Methanol: A “Smart” Chemical Probe Molecule

A novel chemisorption method was employed for the dissociative adsorption of methanol to surface methoxy intermediates in order to quantitatively determine the number of surface active sites on one-component metal oxide catalysts (MgO, CaO, SrO, BaO, Y₂O₃, La₂O₃, CeO₂, TiO₂, ZrO₂, HfO₂, V₂O₅, Nb₂O₅, Ta₂O₅, Cr₂O₃, MoO₃, WO₃, Mn₂O₃, Fe₂O₃, Co₃O₄, Rh₂O₃, NiO, PdO, PtO, CuO, Ag₂O, Au₂O₃, ZnO, Al₂O₃, Ga₂O₃, In₂O₃, SiO₂, GeO₂, SnO₂, P₂O₅, Sb₂O₃, Bi₂O₃, SeO₂ and TeO₂). The number of surface active sites for methanol dissociative adsorption corresponds to 3 mol/m² on average for many of the metal oxide catalysts. Furthermore, the methanol oxidation product distribution at low conversions reflects the nature of the surface active sites on metal oxides since redox sites yield H₂CO, acidic sites yield CH₃OCH₃ and basic sites yield CO₂. The distribution of the different types of surface active sites was found to vary widely for the different metal oxide catalysts. In addition, the commonality of the surface methoxy intermediate during dissociative chemisorption of methanol and methanol oxidation on oxide catalysts also allows for the quantitative determination of the turnover frequency (TOF) values. The TOF values for the various metal oxide catalysts were found to vary over seven orders of magnitude (10^–3 to 10⁴ s^–1). An inverse relationship (for metal oxide catalysts displaying high (>85%) selectivity to either redox or acidic products) was found between the methanol oxidation TOF values and the decomposition temperatures of the surface M–OCH₃ intermediates reflecting that the decomposition of the surface M–OCH₃ species is the rate-determining step during methanol oxidation over the metal oxide catalysts.     

The excellent performance of amorphous Cr2O3, SnO2, SrO and graphene oxide–ferric oxide in glucose conversion into 5-HMF

Amorphous Cr₂O₃, SnO₂ and SrO presented an excellent performance in the conversion of glucose to 5-hydroxymethylfurfural (5-HMF), and 5-HMF yields achieved 84%, 81% and 99%, however, the calcined metal oxides almost completely lost the catalytic activities. Although Fe₂O₃ exhibited very poor catalytic activity, the graphene oxide–Fe₂O₃ (GO–Fe₂O₃) displayed a better performance in catalytic glucose conversion to 5-HMF (86% yield) in 1-ethyl-3-methylimidazolium bromide ([EMIM]Br). The plausible mechanisms of glucose conversion to 5-HMF over amorphous Cr₂O₃, SnO₂, SrO and GO–Fe₂O₃ were proposed.     

Measurement of the adhesion strength of metal oxide and metal nitride thin films sputtered onto glass by the direct pull-off method

We have measured the adhesion strengths of metal oxide and metal nitride thin films reactively sputtered onto glass substrates using a specially devised direct pull-off test. For double-layer coatings such as metal nitride (CrN_x, TiN_x)/metal oxide (Al₂O₃, SnO₂, Ta₂O₅, TiO₂, ZnO, ZrO₂)/glass, separation usually took place at the nitride/oxide interface. The adhesion strength at the interface was found to depend on the strength of chemical bonding in the films concerned: for the same nitride top layer, the adhesion strength increased as the strength of the metal-oxygen (M-O) bond in the oxide underlayer decreased. X-ray photoelectron spectroscopy (XPS) measurements showed that a mixed layer was created at the nitride/oxide interface and that the adhesion strength at the interface increased with increasing thickness of the mixed layer. For single-layer coatings such as metal nitride (CrN_x, TaN_x, TiN_x, ZrN_x)/glass, the adhesion strength of the film to the glass substrate was found to increase with increasing strength of the M-O bond between the metal atom (M) in the nitride film and an oxygen atom (O). These adhesion behaviors could be explained by adhesion models based on chemical bonds at the interfaces.     

Effect of γ-Irradiation on Electrical Conductivity of Metal-Chloride-Treated Polyacrylamide

The electrical conductivity of polyacrylamide (PAAm) before and after treatment with low concentrations of ZnCl₂, NiCl₂, and CoCl₂ was determined at different temperatures. The effects of γ-irradiation on the electrical conductivity and activation energy of the original and the metal-chloride-treated specimens were investigated. The experimentally obtained data revealed that the conduction in PAAm is ionic in nature. The treatment of the polymer with 2% or 4% (w/w) of ZnCl₂, NiCl₂, or CoCl₂, as determined from its weight, either increases or decreases its conductivity according to the nature of the metal ions, concentration of metal chloride, ratio of KOH/metal chloride, and temperature and cycle of measurement. The exposure of PAAm to 2 to 10 Mrad of γ-radiation produces no significant changes in its conductivity. On the other hand, the exposure of the PAAm pretreated with a metal chloride produces considerable changes in its conductivity. Also, the γ-irradiation of PAAm increases its activation energy. The extent of the γ-induced changes in activation energy was influenced by the pretreatment of PAAm with metal chlorides.     

Single-step catalytic synthesis of diphenyl carbonate over transition-metal-substituted Keggin-type tungstophosphoric acid

Single-step catalytic synthesis of diphenyl carbonate (DPC) through the transesterification of dimethyl carbonate (DMC) and phenol could be firstly arrived by using the transition-metal-substituted polyoxometalates (TMS-POMs) K₅[PW₁₁O₃₉M(H₂O)]/TiO₂ system (M = Mn^II, Co^II, Ni^II, Cu^II, Zn^II). The catalytic activity of this transesterification was strongly influenced by the type of transition metal in the TMS-POMs. Among them, the K₅[PW₁₁O₃₉Zn(H₂O)]/TiO₂ catalytic system showed the highest activity and selectivity for DPC. The conversion of phenol reached 12.8%, and the selectivity to DPC was 83.6%. The turnover number (TON) reached 6.44 × 10⁴ mol/mol [PW₁₁O₃₉Zn(H₂O)]⁵⁻/TiO₂. A possible mechanism that the transition metal in the polyoxometalates anchored DMC to form intermediate compound in the transesterification was proposed.     

Investigation of composition and structure for a novel Ti–Zr chemical conversion coating on 6063 aluminum alloy

A novel chemical conversion coating was prepared by adding tannic acid and coating-forming accelerator in the treatment solution containing titanium and zirconium ions. Corrosion behavior of the coatings in contact with 3.5% NaCl solution was investigated using potentiodynamic measurement. The structure and composition of the coatings were determined with EDS, XPS and IR. The morphologies of the coatings were observed with scanning electron microscopy (SEM). According to the results, the modified Ti–Zr based conversion coating (MTZ) shows a smoother and more compact morphology characterization comparing with the traditional Ti–Zr treated (TZ) substrates; The Tafel results and the long-time immersion experiments also indicate that the MTZ coating presents a more effective corrosion protection property compared with the TZ coating; The MTZ coating is a multi-components chemical conversion coating which is mainly composed of metal oxide (TiO₂, ZrO₂, V₂O₅, Al₂O₃), fluoride (AlF₃ and ZrF₄) and metal–organic complex.     

The effects of several heavy metal oxides on the formation of ettringite and the microstructure of hardened ettringite

The study was conducted on the effects of Cr₂O₃, Fe₂O₃, Cu(OH)₂, ZnO and Pb₂O(OH)₂ on the formation of ettringite and microstructure of hardened ettringite. The cement samples were prepared by mixing C₃A synthesized and CaSO₄·2H₂O and adding 5 % by weight of above additives. The heavy metal oxides and hydroxides promote the crystal growth of ettringite and produce some changes in microstructure and Cr₂O₃ and Cu(OH)₂ exert a considerable influence.     

Dispersion and Solid State Ion Exchange of VCl3, CrCl3?6H2O, MnCl2?4H2O and CoCl2?6H2O onto the Surface of NaY Zeolite Using Microwave Irradiation

Transition metal/Y zeolites have been prepared by solid state ion exchange with microwave irradiation of mechanical mixtures of VCl₃, CrCl₃ ⋅ 6H₂O, MnCl₂ ⋅ 4H₂O or CoCl₂ ⋅ 6H₂O with NaY zeolite at 900 W in 10–20 min. The prepared transition metal/Y zeolites were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), simultaneous thermal analysis (STA) and surface area measurement (BET). Concentration of dispersed transition metal on zeolite was measured and results revealed that transition metal was dispersed and ion exchanged onto the surface of NaY zeolite.     

Polymer pendant ligand chemistry, 4. Recovery of precious metal ions from strongly acidic solution with a polymer-supported o-phenylenediamine hydrochloride ligand

We report on the synthesis and reactivity of a polymer-supported o-phenylenediamine hydrochloride ligand, PS-PDHC, using macroporous 6% crosslinked polystyrene-divinylbenzene beads. The PS-PDHC ligand was found to be highly selective to AuCl₄⁻ ions in strongly acidic solutions in the presence of other precious metal ions, PdCl₄²⁻, PtCl₄²⁻, RhCl₆³⁻, and RuCl₅²⁻ (selectivity values: 2.5, Au/Pd; 7.5, Au/Pt; 7, Au/Rh; 2.2, Au/Ru) as well as other transition metal ions, Fe ³⁺, Cr³⁺, CU²⁺, Nit+, and Mn²⁺. The sorption capacity, selectivity, kinetics of removal and recovery, and solution isotherms have been determined for AuCl₄⁻ ions in competition with the above-mentioned metal ions. The relative ease of formation of the anionic complex in 0.5 M HCI, AuCl₄⁻ was thought to be the primary reason for its selective ability to bind to the PS-PDHC ligand by an anion-exchange mechanism. Therefore, the effect of the HCI concentration on the kinetics of AuCl₄⁻ ion removal from solution was also investigated to clearly show that raising the pH from 0 to 5 caused a dramatic decrease in rate. The AuCl₄⁻ ion can be recovered quantitatively from the PS-PDHC beads using a 5% thiourea solution in 0.1 M HCl, allowing the polymer-supported ligand to be reused.     

Influence of MWCTs and nanometal oxide/MWCTs hybrids on the thermal conduction of their acrylic-based nanocomposites

In this study, acrylic-based nanocomposites containing different contents of multi-walled carbon nanotubes (MWCNTs) and metal oxide nanoparticles (i.e., TiO₂, CuO and Fe₂O₃) were fabricated by solvent mixing method. The thermal conductivity of these samples was evaluated. The results indicated that the thermal conductivity of all fabricated samples was significantly improved even at small loading of MWCNTs. It was found that the thermal conductivity was enhanced by increase in MWCNTs content up to 5 wt%. Similarly, the metal oxide nanoparticles caused up to 75 % increment in thermal conductivity at 1.5 wt% of their loading in acrylic film. Contrary to expectations, the thermal conductivity of acrylic film was more increased by nanometal oxides (i.e., TiO₂, CuO and Fe₂O₃) than MWCNTs. The effect of hybridizing of nanometal oxide particles (1.5 wt%) and MWCNTs (1.5 wt%) on thermal conduction was investigated as well. It was found that hybridizing improved thermal conductivities by about 85, 94 and 97 % for Fe₂O₃, TiO₂ and CuO, respectively. Finally, the effects of TiO₂ pigment and CaCO₃ extender on the thermal conductivity of acrylic polymer and nano-TiO₂ acrylic composites were studied. It was found that TiO₂ could increase considerably thermal conduction of its acrylic films and acrylic nanocomposites.     

Concentration effects of methylalumoxane, palladium and nickel pre-catalyst and monomer in the vinyl polymerization of norbornene

Summary The vinyl polymerization of norbornene with di-μ-chloro-bis-(6-methoxybicyclo-[2.2.1]hept-2-ene-5σ,2π)-palladium(II), Ni(acetylacetonate)₂ and Ni(2-ethylhexanoate)₂ in combination with methylalumoxane (MAO) was investigated by varying the molar MAO:metal-complex ratio, the norbornene:metal ratio and the metal concentration. The effects on the catalyst activity could be explained with a complexation equilibrium for the active homogeneous complex. Activity data in combination with polymer analyses suggest that at low, yet economical Al(MAO):metal ratios of 100 the fraction of active metal centers is less than 15%. The turnover frequency for the monomer insertion was found to reach 50 s⁻¹. Polydispersities around M_w/M_n= 2 indicate a coordination polymerization with chain transfer and a single-site character of the active centers. Received:27 February 2001/Revised version:11 November 2001/ Accepted: 20 November 2001     

Selective oxidation of propane over PMoV?M/α‐Al2O3 (M: Co,Fe, or Ni)

Alumina supported phosphovanodomolybdic acid and alumina supported phosphovanodomolybdic acid‐transition metal ions (M: Fe³⁺, Co²⁺, or Ni²⁺) were prepared by impregnation. The thermal decomposition, in situ at 400°C, of supported catalysts showed the formation of V₂O₅, P₂O₅, MoO₃ and MoO₃, CoMoO₄, (Mo_0.3V_0.7)₂O₅ phases, on the alumina surface, in the presence of H₄PMo₁₁VO₄₀/α‐Al₂O₃ and H₄PMo₁₁VO₄₀? Co/α‐Al₂O₃, respectively. The catalytic activity of alumina‐supported catalysts was evaluated in the reaction of propane oxidation at 380 and 400°C. The addition of transition metal increases the conversion and changes the reaction products distribution. The reaction conditions (temperature and propane/oxygen ratio) have also modified the behaviour of the studied catalysts.     

A comparative study of different leaching processes for the extraction of Cu,Ni and Co from a complex matte

The extraction behaviors of Cu, Ni and Co from a complex matte under different leaching conditions have been discussed. The synthetic Cu-Ni-Co-Fe-S matte was prepared by melting the pure metals. The matte contained 24.95% Cu, 35.05% Ni, 4.05% Co, 11.45% Fe, 24.5% S, similar composition as is expected to be obtained by reduction smelting of the Pacific Ocean nodules followed by sulphidisation of the alloy. The different phases identified are CuFeS₂, CuS₂, (FeNi)₉S₈, (FeNi)S₂, Ni₉S₈, Ni₃S₂, (CoFeNi)₉S₈ and Co metal. The merits and demerits of each process of dissolution i.e., H₂SO₄/oxygen pressure leaching, atmospheric FeCl₃ leaching, NH₄OH/(NH₄)₂SO₄ pressure leaching are discussed in detail. Out of the three, the H₂SO₄/oxygen pressure leaching process is found to be the most suitable with more than 99% metal extraction efficiency within 1 h of leaching time. From the X-ray diffraction analysis, the different undissolved phases corresponding to different leaching processes have been identified. The metal extraction efficiency decreased in case of atmospheric FeCl₃ leaching and NH₄OH/(NH₄)₂SO₄ pressure leaching processes due to the formation of product layer such as elemental sulfur and goethite, respectively.     

Compaction of metal salt-urea complexes with triple superphosphate

It has been the experience of the fertilizer industry that urea should not be cogranulated or blended with superphosphate because urea reacts with monocalcium phosphate monohydrate (MCP·H₂O) in superphosphate to form an adduct. This reaction releases the water of hydration and causes the product to become wet and sticky or severely caked during storage. The objectives of this study were [1] to test the feasibility of preventing or retarding the reaction by complexing the urea with various salt hydrates and [2] to measure ammonia volatilization from metal salt-urea complexes on the soil surface.Three metal salt-urea complexes — Al(urea)₆(NO₃)₃, Fe(urea)₆(NO₃)₃, and Mn(urea)₄Cl₂ — were prepared and cogranulated by compaction with pure MCP·H₂O or triple superphosphate (TSP) at a mole ratio of MCP:urea as 1:2. These materials were then compared with the same material without metal salts in terms of changes in free water content during a storage period of 6 weeks. Without metal salts a rapid and significant increase in free water content of the cogranulated MCP·H₂O + urea or TSP + urea was observed. The increases in free water content were found to range from 1.5% to 1.8%, corresponding to approximately 63% and 78% of the added MCP·H₂O that reacted with urea in the cogranulated products. On the other hand, little change or only a slight increase (less than 0.5%) in free water content was observed with the cogranulated metal salt-urea complexes.Ammonia volatilization losses from urea on the soil surface were measured in a period up to 14 d with two soils: Windthorst (pH 7.6) and Savannah (pH 7.0). The fertilizer materials used were granular. In Windthorst soil, the amounts of NH₃-N lost were 25% for prilled urea, 11% for Mn(urea)₄Cl₂, and essentially none for Mn(urea)₄Cl₂ compacted with TSP at a mole ratio of MCP:urea as 1:1 or 1:2. In Savannah soil, the amounts of NH₃-N lost were 39% for prilled urea, 24% for Mn(urea)₄Cl₂, 15% for Fe(urea)₆(NO₃)₃, and less than 6% for each of the two metal salt-urea complexes compacted with TSP. The acidity that resulted from metal complexing of urea reduced NH₃ volatilization from hydrolyzed urea in soils, and additional acidity produced from hydrolysis of MCP·H₂O further reduced NH₃ losses when materials were applied as multicomponent granules (metal salt + urea + TSP).     

Synthesis,Characterization, and Thermal Degradation of Oligo-2-[(4-Chlorophenyl) Imino Methylene] Phenol and Its Oligomer-Metal Complexes

The oxidative polycondensation reaction conditions of 2-[(4-chlorophenyl) imino methylene] phenol (CPIMP) were studied by air O₂ and NaOCl oxidants at various temperatures and times. Optimum reaction conditions of air O₂ and NaOCl were determined for CPIMP. Oligo-2-[(4-chlorophenyl) imino methylene] phenol (OCPIMP) was synthesized from the oxidative polycondensation of CPIMP with air O₂ and NaOCl in alkaline medium between 50 and 90°C. The number-average molecular weight (M_n) weight-average molecular weight (M_w) and polydispersity index (PDI) values of OCPIMP were found to be 470 g mol^?1, 895 g mol^?1, and 1.90, using NaOCl, and 455 g mol^?1, 765 g mol^?1, and 1.68, using air O₂, respectively. At the optimum reaction conditions, the yield of OCPIMP was found to be 62.80% (for air O₂ oxidant) and 87.50% (for NaOCl oxidant). The OCPIMP was characterized by ¹H-NMR, FT-IR, UV-Vis and elemental analysis. The thermogravimetric (TGA)-DTA analyses were shown to be stable of OCPIMP and its oligomer metal complexes (such as Co⁺², Ni⁺², and Cu⁺²) against thermo-oxidative decomposition. The weight loss of OCPIMP and its oligomer metal complexes (such as Co⁺², Ni⁺², and Cu⁺²) were found to be 98%, 85%, 80%, and 82%, respectively, at 1000°C.     

Proton exchange composite membranes comprising SiO2, sulfonated SiO2, and metal–organic frameworks loaded in SPEEK polymer for fuel cell applications

Proton exchange membrane fuel cell (PEMFC) is a promising technology that offers a clean and efficient renewable energy source. The hybrid SiO₂, sulfonated SiO₂ (S SiO₂), and metal–organic framework-5 (MOF-5) incorporated sulfonated poly (ether ether ketone) (SPEEK) ternary composite membranes are fabricated using dry phase inversion technique for PEMFC. The membrane performance is evaluated in terms of water uptake, ion exchange capacity, methanol permeability, and proton conductivity (PC) measurements. The morphological study of fabricated membranes was carried out using scanning electron microscopy and atomic force microscopy analysis. The mechanical stability is strengthened up to 30–40%, and the PC gets enhanced with the incorporation of MOF-5, achieving simultaneous improvement in proton conduction and membrane stability. The PC of the ternary SPEEK/S SiO₂/MOF-5 membrane is 3.69 × 10⁻³ S cm⁻¹, 32% more than the neat membrane. A significant increase in selectivity of 23% is observed by incorporating S SiO₂ and MOF-5 fillers when compared with the neat membrane. The synergistic effect of MOF-5 and S SiO₂ in the ternary membrane has significantly improved water retention and proton conductivity. The functional  SO₃H groups of SiO₂ and MOF-5 bonded via acid–base electrostatic interactions with the SPEEK; enhances proton conduction accompanied by suppressing the methanol penetration through membranes.     

Synthetic ionophores for the separation of Li, Na, K, Ca, Mg metal ions using liquid membrane technology

Carrier-assisted transport through liquid membranes is one of the important applications of supramolecular chemistry. This work investigates the use of synthetic carrier (ionophore) for the separation of metal ions. We have tested the effect of structure of ionophore on the separation of metal ions. For this purpose, we have used a new series of non-cyclic ionophores having different end groups and chain length (R₁–R₅). 1,5 bis (2-naphthyloxy)-3-oxapentane (R₁), 1,8 bis (2-naphthyloxy)-3,6-di-oxaoctane (R₂), 1,11 bis (2-naphthyloxy)-3,6,9-tri-oxaundecane (R₃) 1,11-(dianthraquinonyloxy) 3,6,9-trioxaundecane (R₄), 1,8 (dianthraquinonyloxy) 3, 6-dioxaoctane (R₅) have been used in extraction, bulk liquid membrane (BLM) and supported liquid membrane (SLM) transport of alkali (Li⁺, Na⁺, K⁺) and alkaline earth metal cations (Ca²⁺, Mg²⁺). The supported liquid membrane consisted of a porous cellulose nitrate and and an onion membrane support impregnated with ionophore using chloroform as a solvent. The results reveal that ionophores R₁, R₂ and R₃ are better extractants for K⁺ while R₄ and R₅ are better extractants for Ca²⁺. Among these ionophores R₃ and R₄ are best extractants for K⁺ and Ca²⁺ ions. The results of BLM reveal that ionophores R₁, R₂ and R₃ transport Na⁺ at a greater extent, while R₄ and R₅ transport Ca²⁺ and K⁺ at a greater extent. In SLM experiments using a cellulose nitrate membrane support, it was observed that naphthyl end group bearing ionophores (R₁–R₃) transports Na⁺ > K⁺, and anthraquinone bearing ionophores (R₄ and R₅) transport K⁺ > Na⁺ > Ca²⁺ respectively. In the onion membrane support R₄ transports Ca²⁺ and Na⁺ equally and R₅ transports K⁺ selectively. On comparing the membrane support, the cellulose nitrate membrane is found better support for the transport of metal ions. The results suggest that due to the presence of different end groups and chain lengths the selectivity of non-cyclic ionophores towards metal ions is enhanced. Thus selectivity of ionophores may have fruitful application in ion selective electrodes and separation of metal ions.     

Poly(oligo-oxyethylene methacrylate-co-alkali metal acrylamidocaproate) as a single ion conductor

Summary The new single ion conductors, poly(oligo-oxyethylene methacrylate-co-alkali metal acrylamidocaproic acid) ((CH₂CCH₃COO(CH₂CH₂O)₉H)_x–(CH₂CHCONH(CH₂)₅ COO-M⁺)_1-x), M⁺=Li⁺, Na⁺, K⁺, were synthesized and the effects of the cation and the temperature on ionic conductivity were investigated. The alkyl spacer in the alkali metal acrylamidocaproate was introduced to increase the flexibility of the side chain for the complex formation between the ionic groups and the oxygens in PEO unit. The room temperature(30°C) conductivity of the K single ion conductor was found to be 5x10^-7 S/cm which is the highest value reported for the single ion conductors having carboxylate groups without any additives. The pseudo-activation energy in the VTF equation was not dependent on the type of the cation, which indicates that the ion hopping rate is higher than the string renewal rate in these single ion conductors.     

Efficient photocatalytic removal of N-nitrosamines from amine washing wastewater using bismuth tungstate

The most mature and practical technology to reduce industrial CO₂ emissions, the main contributor to global warming, is amine-based post-combustion CO₂ capture. However, this results in amine degradation products that pose a threat to human health as well as marine life. To reduce the impact on human health and marine life, identifying and treating carcinogenic and mutagenic compounds like N-nitrosamines is extremely important. Photocatalysis, in particular, an advanced oxidation process which uses a UV light source and semiconductor catalysts is studied for the degradation of organic and inorganic pollutants. N-Nitrosodiethylamine (NDEA) is treated with strong reactive hydroxyl radicals generated by a bismuth tungstate (Bi₂WO₆) semiconductor under UV/visible irradiation. The Bi₂WO₆ was studied both in pure form and surface-modified forms using transition metal impregnation like Ag, Fe, Cu, and La. Various catalyst characterization techniques like Brunauer–Emmett–Teller (BET), X-ray diffraction analysis (XRD), UV–visible, and scanning electron microscopy–energy-dispersive X-ray (SEM-EDS) are used to study the surface textural and morphological properties of the catalyst. Furthermore, the effect of pH of the solution, catalyst dosing, and metal impregnation (%) on the photocatalytic degradation of NDEA is analyzed. The face centred-central composite design (FC-CCD) experimental design method was used through response surface methodology (RSM) and optimization studies for removal of NDEA. The quadratic model was obtained as a functional link between NDEA concentration and three operation variables for all metal impregnated Bi₂WO₆. The results showed that the pH of the solution was the most significant factor compared to other variables like catalyst dosing and metal impregnation. The average degradation efficiency of NDEA was 89.2% for Fe-Bi₂WO₆, 87.4% Ag-Bi₂WO₆, 86.9% for La-Bi₂WO₆, and 85% for Cu-Bi₂WO₆.     

Coordination Polymers of 1,9-Bis(8-Hydroxyquinolin-5-yl)-2,5,8-Trioxanonane

ABSTRACT

Coordination polymers of a novel bis(oxine) bidentate ligand, namely 1,9-bis(8-hydroxyquinolin-5-yl)-2,5,8-trioxanonane (BHQTN) (H₂L) have been prepared with the metal ions Zn⁺², Cu⁺², Ni⁺², Co⁺², and Mn⁺². The novel bis(bidentate) ligand BHQTN was synthesized by condensation of 5-chloromethyl-8-hydroxyquinoline hydrochloride with diethylene glycol in the presence of a base catalyst. All of these coordination polymers and the parent ligand were characterized by elemental analyses and IR spectral studies. The diffuse reflectance spectral studies and magnetic susceptibilities of all of the coordination polymers have also been performed. Thermogravimetric parameters such as T_o, T₁₀, T_max., IPDT, and the activation energy of the thermo-degradation process were calculated.