Norazilawati Muhamad Sarih

Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, 1H Nuclear Magnetic Resonance (1H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 104 L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.

Synthesis of chitosan grafted-polyaniline/Co3O4 nanocube nanocomposites and their photocatalytic activity toward methylene blue dye degradation

In the present investigation, chitosan-grafted-polyaniline copolymer (ChGP) and Co3O4 nanocube-doped ChGP nanocomposites have been successfully synthesised via oxidative-radical copolymerisation using ammonium persulfate in an acidic medium for the photocatalytic degradation of methylene blue dye. The prepared nanocomposites were characterised by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). FESEM and TEM images confirmed the formation of Co3O4 nanocubes and a crosslinked polymeric network. The photocatalytic activities of ChGP and Co3O4 nanocube-doped copolymers were evaluated by monitoring the degradation of methylene blue dye under UV illumination. The degradation efficiency of the copolymer photocatalysts that were doped with Co3O4 nanocubes was higher than that of the undoped copolymer. Furthermore, the nanocomposite with 2 wt% Co3O4 nanocubes with respect to aniline was an optimum photocatalyst, with an 88% degradation efficiency after 180 minutes of irradiation under UV light.

Synthesis and characterization of Co3O4 nanocube-doped polyaniline nanocomposites with enhanced methyl orange adsorption from aqueous solution

In the present study, Co3O4 nanocube-doped polyaniline nanocomposites have been successfully synthesised via an in situ oxidative polymerisation technique using ammonium persulfate (APS) as an oxidant in acidic medium for efficient removal of methyl orange (MO) from aqueous solution. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer–Emmett–Teller analysis (BET) and Fourier transform infrared spectroscopy (FT-IR) measurements were used to characterise the prepared nanocomposites. The adsorption efficiencies of the PANI homopolymer and Co3O4 nanocube-doped nanocomposites were evaluated by monitoring the adsorption of methyl orange model dye from aqueous solution. The results revealed that the adsorption efficiency of the nanocomposites that were doped with Co3O4 nanocubes was higher than that of the undoped PANI and the adsorption kinetics followed a pseudo-second order reaction. Moreover, the nanocomposite with 4 wt% Co3O4 nanocubes with respect to aniline exhibited a superior adsorption capacity (107 mg g−1) as compared to other absorbents.

SrTiO3 Nanocube-Doped Polyaniline Nanocomposites with Enhanced Photocatalytic Degradation of Methylene Blue under Visible Light

The present study highlights the facile synthesis of polyaniline (PANI)-based nanocomposites doped with SrTiO3 nanocubes synthesized via the in situ oxidative polymerization technique using ammonium persulfate (APS) as an oxidant in acidic medium for the photocatalytic degradation of methylene blue dye. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), UV–Vis spectroscopy, Brunauer–Emmett–Teller analysis (BET) and Fourier transform infrared spectroscopy (FTIR) measurements were used to characterize the prepared nanocomposite photocatalysts. The photocatalytic efficiencies of the photocatalysts were examined by degrading methylene blue (MB) under visible light irradiation. The results showed that the degradation efficiency of the composite photocatalysts that were doped with SrTiO3 nanocubes was higher than that of the undoped polyaniline. In this study, the effects of the weight ratio of polyaniline to SrTiO3 on the photocatalytic activities were investigated. The results revealed that the nanocomposite P-Sr500 was found to be an optimum photocatalyst, with a 97% degradation efficiency after 90 min of irradiation under solar light.

Multi-end functionalised polymer additives synthesised by living anionic polymerisation —the impact of additive molecular structure upon surface properties

Numerous applications require specific properties at polymer surfaces that differ from the bulk. Herein we describe the novel synthesis of a series of multi-end functionalised poly(styrene) and poly(isoprene) additives carrying 1 to 3 fluoroalkyl (CF) groups. The additives were prepared by endcapping the living chain ends of polymers prepared via living anionic polymerisation. The resulting polymers have been used as additives to render the surface of polymer films hydrophobic/lipophobic and we have characterised these polymer films using static contact angle measurements with water as the contact fluid. We have found that the additive molecular weight, the number of CF groups, additive concentration and annealing conditions have a significant impact upon the resulting surface properties. Increasing the additive concentration and/or number of CF groups resulted in higher contact angles whereas increasing the molecular weight of additive reduced contact angles and surface hydrophobicity. It has been discovered that these additives undergo rapid adsorption to the surface of a thin film in the time taken to produce the film by spin coating and the result is significantly enhanced surface properties. Annealing polystyrene films above the glass transition temperature revealed some interesting behaviour in so much that it demonstrated that on many occasions it is preferable to anneal films containing very small quantities of additive rather than to simply add greater quantities of additive. In addition to contact angles measurements, Rutherford backscattering (RBS) analysis has been carried out on examples of modified poly(isoprene) films to quantitatively analyse the effect of additive molecular weight and number of fluoroalkyl groups on the near surface elemental composition of the modified thin films and confirming the relationship (described above) between these additive molecular parameters and surface adsorption. Finally, we have described a model which compares the behaviour of the additives in thin films to surfactants in solution.

Exploiting β-Cyclodextrin in Molecular Imprinting for Achieving Recognition of Benzylparaben in Aqueous Media

The molecularly imprinted polymer (MIP) based on methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) monomer was synthesized for the purpose of selective recognition of benzylparaben (BzP). The MAA-β-CD monomer was produced by bridging a methacrylic acid (MAA) and β-cyclodextrin (β-CD) using toluene-2,4-diisocyanate (TDI) by reacting the –OH group of MAA and one of the primary –OH groups of β-CD. This monomer comprised of triple interactions that included an inclusion complex, π–π interaction, and hydrogen bonding. To demonstrate β-CD performance in MIPs, two MIPs were prepared; molecularly imprinted polymer-methacrylic acid functionalized β-cyclodextrin, MIP(MAA-β-CD), and molecularly imprinted polymer-methacrylic acid, MIP(MAA); both prepared by a reversible addition fragmentation chain transfer polymerization (RAFT) in the bulk polymerization process. Both MIPs were characterized using the Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Brunauer-Emmett-Teller (BET). The presence of β-CD not only influenced the morphological structure, it also affected the specific surface area, average pore diameter, and total pore volume of the MIP. The rebinding of the imprinting effect was evaluated in binding experiments, which proved that the β-CD contributed significantly to the enhancement of the recognition affinity and selective adsorption of the MIP.

Molecular Imprinted Polymer of Methacrylic Acid Functionalised β-Cyclodextrin for Selective Removal of 2,4-Dichlorophenol

This work describes methacrylic acid functionalized β-cyclodextrin (MAA-βCD) as a novel functional monomer in the preparation of molecular imprinted polymer (MIP MAA-βCD) for the selective removal of 2,4-dichlorophenol (2,4-DCP). The polymer was characterized using Fourier Transform Infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) and Field Emission Scanning Electron Microscopy (FESEM) techniques. The influence of parameters such as solution pH, contact time, temperature and initial concentrations towards removal of 2,4-DCP using MIP MAA-βCD have been evaluated. The imprinted material shows fast kinetics and the optimum pH for removal of 2,4-DCP is pH 7. Compared with the corresponding non-imprinted polymer (NIP MAA-βCD), the MIP MAA-βCD exhibited higher adsorption capacity and outstanding selectivity towards 2,4-DCP. Freundlich isotherm best fitted the adsorption equilibrium data of MIP MAA-βCD and the kinetics followed a pseudo-second-order model. The calculated thermodynamic parameters showed that adsorption of 2,4-DCP was spontaneous and exothermic under the examined conditions.

Novel Functionalized Polythiophene-Coated Fe3O4 Nanoparticles for Magnetic Solid-Phase Extraction of Phthalates

Poly(phenyl-(4-(6-thiophen-3-yl-hexyloxy)-benzylidene)-amine) (P3TArH) was successfully synthesized and coated on the surface of Fe3O4 magnetic nanoparticles (MNPs). The nanocomposites were characterized by Fourier transform infra-red (FTIR), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, analyzer transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). P3TArH-coated MNPs (MNP@P3TArH) showed higher capabilities for the extraction of commonly-used phthalates and were optimized for the magnetic-solid phase extraction (MSPE) of environmental samples. Separation and determination of the extracted phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCP), di-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP), were conducted by a gas chromatography-flame ionization detector (GC-FID). The best working conditions were as follows; sample at pH 7, 30 min extraction time, ethyl acetate as the elution solvent, 500-µL elution solvent volumes, 10 min desorption time, 10-mg adsorbent dosage, 20-mL sample loading volume and 15 g·L−1 concentration of NaCl. Under the optimized conditions, the analytical performances were determined with a linear range of 0.1–50 µg·L−1 and a limit of detection at 0.08–0.468 µg·L−1 for all of the analytes studied. The intra-day (n = 7) and inter-day (n = 3) relative standard deviations (RSD%) of three replicates were each demonstrated in the range of 3.7–4.9 and 3.0–5.0, respectively. The steadiness and reusability studies suggested that the MNP@P3TArH could be used up to five cycles. The proposed method was executed for the analysis of real water samples, namely commercial bottled mineral water and bottled fresh milk, whereby recoveries in the range of 68%–101% and RSD% lower than 7.7 were attained.

β-Cyclodextrin based Molecular Imprinted Solid Phase Extraction for Class Selective Extraction of Priority Phenols in Water Samples.

Molecular imprinted polymer (MIP MAA-β-CD) with 2,4-dichlorophenol (2,4-DCP) and methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) as the template molecule and the functional monomer, respectively, was prepared and used in molecular imprinted-solid phase extraction (MISPE) for the extraction of phenols (2,4-dichlorophenol, 2-chlorophenol, 4-chloro-3-methylphenol, 4-chlorophenol, 2,4,6-trichlorophenol, and 2-nitrophenol) from water samples. The MISPE method was optimized prior to the determination using gas chromatography coupled with a flame ionization detector (GC-FID). Under the optimized conditions, the MIP MAA-β-CD sorbent showed good linearity (0.01-12 mgL−1), low limits of detection (0.14-0.75 µgL−1), and good repeatability (RSD 2.3-3.6%, n = 3). Good recoveries were obtained in the range of 97-115% for tap water and between 88-103% for river water. The developed MIP MAA-β-CD SPE was then compared with other adsorbents. The unique properties of β-CD and presence of imprinted cavities explains the higher extraction recoveries obtained for phenols when using MIP MAA-β-CD SPE.

Removal of endocrine disruptor di-(2-ethylhexyl)phthalate by modified polythiophene-coated magnetic nanoparticles: characterization, adsorption isotherm, kinetic study, thermodynamics

Core–shell magnetic nanoparticles have received significant attention and are actively explored due to their prospective applications. In the current study, superparamagnetic nanosorbent poly(phenyl(4-(6-thiophen-3-yl-hexyloxy)-benzylidene)-amine)/Fe3O4 nanoparticles (Fe3O4@P3TArH) was successfully synthesized via a simplistic method for the enhanced extraction of a potent endocrine disruptor, di-(2-ethylhexyl)phthalate (DEHP). The synthesized materials were characterized by Fourier transform infra-red (FTIR), X-ray diffractometry (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The extraction efficiencies of the synthesized sorbent materials were evaluated by monitoring the extraction of DEHP from aqueous solution. Removal of DEHP using Fe3O4@P3TArh was found to be pH and temperature dependent with a maximum adsorption capacity found to be at 298.15 K at pH 7 and the adsorption kinetics followed a pseudo second-order kinetics model. Thermodynamic studies revealed that adsorption occurred heterogeneously on the adsorption sites, and adsorption of di-(2-ethylhexyl)phthalate onto Fe3O4@P3TArh was found to be spontaneous, feasible, ordered, and exothermic. The activation energy was determined to be −40.6 kJ mol−1, which indicated the adsorption process was physisorption.