymeric fibers by introducing in their structure ionizable functional groups. Conditions for preparation of ion exchange fibers with high exchange capacity, optimal swelling and acceptable mechanical properties have been outlined.     

Synthesis and characterization of chelating resins with amino moieties and application on removal of copper(II) from EDTA complexes

Strong‐field ligands (amino moieties) are introduced into a hydrogel resin to obtain a chelating resin via inversion suspension polymerization. The characteristics of chelating copolymers are measured by using Fourier transform IR spectroscopy (FTIR), elemental analysis (EA), and scanning electron microscopy (SEM). After chelating copolymers adsorb cupric ions, the absorption peak of stretch N? H is shifted to higher frequency because of a coordination reaction from the FTIR spectra. Furthermore, the mechanism of metal complex adsorption on the chelating copolymer is that the strong‐field chelating ligand decomposes the bonding of the metal complexes and recoordinates the cupric ion to a chelating polymer, which is examined via FTIR, SEM with EA, and ionic chromatography analysis. The maximum adsorption capacity of cupric ions is 1.08 mmol/g and the adsorption capacity increases with the increase of the pH of the solution. The stability constant of the Cu chelating copolymer is 10^18.72, and it can have competition adsorption with EDTA in aqueous solution. These amino chelating copolymers can be used not only to recover metal ions but also to move anion pollution in wastewater. It is interesting that parts of the cupric ions adsorbed on the chelating copolymer are reduced into cupreous ions and/or copper atoms after electron spectroscopy for chemical analysis measurement. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2457–2468, 2005     

Effect of an allyl pretreatment of starch on the grafting efficiency and properties of allyl starch‐g‐poly(acrylic acid)

Starch was pretreated with allyl etherification to enhance the grafting efficiency of the copolymerization of granular starch with acrylic acid and to improve the properties of starch‐g‐poly(acrylic acid) used as a warp sizing agent. The graft copolymerization was carried out in an aqueous dispersion with ferrous ammonium sulfate and hydrogen peroxide as initiators. Through the introduction of allyl groups into starch before the copolymerization, the grafting efficiency could evidently be enhanced, and properties such as fiber adhesion and film behaviors of the copolymer were improved. The pretreatment was capable of enhancing the grafting efficiency by about 10–20% when the degree of substitution of allyl starch ranged from 0.011 to 0.037. The adhesion and film behaviors also depended on the modification extent of the starch pretreatment and on the grafting ratio of the copolymer. The adhesion reached a maximum at a degree of substitution of 0.025, and the film behaviors were best when the degree of substitution ranged from 0.011 to 0.025. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of comb‐type grafted hydrogels composed of polyacrylamide and chitosan and their use for DNA adsorption

Comb‐type grafted hydrogels composed of polyacrylamide (PAAm) and chitosan (CT) were prepared and used for DNA adsorption. Instead of direct grafting of the acrylamide monomer onto the CT chain, semitelechelic PAAm with carboxylic acid end groups (PAAm–COOH) was synthesized by free‐radical polymerization with mercaptoacetic acid as the chain‐transfer agent, and it was grafted onto CT with amino groups. The synthesis of telechelic PAAm–COOH and the formation of comb‐type grafted hydrogels were confirmed by attenuated total reflectance/Fourier transform infrared spectroscopy and scanning electron microscopy measurements. The prepared comb‐type grafted hydrogels were used as sorbents in DNA adsorption experiments conducted at +4°C in a tris(hydroxymethyl)aminomethane/ethylenediaminetetraacetic acid solution of pH 7.4. DNA adsorption capacities as high as 2.0 × 10³ μg of DNA/g of dry gel could be achieved by the comb‐type hydrogels with higher PAAm contents. This value was approximately 6 times higher than that of CT alone. In addition, the comb‐type hydrogels showed a high adsorption/desorption rate depending on the PAAm content in the hydrogel. As a result, these comb‐type hydrogels carrying higher amounts of DNA may be considered good candidates for achieving higher removal rates for anti‐DNA antibodies and for effective gene therapy systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of the radiation grafting conditions on the cross‐sectional distribution of poly(vinylbenzyl chloride) grafted polymer onto poly(tetrafluoroethylene‐co‐hexafluoropropylene) films

Poly(vinylbenzyl chloride) (PVBC)‐grafted poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) films were prepared as precursors for ion‐exchange membranes with a radiation grafting technique. A scanning electron microscopy–energy dispersive X‐ray spectroscopy (SEM‐EDX) instrument was used to investigate the effects of the radiation grafting conditions on the distribution profiles of the grafts in the FEP‐g‐PVBC films because the properties of the ion‐exchange membranes were largely affected not only by the degree of grafting (DOG) but also by the distribution of the graft chain. These results indicate that the distribution profile of the grafts largely depended on the grafting parameters, such as the solvent, monomer concentration, film thickness, and irradiation dose. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Copper (II) ions and copper nanoparticles‐loaded chemically modified cotton cellulose fibers with fair antibacterial properties

This work describes the release of copper(II) ions from cellulose fibers, which have been chemically modified by periodate‐induced oxidation of cellulose, followed by covalent attachment of biopolymer chitosan. The release of copper(II) ions has been investigated in physiological fluid (PF) and protein solution (PS) both at 37°C. Fibers have demonstrated excellent antibacterial activity against E. coli. Finally, their borohydride‐induced reduction has yielded copper nanoparticle‐loaded fibers, with average diameter of particles, nearly 28.94 nm. The formation of copper nanoparticles has been established by surface plasmon resonance and FTIR spectroscopy. These fibers also show fair biocidal action against E. coli. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of eugenol‐grafted chitosan hydrogels and their antioxidant activities

The hydrogels composed of chitosan and eugenol were prepared to enhance and sustain antioxidant activities. The vinyl groups of eugenol monomer were directly grafted on the amino groups of chitosan, using ceric ammonium nitrate. The graft of eugenol onto chitosan was confirmed by using Fourier‐transform infrared and proton nuclear magnetic resonance spectroscopies. Results from the swelling behavior, thermal stability, and wide‐angle X‐ray diffraction revealed that the equilibrium water content decreased with increase of graft yields, because of the hydrophobicity of eugenol, although the introduction of eugenol as a side chain disturbed the ordered arrangement of chitosan's crystalline structure. The eugenol‐grafted chitosan hydrogels showed lower pH sensitivity in comparison with chitosan alone, because the amino groups, which were pH sensitive, of chitosan were grafted with eugenol. The scavenging activity of the tested hydrogels increased with graft yield of eugenol, because phenolic groups in the eugenol could play a major role as potent free‐radical terminators, in the results of improved antioxidant activity in eugenol‐grafted chitosan hydrogel in comparison with chitosan alone. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3500–3506, 2006