Yazar "Ajmal, Muhammad" seçeneğine göre listele
Listeleniyor 1 - 6 / 6
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Amidoximated poly(acrylonitrile) particles for environmental applications: Removal of heavy metal ions, dyes, and herbicides from water with different sources(Wiley, 2016) Ajmal, Muhammad; Demirci, Şahin; Siddiq, Mohammad; Aktaş, Nahit; Şahiner, NurettinMonodispersed poly(acrylonitrile) [p(AN)] particles were prepared by surfactant free emulsion polymerization and the hydrophobic nitrite groups were converted to hydrophilic amidoxime groups by treatment with hydroxylamine hydrochloride (NH2OH center dot HCl) in water. The p(AN) and amidoximated p(AN) [amid-p(AN)] particles were characterized by Fourier transformation infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The prepared particles were used as adsorbents in the removal from aqueous media of three different types of pollutants; organic dyes methylene blue (MB), and rhodamine 6 G (R6G), a heavy metal ion Cd (II), and a herbicide paraquat (PQ). The effects of various parameters such as amidoximation, pH of solution, amount of particles, and the initial concentration of solution were investigated. Upon amidoximation, a great increase in the adsorption capacity of the prepared particles was observed as the adsorbed amounts were increased to 87, 91, 74, and 91 mg/g from 5, 1.54, 1.06, and 1.22 mg/g for Cd (II), MB, R6G, and PQ, respectively. The amid-p(AN) particles were also able to remove considerable amounts of these pollutants from tap, river, and sea water. Langmuir, Freundlich, and Temkin adsorption isotherms were applied and it was found that the adsorption of Cd (II) and PQ followed the Langmuir adsorption model, whereas the adsorption of MB was found to obey the Freundlich adsorption isotherm. Pseudo first-order and pseudo second-order kinetics were also applied and the results showed that the adsorption processes of Cd (II), PQ, MB, and R6G follow pseudo second-order kinetics. (C) 2015 Wiley Periodicals, Inc.Öğe Betaine microgel preparation from 2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide and its use as a catalyst system(Elsevier, 2015) Ajmal, Muhammad; Demirci, Şahin; Siddiq, Mohammad; Aktaş, Nahit; Şahiner, NurettinWe demonstrate the synthesis of poly(sulfobetain methacrylate) (p(SBMA)) hydrogels of micro dimensions by inverse suspension polymerization of a zwitterionic monomer 2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide (SBMA). The prepared microgels were used as microreactors for the synthesis of nickel (Ni) nanoparticles by in situ reduction of Ni (II) loaded into microgels from an aqueous medium. The prepared microgels and microgel metal nanoparticle composites were characterized by Fourier Transformation Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Thermal properties of the microgels were studied by thermal gravimetric analysis (TGA). The amount of Ni nanoparticles generated within the microgels was determined by Atomic Absorption Spectroscopy (AAS) after dissolving the Ni nanoparticles to form Ni (II) ions by treating with concentrated hydrochloric acid (5 M HCl). The prepared composites were used as catalysts for the reduction of nitro aromatic compounds such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP) and 4-nitroaniline (4-NA) and excellent catalytic performances were observed. The effects of temperature and amount of catalyst were also evaluated. A mild activation energy in comparison to the literature was calculated as 35.64 kJ/mol, and very high k p value of 0.42 min(-1) as a function of temperature was estimated for the reduction of 4-NP catalyzed by p(SBMA)-Ni composite catalyst system. (C) 2015 Elsevier B.V. All rights reserved.Öğe Facile synthesis of hydrogel-nickel nanoparticle composites and their applications in adsorption and catalysis(Walter De Gruyter Gmbh, 2019) Shafiq, Zahid; Ajmal, Muhammad; Kiran, Sonia; Zulfiqar, Sonia; Yasmeen, Ghazala; Iqbal, Muzaffar; Farooqi, Zahoor H.Homopolymer bulk hydrogel of methacrylic acid was synthesized through a new single-step facile rout and used as a template for the fabrication of nickel (Ni) nanoparticles and as adsorbent to remove methylene blue (MB) and Rhodamine-6G (Rh-6G) from water. The Ni nanoparticles containing composite hydrogel was applied as catalyst for the degradation of a nitro compound. The carboxylic groups acted as highly efficient adsorption sites and their high degree was responsible for the removal of huge amounts of MB and Rh-6G from water. The maximum adsorption capacity of poly (methacrylic acid) hydrogel was 685 mg g(-1) for MB and 1571 mg g(-1) for Rh-6G. The adsorption data of MB was best fitted with Langmuir adsorption isotherm while that of Rh-6G with Temkin adsorption isotherm. Catalytic property of prepared hydrogel integrated with Ni nanoparticles was evaluated by using it as a catalyst for the degradation of 4-nitrophenol (4-NP). The apparent rate constant (k(app)) observed in this study for the reduction of 4-NP was as high as 0.038 min(-1). It was found that this catalyst system can be used repetitively with a slight decrease in catalytic activity.Öğe 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(Academic Press Inc Elsevier Science, 2016) Ajmal, Muhammad; Demirci, Şahin; Uzun, Yusuf; Siddiq, Mohammad; Aktaş, Nahit; Şahiner, NurettinIn 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 (Cr2O72- and arsenate (HAsO42-) 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 (Sancay, Canakkale-Turkey) water. (C) 2016 Elsevier Inc. All rights reserved.Öğe Simultaneous catalytic degradation/reduction of multiple organic compounds by modifiable p(methacrylic acid-co-acrylonitrile)-M (M: Cu, Co) microgel catalyst composites(Royal Soc Chemistry, 2016) Ajmal, Muhammad; Demirci, Şahin; Siddiq, Mohammad; Aktaş, Nahit; Şahiner, NurettinWe prepared poly(methacrylic acid-co-acrylonitrile) (p(MAc-co-AN)) microgels by inverse suspension polymerization, and converted the nitrite 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 MS 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.Öğe Synthesis and characterization of cobalt nanoparticles containing anionic polymer hydrogel nanocomposite catalysts for fast reduction of nitrocompounds in water(Springer, 2021) Jabeen, Nusrat; Farooqi, Zahoor H.; Shah, Attaullah; Ali, Abid; Khurram, Muhammad; Mahmood, Khalid; Şahiner, Nurettin; Ajmal, MuhammadDesign and development of hydrogel based metal nanocomposites is of vital signifcance in the feld of industrial waste management. In this study, the synthesis of poly (N-isopropylacrylamide-co-2-Acrylamido-2-methylpropane sulfonic acid) hydrogel and embedment of cobalt nanoparticles in the prepared hydrogel was demonstrated followed by the evaluation of catalytic potential of the as-prepared cobalt nanoparticles-hydrogel nanocomposite. The prepared hydrogel and corresponding nanocomposite were characterized by Fourier Transform Infrared (FTIR) spectroscopy to identify functional groups, Energy Dispersive X-ray (EDX) and Inductively Coupled Plasma—Optical Emission Spectrometry (ICP-OES) analysis to confrm the presence of cobalt, and Transmission Electron Microscopy (TEM) to assess the spatial morphology of cobalt nanoparticles. The prepared hydrogel showed absorption of water via non-Fickian mechanism, resulting in swelling as much as 69 times of its dry weight. The nanoparticles were found to be spherical in shape and having diameters around 25 nm. The potential catalytic properties of the cobalt nanoparticles-hydrogel nanocomposite were assessed while reducing 4-nitrophenol, 2-nitrophenol, 4-nitroaniline, and 2-nitroaniline to their corresponding amino compounds. The catalytic reactions were performed under varying temperatures and catalyst quantities, besides the catalyst was also subjected to rigorous repeated usage to evaluate its recycling potential. The thermodynamic parameters such as activation energy, activation entropy change, and activation enthalpy change were also calculated. The catalyst was found to be more efective in reducing 4-nitrophenol with a maximum rate constant of 4.67 min−1. A gradual decline in catalytic reduction rate was observed when the same catalyst was repeatedly used for fve consecutive cycles.
