18 research outputs found

    Effect of gallium and arsenide adsorbed on graphene : a first-principles study on structural and electronic properties

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    In this study, the adsorption influence of two different metals, gallium (Ga) and arsenide (As) adatoms on the stabilities and electronic structure of single graphene layer has been systematically studied using first-principles pseudopotentials calculations within the framework of density functional theory (DFT). The generalized gradient approximation used is PW91 exchange-correlation functional. The results of our calculations reveal that the adsorption of Ga atom on graphene resulted in electron transfer mainly from p-orbital of the Ga adatom to graphene and subsequently, altered the electronic state of graphene by shifting the Fermi level away from Dirac point, up to ∼1.5 eV. Meanwhile, the d-orbitals of Ga adatom have spin polarization at the Fermi level where the minority spin d-orbitals are unoccupied. The As adatom was found to have larger adsorption energy value on H, B and T sites of graphene compared to Ga adatom. Thus, we described this energy difference as a result of the bonding configurations between both Ga and As atoms with carbon in the graphene structure. While B-site favored the adsorption of arsenic adatom, we found that the most favored adsorption site for Ga adatom on graphene is above H-sites

    Density functional study of manganese atom adsorption on hydrogen-terminated armchair boron nitride nanoribbons

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    In this paper, we have investigated stable structural, electric and magnetic properties of manganese (Mn) atom adsorption on armchair hydrogen edge-terminated boron nitride nanoribbon (A-BNNRs) using first principles method based on density-functional theory with the generalized gradient approximation. Calculation shows that Mn atom situated on the ribbons of A-BNNRs is the most stable configuration, where the bonding is more pronounced. The projected density of states (PDOS) of the favored configuration has also been computed. It has been found that the covalent bonding of boron (B), nitrogen (N) and Mn is mainly contributed by s, d like-orbitals of Mn and partially occupied by the 2p like-orbital of N. The difference in energy between the inner and the edge adsorption sites of A-BNNRs shows that Mn atoms prefer to concentrate at the edge sites. The electronic structures of the various configurations are wide, narrow-gap semiconducting and half-metallic, and the magnetic moment of Mn atoms are well preserved in all considered configurations. This has shown that the boron nitride (BN) sheet covered with Mn atoms demonstrates additional information on its usefulness in future spintronics, molecular magnet and nanoelectronics devices

    Low coverage palladium adsorption on graphene: first principles study

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    In this paper, we investigate stable geometries, electronic and magnetic properties of low coverage palladium (Pd) atom adsorption on graphene using first principles calculations with the generalized gradient approximation. Calculations show that single Pd atom located at the top of carbon atom is the energetically favorable configuration, and is found to be semiconductor and non-magnetic. We also compute the projected density of states (PDOS) around Fermi level and beyond. It is found that, C-Pd covalent interaction is mainly dominated by 2 pz of C, 5s and 4d like states of Pd. For low coverage stable Pd dimer, the adsorption is characterized by strong hybridization between the palladium atoms and the two carbon atoms bonded directly to it. A much weakening of Pd–Pd bond is observed and the C-Pd covalent bonds mainly dominate by 2pz of C orbital indicating that planar coating can be achieved. Thus, this work reveals that uniform coating of Pd atom can be achieved and may be useful in transport measurements

    Density functional study of spin polarization on a carbon material with a hexagonal structure induced by iron atoms

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    We investigate the spin polarization of a non magnetic material, e.g., a carbon material made from ten C atoms forming a hexagonal structure with total spin S = 0, induced by a ferromagnetic material, e.g., two Fe atoms with a total spin S = 4. Based on the density functional theory, we calculate the total spin density of the system. Our preliminary results show that the total spin for the ten C atoms changes from S = 0 to S = 4, while the total spin of the two Fe atoms changes from S = 4 to S =0. These results seem to indicate that there is a promising possibility to induce spin polarization on a carbon material by Fe atoms

    Electrochemical degradation of methylene blue using Ce(Iv) ionic mediator in the presence of Ag(I) ion catalyst for environmental remediation

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    Methylene blue (MB) is often used in textile industries and is actively present in the wastewater runs-off. Recently, mediated electrochemical oxidation (MEO) offers a fast, reliable and promising results for environmental remediation. Thus, we aimed to evaluate the electro-degradation potential of MB by MEO using Ce(IV) ionic mediator. Furthermore, we also observed the influence of addition Ag(I) ion catalyst in MEO for degradation of MB. The electro-degradation of MB was evaluated by cyclic voltammetry technique and was confirmed by UV-Vis spectrophotometry, high performance liquid chromatography (HPLC) analysis and back-titration analysis. The results showed that in the absence of Ag(I) ion catalyst, about 89 % of MB was decolorized within 30 min. When 2 mM of Ag(I) ion catalyst was applied, the electro-degradation of MB was increased to maximum value of 100%. The UV-Vis spectrum confirmed the electro-degradation of MB as suggested by decreased maximum absorbance value at λ 668 nm from 2.125 to 0.059. The HPLC analysis showed the formation of five new peaks at retention time of 1.331, 1.495, 1.757, 1.908, and 2.017 min, confirming the electro-degradation of MB. The back-titration analysis showed about 52.9% of CO2 was produced during electro-degradation of MB by MEO. More importantly, more than 97% of Ce(IV) ionic mediator were recovered in our investigation. Our results showed the potential of MEO using Ce(IV) ionic mediator to improve the wastewater runs-off quality from textile as well as other industries containing methylene blue

    STUDY ON THE FENTON REACTION FOR DEGRADATION OF REMAZOL RED B IN TEXTILE WASTE INDUSTRY

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    Remazol Red B is a reactive dye that is often used in the textile industry. The dye can cause serious problems in the environmental / water because it is difficult to be degraded by microorganisms. Decolorization of reactive azo dyes (Remazol Red B) before being discharged into the environment is an important aspect in creating technology (method) that are environmentally friendly. The method chosen for this decolorization is Advanced Oxidation Process (AOP) using the Fenton reaction. The optimum conditions for this reaction is 25 mg/L H2O2 and 1.25 mg/L of Fe2+ to Remazol Red B with initial concentration at 83 mg/L ( with ratio [H2O2]/[Fe2+] = 20). The optimum conditions of this reaction were obtained at pH 3 and temperature of 27 0C, with decolorization efficiency up to 100% for a reaction time of 60 minutes. The kinetic model of dye decoloritation follow the second order reaction. Some of the metal ions were added i.e. Cu2+, Pb2+ and Zn2+ , given no significant impact on the degradation performed

    Effect of temperature and kinetic modelling of lignosulfonate adsorption onto powdered eggshell in batch systems

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    The sorption of lignosulfonate onto powdered eggshell under the influence of temperature has been studied. The rate of adsorption onto eggshell was investigated under a variety of adsorbent dosages. The kinetic data from these investigations were correlated to a number of adsorption models in an attempt to elucidate the mechanism of the adsorption processes. Thermodynamic parameter data indicated that the lignosulfonate sorption process was non-spontaneous and endothermic under the experimental conditions, with the Gibbs free energy (Go) in the range of 1.83-1.07 kJ mol-1, enthalpy (Ho) andentropy (So) of 5.66 kJ mol-1 and 12.82 J mol-1, respectively and the activation energy of 18.17 kJ mol-1. The adsorption mechanism was found to follow a pseudo-second-order model, with the kinetic constants in the range of 0.689–1.430 g mg-1 min-1. Both the intra-particle diffusion and Boyd kinetic models indicated that boundary layer/film diffusion was the main rate determining step in lignosulfonate adsorption process

    Paremeter optimasi Xylenol Neodimium -Polime bercetakan (Nd-IPs) untuk adsoprsi ion Neodimium (III)

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    Performance evaluation of metal Neodymium Imprinted Polymers (Nd-IPs) through the polymerization of methyl metaacrylate with divinyl benzene in the presence of a metal complex Nd(III)-Xylenol Orange (XO) has been investigated. The adsorption capability towards Nd(III) ion were optimized based on ion retention parameters, such as pH, contact time, concentration, adsorption isotherm, and kinetic studies. The synthesized Nd-IPs obtained Nd(III) adsorption capacity reached 30.36 mg.g-1 at a pH of 5 with 20 minutes contact time. The isotherm studies showed the preference of Freundlich isotherm over Langmuir isotherm. The selectivity coefficient of Nd-IPs to ion Nd+3/La+3 are 1.35 and 1.38, then selectivity coefficient value obtained 1.35 and 1.40 for Nd+3/Y+3
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