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Thesis(M.Sc.(Chemistry)) -- University of Limpopo, 2020 / An extensive search for a highly efficient, reusable, and non-toxic adsorbent materials for the removal of organic dyes from wastewater continues to be of great importance to the world. Activated carbon is the most widely used adsorbent material for treating dye contaminants from water owing to its high removal capacity and large surface area. However, activated carbon is expensive and not easy to regenerate. Hence, the use of biodegradable, non-toxic, and cost-effective biopolymer-based hydrogel adsorbents has attracted great attention. These adsorbents have high swelling capacity and number of adsorptive functional groups to allow adsorption of methylene blue dye. Hence in this work, we present carboxymethyl cellulose crosslinked with poly (acrylic acid) incorporated with magnetic cloisite 30B clay (CMC-cl-pAA/Fe3O4-C30B) and sodium alginate crosslinked with poly (acrylic acid) incorporated with zinc oxide (SA-cl pAA/ZnO) hydrogel nanocomposites (HNCs) for the removal of methylene blue from aqueous solution. The hydrogel nanocomposites were synthesised through in situ free radical polymerisation. The structural properties of the prepared materials were studied using Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The FTIR and XRD confirmed the successful synthesis of the CMC-cl-pAA and SA-cl-pAA hydrogels, Fe3O4-C30B and ZnO nanoparticles (NPs) and their hydrogel nanocomposites. Furthermore, the co-existence of the metal oxide nanoparticles in the CMC-cl-pAA and SA-cl-pAA hydrogel matrices was confirmed by XRD. The SEM revealed that upon the incorporation of the Fe3O4- C30B NPs onto CMC-cl-pAA, the resulting material showed spherical particles of the magnetite nanoparticles on the irregular shaped hydrogel structure. As well as on the SA-cl-pAA after modification by ZnO nanoparticles, the spherical ZnO particles were embedded on the hydrogel surface. The successful modification with metal oxide nanoparticles was also confirmed by the presence of characteristic elements of the incorporated materials on the EDS. The TEM coupled with selected area electron diffraction (SAED) confirmed the presence of Fe3O4-C30B on the hydrogel structure, in which circular bright dotted lines were observed corresponding to light diffracted by the lattice planes of different energies on the Fe3O4 structure. The thermogravimetric analysis was conducted to study the thermal stability of the materials, the results showed that the incorporation of Fe3O4-C30B and ZnO nanoparticles on CMC-cl-pAA and SA-cl-pAA hydrogels, respectively improved their thermal stability. Furthermore, DMA was used to study the mechanical stability of the prepared hydrogels and their composites. In the case of CMC-cl-pAA hydrogel, the storage modulus of CMC-cl pAA/Fe3O4-C30B nanocomposite was higher than of the hydrogel, indicating improved mechanical stability, and on SA-cl-pAA hydrogel the storage modulus decreased, indicating a decrease in mechanical stability on the SA-cl-pAA/ZnO HNC. Consequently, the swelling studies revealed that the SA/AA/ZnO HNC was highly efficient for water uptake in comparison to SA/AA hydrogel. Whereas, CMC-cl pAA/Fe3O4-C30B had lower swelling capacity than CMC-cl-pAA hydrogel. Various factors influencing the adsorption of adsorbents were systematically investigated. The kinetics, isotherms, and thermodynamics of adsorption were examined, and results showed that equilibrium data fitted the Langmuir isotherm model, and the adsorption kinetics of MB followed pseudo-second-order model in both the CMC-based HNC and SA-based HNC. Maximum adsorption capacities of 1129 and 1529.6 mg/g were achieved for SA/AA hydrogel and SA/AA/ZnO HNC, respectively, in 0.25 g/L MB solution at pH 6.0 within 40 min. Whereas maximum capacities of 1165 mg/g (pH 5) and 806.51 mg/g (pH 7) for CMC-cl-pAA hydrogel and CMC-cl-pAA/Fe3O4- C30B HNC, respectively. Thermodynamic parameters for SA/AA and CMC-cl-pAA hydrogels exhibited exothermic adsorption processes and their nanocomposites SA/AA/ZnO and CMC-cl-pAA/Fe3O4-C30B exhibited endothermic nature of the adsorption processes, respectively. Moreover, the CMC-cl-pAA/Fe3O4-C30B NCH showed improved mechanical and thermal properties as compared to CMC-cl-pAA hydrogel. In contrast, the SA/AA/ZnO HNC presented outstanding reusability with relatively better adsorption efficiencies than SA/AA hydrogel. / Sasol bursary and National Research Foundation (NRF)

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This research evaluated three variables within an AATCC experimental laboratory procedure for dyeing acetate. Evaluation of color measurement from test samples and transmission, an indicator of dye exhaustion, from final dyebath was focused on reproducibility of color from dyeing to dyeing and maximum dye exhaustion. Experimental effects were 1) pH of dyebath, 2) high dyeing temperature for the test fabric, an acetate tricot, and 3) time at the high dyeing temperature. Major findings included: 1. pH of 4 produces significantly higher X and Y color reflectance values, measured by the Color Eye^R at the .05 level. pH of 4 and 6 produce significantly higher Z color values at the .05 level. Transmission readings, measured by the Spec 20^R, indicate exhaustion for the Disperse Red 4, Disperse Blue 3, and Disperse Yellow 3 dyes and are significantly higher for pH of 4 at the .05 level. 2. Temperature of (150°F) 65.6°C and (175°F) 79.4°C give significantly higher transmission readings for Disperse Red 4 at the .05 level. (175°F) 79.4°C and (200°F) 82°C give significantly higher transmission readings for Disperse Blue 3 at the .05 level. Disperse Yellow 3 is unaffected by temperature. 3. Time at the high dyeing temperature had no effect on color measurements or transmission. 4. Transmission is a qualitative indicator of dye concentration and exhaustion. 5. Leakage was prevented with one time use of Ball Jar Lids^R on the AATCC Wash Cups IIA used on the Atlas LaundryOmeter.^R / Master of Science

Introduction In the past few years there has been a tremendous growth in texturized knit fabrics. Nearly all the texturized filament nylon consumed in 1972 'was used in knitwear (1). In addition to this increased consumer demand for knits, the consumer has also been increasing his demands for durabi1itv and utility in the fabrics he buys. The durability and utility included dyefastness properties of adequate colorfastness and acceptable levelness of dyeing (2). Because of the great amount of nylon used in knitwear and the consumer demand for higher quality, the problems associated with nylon have become increasingly important... / Master of Science

The study was conducted to determine congruence in the role of principals of vocational-technical centers in Virginia as perceived by principals, superintendents, and teachers. Twenty-three out of the 24 vocational-technical centers in the state were included in the study. There were 23 superintendents, 23 principals, and 65 teachers from a 20 percent sample who provided useable returns. Design and method of research. A list of 78 items believed to be the functions of principals of vocational-technical centers was developed from the literature and subjected to a jury of experts. Forty-eight items were included in the final instrument which utilized a Likert-type scale to measure perceptions of the respondents. The mail questionnaire technique was used. Analysis of data. Means and standard deviations were obtained on each item for each of the three subgroups. Factor analysis of the items resulted in the identification of six factors underlying the 48 functions. A z-test was used to determine the differences between the sample of teachers, and the principals and superintendents on each factor. / M.S.