Vaal University of Technology / ii Abstract The use of biosorption to complement conventional water treatment techniques has gained widespread appeal partly due to the abundance of waste materials that can be used as low cost biosorbents. However, some materials have not yet been exploited in this regard. This research was aimed at evaluating the biosorption potential of Mangifera indica (mango) seed shells that are readily available in several farming areas of the Limpopo and Mpumalanga Provinces of South Africa. In this work, powdered ethylenediaminetetraacetic acid (EDTA) functionalized biosorbent was prepared from alkali treated biomass of waste mango seed shells. The influence of alkali treatment and EDTA functionalization on the physicochemical properties of the biomass was characterized using Fourier transform infra-red spectroscopy, X-ray diffraction and thermogravimetric analysis. Results confirmed removal of hemicelluloses, conversion of crystalline to amorphous cellulose and the introduction of carboxyl, ester and tertiary amine groups from EDTA. Furthermore, the powdered biosorbent was immobilized using calcium alginate for adaptation to column sorption. The powdered biosorbents were tested for sorption of lead(II) ions using batch sorption experiment. Through EDTA functionalization, improvement in sorption capacity for lead(II) ions from 59.25 mg.g-1 to 306.33 mg.g-1 was realized. The Langmuir and Pseudo-nth order models most suitably simulated the equilibrium and kinetics of sorption by both functionalized and non-functionalized biomaterials. The calcium alginate immobilized biosorbent was evaluated for non-specific sorption of ionic species of copper, chromium, nickel and iron from electroplating wastewater through discontinuous column sorption experiments. Highest copper, chromium, nickel and iron removal was 12.3%, 14.8%, 4.4% and 13.8% from nonacidified samples at an initial pH of 3.4, and 15.5%, 18.7%, 13.7% and 17.3% from samples acidified to an initial pH of 1.8. Repeated sorption-desorption cycles involving acidified wastewater resulted in successive improvement in metal uptake against declining recovery indicating irreversible binding on –COOH groups formed from –CH2OH groups through a redox reaction involving reduction of chromium(VI) to chromium(III). Keywords: Mangifera indica; biosorption; alkali treatment; carboxyl functionalization; calcium alginate

Orientador: Mauro Dal Secco de Oliveira / Banca: Ricardo Andrade Reis / Banca: Jane Maria Bertocco Ezequiel / Banca: Selma de Fátima Grossi / Banca: Ricardo Dias Signoretti / Resumo: Objetivou-se com este estudo avaliar o valor nutritivo da cana-de-açúcar na alimentação de bovinos. Foram avaliados as variáveis correlacionados com a estabilidade aeróbia, pH microrganismos, composição bromatológica, teores de macro, microminerais, metais tóxicos, digestibilidade, ganho de peso e consumo. Para análise estatística do consumo e ganho de peso foi utilizado delineamento inteiramente casualizado com quatro repetições por tratamento, a análise estatítica das demais variáveis foi feita utilizando o delineamento inteiramente casualizado, em esquema de parcelas subdivididas, sendo as doses de cal alocados nas parcelas (0; 0,5; 1,0; 1,5 e 2,0 %) e os tempos de exposição ao ar nas subparcelas (0, 24, 48, 72 e 96 horas), com quatro repetições por tratamento. As médias em ambos os casos foram comparadas utilizando-se o teste de Tukey ao nível de 5 % de probabilidade. Foi encontrado efeito significativo para todas as variáveis estudas com exceção daquelas relacionadas ao desempenho e consumo. A cal virgem foi capaz de aumentar a estabilidade aeróbia e controlar o desenvolvimento dos microrganismos (leveduras principalmente), solubilizar a fração fibrosa da cana e aumentar a digestibilidade, porém estes efeitos não ocasionaram um maior consumo nem maior desempenho dos animais alimentados com este volumoso, indicando que outros fatores podem estar influenciando no desempenho dos animais. Com o passar das horas a cana-de-açúcar diminui o seu valor nutritivo porém esta diminuição é menor para os tratamentos que continham a cana-de-açúcar tratada com cal virgem. / Abstract: This study objective was evaluete sugar cane nutritional value of in cattle feeding. Variables correlated were evaluated with aerobic stability, pH microorganisms, bromatologic composition, levels of macro, microminerals, toxic metals, digestibility, weight gain and consumption. For consumption and weight gain statistical analysis a randomized design with four replicates per treatment was used, analysis statistical for other variables were made using randomized design in a split-plot, and the doses of lime allocated in pieces (0 , 0.5, 1.0, 1.5 and 2.0%) and the time of exposure to air the subplots (0, 24, 48, 72 and 96 hours), with four replicates per treatment. The averages in both cases were compared using the Tukey test at 5% level of probability. Significant effect was found for all the variables studied except those related to the performance and consumption. The lime was able to increase aerobic stability and control the microorganisms (mainly yeasts) development, solubilizing cane fibrous fraction cane and increasing digestibility, but these effects do not lead to higher consumption and higher performance of animals fed with forage, indicating that other factors may be influencing animals performance. With the passing of the hours the sugar cane diminish their nutritional value but this reduction is lower for the treatments that contained the sugar cane treated with lime. / Doutor

The current trend concerning the thinning of solar cell devices is mainly motivated by economic aspects, such as the cost of the used rare-earth elements, and by the requirements of emergent technologies. The introduction of ultra-thin absorber layers results in a reduction of used materials and thus contributes to a more cost-effective and time-efficient production process.However, the use of absorber layers with thicknesses below 500nm gives rise to multiple apprehensions, including concerns regarding light management and the absorber’s quality.Therefore, this experimental work presents a novel solar cell architecture that aims to tackle the issues of optical and electrical losses associated with ultra-thin absorber layers. To that end, a Hafnium Oxide (H f O2) rear side passivation layer was introduced in-between the copper indium gallium (di)selenide Cu(In, Ga)Se2, CIGS-based absorber layer and the Molybdenum (Mo) back contact. Then, the proposed Potassium Fluoride (KF) alkali treatment successfully established point contacts on the ALD-deposited oxide layer, resulting in a passivation effect with minimum current blockage.The established cell architecture showed significant improvements regarding both open circuit voltage (Open-Circuit Voltage (Voc)) and efficiency when compared to unpassivated reference devices. The used solar cell simulator (SCAPS) attributes the observed improvements to a reduced minority carrier recombination velocity at the rear side of the device. Moreover, the provided photoluminescence (PL) results report a higher peak intensity and lifetime for passivated devices.Furthermore, the overlay of the given external quantum efficiency (EQE) spectra with the performed simulations show that the HfO2 passivation layer improves the optical reflection from the rear contact over a wavelength interval ranging from 500 to 1100 nm, resulting in a short circuit current (Jsc) improvement. An increased quantum efficiency observed throughout almost the entire measurement range, confirms that the enhance in Jsc is also due to electronic effects.Here, a produced solar cell device including a 3nm-thick HfO2 rear passivation layer and a 500nm-thick 3-stage CIGS absorber, achieved a conversion efficiency of 9.8%.Further, the approach of combining an innovative rear surface passivation layer with a fluoride-based alkali treatment resulted in the development and successful characterisation of a 1-stage, 8.6% efficient solar cell. Such result, mainly due to a short circuit current (Jsc) enhancement, supports the introduction of more straightforward production steps, which allows a more cost-effective and time-efficient production process. The produced device consisted of a 500nm-thick CIGS absorber, rear passivated with an ultra-thin (2nm) HfO2 layer combined with a 0.6M KF treatment. / Den nuvarande trenden när det gäller solcellsanordningar huvudsakligen motiveras av ekonomiska aspekter, såsom kostnaden för att använda sällsynta jordartsmetaller, och av kraven i ny teknik. Införandet av ultratunna absorptionsskikt resulterar i en minskning av använda material och bidrar därmed till en mer kostnadseffektiv och tidseffektiv produktionsprocess.Användningen av absorptionsskikt med tjocklekar under 500 nm ger emellertid upphov till flera bekymmer, beträffande ljushantering och absorptorkvalitet.Därför presenterar detta experimentella arbete en ny solcellarkitektur som syftar till att ta itu med frågorna om optiska och elektriska förluster förknippade med ultratunna absorberlager. För detta ändamål infördes ett Hafnium Oxide (H f O2) bakre sidopassiveringsskikt mellan kopparindiumgallium (di) selenid Cu(In, Ga)Se2, CIGSbaserat absorberande skikt och Molybdenum (Mo) kontakt. Sedan upprättade den föreslagna kaliumfluorid (KF) alkali-behandlingen framgångsrikt punktkontakter på det ALD-avsatta oxidskiktet, vilket resulterade i en passiveringseffekt med minimal strömblockering.Den etablerade cellarkitektur visade signifikanta förbättringar avseende både öppna kretsspänningen (Voc) och effektivitet i jämförelse med opassiverad referensanordningar. Den använda solcellsimulatorn (SCAPS) tillskriver de observerade förbättringarna till en minskad minoritetsbärares rekombinationshastighet på enhetens baksida. Dessutom de tillhandahålls fotoluminescens (PL) resultat rapporterar en högre toppintensitet och livslängd för passive enheter.Dessutom visar överläggningen av det givna externa kvantitetseffektivitetsspektrumet (EQE) med de utförda simuleringarna att passiveringsskiktet HfO2 förbättrar den optiska reflektionen från den bakre kontakten över ett våglängdsintervall från 500 till 1100 nm, vilket resulterar i i en kortslutningsström (Jsc) förbättring. En ökad kvantverkningsgrad observerats i nästan hela mätområdet, bekräftar att öka i Jsc är också på grund av elektroniska effekter.Här, en producerad solcellsanordning innefattande en 3 nm-tjock HfO2 bakre passiveringsskikt och ett 500 nm-tjock 3-stegs CIGS absorber, uppnått en omvandlingseffektivitet på 9.8%.Vidare resulterade tillvägagångssättet att kombinera ett innovativt bakre ytpassiveringsskikt med en fluoridbaserad alkalibehandling i utvecklingen och framgångsrik karaktärisering av en 1-stegs, 8.6% effektivitet solcell. Ett sådant resultat, främst på grund av en kortslutningsström (Jsc) förbättring, stöder införandet av mer enkla produktionssteg, vilket möjliggör en mer kostnadseffektiv och tidseffektiv produktionsprocess. Den framställda anordningen bestod av ett 500 nm-tjock CIGS absorber, bakre passiverad med en ultra-tunn (2 nm) HfO2-skikt kombineras med en 0.6M KF behandling.

Made available in DSpace on 2014-06-11T19:33:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-16Bitstream added on 2014-06-13T19:04:36Z : No. of bitstreams: 1 domingues_fn_dr_jabo.pdf: 482237 bytes, checksum: 54c7e0690f2c932a3e29b9f5b2e2bce1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se com este estudo avaliar o valor nutritivo da cana-de-açúcar na alimentação de bovinos. Foram avaliados as variáveis correlacionados com a estabilidade aeróbia, pH microrganismos, composição bromatológica, teores de macro, microminerais, metais tóxicos, digestibilidade, ganho de peso e consumo. Para análise estatística do consumo e ganho de peso foi utilizado delineamento inteiramente casualizado com quatro repetições por tratamento, a análise estatítica das demais variáveis foi feita utilizando o delineamento inteiramente casualizado, em esquema de parcelas subdivididas, sendo as doses de cal alocados nas parcelas (0; 0,5; 1,0; 1,5 e 2,0 %) e os tempos de exposição ao ar nas subparcelas (0, 24, 48, 72 e 96 horas), com quatro repetições por tratamento. As médias em ambos os casos foram comparadas utilizando-se o teste de Tukey ao nível de 5 % de probabilidade. Foi encontrado efeito significativo para todas as variáveis estudas com exceção daquelas relacionadas ao desempenho e consumo. A cal virgem foi capaz de aumentar a estabilidade aeróbia e controlar o desenvolvimento dos microrganismos (leveduras principalmente), solubilizar a fração fibrosa da cana e aumentar a digestibilidade, porém estes efeitos não ocasionaram um maior consumo nem maior desempenho dos animais alimentados com este volumoso, indicando que outros fatores podem estar influenciando no desempenho dos animais. Com o passar das horas a cana-de-açúcar diminui o seu valor nutritivo porém esta diminuição é menor para os tratamentos que continham a cana-de-açúcar tratada com cal virgem. / This study objective was evaluete sugar cane nutritional value of in cattle feeding. Variables correlated were evaluated with aerobic stability, pH microorganisms, bromatologic composition, levels of macro, microminerals, toxic metals, digestibility, weight gain and consumption. For consumption and weight gain statistical analysis a randomized design with four replicates per treatment was used, analysis statistical for other variables were made using randomized design in a split-plot, and the doses of lime allocated in pieces (0 , 0.5, 1.0, 1.5 and 2.0%) and the time of exposure to air the subplots (0, 24, 48, 72 and 96 hours), with four replicates per treatment. The averages in both cases were compared using the Tukey test at 5% level of probability. Significant effect was found for all the variables studied except those related to the performance and consumption. The lime was able to increase aerobic stability and control the microorganisms (mainly yeasts) development, solubilizing cane fibrous fraction cane and increasing digestibility, but these effects do not lead to higher consumption and higher performance of animals fed with forage, indicating that other factors may be influencing animals performance. With the passing of the hours the sugar cane diminish their nutritional value but this reduction is lower for the treatments that contained the sugar cane treated with lime.

Cette étude constitue une contribution à la recherche de nouveau matériau composite originaire des ressources naturelles végétales. Elle vise alors à l’exploitation des fibres naturelles extraites de la plante d’Alfa avec une matrice biopolymère thermoplastique de type Mater-Bi® afin d’élaborer des biocomposites. Trois types de fibres courtes extraites de la plante d’Alfa sont préparés ; non traitées et traitées par un traitement alcalin à 1 et 5%. Les diverses techniques utilisées pour la caractérisation des fibres ont révélé une augmentation de la rugosité, du taux de cellulose, de l’indice de cristallinité ainsi de la stabilité thermique après le traitement alcalin. Les matériaux composites sont préparés par extrusion bivis suivi d’une opération d’injection en faisant varier le pourcentage des fibres de 0 à 25%. Les analyses thermiques des biocomposites ont montré un accroissement significatif de la vitesse de cristallisation suite à l'incorporation des fibres d’Alfa ainsi une amélioration de la stabilité thermique pour les matériaux à base de fibres traitées. La résistance à la traction et le module de Young des biocomposites ont augmenté alors que la ténacité et l’allongement à la rupture ont diminué avec l'augmentation du taux de fibres. Les micrographies MEB des surfaces fracturées indiquent une bonne adhésion entre la matrice et les fibres d’Alfa traitées ou non. L’étude de la cinétique de cristallisation des différents biocomposites a prouvé le fort effet nucléant des fibres d’Alfa traitées ou non / This study is a contribution to the search for new composite material from vegetable natural resources. It aims at the exploitation of natural fibers extracted from the Alfa plant with a bioplastic of the Mater-Bi® type in order to develop biocomposites. Three kinds of short fibers extracted from Alfa plant were prepared; untreated, 1% and 5% alkali treated. The various techniques used for fibers characterization showed an increase in the roughness, cellulose level, crystallinity index and thermal stability after the alkali treatment. The composite materials were prepared by twin screw extrusion flowed by an injection operation by varying the fiber contents of 0 to 25%. Thermal analysis showed significant increase of the crystallization rate with the incorporation of Alfa fibers and enhancement of thermal stability by alkali treatment. Modulus and tensile strength of biocomposites also improved whereas toughness and elongation at break decreased upon increasing the fibers fraction. Scanning electron microscopy (SEM) on fractured surfaces indicated good adhesion between the matrix and the treated or untreated Alfa fibers. The study of crystallization kinetics of biocomposites showed strong nucleating effect of treated or untreated Alfa fibers.