No description available.

In developing countries many industries use dyes to colour their products, such as textiles, rubber, paper, cosmetics, leather, plastics, and food industries. Such a wide range of using dyes in many industries increases the demand of dye, and currently 100,000 dyes are commercially available with a rough estimated production of 10⁶ tones/year. Without proper treatment, dye effluent can be mixed with surface and ground water system and it may finally enter the drinking water system. Therefore, the treatment of dye effluents before discharge to the environment has become an global challenge due to the stability and adverse effects of dyes. Among the present methods, adsorption has been preferred to other conventional techniques due to the simple design and operation, low initial investment,effectiveness and insensitivity to toxic substances. The high surface area and the presence of permanent negative charge on the surface makes cellulose nanocrystal (CNC) an excellent candidate for the adsorption of basic (cationic) dyes. The objective of this project is to evaluate the adsorption properties of CNC for the removal of methylene blue from aqueous solution by changing the parameters, such as adsorbent dosage, initial dye concentration, pH, temperature and salt concentration. It was found that the adsorption is independent of pH, however increase in temperature and ionic strength decreased the removal percentage slightly. The Langmuir and Freundlich isotherms were used to evaluate the feasibility of the adsorption process. The adsorption capacity of CNC was determined using the linearized form of Langmuir model. It possessed a value of 118 mg/g at pH 9 and 25 °C. To enhance the adsorption, CNC was oxidized with TEMPO reagent to convert primary hydroxyl groups to carboxyl groups that provides more negative charge. After the oxidation, the adsorption capacity increased from 118 to 769 mg/g.

In developing countries many industries use dyes to colour their products, such as textiles, rubber, paper, cosmetics, leather, plastics, and food industries. Such a wide range of using dyes in many industries increases the demand of dye, and currently 100,000 dyes are commercially available with a rough estimated production of 10⁶ tones/year. Without proper treatment, dye effluent can be mixed with surface and ground water system and it may finally enter the drinking water system. Therefore, the treatment of dye effluents before discharge to the environment has become an global challenge due to the stability and adverse effects of dyes. Among the present methods, adsorption has been preferred to other conventional techniques due to the simple design and operation, low initial investment,effectiveness and insensitivity to toxic substances. The high surface area and the presence of permanent negative charge on the surface makes cellulose nanocrystal (CNC) an excellent candidate for the adsorption of basic (cationic) dyes. The objective of this project is to evaluate the adsorption properties of CNC for the removal of methylene blue from aqueous solution by changing the parameters, such as adsorbent dosage, initial dye concentration, pH, temperature and salt concentration. It was found that the adsorption is independent of pH, however increase in temperature and ionic strength decreased the removal percentage slightly. The Langmuir and Freundlich isotherms were used to evaluate the feasibility of the adsorption process. The adsorption capacity of CNC was determined using the linearized form of Langmuir model. It possessed a value of 118 mg/g at pH 9 and 25 °C. To enhance the adsorption, CNC was oxidized with TEMPO reagent to convert primary hydroxyl groups to carboxyl groups that provides more negative charge. After the oxidation, the adsorption capacity increased from 118 to 769 mg/g.

No description available.

A method was developed to access the interior of light-guiding structures in order to exploit the enhanced sensing potential of the highly confined electromagnetic field distributions, located within the core of a waveguide. The work presented in this thesis explores therefore the possibilities of optical waveguide spectroscopy utilising transparent mesoporous thin-film waveguides deposited on top of athin gold layer. These multi-layer assemblies are employed in a prism-coupling attenuated total internal reflection (ATR) configuration. The angular read-out of the reflected light intensity allows label-free detection schemes with high sensitivity to changes of the dielectric environment in the case of the presence of analyte molecules within the probing region. This optical waveguide spectroscopy technique has been used to study the real-timediffusion of Ruthenium 535-bisTBA (N-719) dye into mesoporous nanocrystalline titaniumdioxide films. The porous films were prepared on top of gold substrates and prism coupling was used to create a guided wave in the nanocrystalline film. Dying was carried out by bring the film into contact with a 3 x 10-4 moldm-3 dye solution and using optical waveguide spectroscopy to monitor the change in both the refractive index and theextinction coefficient of the nanoporous layer as dye diffused into the porous network. Dyeuptake in a 1.27 μm film was slow with the refractive index of the film still increasing after 22 hours.

In the current study, SAPs of cationic monomer [2 - (Methacryloyloxy) ethyl] trimethylammonium chloride have been prepared by free radical solution polymerisation with different crosslinkers. They were subjected to repeated cycles of swelling and de-swelling in DI water and NaCl solution. The conductivity of the swelling medium was measured and related to the swelling/de-swelling characteristics of the SAPs. The swelling capacity was also determined in saline solution. The swelling and de-swelling processes were described by first-order kinetics. The SAPs exhibited varied swelling capacity for crosslinkers of the same functionality as well as different functionality. The SAPs were used to adsorb, the dye Orange G at different initial concentrations of the dye. The equilibrium adsorption data followed the Langmuir adsorption isotherms. The SAPs were also used to adsorb three other dyes, Congo red, Amido black and Alizarin cyanine green. They exhibited different adsorption capacity for different dyes. The adsorption phenomenon was found to follow first order kinetics. In the later part of the study, the co-monomers of [2 - (Methacryloyloxy) ethyl] trimethylammonium chloride with zwitter-ionic monomers [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and [3-(Methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt were prepared in turns at two different concentrations. The effect of the addition of the zwitter-ionic monomers and their concentration of the swelling capacity and dye adsorption capacity was studied. There was no effect on the swelling capacity of the polymers due to either the species of the zwitter-ionic monomer or their concentration. However, there was a reduction in soluble content of the polymers. The dye adsorption capacity decreased at the higher concentration of the zwitter-ionic monomer.