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    Highly versatile p(MAc)-M (M: Cu, Co, Ni) microgel composite catalyst for individual and simultaneous catalytic reduction of nitro compounds and dyes
    (Royal Soc Chemistry, 2014) Ajmal, M.; Siddiq, M.; Al-Lohedan, H.; Şahiner, Nurettin
    Poly(methacrylic acid) (p(MAc)) microgels were synthesized by inverse suspension polymerization and used as a template for copper, nickel, and cobalt nanoparticle preparation. Upon absorption of Co(II), Ni(II), and Cu(II) by p(MAc) microgels from related aqueous solutions, the metal ion laden microgels were treated with sodium borohydride (NaBH4) to obtain the corresponding metal nanoparticles within the p(MAc) network as p(MAc)-M (M: Co, Ni, Cu). The microgels and metal nanoparticle containing composites were visualized and analyzed by Optical Microscopy, SEM, and TEM analysis. Thermal properties and the metal nanoparticle content of the prepared composites were investigated by TG analysis. However, the exact amounts of metal nanoparticles entrapped within the microgels was calculated by AAS measurements after dissolution of the metal nanoparticles within p(MAc) the microgel composites by concentrated HCl acid treatment. The prepared p(MAc)-M composites were employed as a catalyst for the degradation of some organic dyes such as Eosin Y (EY), and methyl orange (MO), and reduction of nitro aromatic pollutants such as 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) to their corresponding amino phenols. More importantly, we report the simultaneous degradation of EY and 4-NP reduction catalyzed by p(MAc)-Cu microgel composites. Various parameters effecting the degradation of dyes and nitro compound reduction such as metal types, and their amounts, temperature and amount of reducing agent were investigated.
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    Magnetic Co-Fe bimetallic nanoparticle containing modifiable microgels for the removal of heavy metal ions, organic dyes and herbicides from aqueous media
    (Royal Soc Chemistry, 2015) Ajmal, M.; Siddiq, M.; Aktaş, N.; Şahiner, Nurettin
    Poly(methacrylic-co-acrylonitrile) (p(MAc-co-AN)) microgels were prepared and nitrile groups were converted to amidoxime groups by chemical modification. Amidoximated microgels, amid-p(MAc-co-AN) microgels were used for in situ synthesis of cobalt-iron (Co-Fe) bimetallic magnetic nanoparticles by simultaneous reduction of Co(II) and Fe(II) ions within microgel. The prepared magnetic microgels as amid-mag-p(MAc-co-AN) microgel were found to be very effective adsorbents for the removal of metal ion such as Cd(II), Cr(III), and organic dyes e.g., methylene blue (MB), rhodamine 6G (R6G) and a herbicide, paraquat (PQ). A tremendous increase in the adsorption capacities of amid-p(MAc-co-AN) microgels was found as 88.1, 89.9, 190.0, 334.5 and 166.5 mg g(-1) from 40.2, 37.4, 75.3, 57.4, and 56.3 for MB, R6G, PQ, Cd(II), and Cr(III), respectively. Moreover, a further increase in adsorption capacity of amid-mag-p(MAc-co-AN) microgel composites were also accomplished with the existence of magnetic particles. Adsorption of these contaminants from tap, river and seawater was also studied. The effects of different parameters i.e., pH, concentration of adsorbent solution and amount of adsorbate was also studied. Langmuir, Freundlich and Temkin adsorption models were applied, and the adsorption of Cd(II) and Cr(III) was found to obey Langmuir adsorption isotherm better.