Volume 15, Issue 3

In this work, a magnetic molecularly imprinted polymer (MION-MIP) was prepared for the recognition and extraction of sulfadiazine (SDZ). The acrylamide-based MIP was imprinted directly onto the surface of 3-(trimethoxysilyl)propyl methacrylate-modified magnetic iron oxide nanoparticles. The synthesized MION-MIP with a diameter about 100 nm possesses fast adsorption kinetics and high adsorption capacity. The results also indicated that a higher maximum adsorption capacity (775 μg g -1 ) was achieved by the synthesized MION-MIP. The Langmuir adsorption isotherm model was found to describe well the equilibrium adsorption data. The results from the competitive binding experiment showed that MION-MIP was not only selective toward SDZ but the adsorption of sulfamerazine was also dramatically high. SDZ and sulfamerazine have an almost similar substructure where these two compounds were only differentiated by one methyl group. To explain this result, a computational study was carried out. From a different level of calculation with semiempirical (PM3), Hartree-Fock (HF), and density functional theory (DFT) calculation, SDZ and sulfamerazine showed similar interaction energy and interaction mechanism with the acrylamide monomer. Therefore, both SDZ and sulfamerazine could have the same binding property with the MION-MIP.

Ultrafiltration (UF) is one of the most widely used membrane technologies for the effective separation of macromolecules in feed solutions. However, despite good separation efficiency, the UF membranes made up of pure polymers suffer to a greater extent because of low flux problem, which affects the process time and load. To handle this limitation, the base polymer is blended with a suitable additive to modify the structural and surface morphology of the membrane to provide better fluxes. In this current study, a series of polyethersulfone (PES) UF asymmetric membranes blended with polyethylene glycol and iron oxide nanoparticles was prepared using the phase inversion technique. Prepared membranes were analyzed for their morphology, thermal stability, and membrane characterization. Morphology studies using scanning electron microscopy and atomic force microscopy confirmed the increase in the number of pores, pore size in support layer, and surface roughness in the blended membranes, ensuring the chances of enhanced flux. Surface hydrophilicity was increased with the increase in the iron oxide concentration in the composite membranes. Thermal analysis studies showed the better thermal stability of the blended membranes. Pure water flux of the prepared composite membranes was improved to a maximum of four times in comparison with pure PES membrane. Dye rejection studies clearly showed that the blended membranes almost had the same rejection as that of pure PES membrane. Thus, the prepared PES composite UF membrane is a promising candidate for the treatment of dye-polluted wastewater, ensuring high fluxes and effective rejection.

The chelating resin was synthesized by free-radical copolymerization of iminodiacetic acid modified glycidyl methacrylate with a cross-linker N , N ′-methylene biscarylamide at 70°C for removal of heavy metal ions from aqueous solutions. The equilibrium adsorption capacities of the chelating resin from their single-metal ion solutions were 3.28 mmol/g for Cd(II), 2.36 mmol/g for Cu(II), 1.71 mmol/g for Mn(II), 1.69 mmol/g for Ni(II), 1.41 mmol/g for Zn(II), 1.24 mmol/g for Co(II), 0.78 mmol/g for Cr(III) and 0.66 mmol/g for Pb(II). Their related absorption behaviors are discussed in this paper such as thermodynamic equilibrium, pH effect and the Langmuir and Freundlich model to evaluate the experimental data. According to the results, this resin could be used as a promising adsorbent for industrial wastewater disposal.

Eco-friendly bio-composite of polypropylene (PP)/coir-sisal blended yarn was prepared using commingling technique, in which both the fibers are wound onto a metal plate and then compression molded. Various chemical treatments have been done in order to improve the interfacial adhesion between the matrix and reinforcement, thereby to increase the properties of the composite. Thermal stability study was done using thermogravimetric analysis. The resulting thermogram reveals that chemical treatments increase the thermal stability of the commingled composite to a considerable extent. A significant increase is observed in the tensile properties of the treated composite especially maleic anhydride modified PP (MAPP) treated composite as compared to the untreated one. The tensile strength and tensile modulus of MAPP treated composite was found to be 29.24 MPa and 1330 MPa, respectively, which was found to be 7.5% and 6.4% greater than that of untreated composite. The experimentally observed tensile properties of the composites were compared with the existing models of reinforced composites. The surface morphology and fiber surface treatments were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy.

The synthesis of well-dispersed carbon spheres using starch as a carbon source, citric acid as a catalyst, and distilled water as a medium without involving any organic solvent at 120–150°C for 16 h under hydrothermal treatment is presented. The use of citric acid promoted starch dehydration and allowed the use of a lower hydrolysis temperature. Under similar conditions the formation of carbon spheres was not possible in the absence of citric acid. We noticed the significant effect of temperature on the particle size and shape. The particle size increased with the increase in temperature. The synthesized carbon spheres were characterized using field-emission scanning electron microscope (FE-SEM), scanning electron microscope (SEM), X-ray diffraction, Fourier-transform infrared (FTIR) and Raman spectroscopy.

The susceptibility and characteristics of biological degradation of lignocellulosic fibers, such as sisal fibers, are presented in this study using a modified soil burial test (SBT) protocol. The biodegradation profile of untreated sisal fibers as well as of fibers treated with an alkaline emulsion of neem oil and phenolic resin was evaluated by estimating the enzymatic activities during the exposure of fibers to a soil/compost mix. Observation of the results indicated that biodegradation of the fibers was predominated by enzymatic hydrolysis of amorphous materials followed by degradation of crystalline cellulose. It was also evident that “oil-resin” treatment makes the fibers more resistant to biodegradation owing to the removal of amorphous materials, enhanced hydrophobicity, and possible chemical alteration of the surface hydroxyl groups of the fiber surface. This research aims to establish a systematic knowledge on the biodegradation profile of fiber components using a state-of-the-art protocol for SBT.

Three functionalized ionic liquids (ILs) of [HeMIM]Cl, [CeMIM]Cl, and [AeMIM]Br that can dissolve corn stalk were synthesized and characterized via Fourier transform infrared spectroscopy (FTIR) and 1 H NMR. The dissolved corn stalk was in situ blended with phenol and formaldehyde to produce modified phenolic resin composites. The resulting composites were characterized via FTIR, differential scanning calorimetry, and X-ray diffraction analysis, and tested for their mechanical properties. In addition, the effects of ILs on the dissolution rate of corn stalks and on the mechanical properties of the modified phenolic resin were investigated as well. The results showed that the synthesized ILs presented good solubility toward corn stalk at the optimum temperature of 90°C. After modification with corn stalk dissolved in ILs, the mechanical properties of phenolic resin were significantly improved. At the same conditions, the phenolic resin modified with [AeMIM]Br presented the lowest concentration of free formaldehyde and the best mechanical properties, in which the tensile strength and impact strength were improved from 3.28 MPa and 0.93 kJ/m 2 to 9.36 MPa and 5.74 kJ/m 2 , respectively, but the hardness only changed slightly.