Growth, Structural, Spectral, Thermal, Optical, Second and Third Order Nonlinear Optical Properties of Imidazolium Hydrogen Squarate (IHS) Single Crystal

Imidazolium hydrogen squarate (IHS) crystal has been grown by slow evaporation solution growth technique at room temperature. The lattice parameters of grown crystal were determined using single crystal X-ray diffraction data and compared with powder XRD. Single crystal XRD shows that the crystal crystallizes in monoclinic system with noncentrosymmetric space group Pc. The crystallinity of the grown crystal was confirmed by X-ray powder diffraction analysis. FT-IR and FT-RAMAN analyses qualitatively confirm the various functional groups present in the grown crystal. The 1H and 13C NMR spectra were recorded to establish the molecular structure. Thermal properties of title crystal were studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The UV-Vis-NIR transmission spectrum was recorded to find the band width of optical transmittance window and the lower cutoff wavelength. The optical band gap value of the material is evaluated to be 5.6 eV. The second harmonic generation efficiency was calculated by the Kurtz and Perry powder method using a Q-switched mode locked Nd: YAG laser emitting 1064 nm laser as source. Finally, Z-scan technique was employed to determine the nonlinear refractive index, nonlinear absorption coefficient and third-order NLO susceptibility to find suitability of the grown crystal in photonics and optoelectronics applications. Keywords: Single crystal; Powder XRD; thermal analysis; SHG; Z-scan studies

A Study of the Uptake of Cu²⁺ by Calcium Silicate by Batch and Continuous Reactors for Potential Commercialisation

<p>This study presents a significant advancement in the understanding of the uptake of Cu2+ by nanostructured calcium silicate (NCaSil) and to develop a strategy of using it in a continuous manner using packed columns. The NCaSil structure consists of micro-sized agglomeration of nanometre-sized platelets of calcium silicate. This arrangement grants the material a large surface area of 400 to 600 m2 g-1. The kinetics and thermodynamics of the adsorption of Cu2+ onto NCaSil in batch were studied at temperatures ranging from 277 to 333 K. The reaction between Cu2+ and NCaSil occurred rapidly, being endothermic and exhibiting an increase in the entropy meaning that the adsorption process became more spontaneous when the temperature was increased. Furthermore, the uptake resulted in the formation of copper sulfate hydroxide minerals in the form of Cu4(OH)6SO4·nH2O, where n is equal to 2 for wroewolfeite, 1 for posnjakite and 0 for brochantite. Using powder X-ray diffraction and scanning electron microscopy it was proven that at temperatures between 293 and 313 K wroewolfeite and posnjakite were intermediates in the formation of brochantite. Specifically at high temperatures of 333 K and Cu2+ concentrations higher than 15.7 mmol L-1 the reaction proceeded directly to the formation of the thermodynamically stable compound brochantite. A kinetic study of the crystal growth was carried out using powder-XRD which showed that the rate determining step towards the formation of brochantite is the nucleation of SO4 2-. Additionally, a value for the activation energy of 42 kJ mol-1 using powder-XRD data was obtained for the formation of the crystallographic plane 420 in the brochantite crystal. A sample of a real mining waste was collected and analysed. Based on this sample an emulated waste was generated. The NCaSil was tested for the uptake of Cu2+ ions from this emulated mining waste, showing that the use of NCaSil is feasible at pH values greater than 3. The production and use of NCaSil may be coupled to existing mining waste treatment processes in order to remove dissolved copper from solution and produce a copper rich solid as the by-product. NCaSil was packed inside a conventional axial flow column and a radial flow column, which was developed as part of this project. The former proved to be impractical due to a large pressure drop through the column, while the latter was impractical due to short operational times before breakthrough. Nonetheless, the radial flow column was operated by immersion in a tank exhibiting similar kinetics of copper ions uptake to those observed in batch processes. Therefore, the scale-up of this process was proposed including the necessary equations keeping the ratio of the tested radial flow column.</p>

A Study of the Uptake of Cu²⁺ by Calcium Silicate by Batch and Continuous Reactors for Potential Commercialisation

<p>This study presents a significant advancement in the understanding of the uptake of Cu2+ by nanostructured calcium silicate (NCaSil) and to develop a strategy of using it in a continuous manner using packed columns. The NCaSil structure consists of micro-sized agglomeration of nanometre-sized platelets of calcium silicate. This arrangement grants the material a large surface area of 400 to 600 m2 g-1. The kinetics and thermodynamics of the adsorption of Cu2+ onto NCaSil in batch were studied at temperatures ranging from 277 to 333 K. The reaction between Cu2+ and NCaSil occurred rapidly, being endothermic and exhibiting an increase in the entropy meaning that the adsorption process became more spontaneous when the temperature was increased. Furthermore, the uptake resulted in the formation of copper sulfate hydroxide minerals in the form of Cu4(OH)6SO4·nH2O, where n is equal to 2 for wroewolfeite, 1 for posnjakite and 0 for brochantite. Using powder X-ray diffraction and scanning electron microscopy it was proven that at temperatures between 293 and 313 K wroewolfeite and posnjakite were intermediates in the formation of brochantite. Specifically at high temperatures of 333 K and Cu2+ concentrations higher than 15.7 mmol L-1 the reaction proceeded directly to the formation of the thermodynamically stable compound brochantite. A kinetic study of the crystal growth was carried out using powder-XRD which showed that the rate determining step towards the formation of brochantite is the nucleation of SO4 2-. Additionally, a value for the activation energy of 42 kJ mol-1 using powder-XRD data was obtained for the formation of the crystallographic plane 420 in the brochantite crystal. A sample of a real mining waste was collected and analysed. Based on this sample an emulated waste was generated. The NCaSil was tested for the uptake of Cu2+ ions from this emulated mining waste, showing that the use of NCaSil is feasible at pH values greater than 3. The production and use of NCaSil may be coupled to existing mining waste treatment processes in order to remove dissolved copper from solution and produce a copper rich solid as the by-product. NCaSil was packed inside a conventional axial flow column and a radial flow column, which was developed as part of this project. The former proved to be impractical due to a large pressure drop through the column, while the latter was impractical due to short operational times before breakthrough. Nonetheless, the radial flow column was operated by immersion in a tank exhibiting similar kinetics of copper ions uptake to those observed in batch processes. Therefore, the scale-up of this process was proposed including the necessary equations keeping the ratio of the tested radial flow column.</p>

Triple graphite nitrate cointercalation compounds with acetic acid as precursors for thermally expanded graphite and carbon nanoparticles

Triple graphite nitrate cointercalation compounds (GNCCs) with acetic acid were synthesized, characterized by powder XRD and SEM methods, and used as a source of the thermally expanded graphite (TEG). Structural reorganization of graphite nitrate-acetate and triple GNCCs with acetic acid as a result of their exposition in air is discussed on the base of powder XRD data. Dispersions of carbon nanoparticles were prepared by liquid phase exfoliation of TEGs obtained from the GNCCs. It was demonstrated by TEM method that using of the studied TEGs as a source of carbon nanoparticles favours formation of few-layered graphene.

Powder XRD Study of Changes of Cd2+ Modified Clinoptilolite at Different Stages of the Ion Exchange Process

Cadmium exchange on clinoptilolite is performed and structurally studied for different durations of the ion exchange process (2 h, 24 h, 72 h, 168 h, 12 days, 22 days) at room temperature and 90 °C. The distribution of Cd2+ ions in all samples is elucidated after exchange on clinoptilolite using powder XRD data processed by Rietveld structural software. Clinoptilolite is not selective for cadmium cations, but at 90 °C the exchange is ~2.5 cations per unit cell. At RT it reaches ~1.25 cations per unit cell being twice as low. The obtained maximum exchanged sample for 22 days 90 °C was structurally refined in order to find the cadmium positions in the clinoptilolite voids. The structural refinements of the occupations of the incoming and outgoing cations give an idea of how the intracrystalline diffusion is processed. A good correlation between results obtained by structural refinement of the Cd-exchanged samples and the data of the EDS measurements was achieved.

Synthesis, Characterization, Fluorescence and Antimicrobial studies of Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes derived from Schiff’s base (E)-2-(5-chloro-2-hydroxybenzylidene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide

A series of Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes of (E)-2-(5-chloro-2-hydroxybenzylidene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide (HL) with ONO donor ligand was synthesized. The ligand (HL) was prepared by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 5-chloro-2-hydroxybenzaldehyde. The HL and its metal complexes have been characterized using elemental analysis and various spectral techniques such as, FTIR, 1H and 13C NMR, Mass, UV–Visible, ESR, thermal analysis (TGA), magnetic moment, conductivity and powder-XRD. The Powder XRD pattern indicates hexagonal or tetragonal system for HL and its metal complexes. The fluorescence studies exhibits strong emission in the range of 400-500 nm for HL. Further in comparison the HL, Zn(II) and Cd(II) complexes showed enhanced emission whereas Cu(II), Co(II) and Ni(II) showed poor emission. The antimicrobial activities of the HL and its metal complexes were studied by minimum inhibitory concentration (MIC) method wherein the metal complexes showed better activity as compare to free ligand.

LiNa3(SO4)2·6H2O: a lithium double salt causing trouble in the industrial conversion of Li2SO4 into LiOH

Lithium trisodium bis(sulfate) hexahydrate, LiNa3(SO4)2·6H2O was crystallized from aqueous solution at 298 K and the structure solved at different temperatures between 90 and 293 K. The structure is isomorphic with the corresponding molybdate and selenate double salt hydrate. It belongs to the non-centrosymmetric trigonal space group R3c (161). The temperature dependence of the lattice parameters has been determined. Further characterization by powder XRD and thermal analysis is reported.