Sahin Demirci

Simultaneous catalytic degradation/reduction of multiple organic compounds by modifiable p(methacrylic acid-co-acrylonitrile)–M (M: Cu, Co) microgel catalyst composites

We prepared poly(methacrylic acid-co-acrylonitrile) (p(MAc-co-AN)) microgels by inverse suspension polymerization, and converted the nitrile groups into amidoxime groups to obtain more hydrophilic amidoximated poly(methacrylic acid-co-acrylonitrile) (amid-p(MAc-co-AN)) microgels. Amid-microgels were used as microreactors for in situ synthesis of copper and cobalt nanoparticles by loading Cu(II) and Co(II) ions into microgels from their aqueous metal salt solutions and then converted to their corresponding metal nanoparticles (MNPs) by treating the loaded metal ions with sodium borohydride (NaBH4). The characterization of the prepared microgels and microgel metal nanoparticle composites was carried out by SEM, TEM and TG analysis. The amounts of metal nanoparticles within microgels were estimated by AAS measurements by dissolving the MNP entrapped within microgels by concentrated HCl acid treatment. Catalytic performances of the prepared amid-p(MAc-co-AN)–M (M: Cu, Co) microgel composites were investigated by using them as catalysts for the degradation of cationic and anionic organic dyes such as eosin Y (EY), methylene blue (MB) and methyl orange (MO), and for the reduction of nitro aromatic pollutants like 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP) to their corresponding amino phenols. Here, we also report for the first time, the simultaneous degradation/reduction of MB, EY and 4-NP by amid-p(MAc-co-AN)–Cu microgel composites. Different parameters affecting the reduction rates such as metal types, the amount of catalysts, temperature and the amount of reducing agent were investigated.

Introduction of double amidoxime group by double post surface modification on poly(vinylbenzyl chloride) beads for higher amounts of organic dyes, As (V) and Cr (VI) removal

In this study, the synthesis of micron-sized poly(vinylbenzyl chloride) (p(VBC)) beads and subsequent conversion of the reactive chloromethyl groups to double amidoxime group containing moieties by post modification is reported. The prepared beads were characterized by SEM and FT-IR spectroscopy. The amidoximated p(VBC) beads were used as adsorbent for the removal of organic dyes, such as eosin y (EY) and methyl orange (MO), and heavy metals containing complex ions such as dichromate (Cr2O7(2-)) and arsenate (HAsO4(2)(-)) from aqueous media. The effect of the adsorbent dose on the percent removal, the effect of initial concentration of adsorbates on the adsorption rate and their amounts were also investigated. The Langmuir, Freundlich and Temkin adsorption isotherms were applied to the adsorption processes. The results indicated that the adsorption of both dichromate and arsenate ions obeyed the Langmuir adsorption model. Interestingly, it was found that the prepared beads were capable of removing significant amounts of arsenate and dichromate ions from tap and river (Sarıcay, Canakkale-Turkey) water.

Can PEI microgels become biocompatible upon betainization

Polyethylene imine (PEI) microgels prepared via micro emulsion polymerization technique were treated with 1,3-propane sultone to obtained betainized PEI (b-PEI) microgels. The betainization reaction generated zwitterions on PEI microgel that are positive charges from quarternized amine groups of PEI, and the newly formed negative charges from SO3- groups from the modifying agent, 1,3-propane sultone offered interesting properties. The smaller size of b-PEI microgels that are obtained by simple filtration were increased with betainization from 512±14 to 1114±86nm. Also, the betainization of PEI microgel provided negative zeta potential values at high pH values as 9, 10, 11, and 12. Moreover, the b-PEI microgels render more effective dye absorption capabilities for anionic or cationic organic dyes such as Methyl Orange (MO) and Methylene Blue (MB) separately with the significant increase dye adsorption capacity of 354±31 and 274±19mg/g respectively. Moreover, antibacterial properties of b-PEI microgels tested on the E. coli ATCC 8739 and S. aureus ATCC 6538 were diminished whereas bare PEI has low MIC and MBC values (strong antibacterial properties). Interestingly, the PEI microgels known for their strong antibacterial and toxic nature found to be biocompatible upon betainization reaction. The biocompatibility test were carried with WST-1 tests and double staining methods. The cytotoxicity, apoptotic and necrotic cell tests were shown that PEI microgels induce no cytotoxicity up to 400μg/mL whereas PEI microgels possessed 50% toxicity at this concentration, suggesting that b-PEI microgels become biocompatible upon betainization with, 3-propane sultone.

Chapter 9 - 0D, 1D, 2D, and 3D Soft and Hard Templates for Catalysis

Abstract Catalytic reactions are generally catalyzed by metal nanoparticles, metal oxides, or their bi- or trimetallic forms with various formulations, morphology, composition, and shapes. The metal nanoparticle catalytic performances are directly related to the surface features of particles such as crystal structure, atomic stacking and order, surface area, roughness and atomic and/or spatial organizations, and the catalyst environments. Its very well-known that the high surface energy of the metal nanoparticles, which is one of the most important challenges to be considered to overcome, leads to aggregation, deactivation, and oxidation problems. Therefore, many templates such as nanoemulsions prepared from surfactant and polymers and nanogels as zero-dimensional (0D) soft templates; cylindrical or tubular natural or synthetic structures derived from again surfactants, polymers, or peptides or self-assembled structures as one-dimensional (1D) templates; graphene oxide, mica, clay, and silicates as two-dimensional (2D) hard templates; and microgel, bulk hydrogel, and cryogels as three-dimensional (3D) soft templates that are used as stabilizing media will be discussed. Regardless of the sizes of templates, various parameters such as morphology, e.g., core-shell, capsules, guiding direction, porosity, and compartmentation features of the templates, have paramount significance on composition, crystallinity, and shape of the resultant nanoparticle to be used as catalyst. Metal nanoparticles, metal oxides, and metal nanoparticles doped with various elements have been extensively investigated due to their unique physical and chemical properties, and even their bi- or trimetallic forms have been under examination due to synergistic potential application of each of the components. The main concern regarding the nanoparticle synthesis is to overcome their agglomeration, due to their high surface area, high energy, and high surface reactivity resulting in strong tendency to aggregate, leading to deactivation and oxidation. There are a variety of methods available in the synthesis of metal nanoparticles to prevent some of these shortcomings with some catalytic performance sacrifices or with some economical infeasibilities. Nevertheless, the key issue with these methods is the control of the particle size and shapes and the morphology and crystallinity. Therefore, a wide range of templates such as nanoemulsions using surfactant and polymers and nanogels as 0D soft templates; cylindrical or tubular natural or synthetic structures derived from again surfactants, polymers, or peptides or self-assembled structures as 1D templates; graphene, mica, clay, and silicates as 2D hard templates; and microgel, bulk hydrogel, and cryogels as 3D soft templates as stabilizing environments and particle compartments will be discussed. In general, polar molecules or polyelectrolytes stabilizers can be used in both controlling the size and preventing the metal nanoparticles from precipitation processes. Water-soluble polymers, including polyelectrolytes, are the commonly employed stabilizing and/or chelating agents in the preparation of metal ultrafine particles.

Synthesis and Characterization of Terephthalic Acid Based Cr 3+ , Sb 3+ , In 3+ and V 3+ Metal-Organic Frameworks

The metal organic frameworks (MOFs) were synthesized by the reaction of the benzene-1,4-dicarboxylic acid (terephtalic acid (TPA)) ligand with the corresponding metal salts such as CrCl3, SbCl3, In2(SO4)3, and VCl3 in 1:2 molar ratio. These complexes were characterized by the BET measurement, scanning electron microscopy, thermogravimetric analyzer (TGA), magnetic susceptibility measurements, FT-IR and electronic spectral studies. The thermal stability and the magnetic sussepcibility of the MOFs were also studied by TGA analyses and Gouy method. These studies show that all the MOFs have octahedral arrangement around the metal ions except vanadium cxcomplex which is distorted square pyramidal geometry. Zeta potential of TPA, TPA–Cr, and TPA–Sb MOFs were shown that formulations have neutral, TPA–In and TPA–V MOFs positive and negative surface charges.

Conductive PEI semi-IPN cryogels: Synthesis and characterization

F studies of the behavior of single molecules to simple measurements of the roughness of a coating, Atomic Force Microscopy (AFM) has proven itself to be an indispensable tool for polymer research. The ability to visualize structural information, nano-mechanical and other properties with nanometer resolution in a wide variety of media allows for the correlation with performance data. The NanoWizard family of AFMs is unique in that it combines key attributes commonly considered mutually exclusive: Fast Imaging Speed, Quantitative Imaging (QI) of nanomechanical and electrical properties, the combination with high resolution optics, and ease-of-use. Image acquisition times of a few seconds per frame allow for studying dynamic processes like dewetting or crystallization dynamics at temperatures up to 300 C. A variety of fluid and environmental cells enables measurements in controlled environments to simulate e.g. physiological conditions, which is an important step in testing stages of drug delivery systems. QI data reveal mechanical information like modulus and adhesion maps as well as rheology information. The underlying modes of operating the AFM will be explained in a comprehensive fashion and illustrated with application examples.