Study of physical chemistry on biosorption of zinc by using Chlorella pyrenoidosa

Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. Presence of heavy metals in the aquatic system is posing serious problems. Zinc has been used in many industries and removal of Zn ions from waste water is significant. Biosorption is one of the economic methods used for removal of heavy metals. In the present study, the biomass obtained from the dried Chlorella pyrenoidosa was used for evaluating the biosorption characteristics of Zn ions in aqueous solutions. Batch adsorption experiments were performed with this material and it was found that the amount of metal ions adsorbed increased with the increase in the initial metal ion concentration. In this study effect of agitation time, initial metal ion concentration, temperature, pH and biomass dosage were studied. Maximum metal uptake (q _max) observed at pH 5 was 101.11 mg/g. The biosorption followed both Langmuir and Freundlich isotherm model. The adsorption equilibrium was reached in about 1 h. The kinetic of biosorption followed the second-border rate. The biomass could be regenerated using 0.1 M HNO₃. A positive value of ΔH° indicated the endothermic nature of the process. A negative value of the free energy (ΔG°) indicated the spontaneous nature of the adsorption process. A positive value of ΔS° showed increased randomness at solid-liquid interface during the adsorption of heavy metals, it also suggests some structural changes in the adsorbate and the adsorbent. FTIR Spectrums of Chlorella pyrenoidosa revealed the presence of hydroxyl, amino, carboxylic and carbonyl groups. The scanning electron micrograph clearly revealed the surface texture and morphology of the biosorbent.     

Photoluminescence study on amino functionalized dysprosium oxide–zinc oxide composite bifunctional nanoparticles

An organic dispersion of 9–15 nm size stable dysprosium oxide incorporated zinc oxide nanocomposites exhibiting luminescence in the visible region has been synthesised by a wet chemical precipitation technique at room temperature. Tetraethoxysilane TEOS [(C₂H₅O)₄Si], (3-aminopropyl) trimethoxysilane (APTS) and a 1:1 mixture of TEOS–APTS have been used as capping agents to control the particle size as well as to achieve uniform dispersion of composite nanoparticles in methanol medium. X-ray diffractometer (XRD) analysis reveals the formation phase of amino-functionalised colloidal dysprosium oxide incorporated ZnO composite nanoparticles to be of zincite structure. The Transmission Electron Microscopy (TEM) images show that the particles are spheroids in shape, having average crystalline sizes ranging from 9 to 15 nm. The photoluminescence (PL) observed in these composites has been attributed to the presence of near band edge excitonic emission and existence of defect centres. The time correlated single photon counting studies of the composite nanoparticles exhibited three decay pathways. The enhanced PL emission intensity of solid state fluorescence spectra of samples is attributed to the absence of vibrational relaxation process.     

Effect of rotation in generalized thermoelastic solid under the influence of gravity with an overlying infinite thermoelastic fluid

The present problem is concerned with the study of deformation of a rotating generalized thermoelastic solid with an overlying infinite thermoelastic fluid due to different forces acting along the interface under the influence of gravity.The components of displacement,force stress,and temperature distribution are first obtained in Laplace and Fourier domains by applying integral transforms,and then obtained in the physical domain by applying a numerical inversion method.Some particular cases are also discussed in the context of the problem.The results are also presented graphically to show the effect of rotation and gravity in the medium.     

3‐Cyano‐6‐methyl‐4‐(2‐naphthyl­ethenyl)‐1‐benzo­pyran‐2‐one

In the title compound, C₂₃H₁₅NO₂, the naphthyl unit is planar and the benzo­pyran unit is nearly planar. These two moieties are inclined at an angle of 9.10 (6)° with respect to one another.     

具有立方对称性及两个弛豫时间的微极热弹性介质中调和时间源引起的变形

研究了具有立方对称性及两个弛豫时间的微极热弹性介质在调和时间源中的响应．采用了Fourier变换以及数值逆变换技术．在物理域中,得到了位移、应力、微转动和温度分布的数值结果．将微极立方晶体法向位移、法向力应力、切向耦合应力和温度分布的计算结果,与微极各向同性固体的结果进行比较．绘制了指定材料的数值结果图形．还推断了某些特殊情况的结果．     

17‐Oxo‐16‐(2‐pyridyl­methyl­ene)­androst‐5‐en‐3β‐ol monohydrate

The title compound, C₂₅H₃₁NO₂·H₂O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring adopts a 13,14‐half‐chair conformation. The pyridyl­methyl­ene moiety has an E configuration with respect to the carbonyl group at position 17. The structure is stabilized by intermolecular O—H?N and O—H?O hydrogen bonds.     

Low-Temperature,Ambient Pressure Oxidation of Methane to Methanol Over Every Tri-Iron Node in a Metal–Organic Framework Material

In contrast with metal-modified zeolites, metal–organic framework materials (MOFs) provide a platform that may be significantly more amenable to creating catalysts in which every metal site is endowed with the same coordination environment, and hence, catalytic function. Using MIL-100(Fe) as a prototype, we present the first example of a synthetic heterogeneous catalyst comprised exclusively of active tri-iron moieties participating in the low-temperature oxidation of methane to methanol; in contrast with prior reports on iron-MOFs, we report the near-exclusive formation of methanol at low temperatures and sub-ambient methane pressures, and evidence its effectuation solely by Fe²⁺ sites. The study captures the utility of exploring classes of materials endowed with a high level of definition in structure and catalytic function for the purposes of overcoming persistent scientific and technological challenges in the field of synthetic heterogeneous catalysis.     

Carbonylative Suzuki coupling reactions catalyzed by ONO pincer–type Pd(II) complexes using chloroform as a carbon monoxide surrogate

Benzoylhydrazone Schiff base–ligated three new ONO pincer–type palladium(II) complexes, [(PdL¹(PPh₃)] ( 1 ), [(PdL²(PPh₃)] ( 2 ), and [(PdL³(PPh₃)] ( 3 ), were synthesized by the reaction of the respective ligand, N-(2-hydroxybenzylidene)benzohydrazide (HL¹), N-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (HL²), or N-(5-bromo-2-hydroxybenzylidene) benzohydrazide (HL³), with Pd(OAc)₂ and PPh₃ in methanol and isolated as air-stable reddish-orange crystalline solids in high yields (78%–83%). All three complexes were fully characterized by elemental analysis, Fourier-transform infrared spectroscopy, UV–Visible, ¹H nuclear magnetic resonance (NMR), ¹³C{¹H} NMR, and ³¹P{¹H} NMR spectroscopic studies. The molecular structure of all three complexes was established unambiguously by single-crystal X-ray diffraction studies which revealed a distorted square planar geometry of all three complexes. The ONO pincer–type ligands occupied three coordination sites at the palladium, while the fourth site is occupied by the monodentate triphenylphosphine ligand. The catalytic potential of all three complexes was explored in the carbonylative Suzuki coupling of aryl bromides and iodides with arylboronic acids to yield biaryl ketones, using CHCl₃ as the source of carbonyl. The reported protocol is convenient and safe as it obviates the use of carbon monoxide (CO) balloons or pressured CO reactors which are otherwise needed for the carbonylation reactions. The methodology has been successfully applied to the synthesis of two antineoplastic drugs, namely, phenstatin and naphthylphenstatin, in good yields (81% and 85%, respectively). Under the optimized reaction conditions, complex 2 exhibited the best catalytic activity in the carbonylative Suzuki couplings. The reported catalysts have wide reaction scope with good functional group tolerance. All catalysts could be retrieved from the reaction after completion and recycled up to three times with insignificant loss in the catalytic activity.     

Formation of phosphonates and pyrophosphates in the reactions of chlorophosphate esters with strong organic bases

The compounds S(6-t-Bu-4-Me-C₆H₂O)₂P(O)Cl (1), CH₂(6-t-Bu-4-Me-C₆H₂O)₂P(O)Cl (2) and (2,2′-C₂₀H₁₂O₂)P(O)Cl (3) react with diazabicycloundecene (DBU) to give rise to, predominantly, the phosphonate compounds [S(6-t-Bu-4-Me-C₆H₆O)₂P(O)(DBU)]⁺[Cl]⁻ (4), [CH₂(6-t-Bu-4-Me-C₆H₂O)₂P(O) (DBU)]⁺[Cl]⁻ (5) and [(2,2′-C₂₀Hi₂O₂)P(0)(DBU)]⁺[Cl]^- (6). The first two compounds could be isolated in the pure state. In analogous reactions of 1 and 2 with diazabicyclononene (DBN) or N-methyl imidazole, only the pyrophosphates [S(6-t-Bu-4-Me-C₆H₂O)₂P(O)]₂O (7) and [CH₂(6-t-Bu-4-Me-C₆H₂O)₂P(O)]₂O (8) could be isolated, although the reaction mixture showed several other compounds in the phosphorus NMR. A possible pathway for the formation of phosphonate salts is proposed. The X-ray crystal structures of4,7 and8 are also discussed.