Selective removal of heavy metal ions using sol-gel immobilized and SPE-coated thiacrown ethers

Sorbent materials based on three thiacrown ethers, 1,4,7,10-tetrathiacyclododecane (12S4), 1,4,7,10,13-pentathiacyclopentadecane (15S5) and 1,4,7,10.13,16-hexathiacyclooctadecane (18S6) were prepared either by immobilizing the ligands into sol-gel (SG) matrix or coating on commercial solid phase extraction (SPE) column. SG sorbents were characterized by FT-IR, energy dispersive X-ray microanalysis (EDX) and thermogravimetric analysis/derivative thermogravimetric analysis (TGA/DTG). A marked thermal stability of the ligands when immobilized in sol-gel matrix was noted. The competitive sorption characteristics of a mixture of eleven metal ions (Mg²⁺, Zn²⁺, Cd²⁺, Co²⁺, Mn²⁺, Ca²⁺, Cu²⁺, Ni²⁺, Ag⁺, V⁴⁺, Hg²⁺) using: (i) batch method with ligands trapped in SG matrices, and (ii) off-line SPE column containing coated ligands were studied using ICP-MS. The extraction of metals were optimized for key parameters such as pH, contact time/flow rate, particle size (for SG sorbents) and ligand concentration. Under the optimized conditions, all the immobilized thiacrown ethers exhibited highest selectivity toward Ag⁺, with lesser responses to Hg²⁺ while the extraction of other metal ions were negligible. Among the SG sorbents, 18S6-SG offer the highest capacity and the best selectivity over Hg²⁺. However, for practical applications such as for selective isolation and preconcentration of Ag⁺, the SPE type especially based on 18S6 is preferred as analysis time and recoveries are favorable. The sorbents can be repeatedly used three times as there was no significant deterioration in the metal uptake (%E > 90%) or interference from other metal ions. The optimized procedures were successfully applied for the separation and preconcentration of traces Ag⁺ in different water samples.     

Explicit expression of the franck–condon factors in terms of the potentials of the two states

The calculus of the overlap integral for two states represented by the vibrational wave functions ψ and ψ is reduced to that of the Franck–Condon integral ?(0, x) = ∫ ψψ (t) dt. It is proved that for “numerical potentials” (as well as for a Dunham potential), this integral is given on each interval by a simple analytic expression in terms of the two potentials. The Franck–Condon factors are well determined by “coupling constants” related uniquely to the coordinates of the turning points of the potentials. An application to the band system BII? XΣ of Nα₂ is compared with the usual numerical methods.     

Laser ablation and furnace techniques for sampling and detection in atomic emission spectrometry

Summary The potential of furnace techniques and of laser evaporation for the analysis of dry solution residues and of solids by different atomic emission procedures is described. The new one-step FANES technique (furnace atomic nonthermal emission spectrometry) is compared with the two-step procedure ETV-ICP-AES (electrothermal vaporisation—inductively coupled plasma—atomic emission spectrometry). In case of dry solution residues the sensitivity of the FANES is higher (1–2 orders of magnitude) as a result of better discharge conditions (low background) and direct sample introduction, particularly for volatile and moderately volatile substances. For refractory elements the higher gas temperature of the ICP plasma causes better atomisation, which can lead to higher sensitivity of the ETV-ICP-AES. A new Laser-FANES hybride technique is introduced for microanalysis in solid samples and compared with Laser-ICP-AES. The Laser-FANES is shown to combine the advantages of Laser-ETA-AAS (high sensitivity) and of Laser-ICP-AES (multielemental determinations), particularly for volatile and moderately volatile elements.     

Grafting of living poly(ethylene oxide) onto polystyrene via aromatic nucleophilic displacement of activated nitro groups

Polystyrene of M?_ω = 2.2 × 10⁴ was alkylated with 4-nitrophthalimidomethyl groups as grafting sites. Several backbone polymers with various degrees of grafting sites (G = 2–100%) were prepared and characterized by elemental analysis, IR, ¹H- and ¹³C-NMR, and viscosity measurements. “Living” poly(ethylene oxide) with narrow molecular-weight distribution was prepared in the presence of 15-crown-5, and grafted onto the 4-nitrophthalimidomethylated polystyrene. The nitro displacement reaction was fast and the grafting yield was quantitative (100%). The graft copolymers are highly soluble in water and in organic solvents. The intrinsic viscosities of the graft copolymers are higher than those of the backbone polymers. The intrinsic viscosities show an initial increase followed by a decrease as the degree of grafting increase.     

Pyrazole Derivatives Part III Synthesis of Novel Naphtho[1,2-c]pyrazolebenzenesulfonylureas,Thioureas and Their Cycllzed Derivatives

Substituted p-(naphtho[1,2-c]pyrazol-2-yl)benzenesulfonylurea and thiourea derivatives 5–7 were prepared in three series. Cyclization of the thioureido group of compounds 7 by treating with ethyl bromoacetate, ethyl β-bromopropionate and α-bromoacetophenone afforded the corresponding thiazolidinone, thiazinone and thiazoline derivatives 8 , 9 and 10 respectively.     

Detection of hippuric acid: A glue solvent metabolite,using a mobile test kit

Many testing kits for screening common drugs are widely used in Malaysia, such as the dip strip urine drug testing kit which is specified for detecting drug in abuser. However, currently there is no specific testing kit for screening urine samples to detect glue abusers. This research is dedicated to develop a specific color test method to emphasize the screening for glue abusers, known as G.S. Kit. It contains benzenesulphonyl chloride, pyridine and distilled water. The urine sample is mixed with pyridine and benzenesulphonyl chloride and followed by distilled water. A positive result will be in the form of a color reaction from yellow to red. This novel G.S. Kit would be quite useful for the screening and detection of glue sniffing and toluene abusing qualitatively, as a way of helping National Anti Drug Agency, Department of Education and Royal Police of Malaysia in preventing glue sniffing from becoming a social pandemic.     

Evaluation of dose rate and photon energy dependence of PASSAG polymer gel dosimeter

Journal of Radioanalytical and Nuclear Chemistry - In the current study, dose rate and photon energy dependence of PASSAG gel dosimeter is evaluated by using MRI technique. The gel samples were...     

Chronology and characteristics of groundwater along the United Arab Emirates-Oman arid region: a guide for regional sustainability

Journal of Radioanalytical and Nuclear Chemistry - Estimating groundwater recharge rate is essential for water sustainability of the arid region of the United Arab Emirates that receives most...     

Synthesis of Flexible Elastomeric Polyurethane Films with High Elasticity and Evaluation of Their Structural Permanency

Flexible elastomeric polyurethane (EPU) films were synthesized by ultraviolet (UV) curing of thermoplastic polyurethanes (TPUs) through the reaction among poly (oxytetramethylene) diol (PTMO), isophorone diisocyanate (IPDI), cis-2-butene-1,4-diol (cis-BDO), and 1,6-hexanediol diacrylate (HDDA). In order to improve elasticity and structural permanency in the synthesized TPUs, cross-linking reaction involving unsaturated groups of chain extender (cis-BDO) and reactive diluent (HDDA) using 27 and 41 seconds of UV radiation is introduced. Investigation of structure and mechanical properties was performed using FTIR, GPC, and tensile tests. Stress-strain behavior showed that Young's moduli of EPUs were in the range of 0.2 to 0.4 MPa, which is evidence for high flexibility. Three times of repeated loading on one sample up to 100% strain with 10 min intervals for its recovery showed that considerable structural change didn't occur under these conditions and all observed permanent sets vanished within a time not exceeding 10 min.