<p>Glycerol is one of the by-products of transesterification of fatty acids for the production of bio-diesel. Value-added products such as hydrogen, wood stabilizers and liquid chemicals from catalytic treatment of glycerol can improve the economics of the bio-diesel production process. Catalytic conversion of glycerol can be used for production of value-added liquid chemicals. In this work, a systematic study has been conducted to evaluate the effects of operating conditions on glycerol conversion to liquid chemical products in the presence of acid catalysts. </p><p>Central composite design for response surface method was used to design the experimental plan. Experiments were performed in a fixed-bed reactor using HZSM-5, HY, silica-alumina and ã-alumina catalysts. The temperature, carrier gas flow rate and weight hourly space velocity (WHSV) were maintained in the range of 350-500 oC, 20-50 mL/min and 5.40-21.60 h -1, respectively. </p><p>The main liquid chemicals detected in liquid product were acetaldehyde, acrolein, formaldehyde and hydroxyacetone. Under all experimental conditions complete glycerol conversion was obtained over silica-alumina and ã-alumina. A maximum liquid product yield of approximately 83 g/100g feed was obtained with these two catalysts when the operating conditions were maintained at 380 oC, 26 mL/min and 8.68 h-1. Maximum glycerol conversions of 100 wt% and 78.8 wt% were obtained in the presence of HY and HZSM-5 at temperature, carrier gas flow rate and WHSV of 470 oC, 26 mL/min and 8.68 h-1. HY and HZSM-5 produced maximum liquid product of 80.9 and 59.0 g/100 g feed at temperature of 425 and 470 oC, respectively.</p><p>Silica-alumina produced the maximum acetaldehyde (~24.5 g/100 g feed) whereas ã-alumina produced the maximum acrolein (~25 g/100 g feed). Also, silica-alumina produced highest formaldehyde yield of 9g/100 g feed whereas HY produced highest acetol yield of 14.7 g/100 g feed. The effect of pore size of these catalysts was studied on optimum glycerol conversion and liquid product yield. Optimum conversion increased from 80 to 100 wt% and optimum liquid product increased from 59 to 83.3 g/100 g feed when the pore size of catalyst was increased from 0.54 in case of HZSM-5 to 0.74 nm in case of HY, after which the effect of pore size was minimal.

<p>Glycerol is one of the by-products of transesterification of fatty acids for the production of bio-diesel. Value-added products such as hydrogen, wood stabilizers and liquid chemicals from catalytic treatment of glycerol can improve the economics of the bio-diesel production process. Catalytic conversion of glycerol can be used for production of value-added liquid chemicals. In this work, a systematic study has been conducted to evaluate the effects of operating conditions on glycerol conversion to liquid chemical products in the presence of acid catalysts. </p><p>Central composite design for response surface method was used to design the experimental plan. Experiments were performed in a fixed-bed reactor using HZSM-5, HY, silica-alumina and ã-alumina catalysts. The temperature, carrier gas flow rate and weight hourly space velocity (WHSV) were maintained in the range of 350-500 oC, 20-50 mL/min and 5.40-21.60 h -1, respectively. </p><p>The main liquid chemicals detected in liquid product were acetaldehyde, acrolein, formaldehyde and hydroxyacetone. Under all experimental conditions complete glycerol conversion was obtained over silica-alumina and ã-alumina. A maximum liquid product yield of approximately 83 g/100g feed was obtained with these two catalysts when the operating conditions were maintained at 380 oC, 26 mL/min and 8.68 h-1. Maximum glycerol conversions of 100 wt% and 78.8 wt% were obtained in the presence of HY and HZSM-5 at temperature, carrier gas flow rate and WHSV of 470 oC, 26 mL/min and 8.68 h-1. HY and HZSM-5 produced maximum liquid product of 80.9 and 59.0 g/100 g feed at temperature of 425 and 470 oC, respectively.</p><p>Silica-alumina produced the maximum acetaldehyde (~24.5 g/100 g feed) whereas ã-alumina produced the maximum acrolein (~25 g/100 g feed). Also, silica-alumina produced highest formaldehyde yield of 9g/100 g feed whereas HY produced highest acetol yield of 14.7 g/100 g feed. The effect of pore size of these catalysts was studied on optimum glycerol conversion and liquid product yield. Optimum conversion increased from 80 to 100 wt% and optimum liquid product increased from 59 to 83.3 g/100 g feed when the pore size of catalyst was increased from 0.54 in case of HZSM-5 to 0.74 nm in case of HY, after which the effect of pore size was minimal.

In this thesis, it is aimed to design lithium extraction from boron clays using statistical design of experiments and robust design methodologies. There are several factors affecting extraction of lithium from clays. The most important of these factors have been limited to a number of six which have been gypsum to clay ratio, roasting temperature, roasting time, leaching solid to liquid ratio, leaching time and limestone to clay ratio. For every factor, three levels have been chosen and an experiment has been designed. After performing three replications for each of the experimental run, signal to noise ratio transformation, ANOVA, regression analysis and response surface methodology have been applied on the results of the experiments. Optimization and confirmation experiments have been made sequentially to find factor settings that maximize lithium extraction with minimal variation. The mean of the maximum extraction has been observed as 83.81% with a standard deviation of 4.89 and the 95% prediction interval for the mean extraction is (73.729, 94.730). This result is in agreement with the studies that have been made in the literature. However / this study is unique in the sense that lithium is extracted from boron clays by using limestone directly from the nature, and gypsum as a waste product of boric acid production. Since these two materials add about 20% cost to the extraction process, the results of this study become important. Moreover, in this study it has been shown that statistical design of experiments help mining industry to reduce the need for standardization.

Friction Stir Welding (FSW) is an emerging joining technology in which basic process understanding is still inadequate. Knowledge of FSW parameter relationships is needed to better understand the process and implement proper machine control. This study utilized a 3-factor, 3-level factorial design of experiments to investigate relationships between key process inputs and measured output parameters. All experiments utilized 7075-T7 aluminum and a threaded pin tool with a 25.4 mm shoulder diameter, 4.76 mm pin length, and 7.9 mm pin diameter. Spindle speed, feed rate, and tool depth were varied throughout 54 welds while X, Y, and Z forces, X torque, three tool temperatures, and motor power were measured. Empirical models were developed to relate outputs to inputs. The relationships between inputs and outputs are nonlinear and require, at a minimum, a quadratic equation to reasonably model them. These models were further analyzed to explore possible control schemes. Tool depth was found to be the most fundamental means of controlling weld forces and tool temperatures. This research describes the input/output relationships enumerated above for FSW as well as a discussion of possible control schemes.

This thesis illustrates parameter optimization of compressive strength, flexural strength and impact resistance of steel fiber reinforced high strength concrete (SFRHSC) by statistical design and analysis of experiments. Among several factors affecting the compressive strength, flexural strength and impact resistance of SFRHSC, five parameters that maximize all of the responses have been chosen as the most important ones as age of testing, binder type, binder amount, curing type and steel fiber volume fraction. Taguchi and regression analysis techniques have been used to evaluate L27(313) Taguchi&amp / #65533 / s orthogonal array and 3421 full factorial experimental design results. Signal to noise ratio transformation and ANOVA have been applied to the results of experiments in Taguchi analysis. Response surface methodology has been employed to optimize the best regression model selected for all the three responses. In this study Charpy Impact Test, which is a different kind of impact test, have been applied to SFRHSC for the first time. The mean of compressive strength, flexural strength and impact resistance have been observed as around 125 MPa, 14.5 MPa and 9.5 kgf.m respectively which are very close to the desired values. Moreover, this study is unique in the sense that the derived models enable the identification of underlying primary factors and their interactions that influence the modeled responses of steel fiber reinforced high strength concrete.

Abstract Fertilizer industry often generates phosphorous rich wastewaters containing heavy metals. While phosphorous is a valuable compound for the industry, heavy metals hinder the recovery of phosphorous due to their detrimental effects on human health and the environment. Consequently, heavy metals must be removed from the wastewaters. In this study the use of micellar-enhanced ultrafiltration (MEUF) was evaluated for the removal of cadmium, copper, zinc and nickel from phosphorous rich wastewaters. This study has been conducted following a systematic methodology from single metal synthetic wastewaters to more complex synthetic and real wastewaters. The experimental work was conducted in a laboratory scale stirred cell using 3, 5 and 10 kDa regenerated cellulose membranes and in a cross flow semi-pilot scale equipment using a 10 kDa spiral wound polyethersulphone membrane. Statistical design of experiments was used as the research methodology to evaluate the effect of factors on the MEUF process performance as well as for finding optimal conditions. The factors studied were heavy metal, phosphorous and surfactant feed concentrations, pH, membrane nominal molecular weight limits, transmembrane pressure and cross flow velocity. The membrane performance was characterized by the heavy metal retention/rejection coefficients and the permeate flux. The experimental results showed that the removal of heavy metals from single synthetic wastewaters by MEUF is more efficient for more diluted systems. In complex systems containing phosphorous, simultaneous removal of heavy metals was successfully achieved obtaining rejection coefficients up to 80%. Phosphorous was not retained by the membrane showing the potential applicability of MEUF to purify phosphorous rich wastewaters. The study of metal complex formation and heavy metal competition has been shown to be very important in order to predict the MEUF results. Concentration polarization phenomenon was insignificant in the synthetic wastewaters but it was more severe when applying MEUF to real wastewaters. In addition, with real wastewaters SDS leakage was insignificant. This study has provided new and valuable knowledge regarding the applicability of MEUF to industrial wastewater treatment. / Tiivistelmä Lannoiteteollisuus tuottaa usein jätevesiä, jotka sisältävät huomattavia määriä fosforia, sekä pieniä määriä raskasmetalleja. Vaikka fosfori on tärkeä raaka-aine lannoiteteollisuudelle, jätevesissä olevat raskasmetallit kuitenkin estävät sen hyötykäyttöä fosforin lähteenä. Raskasmetallit ovat haitallisia sekä luonnolle että ihmisten terveydelle, joten niiden erottaminen jätevesistä on tärkeää. Tässä työssä tutkittiin miselliavusteisen ultrasuodatuksen (MEUF) käyttöä kadmiumin, kuparin, sinkin ja nikkelin poistamiseen fosforipitoisista jätevesistä. Väitöskirjatyössä tutkittiin systemaattisesti synteettisiä jätevesiä, jotka sisälsivät joko yhtä tai useita raskasmetalleja, sekä lannoitetehtaalta kerättyjä jätevesiä. Kokeet tehtiin laboratoriomittakaavan sekoituskennolla, jossa käytettiin 3, 5 ja 10 kDa:n regeneroituja selluloosakalvoja, sekä semi-pilot -mittakaavan spiraalielementillä, jonka materiaalina oli 10 kDa:n polyeetterisulfonikalvo. Väitöskirjatyössä hyödynnettiin tilastollista koesuunnittelua, jonka avulla arvioitiin muuttujien vaikutuksia MEUF-prosessin käyttäytymiseen. Koesuunnittelua hyödynnettiin myös optimiolosuhteiden määrittelemisessä. Koesuunnitelmien muuttujina olivat raskasmetallien, fosforin ja pinta-aktiivisen aineen pitoisuudet, pH, suodatuskalvojen katkaisukoot, paine sekä ristikkäisvirtauksen nopeus. Kalvon käyttäytymistä arvioitiin raskasmetallien erotustehokkuuden ja permeaattivuon avulla. Koetulokset osoittivat raskasmetallien erotuksen olevan tehokkainta synteettisistä, yhtä metallia sisältävistä jätevesistä, joiden raskasmetallipitoisuus oli pieni. Fosforia sisältävistä monimetalliliuoksista saavutettiin 80&#160;%:inen raskametallien poistotehokkuus. Kalvoerotuksessa fosforipitoisuus ei muuttunut merkittävästi, mikä osoittaa MEUF:n olevan potentiaalinen menetelmä raskasmetallien poistamiseen fosforipitoisista jätevesistä. Metallikompleksien muodostumisen ja raskasmetallien välisen kilpailun ymmärtäminen osoittautuivat erittäin tärkeiksi MEUF-tuloksien ennustamisessa. Konsentraatiopolarisaatioilmiö ei ollut merkittävä käsiteltäessä synteettisiä jätevesiä, mutta teollisten jätevesien käsittelyssä ilmiöllä oli huomattava vaikutus permeaattivuohon. Kuitenkin teollisen jätevesien käsittelyssä SDS:n vuotaminen kalvon läpi oli merkityksetöntä. Tämä tutkimus on antanut uutta ja merkittävää tietoa MEUF:n soveltuvuudesta teollisten jätevesien käsittelyn.

>Magister Scientiae - MSc / Millions of tonnes of fly ash are generated worldwide every year to satisfy the large demand for energy. Management of this fly ash has been a concern and various approaches for its beneficial use have been investigated. Over the last two decades, there has been intensive research internationally that has focused on the use of different sources of fly ash for zeolite synthesis.However, most of the studies have concentrated on class C fly ash and very few have reported the use of South African class F fly ash as feedstock for zeolite synthesis.Class F fly ash from South Africa has been confirmed to be a good substrate for zeolite synthesis due to its compositional dominance of aluminosilicate and silicate phases. However, because differences in quartz-mullite/glass proportions of fly ash from different sources produces impure phases or different zeolite mineral phases under the same activation conditions, the present study focused on optimization of synthesis conditions to obtain pure phase zeolite Na-P1 from class F South African coal fly ash. Synthesis variables evaluated in this study were; hydrothermal treatment time (12 - 48 hours), temperature (100 – 160 oC) and addition of varying molar quantities of water during the hydrothermal treatment step (H2O:SiO2 molar ratio ranged between 0 - 0.49).Once the most suitable conditions for the synthesis of pure phase zeolite Na-P1 from fly ash were identified, a statistical approach was adopted to refine the experiments, that was designed to evaluate the interactive effects of some of the most important synthesis variables. In this case, the four synthesis variables; NaOH concentration (NaOH: SiO2 molar ratio ranged between 0.35– 0.71), ageing temperature (35 oC – 55 oC), hydrothermal treatment time (36 - 60 hours) and temperature (130 oC – 150 oC) were studied. The response was determined by evaluating the improvement in the cation exchange capacity of the product zeolite.The starting materials (fly ashes from Arnot, Hendrina and Duvha power stations) and the synthesized zeolite product were characterized chemically, mineralogically and morphologically by X-Ray fluorescence spectrometry, X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. Other characterization technique used in the study were Fourier transform infrared spectroscopy to provide structural information and also monitor evolution of crystallinity during synthesis, as well as cation exchange capacity to determine the amount of exchangeable positively charged ions. Nitrogen adsorption was used to determine the surface area and porosity, and inductively coupled mass spectrometry for multi-elemental analysis of the post-synthesis supernatants.The results from the X-ray diffraction spectroscopy showed that the most pure zeolite Na-P1 phase was achieved when the molar regime was 1 SiO2 : 0.36 Al2O3 : 0.59 NaOH : 0.49 H2O and at synthesis conditions such that ageing was done at 47 oC for 48 hours while the hydrothermal treatment time and temperature was held at 48 hours and 140 oC, respectively. Results from statistically designed experiments show that there was a distinct variation of phase purity with synthesis conditions. From the analysis of linear and non linear interactions, it was found that the main effects were ageing temperature and hydrothermal treatment time and temperature, which also showed some interactions. This experimental approach enabled a clearer understanding of the relationship between the synthesis conditions and the purity of the zeolite Na-P1 obtained.The quality of zeolites is a major determinant in the efficiency of toxic element removal from waste water. Preliminary experiments conducted using optimised zeolite Na-P1 obtained in this study with a cation exchange capacity of 4.11 meq/g showed a high percentage removal of Pb,Cd, Ni, Mn, V, As, B, Fe, Se, Mo Sr, Ba and Zn from process brine obtained from Emalahleni water reclamation plant.In summary, a pure phase of zeolite Na-P1 was obtained from South African class F fly ash feedstock at relatively mild temperature. The systematic approach, incorporating statistical design of experiments, developed in this study resulted in a better understanding regarding the relationships of synthesis parameters in the formation of zeolites from fly ash. The zeolite Na-P1 synthesized with a high cation exchange capacity was effective for removal of toxic elements from brine.