The Differences in Thermal Breakdown of H2PtC16 and cisPt( NH3)2C12 in Carbon Furnace Atomic Absorption.

A study using a combination of thermogravimetric and x-ray diffraction analyses has shown that a solution of hexachloroplatinic acid (Hj'tCI(), usually used as a standard in atomic absorption spectrophotometric (AAS) measurements, was broken down to yield volatile PtCt before being converted to metallic platinum. On the other hand, a solution of cis-diaminodichloroplatinum(II) (cis-Pt(NH)zClz ; cis-DDP) was converted to metallic platinum in a single step. The differences in their thermal decomposition mechanisms could be one of the leasons as to why carbon furnace atomic absorption spectrophotometric (CFAAS) signal from Hj'tCI~ was found to be lower than that of cis-DDP in aqueous solution. INTRODUCTION Studies by earlier workers have shown differences in absorbance signals of platinum from different platinum complexes when analyses by flame AAS technique. For example, the platinum absorbance of ( H4)2PtC14 (50 ppm) is about twofold greater than that of ~PtCI6 (Macquet and Theophanides 1974) and the cis-DDP signal is about 12% higher than that of H2PtCI6 (Macquet et al. 1974). These differences are said to be due to the differences in thermal stability of the complexes. The ability of the more stable complex to survive as volatile species in the flame is greater than the less stable complexes; a volatile species is more easily decomposed to free atoms hence a higher AAS signal is obtained. (Macquet and Theophanides 197

Preparation of a Poly (Hydroxamic Acid) Ion-Exchange Resin from Poly (Ethyl Acrylate-Divinyl Benzene) Beads and its Properties.

A method to synthesize a poly (hydroxamic acid) chelating ion-exchange resin from poly (ethyl acrylate-divinyl benzene) and its behaviour towards some metal ions are described. The resin was prepared from this copolymer by treatment with hydroxylamine in the presence of sodium hydroxide. The hydroxamic acid capacity of the product is 2.29 mmol/g and its sorption rate, based on sorption of copper ion at pH 4, is rapid. Sorption capacities of Fe(/II), Cu, Co, Ni and Zn ions are pH dependent and its selectively towards these metal ions is in the following order: Fe(II/) >Cu >Ni >Co >Zn. The ability of this resin to extract and to separate these metal ions are also reported

Chemical modification of polymers: current and future routes for synthesizing new polymeric compounds

Chemical modification of polymers is one of the methods used to synthesize new polymeric compounds. It is the most active fields of research in polymer sciences for the past 30 years and enables us to introduce functional or reactive groups into polymers, to alter polymer surfaces, to provide side chain substituents, etc,. Important products of polymer modification include polymeric reagents, functionalised resins, catalyst and media for trapping reaction interdiates organometallic polymers acid carrier for active molecules. This lecture give an overview of our work on preparation and application of poly (hydroxamic acid) resins, lipase modification and immobilization for hydrolysis of palm oil and fatty ester syntheses, and graft copolymerization of sago starch

Measurement of Thermal Diffusivity, Optical Transmission and Optical Absorption Peaks of Laser Dyes R6G Doped in Poly (Methylmethacrylate) Using Photoacoustic Technique and Fibre Optics Spectrophotometer

Using the photoacoustic (PA) spectroscopic technique, we report the thermal diffusivity measurement of the Rhodamine 6G (R6G) doped at different concentrations in solid matrix poly(methylmethacrylate) (PMMA). The value of the thermal diffusivity was found increasing with dye concentration due to the increase of optical absorption of dye molecules in the polymer matrices. A uv-visible fibre optics spectrophotometer was also used to measure the optical spectrum of the samples. The result shows that the transmission cut off in a red region (500-600) nm shifted to the higher wavelength when the dye concentration increased. The maximum transmission (83%) was observed for the PMMA sample doped with the lowest concentration of dye, i.e. 3.1 x 104 mol/ l of R6G

Separation of Gold from Nickel, Cobalt and Zinc by a Poly(hydroxamic acid) Ion-exchange Resin

Behaviour of poly(hydroxamic acid) resin prepared from poly(ethylacrylate) towards gold, silver, copper, iron, nickel, cobalt, and zinc in dilute acid solutions was evaluated. Batch method study shows that although this resin shows high affinity towards the gold ion, it can also be used for the extraction of other metal ions. Sorptions of these metal ions by the resin column are complete and their desorptions from the column can be carried out quantitatively by suitable eluants. Further investigations show that gold can be completely separated from nickel, cobalt and zinc in addition to its separations from silver, iron and copper

A Spectrophotometric Method for the Determination of Glucose with Glucose Oxidase [E.C. 1.11.1.7] Using Titanium (IV)-4-(2'-pyridylazo)Resorcinol Reagent

A mixture of Ti(IV) and 4-(2-pyridylazo) resorcinol was found to be useful in the spectrophotometric determination of trace amounts of hydrogen peroxide. The absorbance of the complex formed at 508 nm was proportional to the concentration of hydrogen peroxide added. The reagent was applied to the assay of glucose through coupling with glucose oxidase which produces HP2' This method of glucose determination was rapid, convenient and showed minimal interference from reducible substances

Synthesis of polymeric nanogel via irradiation of inverse micelles technique

Covalently cross-linked nanogels were prepared via irradiation of inverse micelles that had been prepared from radiation crosslinkable polymer, water, oil and surfactant. A mixture of polymer, water, heptane and sodium dioctyl sulfosuccinate (AOT) at certain compositions forms inverse micelles with the size ranging from 2 to 8 nm. The hydrophilic head of the surfactant facilitates encapsulation of water soluble polymer. If the entrapped polymer is radiation crosslinkable, it is expected that upon irradiation, polymerization shall take place in such small and confined space, leading to formation of nano-sized polymeric gel. Meanwhile, emulsion at 2 nm size was chosen for gamma irradiation process. The formation of the nano-sized discreet gel using irradiation of inverse micelles technique was proven at a dose as low as 5 kGy to obtain nanogel sized ~ 95 nm

Morphology, thermal and mechanical properties of biodegradable poly(butylene succinate)/poly(butylene adipate-co-terephthalate)/clay nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay

Enhancement of tensile strength and flexibility of Polycaprolactone/Tapioca starch blends by Octadecylamine modified clay.

Polycaprolactone/tapioca starch/octadecylamine modified clay (OMMT) nanocomposites were successfully prepared by melt blending. X-ray diffraction and transmission electron microscopy (TEM) of the products showed that they are nanocomposites of a mixture intercalated and exfoliated types. In addition, the TEM also revealed that the OMMTlayers are homogeneously distributed in the polymer matrix. The presence of 1 php of OMMT improved the compatibility of the polymers in the blends which consequently increased the tensile strength of the blend of more than 60% and elongation at break of more than 1,000%

Effect of organo-modified montmorillonite on poly(butylene succinate)/poly(butylene adipate-co-terephthalate) nanocomposites

The composite material based on poly(butylene succinate) (PBS), poly(butylene adipate-co-terephthalate) (PBAT) and organo-modified montmorillonite (OMMT) were prepared by melt blending technique and characterized. Sodium montmorillonite (Na-MMT) was successfully modified by octadecylammonium (ODA) and dimethyldioctadecylammonium (DDOA) salts to become OMMT through cation exchange technique which is shown by the increase of basal spacing of clay by XRD. The addition of the OMMT to the PBS/PBAT blends produced nanocomposites which is proved by XRD and TEM. Tensile tests showed increase in tensile strength and modulus which is attributed to the existence of strong interactions between PBS/PBAT and clay, particularly with OMMT. Highest tensile strength of nanocomposite was observed at 1 wt% of OMMT incorporated. TGA study showed that the thermal stability of the blend increased after the addition of clays. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes homogeneous and smoother with presence of OMMT