This final thesis goal has been to try and develop a titanium dioxide coating for water purification. The coating should be used in a manufacturing industry on textiles. Water purification is achieved through photocatalysis with titanium dioxide and UV-radiation, where hydroxyl radicals form through oxidation. The kind of textile fiber chosen for the substrates is a polyester fiber. The substrates have been developed in several different shapes. Two different knitted patterns was developed, one flat patterned and one wavy patterned. Another kind of substrate was a spacer-type and there was also a substrate made from a PET-bottle. The different substrates were chosen to compare the different coatings effect on different surfaces and the different coatings were developed from two types of titanium dioxide. The coated substrates have been analyzed for hydroxyl radical generating properties. By testing a sample of water with titanium dioxide against a sample with water that had no additives, it was shown that titanium dioxide generates more hydroxyl radicals. The results of the work showed that the recipe containing 3 % titanium dioxide and 3 % acrylic binder showed good properties for water purification. In addition, the results showed a stronger effect for the wavy patterned substrate then the flat patterned, which is an interesting result that should be researched further in the future. / Program: Textilingenjörsutbildningen

Magister Scientiae - MSc (Biotechnology) / The treatment of mine water at the eMalahleni Water Reclamation Plant (EWRP) results in the production of large volumes of brine. Different brine management methods have been applied to dispose the brine but the evaporation pond method is regarded as the cheaper, most effective and less laborious method for brine disposal. Brine wastewater is pumped into the pond where it evaporates resulting in the mixture of salts. The rate at which evaporation occurs is influenced by many factors such as temperature, salinity, humidity and wind. Due to high salinities in brine the EWRP is currently experiencing a challenge with low evaporation rate. Here, a comparative study was done to determine the efficiency of using a chemical and a biological approach to enhance the evaporation rate of reject brine. The chemical approach involved the addition of various concentrations of methylene blue dye (100 to 300 ppm with 50 ppm increments) to 1L volumes of brine, and measuring the evaporation rate. On the other hand, the biological approach involved the isolation of pigmented halophilic bacteria from eMalahleni brine and Cerebos salt samples. Isolated bacterial strains were characterised based on their morphology, biochemical and salt tolerance characteristics. Furthermore, the strains were identified using 16S rRNA gene sequence analysis. Among the isolated halophilic bacterial strains, EP-3, an Arthobacter agilis isolated from the eMalahleni brine produced a darker pigment compared to the other strains. Therefore, EP-3 was evaluated for its effect on the evaporation of brine using a culture inoculum or the addition pigment extracted from an EP-3 culture. The addition of MB above 100 ppm overcame the effect of salt precipitation and resulted in higher evaporation (41%) rate. Addition of pigmented bacteria or bacterial extracted pigment to the brine respectively resulted in 18% and 24% increase in the evaporation rate.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-01-23T17:09:40Z No. of bitstreams: 1 Thaynara_Schafer_2017.pdf: 1932282 bytes, checksum: 89dd37a8b10b1470458f461465755dfc (MD5) / Made available in DSpace on 2018-01-23T17:09:40Z (GMT). No. of bitstreams: 1 Thaynara_Schafer_2017.pdf: 1932282 bytes, checksum: 89dd37a8b10b1470458f461465755dfc (MD5) Previous issue date: 2017-11-20 / The textile industries present a high polluting potential, due to the generation of large volumes of liquid waste, containing high organic load and strong coloration derived from the dyes. These effluents can be treated by physical, chemical and biological processes. Among these processes, the adsorption has been widely studied for the removal of water dyes, due to the lower costs, simplicity of operation and high efficiency. Methylene blue (AM), a dye widely used in the textile industry is responsible for the strong staining in the effluents. Even in small amounts (<5 mg Pt Co / L), just as other textile dyes are very visible and affect the appearance, transparency and solubility of the gases, damaging the environment. A material that has been applied as adsorbent for dye removal in wastewater treatment is the magnetic nanoparticle, because it has high adsorption capacity, low cost and magnetic character. The nanoparticles can be prepared by the electrochemical method, thermal decomposition, hydrothermal synthesis, microemulsion, decomposition-precipitation, coprecipitation, chemical vapor deposition and impregnation. Of the most well-known methods of preparation, the coprecipitation method is the oldest, the simplest, the most efficient, and the one that allows greater production on a large scale. In this work, the coprecipitation method was used to synthesize the iron oxide (Fe3O4) nanoparticle obtained by the stoichiometric mixture of Fe2+ and Fe3+ salts in aqueous medium. This material was characterized and applied in solutions with different concentrations of the methylene blue dye in order to study its adsorption capacity. The same procedure was performed with the nanoparticulate compound (Sigma-Aldrich), in order to compare the adsorption capacity. The nanoparticulate material was characterized by magnetization, X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), ultraviolet/ visible (UV/VIS) spectroscopy, scanning electron microscopy) and optical microscopy (MO). By magnetization it was possible to observe the movement of the dispersed particles in aqueous medium toward the magnetic field of the neodymium magnet, which is a property of the ferromagnetic materials. With the solid samples, the supported weight capacity was tested, whereas for the synthesized compound it was 85, 3 g and for the nanoparticulate compound was 105,3 g, it being possible to explain this difference by packaging the particles. The greater the packing of the particles, the greater the magnetic force exerted. By the study of the effect of the pH and temperature of the medium, it was confirmed that at pH 7 and ambient temperature, the interference of the medium does not occur by the surface charges of the adsorbents and thus favoring the dye adsorption process. By reading the absorbances of the AM solutions, it was possible to calculate the equilibrium concentrations and to determine the amount of dye adsorbed by the nanoparticles. At low concentrations (5,0 x 10-6 mol L-1 to 1,0 x 10-5 mol L-1) a linear behavior is observed due to the presence of monomers already in concentrations higher than 1,0x10-5 mol. L-1 has the alteration of the linear behavior of the adjusted line, characteristic of the formation of aggregate and alteration of the coefficient of molar absorption. Scanning and optical electron microscopy showed that the images presented different forms for the nanoparticulate and nanoparticulate nanoparticles (Sigma-Aldrich), and the nanoparticulate presented reduced size and rounded shape when compared to the synthesized compound. By the diffractograms it was inferred that the synthesized material presented in its composition the magnetite (Fe3O4) and hematite (Fe2O3), the nanoparticulate only the presence of magnetite. Through the FTIR spectra for the nanoparticle samples, the major bands corresponding to the Fe-O and O-H bonds were investigated. By means of the TGA analysis, a loss of 2,31% of mass was observed in the variation of 50 to 150ºC, attributed to the presence of water in the sample. Above 150°C, there was another loss of 1,20% corresponding to the mass of gaseous substances, possibly carbon dioxide (CO2) or oxygen gas (O2). / As indústrias têxteis apresentam um elevado potencial poluente, devido à geração de grandes volumes de resíduos líquidos, contendo alta carga orgânica e forte coloração derivada dos corantes. Esses efluentes podem ser tratados por processos físicos, químicos e biológicos. Dentre estes processos, a adsorção vem sendo amplamente estudada para a remoção de corantes de águas, devido os menores custos, simplicidade de operação e alta eficiência. O azul de metileno (AM), um corante amplamente utilizado na indústria têxtil é responsável pela forte coloração nos efluentes. Mesmo em pequena quantidade (< 5 mg Pt Co/L), assim como os demais corantes têxteis são bastante visíveis e afetam a aparência, a transparência e a solubilidade dos gases, prejudicando o meio ambiente. Um material que vem sendo aplicado como adsorvente para a remoção de corante no tratamento de águas residuarias é a nanopartícula magnética, pois possui alta capacidade de adsorção, baixo custo e caráter magnético. As nanopartículas podem ser preparadas pelo método eletroquímico, decomposição térmica, síntese hidrotérmica, microemulsão, decomposição-precipitação, coprecipitação, deposição química a vapor e a impregnação. Dos métodos de preparo mais conhecidos, o método da coprecipitação é o mais antigo, simples, eficiente e o que permite maior produção em larga escala. Neste trabalho, o método da coprecipitação foi utilizado para sintetizar a nanopartícula de óxido de ferro (Fe3O4), obtida pela mistura estequiométrica de sais de Fe2+ e Fe3+ em meio aquoso. Este material foi caracterizado e aplicado em soluções com diferentes concentrações do corante azul de metileno, a fim de, estudar a sua capacidade de adsorção. O mesmo procedimento foi realizado com o composto nanoparticulado (Sigma–Aldrich), com o propósito de comparar a capacidade de adsorção. O material sintetizado e o composto nanoparticulado foram caracterizados por magnetização, difração de raios-X (DRX), análise termogravimétrica (TGA), espectroscopia de infravermelho (FTIR), espectroscopia ultravioleta/visível (UV/VIS), microscopia eletrônica de varredura (MEV) e microscopia óptica (MO). Por magnetização foi possível observar o movimento das partículas dispersas em meio aquoso em direção ao campo magnético do ímã de neodímio, sendo esta uma propriedade dos materiais ferromagnéticos. Com as amostras sólidas, testou-se a capacidade de peso suportado, sendo que para o composto sintetizado foi de 85,3 g e para o composto nanoparticulado foi de 105,3 g, sendo possível explicar esta diferença pelo empacotamento das partículas. Quanto maior o empacotamento das partículas, maior a força magnética exercida. Pelo estudo do efeito do pH e temperatura do meio, confirmou-se que em pH 7 e temperatura ambiente, não ocorre a interferência do meio pelas cargas da superfície dos adsorventes e assim tem-se o favorecimento no processo de adsorção do corante. Por meio da leitura das absorbâncias das soluções de AM, foi possível calcular as concentrações no equilíbrio e determinar a quantidade de corante adsorvido pelas nanopartículas. Em baixas concentrações (5,0x10-6 mol. L-1 a 1,0x10-5 mol. L-1) tem-se um comportamento linear, devido à presença de monômeros, já em concentrações superiores a 1,0x10-5 mol. L-1 tem-se a alteração do comportamento linear da reta ajustada, característica da formação de agregado e alteração do coeficiente de absorção molar. Por microscopia eletrônica de varredura e óptica foi observado que as imagens apresentaram formas diferenciadas para a nanopartícula sintetizada e nanoparticulado (Sigma– Aldrich), sendo que o nanoparticulado apresentou tamanho reduzido e formato arredondado quando comparado ao composto sintetizado. Pelos difratogramas inferiu-se que o material sintetizado apresentou em sua composição a magnetita (Fe3O4) e hematita (Fe2O3), já o nanoparticulado somente a presença de magnetita. Através dos espectros de FTIR para as amostras das nanopartículas, averiguaram-se as principais bandas correspondentes as ligações Fe-O e O-H. Por meio da análise TGA, observou-se uma perda de 2,31% de massa na variação de 50 a 150ºC, atribuído a presença de água na amostra. Acima de 150ºC, houve outra perda de 1,20% correspondente a massa de substâncias gasosas, possivelmente dióxido de carbono (CO2) ou O2 (gás oxigênio).

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / For centuries the contamination of surface water has been problematic, especially in third world countries whereby socio-economic issues are prevalent. With the development of various technologies for surface water rehabilitation, adsorption has been found to be the most viable due to its lower cost implications. As such the development of innovative adsorbents which are synergistic to the low cost method have been sought. Herein, the use of fossil coral limestone from Mauritius as adsorbents for the removal of Pb(II), Cr(VI) and methylene blue is presented. The pristine material (PCLS) was thermally treated by calcination to temperatures 800°C (CLS-800) and 900°C (CLS-900) and chemically treated by using an acid HCl (ACL) and base NaOH (BCL). The optimum conditions found for chemical and thermal treatment of the pristine material were used for the one pot synthesis of magnetite and maghemite calcium carbonate based nanocomposites. The pristine fossil coral limestones were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray fluorescence XRF), X-ray diffractometer (XRD), Brunauer, Emmett and Teller (BET) and Fourier transformed infrared (FTIR) spectroscopy, UV visible spectrophotometer (UV/vis) and Photolumiscent spectroscopy (PL). Surface morphology of the material was found to contain an interconnected framework of pores, with a surface area of 20.45 m2/g and pore with of 4.04 nm. Thermal treatment of the material was found to increase the surface area of the materials to 64.10 and 63.28 m2/g for CLS-800 and CLS-900. The surface morphology of the calcined materials compared to the pristine were fibrous like and irregularly shaped for CLS-800 and CLS-900 respectively. The FTIR revealed the dominant surface groups to be (-C-O) and (-C=O) asymmetric stretch of the in and out of plane bend of carbonate (-CO32-), with the composition of the material being 91.76 % (-CaO) and 3.32% SrO. The thermally treated materials also exhibited vibrations of asymmetric stretch, which are characteristics of the carbonates as with the pristine material. However, EDS of the pristine compared to that of the calcined materials show a decline in the carbon and oxygen content, due to calcination. The XRD analysis confirmed the orthorhombic structure of aragonite, while CLS-800 was rhombohedral calcite with newly developed (-CaO) peaks. CLS-900 showed complete removal of CaCO3 polymorphs with more (-CaO) peaks. The surface morphology of the chemically modified samples show irregularly shaped surface. The XRD analysis confirmed that chemical treatment did convert the materials to a different polymorph. The FTIR of the chemically modified materials compared to the pristine, were found to reveal a removal of the vibrations of the asymmetric stretch associated with carbonates. However, vibrations associated with (-CaO) were observed. The SEM of the nanocomposites was observed to deviate from sphericity with variable size distribution. The materials were both red and blue shifted due to their variable sizes. Their UV/vis revealed absorption bands in the visible region. The adsorption analysis was done by varying parameters such as time, pH, concentration and temperature. The data was such that the highest capacity for the pristine material was found to be 37.24, 39.26 and 69.42 mg/g for MB, Pb(II) and Cr(VI) respectively. The removal of MB and Pb(II) pollutants were due to physical adsorption, as observed from the good fitting to pseudo first order model (PFOM). The removal of Cr(VI) was due chemisorption and the good fit on pseudo second order model (PSOM). The adsorption process was supported on a heterogeneous surface whereby multilayer adsorption could occur. Adsorption was spontaneous and feasible, exothermic for MB and Pb(II) and endothermic for Cr(VI) at all the studied temperatures as observed from thermodynamics. The adsorption of methylene blue was found to be more favourable on adsorption compared to photo-degradation Chemical modification was observed to increase adsorption and the maximum removal capacities for PCLS, ACL and BCL for Cr(VI) ions were 69.42, 65.04, 64.88 mg/g, Pb(II) ions 39.36, 74.11, 78.34 mg/g and methylene blue 37.24, 46.28, 46.39 mg/g, respectively. Uptake of Cr(VI) and methylene blue on ACL and BCL was feasible on a heterogeneous surface whereby multilayer adsorption took place. Monolayer adsorption on a homogenous surface of ACL and BCL was observed for Pb(II) uptake. The uptake of Pb(II) was exothermic on PCLS and ACL while methylene blue only on PCLS. The adsorption of Cr(VI) ions onto PCLS, ACL and BCL and methylene blue dye onto ACL and BCL were endothermic in nature. The adsorption process was spontaneous and feasible at all the studied temperatures. Thermal modification further increased the adsorption uptake of the pollutants. The recorded uptake for Cr(VI) and Pb(II) were 99.12 and 98.42 mg/g onto CLS-800 and CLS-900, respectively. The adsorption process was found to be physisorption, due to the good fit on PFOM. In addition, the adsorption occurred on a heterogeneous surface whereby multilayer adsorption was possible. The removal of Cr(VI) was found to be exothermic for both the materials and Pb(II) was found to be endothermic. The materials were tested for their reusability to up to four cycles, whereby the removal on the fourth cycle were 16.87, 63.60, 73.13 mg/g for Cr(VI), 9.87, 64.19 and 70.95 mg/g for Pb(II) on PCLS, CLS-800 and CLS-900. While the leaching test for PCLS, CLS-800 and CLS-900 for the release of Ca2+ into solution was found to be within the permissible limits of world health organisation (WHO). The as synthesized nanocomposites increase adsorption of the pollutants. Maximum capacities were found to be 345.34, 388.31, 377.92 and 375.35 mg/g for Pb(II) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively and 308.01, 335.3, 335.29 and 335.27 mg/g for Cr(VI) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively. From the data it was observed that the maghemite samples were much more favourable for the removal of the pollutants. The removal was due to chemical adsorption, as observed from the good fit onto PSOM and intraparticle diffusion (IPD), whereby surface adsorption was the rate limiting step. The adsorption process was heterogeneous and multilayer, while thermodynamic data reveal that adsorption was spontaneous and favourable at the studied temperature.

PhD (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Water is a basic resource to mankind. The environment is deteriorating daily due to industrial pollution of water resources. Industrial effluents containing organic pollutants such as dyes are undesirable even at low concentrations in the environment. Natural biomaterials have been applied as adsorbents for dye removal from water systems, however, their application has been limited by their low adsorption capacity. Much attention has been focused on the chemical modification of natural biomass via grafting processes. The modification of natural polymers by graft copolymerization is a promising technique since it functionalizes a biopolymer thus imparting desirable properties. The purpose of the study was to prepare and optimize the working conditions for the pine-magnetite bionanocomposites (PMC) as adsorbents and as photocatalysts modifiers. First, this work focuses on the synthesis and optimization of reaction variables in the preparation of PMC for the removal of methylene blue (MB). The thesis also explores the synthesis of acrylamide and acrylic acid-grafted PMC, resulting in the formation of acrylamide-grafted PMC (GACA) and acrylic acid-grafted pine-magnetite bionanocomposites (GAA), respectively. The grafting of functional groups such as –CO, –NH2 onto cellulose from acrylamides is also explored in detail. The adsorption conditions optimized were used to investigate the adsorption efficiency of GAA and GACA on MB. Finally, the application of PMC and GAA as modifiers for amorphous TiO2 and N-doped TiO2was carried out. The photocatalytic bionanocomposites from PMC (namely PMC–a-C,TiO2 and PMC–a-C,NTiO2) and those from GAA (labeled GAA–a-C,TiO2 and GAA–a-C,NTiO2) are compared by their photocatalytic efficiency on the degradative removal of an alkaline dye mixture formed from Reactive red 120 (RR 120) and Rhodamine B (Rh B). The synthesis procedure for PMC involved treating pinecone biomass with 0.15 M NaOH solution to remove unwanted plant extracts and the subsequent coating of the treated pinecone with iron oxide magnetic particles through a co-precipitation method. The variables used for the experiments were volume of NH4OH (5 to 40 cm3), reaction temperature (40 to 100 °C), effect of time (15 to 60 min) and mass (1.0 to 3.5 g). The PMC and acrylic acid grafted pine-magnetite composite (GAA) were probed for structural morphology and surface properties using various surface characterization instrumental techniques. Strong chemical interactions between pinecone magnetite and acrylic acid were demonstrated by thermogravimetric (TGA), differential thermal analysis (DTA) and X-ray photoelectron spectroscopy (XPS) for these unique bionanocomposites as such suggesting high chemical stability. Grafting acrylic acid was shown by XPS to form polyacrylic acid on the surface of the bionanocomposites and thus capping the surface groups. Significant differences in size were shown by transmission electron spectroscopy (TEM) and scanning electron microscopy (SEM); i.e., smaller particle sizes (Ave = 13.0 nm) for GAA and slightly larger for PMC (Ave = 14.0 nm). Brunauer Emmett Teller (BET) surface analysis demonstrated a larger surface area, pore volume and pore diameter (59.9 m2.g-1, 0.2254 cm3.g-1 and 28.14) for GAA compared to PMC. These characteristics coupled with the point of zero charge for GAA (pHpzc = 6.8) were critical in enhancing the efficiency of GAA adsorption of MB at pH 12 and further enable GAA to have a higher desorption efficiency of up to 99.7% after four cycles of washing with 0.10 M HCl. The adsorption kinetics and isotherm studies indicated that the adsorption process follows the pseudo second order kinetics and Langmuir isotherm respectively. The adsorbent also showed improvement in the adsorption capacity and reusability promising to be used for the removal of dyes in a prototype scale. GAA and MB adsorption mechanism was confirmed to be through intra particle diffusion. The overall performance of the GAA bionanocomposites is hinged on the formation of polyacrylic acid on the surface, its structural morphology, and the enhanced surface properties. Most importantly, the plant-based materials (lignin and cellulose) provide an environment that is rich with surface (–COOH and –OH) groups for the attachment of the magnetite nanoparticles while the polyacrylic acid stabilizes the magnetite onto the pinecone nanoparticles while reducing the point of zero charge for increased adsorption of cationic species. The photocatalytic bionanocomposites were fabricated from the adsorptive bionanocomposites using a simple solgel process in which ~10 wt.% of PMC and GAA, respectively, were used as a starting agent. Titanium butoxide was used as a precursor, acetylacetone as a dispersant and ethylene diamine as a nitrogen source. Using this procedure, amorphous carbon-doped titania (a-C,TiO2) and amorphous carbon and nitrogen co-doped titania (a-C,NTiO2) were fabricated except that the biopolymer was not added. Two sets of amorphous titania bionanocomposites were fabricated. One set was the nitrogen doped forms that had been modified with PMC and GAA (PMC–a-C,TiO2 and GAA–a-C,NTiO2). The other set of photocatalytic bionanocomposites produced in this work were without nitrogen (PMC–a-C,TiO2 and GAA–a-C,TiO2). TEM and SEM micrographs showed that all the photocatalysts consisted of globular, smooth aggregates of nanosized a-CTiO2 and a-C,NTiO2 which decreased in size with N-doping and the incorporation of GAA and PMC to as low as <30 nm. Surface chemical analysis through FTIR, XPS and EDS confirmed the presence of C, O, Ti and N (for the N-doped photocatalysts). In addition, it was demonstrated that N-doping into TiO2 had taken place, albeit with most of the N incorporated as organic nitrogen. It was further demonstrated that because of the absence of high temperature calcination, the process chemicals played a significant role in doping the photocatalysts with carbon resulting in the promotion of photocatalytic activity for a-C,TiO2 to the point of surpassing that of, a-C,NTiO2 and all the PMC-modified photocatalytic bionanocomposites. a-C,TiO2 had an overall 94% removal of the dyes, Rhodamine B (RhB) and Reactive red 120(RR 120), under UV illumination. The benefit of co-doping a-TiO2 with C, N and the biopolymers was realized with the incorporation of GAA as a modifier. The result was 97% removal of the dyes by GAA–a-CTiO2 and 99% for GAA–a-C,NTiO2. It was further observed that the degradation of the binary mixture of the dyes (RhB and RR 120) proceeded through the zero order kinetics for the a-C,TiO2 based photocatalysts and first order kinetics for the N-doped photocatalysts. The work, has, therefore demonstrated the applicability of plant-based biopolymers in the fabrication of nanoadsorbents and nanophotocatalysts. While the photocatalytic degradations were carried out under UV-light, there still remains a number of possible avenues that researchers can build on to improve the visible light-driven photocatalytic bionanocomposites. The research work has proven the effectiveness of novel pinecone magnetic nanoparticle materials and TiO2-based photocatalyst for the degradation of undesirable dyes from wastewater.