VOLUME 37, NO5, OCT-2015

Electrochemical Properties of Barium Cerate Doped with Zinc for Methanol Oxidation

Barium cerate and its zinc doped series, BaCe1-xZnxO3 with 0.02 ≤ x ≤ 0.16, were synthesized using ammonia as a co-precipitant. The influence of zinc on phase and morphology was characterized using XRD and SEM, respectively. XRD revealed orthorhombic crystallinity for x= 0 to 14 mol% but distorted hexagonal phase for x = 16 mol%. SEM images revealed homogeneity of synthesized powders. The synthesized materials were then tested for their function as electrocatalyst for model analyte, methanol. Methanol electro-oxidation in acidic media was studied by modifying platinum electrode with BaCeO3 materials using cyclic voltammetry. Kinetic (ks,h, Do) and thermodynamic parameters (Ea, ΔG, ΔH, ΔS) were estimated for methanol electroxidation. The deduced value of diffusion coefficient of order of 10-10 cm2s-1 indicated faster kinetics of methanol oxidation using BaCeO3 than zinc doped sample in H2SO4 medium. The increasing temperature and methanol concentration enhanced the peak currents which pointed to the suitability of these materials as electrocatalysts. The stability and catalytic activity of these materials at various temperatures also aided to their potentiality in PEMFC application.read more

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Naveed Kausar Janjua, Mahwish Jabeen, Mehrosh Islam, Azra Yaqub, Sana Sabahat, Sadia Mehmood, Misbah Mumtaz, Ayesha Mujtaba, Rizwan Raza and Ghazanfer Abbas

Investigation of Catalytic Properties of Manganese Peroxidase (MnP) Produced from Agaricus bisporus A21 and its Potential Application in the Biotransformation of Xenobiotic Compound

In this study Manganese peroxidase, from novel fungus Agaricus bisporus A21 was purified, thermally characterized and its catalytic properties were investigated. The four step purification procedure i.e., ammonium sulphate precipitation, dialysis, ion exchange and gel filtration chromatography yielded 6.9 % activity with a purification factor of 8.48. The optimum temperature and pH of Manganese peroxidase for the oxidation of Manganese peroxidase were 40˚C and pH 6.0 respectively and remain active within the pH range of 3-10 after 24 h.The catalysis of MnSO4 by Manganese peroxidase was expressed by the Michaelis-Menten equation, suggesting that the maximum velocity (Vmax) was 231 U/mL and the Michaelis constant was 3.33mM revealing a binding site with higher substrate affinity. Enthalpy of activation decreased where Free energy of activation for thermal denaturation increased at higher temperatures. The partially purified manganese peroxidase shows excellent decolorization potential for Orange G (from 19.32 to 96 %) by the addition of natural mediator of wheat bran. UV–Vis spectrum and HPLC chromatogram clearly revealed that orange G transformed into different products. Thermostability and efficient decolorization suggest that this enzyme could be receiving substantial attention for its potential application in the biotransformation of organo-pollutants.read more

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Ismat Bibi, Haq Nawaz, Shagufta Kamal, Kashif Jilani, Tahira Ruby Farooq Warsi and Shazia Nouren

Activity on Leishmania tropica of Metal Complexes with NNOO Tetradentate Schiff Base Ligand: Kinetic and Thermodynamic Studies from TG-DTA Analysis

In the search for antileishmanial drug, tetradentate Schiff base ligand 2-{(E)-[(2-{[(Z)-(2-hydroxyphenyl)methylidene]amino}phenyl)imino]methyl}phenol (H2L) was reacted with transition metal ions to yield the complexes of the composition ML [where M = Co (II), Ni (II), Cu (II), & Zn (II)]. The copper based compound 3 (IC50 = 5.857 µM) showed activities even higher than the standard drug. TG and DTA analyses under static air in the temperature range 30-1000 oC were also observed for all the compounds. The TG-DTA analyses and the subsequent themodynamic and kinetic parameters calculated using the TG-DTA curves, have potential relevance for the biological activities. Horowitz–Metzger method was applied for calculating the activation energies and order of pyrolysis. Thermodynamic parameters like ∆S*, ∆H* and ∆G* were subsequently calculated using the corresponding expressions. The order of decreasing thermal stability and decreasing activation energy follow the orders Ni(II) ˃Co(II)˃Zn(II) ˃Cu(II) and E*Cu˃E*Co˃E*Ni˃E*Zn, respectively.read more

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Muhammad Ikram, Sadia Rehman, Qaisar Jamal and Akram Shah

Continuous Conversion of Rapeseed Oil to Bio-Fuels on 10VNi-10Ce /γ- Al2O3 Catalyst

Deoxygenation of rapeseed oil over V and Ni supported on Al2O3 promoted by Ce was investigated. The supported catalyst was prepared by incipient wetness impregnation method. The obtained catalyst was characterized using techniques of XRD, BET, NH3 -TPD, H2-TPD and TPR analysis. The results revealed that the catalyst had good thermal stability and three kinds of acidities sites. Compared with sintering, the catalyst deactivation was due to coke deposition. The results of FT-IR, SF-3, GC and GC-MS indicated that reaction temperature is the key factor and that oil velocity is very important factor and that reaction pressure is a less important one in producing bio-fuels. The condition was optimized under such circumstances -- reaction temperature at 450°C, reaction pressure at 3.0MPa, oil velocity at 0.1mL/min and the gas velocity at 30mL/min, respectively. The alkanes content and alkenes content of liquid products are 60.03% and 29.44%, respectively, under the optimized condition. The main products are the hydrocarbon compounds under C18. The results of GC and SF-3 showed that the reaction of decarboxylation and decarbonylation occurred at the same time, and that the oxygen in the oil is mainly removed by the forms of CO and CO2, and that small part is removed by the form of H2O. From the results of FT-IR，SF-3 and GC-MS, the generating mechanism of Non- ester renewable diesel was deduced.read more

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Xigen Huang, Zhiping Le and Lin Li

Investigation of Adsorption of Lead(II) onto a Montmorillonite Clay modified by Humic Acid

This study investigated the adsorption of Pb(II) in aqueous solution onto humic acid (HA) surface. The adsorption of lead(II) ions was studied using montmorillonite clay as adsorbent in the presence of humic acid under fix pH condition. The effect of HA on the adsorption of Pb(II) onto montmorillonite depends on its concentration in the solution, i.e., metal adsorption decreases with increasing concentration of HA in the solution. The HA was found to enhance the metal adsorption capacity of mineral surfaces in ternary system. The adsorption for Pb(II) on HA was high and this may due to its strong affinity for carboxylic and phenolic groups of humic substances. Since Pb(II) is divalent cation so its adsorption may have consumed two carboxylic/phenolic groups of HA. The decrease in adsorption of Pb(II) in the presence of HA in a ternary system is may be due to the blocking of adsorptive surfaces and reduction of cation exchange capacity by the clay in the presence of HA through its polar adsorption on mineral surface.read more

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Iffat Aziz, Muhammad Sirajuddin, Muhammad Haleem Khan, Shafqat Nadeem, Syed Ahmad Tirmizi and Rafaqat Ali Khan

Colour Fastness and Tensile Strength of Cotton Fabric Dyed with Natural Extracts of Alkanna tinctoria by Continuous Dyeing Technique

A natural dye extracted from the roots of alkanet (Alkanna tinctoria) was applied on cotton fabric by pad-steam dyeing technique. The study was designed to evaluate the colour fastness and tensile properties of dyed cotton after using various mordants, cationizing agents, UV absorbers and crosslinkers with this natural dye. Metallic mordants included aluminium sulphate, copper sulphate, ferric chloride, potassium dichromate and hydrated potassium aluminum sulphate or alum. Alkanet root extract produced variety of green shades with different dyeing auxiliaries. Better wash, light, crocking fastness; good colour coordinates such as chroma, hue, colour strength and increase in tensile strength was accomplished with post-mordanting of CuSO4. Cationization of cotton with quaternary ammonium compound (both pre-treatment and post-treatment) and post-finishing with soft polyurethane emulsion has enhanced the fastness properties, tensile strength as well as relative colour strength (K/S) , whereas, reactive UV absorber based on oxalanilide and heterocyclic compound as UV absorber greatly increased the light fastness of alkanet dyed cotton. Crosslinkers applied with alkanet dye on cotton (methylolation product based on glyoxalmonourein, modified dimethyloldihydroxyethylene urea, modified dihydroxy ethylene urea) also improved the fastness but could not bring further development in the shade and K/S value of the dyed samples.read more

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Shahnaz Parveen Khattak, Shabana Rafique, Tanveer Hussain, Faiza Inayat and Bashir Ahmad

Determination of Arsenic in Soil Alkali by Graphite Furnace Atomic Absorption Spectrophotometery Using Modified Corn Silk Fiber as Adsorbent

A safe, rapid, simple and environmentally friendly method based modified corn silk fiber (MC), chemical modified with succinic anhydride (C4H4O3),was developed for the extraction and preconcentration of As(Ш)in food additives soil alkali sample prior to graphite furnace atomic absorption spectrometry (GFAAS) analysis. The structure and properties of VC (unmodified corn silk fiber) and MC were analyzed and discussed by means of FTIR, SEM and TG, and the effect of adsorbent amount, pH, soil alkali solution concentration, adsorption time and adsorption temperature were carefully optimized. Under the optimum conditions, the relative standard deviations (RSD, n=6) were1.27-3.05%, the calibration graph was linear in the range of 0-100ug/ L and the limits of detection (LOD) was 0.13μg/L.The surface of MC became loose and porous which increased the adsorption area. Comparing with VC, carboxy groups were measured in MC and the increase of negative electron group in fiber molecular made its coordination combining ability with As(Ш) enhanced; In comparison with the removal arsenic rate of VC, MC's significantly increased by 2.86 fold. The recovery rate of soil alkali, treated by VC and MC, reached to 96.85%and 94.32% ,and it did not affected the function of soil alkali.read more

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Xuan Zhou, Yu Zhao, Shuangqiao Ju and Mousheng Liu

Determination of Silver in Rocks and Ores Samples using Modified Voltammetric Technique

Novel modified electrochemical method were used to analyze sedimentary, metamorphic, igneous, fined grained, coarse grain granite, granite with feldlaths and ferrogenous sand stone rocks along with boulangerite, stibnite, magnetite and scheelite ores for the presence of silver. Rocks and ores samples were processed through fire assay and acid digestion methods. Effect of various interfering metal ions was studied and it was observed that Hg(I) ions contributed maximum increment in the peak current of Ag(I). Differential pulse anodic stripping voltammetry (DPASV) and cyclic voltammetry (CV) were applied for the determination of silver. Glassy carbon bare and modified electrodes were used as working electrodes. Platinum and saturated calomel electrodes were applied as auxiliary and reference electrodes respectively. The modified method has high affinity, selectivity and sensitivity and can be applied for trace level determination of metal ions. The limits of detection (LDL), quantification (LOQ) and linear regression coefficient (R2) were found 1.14µg/L, 3.2µg/L and 0.9969 respectively.read more

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Afzal Shah, Salah Ud-Din Khan and Usman Ali Rana

Batch Scale Removal of an Organic Pollutant Amaranth Dye from Aqueous Solution using Pisum sativum Peels and Arachis hypogaea Shells as Adsorbents

The goal of this study was to utilize low cost and environmentally friendly adsorbents for batch scale removal of Amaranth dye from aqueous medium. Peels of Pisum sativum (Pea) and Arachis hypogaea (Peanut) were utilized to investigate their dye removing capacity. The optimized adsorption conditions for Pisum sativum (P.S.P) and Arachis hypogaea (A.H.S) were: adsorbent dose; 0.6 and 0.4 g, contact time; 45 and 10 minutes, pH; 2.0 for both, agitation speed; 150 and 100 rpm and temperature; 60 and 50 0C for P.S.P and A.H.S respectively. The adsorption data well suited to Langmuir isotherm. Maximum adsorption capacities were found to be 144.93 and 10.53mg/g for P.S.P and A.H.S respectively. Feasibility of the process was indicated by negative values of thermodynamic parameters ∆G0 for both adsorbents. Kinetic studies indicated that adsorption of Amaranth dye from aqueous medium by Pisum sativum peels and Arachis hypogaea shells followed pseudo-seconder order kinetics. It was concluded that Pisum sativum peels are more effective adsorbent for removal of Amaranth from aqueous solution as compared to Arachis hypogaea shells.read more

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Rabia Rehman and Ayesha Afzal

Selective Adsorption of Di(2-ethylhexyl) Phthalate by Surface Imprinted Polymers with Modified Silica Gel as Functional Support

A novel surface molecularly imprinted polymer (SMIP) selective for di(2-ethylhexyl) phthalate (DEHP) was prepared on the surface of silica gel, which was modified by aminopropyltriethoxysilane and acryloyl chloride in a two-step method, with DEHP as template, methyl acrylic acid (MAA) as functional monomer, ethyleneglycol dimethacrylate (EGDMA) as cross-linker and azobisisobutyronitrile (AIBN) as initiator. The prepared SMIP was characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and nitrogen adsorption-desorption analysis. The adsorption properties of the SMIP for DEHP were investigated. The results showed that the SMIP was porous and rough. Its specific surface area and pore volume were 292.05 m2/g and 0.299 cm3/g, respectively, which increased to 15 and 10 times that of silica gel, respectively. The adsorption performance is optimal under the conditions of pH value in the range 6~7. The adsorption equilibrium time was about 150 min. The isothermal adsorption process and adsorption kinetics could be well described by Langmuir and the pseudo-second-order kinetic model respectively. The saturated adsorption capacity is 16.08 mg/g. The SMIP exhibited excellent adsorption selectivity for DEHP. The SMIP prepared is a desirable solid-phase extraction agent for separation and enrichment of DEHP in complicated environmental samples.read more

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Zhan Yang, Fangyan Chen, Yubin Tang and Shaoli Li