Preparation and characterization of novel thermostable polyamides bearing different photoactive pendent architectures with antibacterial properties

Three diamine monomers with different derivatives of imidazole heterocyclic ring, aryl ethers and electron withdrawing trifluoromethyl groups in the backbone were synthesized and used in polycodensation reaction with various aliphatic and aromatic dicarboxylic acids for preparation of a series of novel polyamides(PAs). The PAs were obtained in high yields and possessed inherent viscosities in the range of 0.26-0.75 d L/g. All of the polymers were amorphous in nature,showed outstanding solubility and could be easily dissolved in amide-type polar aprotic solvents. They showed good thermal stability with glass transition temperatures between 162-302 ℃. Thermogravimetric analysis showed that all polymers were stable, with 10% weight loss recorded above 421 ℃ in N_2 atmospheres. All the PAs presented fluorescence upon irradiation with ultraviolet light and thus showed promise for applications in electroluminescent devices. The monomers and PAs were also screened for antibacterial activity against Gram positive and Gram negative bacteria.     

Phosphorylated polyacrylonitrile‐based electrospun nanofibers for removal of heavy metal ions from aqueous solution

The phosphorylated polyacrylonitrile‐based (P‐PAN) nanofibers were prepared by electrospinning technique and used for removal of Cu²⁺, Ni²⁺, Cd²⁺, and Ag⁺ from aqueous solution. The morphological and structural properties of P‐PAN nanofibers were characterized by scanning electron microscope and Fourie transform infrared spectra. The P‐PAN nanofibers were evaluated for the adsorption capacity at various pH, contact time, and reaction temperature in a batch system. The reusability of P‐PAN nanofibers for the removal of heavy metal ions was also determined. Adsorption isotherms and adsorption kinetics were also used to examine the fundamental adsorption properties. It is found that the P‐PAN nanofibers show high efficiency, and the maximal adsorption capacities of metal ions as calculated from the Langmuir model were 92.1, 68.3, 14.8, and 51.7 mg/g, respectively. The kinetics of the heavy metal ions adsorption were found to follow pseudo‐second‐order rate equation, suggesting chemical adsorption can be regarded as the major factor in the adsorption process. Sorption/desorption results reveal that the obtained P‐PAN nanofibers can remain high removal efficiency after four cycles.     

Preparation of hydrazinodeoxycellulose and carboxyalkyl hydrazinodeoxycelluloses and their adsorption behavior toward heavy metal ions

Nitrogen-containing cellulose derivatives hydrazinodeoxycellulose (HDC) and carboxyalkyl hydrazinodeoxycelluloses (α- and β-CAHDCs) were prepared from 6-chlorodeoxycellulose (CDC). Their adsorption of divalent transition metal ions was determined from dilute aqueous solutions and compared with that of aminoalkyl celluloses (AmACs) reported previously. HDC scarcely adsorbs metal ions in the pH range of 1–2, whereas α- and β-CAHDCs adsorb metal ions in this pH range. However, the adsorption of metal ions on HDC increases rapidly with increasing pH and HDC more effectively adsorbs metal ions than α- and β-CAHDCs in weakly acidic conditions. The ability to adsorb Cu²⁺ ions was in the order of AmAC (carbon number in the diamine moiety m = 2) > HDC > α-CAHDC > β-CAHDC in the weakly acidic region. These adsorbents selectively adsorb Cu²⁺ ions from the solutions containing other metal ions such as Mn²⁺, Co²⁺, and Ni²⁺, and the Irving–Williams series is obeyed in these adsorbent/metal ion systems. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3359–3363, 1997     

Optically high transparency and light color of organosoluble fluorinated polyamides with bulky xanthene pendent groups

New fluorinated polyamides were prepared directly from a diamine, 9,9‐bis[4‐(2‐trifluoromethyl‐4‐aminophenoxy)phenyl]xanthene ( BTFAPX ) with various aromatic dicarboxylic acid chlorides by low‐temperature polycondensation. The polymers were produced with moderate‐to‐high inherent viscosities of 0.65–1.01 dl/g while the weight‐average molecular weight and number‐average molecular weight were in the range of 69,000–82,000 and 39,000–43,000, respectively. Nearly all the polymers were readily soluble in amide‐type polar aprotic solvents [e.g. N, N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidinone], and even in less polar solvents such as dimethyl sulfoxide and pyridine, and afforded transparent, light‐colored, and flexible films upon casting from DMAc solvent. The polymers showed glass transition temperatures between 235 and 284°C, and 10% weight loss temperatures ranging from 495 to 532°C and 476 to 510°C in nitrogen and air, respectively, and char yields higher than 55% at 800°C in nitrogen. All polymers were amorphous and their films exhibited tensile strengths of 64–95 MPa, elongations at break of 6–9%, and tensile moduli of 1.9–2.5 GPa. These polymers had dielectric constants ranging from 3.65 to 4.03 (100 Hz), low‐moisture absorption in the range of 0.56–1.14%, and high transparency with an ultraviolet–visible absorption cut‐off wavelength in the 334–372 nm range. Copyright © 2010 John Wiley & Sons, Ltd.     

Dye-ligand immobilized IPNs membrane for removal heavy metal ions

We have developed a novel approach to obtain high metal sorption capacity utilizing a membrane containing chitosan and an immobilized reactive dye (i.e. Reactive Yellow-2). The composite membrane was characterized by SEM, FT-IR, swelling test, and elemental analysis. The membrane has uniform small pores distribution and the pore dimensions are between 5 and 10 μm, and the HEMA:chitosan ratio was 50:1. The reactive dye immobilized composite membrane was used in the removal of heavy metal ions [i.e., Pb(II), Hg(II) and Cd(II)] from aqueous medium containing different amounts of these ions (5-600 mg l⁻¹) and at different pH values (2.0-7.0). The maximum adsorption capacities of heavy metal ions onto the composite membrane under non-competitive conditions were 64.3 mmol m⁻² for Pb(II), 52.7 mmol m⁻² for Hg(II), 39.6 mmol m⁻² for Cd(II) and the affinity order was Pb(II) > Hg(II)>Cd(II).     

Mussel‐inspired method to decorate commercial nanofiltration membrane for heavy metal ions removal

Nanofiltration (NF) membranes have been widely used for the treatment of electroplating, aerospace, textile, pharmaceutical, and other chemical industries. In this work, halloysite nanotubes (HNTs) were directly anchored on the surface of commercial nanofiltration (NF) membrane by dopamine modification following advantageous bio‐inspired methods. SEM and AFM images were used to characterize the HNTs decorated membrane surface in terms of surface morphology and roughness. Water contact angle (WCA) was employed in evidencing the incorporation of HNTs and dopamine in terms of hydrophilicity or hydrophobicity. Augmentation of HNTs was found to obviously enhance the hydrophilicity and surface roughness resulting in improved water permeability of membrane. More importantly, the rejection ratios of membrane also increased during the removal of heavy metal ions from wastewater. The permeability and Cu²⁺ rejection ratio of modified NF membrane were as high as 13.9 L·m^?2·h^?1·bar^?1 and 74.3%, respectively. Incorporation of HNTs was also found to enhance the anti‐fouling property and stability of membrane as evident from long‐term performance tests. The relative concentration of HNTs and dopamine on membrane surface was optimized by investigating the trade‐off between water permeability and rejection ratio.     

Synthesis and characterization of new polyamides based on Diphenylaminoisosorbide

New aromatic polyamides were synthesized by the microwave‐assisted polycondensation of an optically active isosorbide‐derived diamine with different diacyl chlorides in the presence of a small amount of N‐methylpyrrolidinone. Polymers with inherent viscosities between 0.22 and 0.73 dL/g were obtained corresponding to molecular weights up to 140,000 g/mol. With interfacial polymerization or the Higashi method, lower molecular weight polymers were obtained with inherent viscosities in the range of 0.04–0.36 dL/g. Differential scanning calorimetry measurements clearly demonstrated the high thermal stability of these polymers (mp = 180–300 °C) and the absence of decomposition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6480–6491, 2005     

Synthesis of thiol chelating resins and their adsorption properties toward heavy metal ions

A series of chelating resins, derived from a macroreticular styrene-divinylbenzene (2%) copolymer beads grafted with various poly(ethylene glycols) HO? (? CH₂? CH₂? O? )_n? H(n = 0, 4, 9, 13) and containing thiol groups as chelating functions, have been synthesized in a three-step reaction sequence. The structure of the functionalized resins was confirmed by IR spectrophotometry, elemental analysis, and differential scanning calorimetry. The complexation behavior of these thiol resins was investigated towards Hg(II), Cu(II), and Pb(II) ions in aqueous solution by a batch equilibration technique. The influence of pH on adsorption capacity was also examined. The adsorption values for metal ions' intake followed the order Hg(II) > Cu(II) > Pb(II). The affinity of these polymers towards Hg(II) ions was so high that the total mercury level in the liquid decreased from 20 ppm to below 10 ppb after 2 h of treatment. Polymers can be regenerated by washing with a solution of hydrochloric acid (6N) and 10% by weight of an aqueous solution of thiourea. © 1994 John Wiley & Sons, Inc.     

Fast removal of heavy metal ions and phytic acids from water using new modified chelating fiber

The graft copolymerization of acrylic acid(AA) onto polyethylene glycol terephthalate(PET) fiber initialed by benzoy peroxide (BPO) was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber(PET-AA) was done by changing the carboxyl group into acylamino group through the reaction with dimethylamine.The modified chelating fiber(NDWJN1) was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curves indicated that NDWJNl could fast remove heavy metal ions and phytic acids from water effectively.Furthermore,batch kinetic studies indicated that heavy metal ions adsorbed to NDWJNl could be filted well by both pseudo-first-order and pseudo-second-order adsorption equations,but the intra-particle diffusion played a dominant role in the adsorption of phytic acids.     

石墨烯基复合材料去除和检测重金属离子的研究进展

石墨烯具有超大的比表面积、较快的载流子迁移速率和优异的电催化活性,广泛用于环境保护与检测领域。过去几年,基于石墨烯的大批高效吸附剂和传感器均被开发并应用于重金属离子的污染治理。本文详细阐述了石墨烯基复合材料在重金属离子去除和检测方面的研究进展,同时比较了不同方法的优缺点,最后对后续研究方向进行了展望。     

Static and dynamic sorption study of heavy metal ions on amino-functionalized SBA-15

Amino-functionalized SBA-15 mesoporous silica (SBA-15-NN) was synthesized using the normal grafting procedure of SBA-15 with [3-(2-Aminoethyl) aminopropyl] trimethoxysilane. Under optimal conditions, SBA-15-NN exhibited a higher adsorption capacity toward metal ions than SBA-15 in static adsorption. The results showed that the flow rate of 2?mL?min^?1 might be the optimum flow rate in dynamic adsorption, and the higher initial metal ion concentration is favorable for the adsorption of Zn(II), Co(II), and Ni(II) onto SBA-15-NN. The results indicated that SBA-15-NN could effectively remove multiple metal ions from aqueous solution as a good adsorption material.     

Optical sensors for determination of heavy metal ions

A review is given on optical means for single shot testing (probing) as well as continuous monitoring (sensing) of heavy metal ions (HMs). Following an introduction into indicator based approaches, we discuss the types of indicator dyes and polymeric supports used, as well as existing sensing schemes for HMs. The wealth of information is compiled in the form of tables and critically reviewed. Notwithstanding the tremendous work performed so far, it is obvious that still severe limitations do exist in terms of selectivity, limits of detection, dynamic ranges, applicability to specific problems, and reversibility. On the other hand, such sensors have found — and will find — their application whenever rapid and cost-effective testing is required, where personnel is scarce or unskilled, and in field tests. Despite their limitations, the number of such sensors (and of irreversible probes) for HMs is likely to increase in future.     

Treatment of heavy metal ions in wastewater using layered double hydroxides: A review

Heavy metal ions are toxic, and their toxicities change with different valence states, charges, and radii. Among the methods used for heavy metal ion removal, adsorption is widely employed due to its low cost and simple operation. As natural anionic clays, layered double hydroxides (LDHs) have drawn considerable attention for their use in the removal of anionic pollutants (such as heavy metal anions) due to their high removal efficiency and environmental friendliness. This article reviews the effects of the charge, type, and radius of the cations in the laminates of LDHs and the anions in the LDH interlayers, as well as the charge and radius of the heavy metals and the conditions (such as pH, coexisting ions, and temperature) on removing heavy metal ions with LDHs. The removal mechanisms have also been discussed. LDHs are hugely promising as an application for removing heavy metal ions that exist in different ionic forms by controlling the type and condition of LDHs.     

Chemically modified silica gel for selective solid-phase extraction and preconcentration of heavy metal ions

This paper describes our research on the synthesis of the sorbent with chemically bonded ketoimine groups, and, furthermore, using this sorbent in the SPE technique to extract and preconcentrate trace amounts of metal ions in water samples. Surface characteristics of the sorbent were determined by elemental analysis, NMR spectra for the solid phases (²⁹Si CP MAS NMR), and analysis of pore size distribution of the sorbent and nitrogen adsorption-desorption. The newly proposed sorbent with ketoimine groups was applied for the extraction and preconcentration of trace amounts of Cu (II), Cr (III) and Zn (II) ions from the water from a lake, post-industrial water and purified water unburdened back to the lake. The determination of the transition-metal ions was performed on an emission spectroscope with inductively coupled plasma ICP-OES. For the batch method, the optimum pH range for Cu (II) and Cr (III) extraction was equal to 5, and Zn(II)–to 8. All the metal ions can be desorbed from SPE columns with 10?mL of 0.5?mol?HNO₃. The detection limits of the method were found to be 0.7?µg?L^?1 for Cu (II), 0.08?µg?L^?1 for Cr (III), and 0.2?µg?L^?1 for Zn (II), respectively.     

Progress and challenges in molecularly imprinted polymers for adsorption of heavy metal ions from wastewater

Molecularly imprinted polymers (MIPs), prepared by the interaction forces such as forming covalent or non-covalent bonds by crosslinkers and initiators, are new types of specific recognition polymers with particular cavities. This is an ideal class of materials for wastewater treatment because of the particular holes left by the elution process. This review discusses the development process, classification, synthesis principles, systems, and polymerization methods of MIPs. At the same time, the adsorption mechanism of Copper (Cu), Mercury (Hg), Chromium (Cr), Silver (Ag), and Lead (Pb) in the MIPs technique are studied. Finally, some suggestions and prospects for the future development of MIPs are also put forward.     

Synthesis and characterization of new soluble aromatic polyamides from diaminotetraphenylimidazolin-2-one and various aromatic dicarboxylic acid chlorides

Novel aromatic polyamides, having inherent viscosities of 0.76-2.31 dL/g, were synthesized by the low temperature solution polycondensation of a new highly phenylated diamine monomer having an imidazolinone group, 1,3-bis(4-aminophenyl)-4,5-diphenylimidazoline-2-one (TPIDA), with various aromatic diacid chlorides. All the polymers were amorphous, and most of the polyamides were readily soluble in organic solvents such as N-methyl–2-pyrrolidone, N,N-dimethylacetamide (DMAc), and m-cresol. Flexible and tough films could be prepared from the DMAc solutions of these soluble aromatic polyamides. The glass transition temperatures and 10% weight loss temperatures under nitrogen of the polyamides were in the range of 275–315°C and 430–505°C, respectively. © 1995 John Wiley & Sons, Inc.     

Sensitive detection of heavy metals ions based on the calixarene derivatives-modified piezoelectric resonators: a review

Heavy-metal pollution is a foremost concern, as excessive heavy metals produce environmental contamination, and the accumulative effects of heavy metals pose a major hazard to human health. There is an urgent need for a fast, sensitive and effective method for detecting heavy metal cations in the environment. In recent years, using Quartz Crystal Microbalance (QCM) technique, significant progress was achieved in quantitative analysis by providing a new approach for determination of chemical content analysis. The objective aim of this review is to assess the research development of QCM applications in detection of heavy metal cations in natural water (or aqueous solution) and reflect the challenges and forthcoming point of view for QCM-based sensors for heavy-metal ions. A brief outline about the basic measurement methodologies and analytical techniques is given. To illustrate applications of the QCM techniques, the influence of the structural transformation resulting from polymer, macrocyclic ‘calixarenes’ and nanostructural coating on sensation will be discussed. Lastly, we summarise fields of applications and future forecast for the utilisation of functionalised QCM surface as a chemical sensor to study the interaction of heavy metal ions with calixarenes.     

Synthesis,characterization, and water sorption properties of new aromatic polyamides containing benzimidazole and ethylene oxide moieties

New polyamides, containing a benzimidazole side group and ethylene oxide moieties in the structural repeat unit, were synthesized by low‐temperature polycondensation. The aim of this design was to obtain polyamides that were more soluble in common organic solvents and hence had better processability than benzimidazole polyamides while maintaining the water sorption properties characteristic of the latter. The results showed that the number of ether linkages of the repeat unit played an important role in the glass‐transition temperature and in the water sorption properties, the polyamides with one or two ethylene oxide units being more hydrophilic than benzimidazole polyamides. However, the length of the ethylene oxide chain played a minor role in the solubility because the second member of the series, with two ether linkages (i.e., one ethylene oxide unit), reached the same level of solubility as those polyamides with more ethylene oxide moieties. No crystallinity was observed by X‐ray and calorimetric measurements for the new polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 112–121, 2005     

Synthesis and characterization of aromatic polymers containing pendant silyl groups. II. Aromatic polyamides

In order to improve the solubility of aromatic polyamides without significant loss of thermal stability, synthesis of aromatic polyamides containing pendant silyl groups was carried out by direct polycondensation of silylated aromatic diacids such as 2-trimethylsilylterephthalic acid (TSTA), 2,5-bis (trimethylsilyl) terephthalic acid (BTSTA), 5-trimethylsilylisophthalic acid (TSIA), 5-dimethylphenylsilylisophthalic acid (DMSIA), and 5-triphenylsilylisophthalic acid (TPSIA) with various aromatic diamines. The resulting polyamides had inherent viscosities in the range of 0.18–1.10 dL/g and showed improved solubilities toward aprotic polar solvents such as NMP, DMF, DMSO, etc. The prepared aromatic polyamides exhibited fairly good thermal stabilities, which were almost comparable to those of corresponding nonsubstituted aromatic polyamides. That is, thermogravimetric analysis (TGA) data revealed 10% weight losses at 358–500°C and residual weights at 700°C were 46–67% under nitrogen atmosphere. © 1992 John Wiley & Sons, Inc.     

Synthesis and properties of novel fluorinated polyurethane based on fluorinated gemini diol

In the current study, the novel fluorinated polyurethanes (FPUs) that contained the gemini branched fluoroether side groups on the hard segments were developed. In brief, to obtain these FPUs, a new class of fluorinated gemini diol with double‐branched fluoroether side groups was first synthesized and characterized by using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and mass spectrometry. Subsequently, a series of FPUs were designed and prepared by using hexamethylene diisocyanate, poly (tetramethylene oxide glycol), 1,4‐butanediol, and fluorinated gemini diol. Analysis of the FPUs' surface properties from contact angle analysis indicated that the water contact angle increased from 81° to more than 120° when the content of fluorinated gemini diol was increased. Differential scanning calorimetry results revealed that introduction of fluorinated gemini dio decreased the T_g of FPUs, causing a better phase separation. Results from thermogravimetric analysis studies indicated the thermal stability of FPUs was improved. Scanning electron microscopy and energy dispersive X‐ray spectroscopy revealed that fluoroether groups migrate to and enrich on the outmost surface of FPUs.