Activation of molecular oxygen for the oxidation of 2-mercaptoethanol: A kinetic and mechanistic approach

M.Z.A. Rafiquee,Masoom R. Siddiqui,H.N. Haque,M. Shamsul Ola,Hamad A. Al-Lohedan,Z.A. ALOthman,Saikh M. Wabaidur 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-

Reduction of molecular oxygen by 2-mercaptoethanol in the presence of cobalt(II)histidine is described. Cobalt(II)histidine complex forms dinuclear 2:1 (Co:O2) complex with molecular oxygen (m-dioxyte-trakis(histidinato)dicobalt(II)). The molecular oxygen did not directly react with 2-mercaptoethanol, but,reacted in the form of an adduct with cobalt(II)histidine complex. During the course of the reaction themolecular oxygen is reduced to hydroxide ion while the cobalt(II)histidine complex was oxidized tocobalt(III)histidine while 2-mercaptoethanol is reduced into 2,20-dithiodiethanol. The decrease inabsorbance for the dioxygen complex was monitored spectrophotometrically and was observed that thevalues of rate constant increased with the increase in [2-mercaptoethanol]. The values of kobs also increasedwith increasing [NaOH]. Thus, from the results of these studies, mechanism of the reaction has beenproposed. In addition, the values of various equilibrium constants and rate constants were also determinedusing nonlinear least square techniques.

Combination of dispersive liquid–liquid microextraction and multivariate optimization for separation-enrichment of traces lead by flame atomic absorption spectrometry

M.A. Habila,E. Yilmaz,Z.A. ALOthman,M. Soylak 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.37 No.-

This work presents a method for the preconcentration of lead using dispersive liquid-liquidmicroextraction. 2,20 Dithiobis (benzothiazole) was used as the chelating agent, and chloroform wasselected as the extraction solvent. Parameters such as: pH, volume of ligand, volume of extractionsolvent and dispersive solvent volume affecting on the extraction efficiency of method has beenevaluated by Plackett–Burman design. The limit of detection and limit of quantification were 4.3 mg L 1and 14.2 mg L 1, respectively. The accuracy of the method was evaluated by analyzing certified referencematerials. Method was applied to the determination of lead in water samples.

Polystyrene bound stationary phase of excellent separation efficiency based on partially sub-2μm silica monolith particles

Ali, F.,Cheong, W.J.,ALOthman, Z.A.,ALMajid, A.M. Elsevier 2013 Journal of chromatography A Vol.1303 No.-

Partially sub-2μm porous silica monolith particles have been synthesized by a renovated procedure and modified to polystyrene coated silica particles with excellent separation efficiency when used as chromatographic media. In the procedure of preparing silica monolith particles in this study, subtle control of formulation of the reaction mixture and multi-step heating followed by calcination, without any washing and sieving process, enabled formation of silica particles characterized by proper particle and pore size distribution for high separation efficiency. 3-Chloropropyl trimethoxysilane was used as the halogen terminal spacer to combine the initiator to silica particles. Uniform and thin coating of polystyrene layer on initiator attached silica particles was formed via reversible addition-fragmentation chain transfer (RAFT) polymerization. Micro-columns (1.0mm ID and 300mm length) were packed with the resultant phase and their chromatographic performance was elucidated by HPLC. A mobile phase of 60/40 (v/v) acetonitrile/water containing 0.1% TFA and a flow rate of 15μL/min were found to be the optimized conditions leading to number of theoretical plates close to 50,000 (165,000m<SUP>-1</SUP>). This is the very first study to get such highly efficient HPLC columns using a silica monolith particulate stationary phase.

Improved Photoelectrochemical Cell Performance of Tin Oxide with Functionalized Multiwalled Carbon Nanotubes–Cadmium Selenide Sensitizer

Bhande, Sambhaji S.,Ambade, Rohan B.,Shinde, Dipak V.,Ambade, Swapnil B.,Patil, Supriya A.,Naushad, Mu.,Mane, Rajaram S.,Alothman, Z. A.,Lee, Soo-Hyoung,Han, Sung-Hwan American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.45

<P>Here we report functionalized multiwalled carbon nanotubes (<I>f</I>-MWCNTs)–CdSe nanocrystals (NCs) as photosensitizer in photoelectrochemical cells, where <I>f</I>-MWCNTs were uniformly coated with CdSe NCs onto SnO<SUB>2</SUB> upright standing nanosheets by using a simple electrodeposition method. The resultant blended photoanodes demonstrate extraordinary electrochemical properties including higher Stern–Volmer constant, higher absorbance, and positive quenching, etc., caused by more accessibility of CdSe NCs compared with pristine SnO<SUB>2</SUB>–CdSe photoanode. Atomic and weight percent changes of carbon with <I>f</I>-MWCNTs blending concentrations were confirmed from the energy dispersive X-ray analysis. The morphology images show a uniform coverage of CdSe NCs over <I>f</I>-MWCNTs forming a core–shell type structure as a blend. Compared to pristine CdSe, photoanode with <I>f</I>-MWCNTs demonstrated a 257% increase in overall power conversion efficiency. Obtained results were corroborated by the electrochemical impedance analysis. Higher scattering, more accessibility, and hierarchical structure of SnO<SUB>2</SUB>-<I>f</I>-MWCNTs-blend–CdSe NCs photoanode is responsible for higher (a) electron mobility (6.89 × 10<SUP>–4</SUP> to 10.89 × 10<SUP>–4</SUP> cm<SUP>2</SUP> V<SUP>–1</SUP> S<SUP>1–</SUP>), (b) diffusion length (27 × 10<SUP>–6</SUP>), (c) average electron lifetime (32.2 ms), and transit time (1.15 ms).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-45/acsami.5b05385/production/images/medium/am-2015-05385e_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b05385'>ACS Electronic Supporting Info</A></P>

Equilibrium, kinetics and thermodynamic studies for the removal of organophosphorus pesticide using Amberlyst-15 resin: Quantitative analysis by liquid chromatography–mass spectrometry

Mu. Naushad,Z.A. ALOthman,M.R. Khan,N.J. ALQahtani,I.H. ALSohaimi 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

In the present paper, Amberlyst-15 resin was used for the removal of malathion. Various experimentalparameters such as effect of pH, contact time, resin dose, initial malathion concentration andtemperature were studied to find the optimum conditions for malathion removal. The removal rate ofmalathion by Amberlyst-15 was rapid and equilibrium was established within 30 min. Kinetic studiesshowed better applicability for pseudo-second-order model and equilibrium data was best fitted toFreundlich isotherm model. The thermodynamic parameters showed that the adsorption of malathionwas feasible, endothermic and spontaneous. The concentration of malathion was determined usingultra-performance liquid chromatography–tandem mass spectrometry.

Removal of Pb(II) from aqueous solution using ethylene diamine tetra acetic acid-Zr(IV) iodate composite cation exchanger: Kinetics, isotherms and thermodynamic studies

M. Naushad,Z.A. ALOthman,Inamuddin,H. Javadian 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.25 No.-

EDTA-Zr(IV) iodate was prepared via the incorporation of aqueous solution of EDTA into the inorganic precipitate of Zr(IV) iodate. Distribution coefficient values for different metals showed that EDTA-Zr(IV) iodate had the highest adsorption capacity for Pb(II). The practical applicability of EDTA-Zr(IV) iodate was explored by separating Pb(II) metal from a synthetic mixture of metal ions. Dependence of adsorption on contact time, pH of the solution, exchanger dose and temperature was studied to achieve the optimum conditions. Kinetic studies showed better applicability for pseudo-second-order model. Thermodynamic parameters viz. – entropy change, enthalpy change and Gibb’s free energy change were also calculated.

Characterization of reactive amphiphilic montmorillonite nanogels and its application for removal of toxic cationic dye and heavy metals water pollutants

Ayman M. Atta,Hamad A. Al-Lohedan,Z.A. ALOthman,Ahmed A. Abdel-Khalek,Ahmed M. Tawfeek 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.31 No.-

The present work aims to reduce the water surface tension using dispersed organophilic clay minerals toincrease the adsorption water pollutants (organic and inorganic) into the clay galleries. Therefore,sodium montmorillonite (Na-MMT) was functionalized with amphphiles based on crosslinked nanogelpolymers of N-isopropylacrylamide (NIPAm), sodium 2-acrylamido-2-methylpropane sulfonate (Na-AMPS), acrylamide (AAm) and acrylamidopropyl)trimethylammonium chloride solution (APTAC) usingsurfactant free technique. The chemical interactions between nanogels and Na-MMT and their chemicalstructure were confirmed by FTIR analysis. The intercalation and exfoliation of Na-MMT were confirmedby wide-angle X-ray diffraction. The morphology of Na-MMT nanogel composites was investigated byTEM analysis. The adsorption capacities of the prepared Na-MMT nanogels for methylene blue dye,cobalt and nickel cations from water were investigated. The data indicated that the Na-MMT nanogelsreduced the surface tension of water and efficiently remove dye and metal ions from water.

DSSCs synergic effect in thin metal oxide layer-functionalized SnO₂ photoanodes

Bhande, S.S.,Shinde, D.V.,Tehare, K.K.,Patil, S.A.,Mane, R.S.,Naushad, Mu.,Alothman, Z.,Hui, K.N.,Han, S.H. Elsevier Sequoia 2014 Journal of photochemistry and photobiology Chemist Vol.295 No.-

DSSCs synergic effect, for reducing charge recombination and energizing charge transfer, in SnO<SUB>2</SUB> photoanodes functionalized with thin layers of several metal oxides including ZrO<SUB>2</SUB>, MgO, CaCO<SUB>3</SUB> and ZnO etc., for boosting overall dye-sensitized solar cells (DSSCs) performance is investigated. The SnO<SUB>2</SUB> photoanodes composed with upright-standing nanosheets were initially fabricated using a simple and cost-effective wet chemical method. Both pristine and functionalized SnO<SUB>2</SUB> photoanodes were explored in DSSCs application in addition to other photoelectrochemical properties where, functionalized photoanodes exhibited remarkably improved light-to-electrical power conversion efficiencies compared to that of pristine one. To corroborate synergic effect and for probing the charge transport properties including charge transfer resistance and electron life time in thin metal oxide functionalized SnO<SUB>2</SUB> photoanodes, electrochemical impedance spectroscopy measurement was undertaken.

Drug-clay nanohybrids as sustained delivery systems

Yang, J.H.,Lee, J.H.,Ryu, H.J.,Elzatahry, A.A.,Alothman, Z.A.,Choy, J.H. Elsevier 2016 Applied clay science Vol.130 No.-

<P>Biocompatible 2-dimensional layered compounds such as clays and layered double hydroxides (anionic clays) have been explored and utilized in drug delivery system for therapeutic application because they can safely encapsulate drug molecules via intercalation reaction. Therefore, various kinds of drug molecules and bio-functional molecules with cationic or anionic charge have been incorporated into clay delivery carriers, giving rise to the heterostructured layered nanohybrids with chemo-therapeutic and gene-therapeutic functions. Recently, such inorganic delivery systems have received growing attention because their inertness and low toxicity gives rise to safety and stability in bio-systems. Furthermore, the hybridization of drug with clays offers the fascinating features such as controlled and sustained release, improved water-solubility, and even protective and targeted delivery. Unique release behaviors of drugs from the drug-clay nanohybrids are originated from molecular level incorporation, and strong interaction between drug and inorganic layers including electrostatic and hydrogen bonding interactions. In the present review, various drug-clay nanohybrids will be introduced, and their recent development will be highlighted in the viewpoint of oral administration drugs with controlled and sustained release. (C) 2016 Elsevier B.V. All rights reserved.</P>

Influence of Bi³⁺-doping on the magnetic and Mössbauer properties of spinel cobalt ferrite

Gore, Shyam K.,Mane, Rajaram S.,Naushad, Mu.,Jadhav, Santosh S.,Zate, Manohar K.,Alothman, Z. A.,Hui, Biz K. N. The Royal Society of Chemistry 2015 Dalton Transactions Vol.44 No.14

<P>The influence of Bi<SUP>3+</SUP>-doping on the magnetic and Mössbauer properties of cobalt ferrite (CoFe<SUB>2</SUB>O<SUB>4</SUB>), wherein the Fe<SUP>3+</SUP> ions are replaced by the Bi<SUP>3+</SUP> ions to form CoBi<SUB><I>x</I></SUB>Fe<SUB>2−<I>x</I></SUB>O<SUB>4</SUB> ferrites, where <I>x</I> = 0.0, 0.05, 0.1, 0.15 or 0.2, has been investigated. The structural and morphological properties of undoped and doped ferrites, synthesized chemically through a self-igniting sol–gel method, are initially screened using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. The changes in magnetic moment of ions, their coupling with neighboring ions and cation exchange interactions are confirmed from the Mössbauer spectroscopy analysis. The effect of Bi<SUP>3+</SUP>-doping on the magnetic properties of CoFe<SUB>2</SUB>O<SUB>4</SUB> ferrite is examined from the vibrating sample magnetometry spectra. Saturation magnetization and coercivity values are increased initially and then decreased, as result of Bi<SUP>3+</SUP>-doping. The obtained results with improved saturation magnetization (from 26.36 to 44.96 emu g<SUP>−1</SUP>), coercivity (from 1457 to 1863 Oe) and remanence magnetization (from 14.48 to 24.63 emu g<SUP>−1</SUP>) on 0.1–0.15 mol Bi<SUP>3+</SUP>-doping of CoBi<SUB><I>x</I></SUB>Fe<SUB>2−<I>x</I></SUB>O<SUB>4</SUB> demonstrate the usefulness for magnetic recording and memory devices.</P> <P>Graphic Abstract</P><P>Bi<SUP>3+</SUP>-doping improves the saturation magnetization, coercivity and the remanence magnetization, which can be applied for magnetic recording and memory devices, of CoFe<SUB>2</SUB>O<SUB>4</SUB> ferrite. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5dt00156k'> </P>