No description available.

No description available.

An experimental investigation was conducted to evaluate the possible use of highly-charged spherical nanoparticles to stabilize an aqueous dispersion of weakly-charged microspheres. At low pH values, the surface of silica is weakly charged, which leads to flocculation of colloidal suspensions of silica microspheres. Binary solutions of weakly charged silica microspheres and highly charged polystyrene latex nanoparticles result in adsorption of the nanoparticles onto the surface of the silica microspheres. This effectively "recharges" the silica spheres, with effective zeta potentials increased to the range that is unfavorable for flocculation of microspheres in a silica-only solution. However, this does not guarantee stability, and comparisons between positively charged amidine latex nanoparticles and negatively charged sulfate latex nanoparticles indicate that the degree of coverage plays an important role in the restabilization. The sulfate latex nanoparticles do not cover the surface sufficiently, and though they seemingly provide sufficient charge, the weakly charged patches of the exposed silica substrate can lead to flocculation. The amidine latex nanoparticles, on the other hand, cover the surface more completely, and effectively prevent flocculation of the silica microspheres. The mechanisms responsible for this different adsorption and stabilizing behavior are not entirely understood, as both the amidine and sulfate latex nanoparticles are of similar size and the magnitude of the zeta potentials of the different particle types are comparable. / Master of Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

LD2668 .T4 1940 A9 / Master of Science

LD2668 .T4 1954 H9 / Master of Science

The presence of asphaltenes in heavy oil is related to its high viscosity which is a major constraint in heavy oil processing and transportation. Moreover, problems associated with the deposition of asphaltenes at different stages of the heavy oil refining steps increase the cost of heavy oil processing. In this research project, we have achieved viscosity reduction of heavy oil by treating it through the novel JetShear destructuring process. Subsequently we have studied the adsorption of the asphaltenes over specific solid adsorbents. Characterization of the raw and treated heavy oil has been conducted. We have experimentally shown that the JetShear destructuring process reduces diluent requirements (up to 50%), decreases the initial viscosity of heavy oil and lowers the oil density (increasing its API degree) thus providing a solution for pipeline transportation.The asphaltenes content of the treated product oil was also found to decrease slightly during the JetShear destructuring as per SARA fractions determination. This implies incipient cracking of the heavy oil induced by the JetShear treatment. Adsorption of asphaltenes over practical adsorbents was conducted to determine whether asphaltenes could be selectively removed from the oil aiming at establishing the basis of a process. that could lead to breakthrough technology in heavy oil processing. Investigations of adsorption of asphaltenes were centered onto two objectives: firstly, asphaltenes characterization based on molecular size and separation of asphaltenes into acidic and basic fractions; secondly, asphaltenes interaction with adsorbents was studied. Experiments using virgin and destructured heavy oil showed that asphaltenes were preferentially removed following a multilayer adsorption model in the pores with significant and practical yields (0.25~0.36 g asphaltenes/g adsorbent) in the 150 [degree centigrade] range. Maximum uptake required 200 min of contact time at heavy oil/adsorbents ratios in the 5:1 range.The adsorption reduced the asphaltenes remaining in the treated heavy oil by allowing the asphaltenes to lodge in the pores as well as getting adsorbed on the surfaces of the adsorbent particularly the lower molecular weight asphaltenes.The combined treatment (i.e. destructuring and adsorption) also changed the functional group of the asphaltenes, and induced loss of heteroatoms lowering sulfur content in the final oil.

No description available.

To live a healthy life, people all around the world need access to safe water. A lot of industries,together with the fast growing population in Blantyre, a city in southern Malawi, pose a threat to theaccess of safe water for the citizens. Several of the industries in Blantyre release contaminated waterto the nearby streams. One serious pollutant emitted from a match factory is chromium (Cr),especially in the occurrence of Cr(VI) which is carcinogenic for humans. Earlier studies have shownthat the concentration of chromium in the match factory’s wastewater was higher than WHO:sguidelines. It has also been published that natural clay minerals can be used for adsorption of Cr(III).This study investigates the removal of Cr(VI) through the adsorption of Cr(VI) to clay minerals or byreduction of Cr(VI) to Cr(III) which is precipitated from solution.The laboratory work performed in this study includes both experiments for adsorption of Cr(VI) andreduction of Cr(VI) to Cr(III). The reducing agents investigated were two clays and Fe(II) sulfate. Foradsorption of negatively charged Cr(VI) compounds, the two clays where used at lower pH and themineral bauxite was also tried as adsorbent agent. Wastewater from the match factory was dilutedand mixed with the removal agents and the concentration of total chromium was measured beforeand after the mixing process. For the agent with highest potential for Cr(VI) removal, the optimalconditions due to pH, dosage of agents and contact time were inspected.None of the investigated reducing agents served its purpose which means that no Cr(VI) was reducedto Cr(III) in this study. The adsorption of Cr(VI) with clay 1 at lower pH was also not successful, butthe adsorption worked for clay 2 at lower pH and for bauxite. In the experiments bauxite adsorbed ahigher amount of Cr(VI) than clay 2. The adsorption with bauxite turned out to be independent interms of pH. The optimal conditions for bauxite in the experiments were with a dosage of 3.5 gbauxite in 50 mL wastewater and a contact time of 40 minutes. The results showed an adsorption of93 percent of total chromium with bauxite at optimal conditions.

Compared to the solid and gaseous phases, liquids are more closely related to biological processes and the life sciences. In fact, it is generally believed that abiogenesis occurred in the liquid environment of the primordial sea which, itself, was formed only when appropriate conditions came to prevail on the young Earth, providing a striking illustration of the marginal character of the liquid state, in contrast with the solid and gaseous phases of the same substances, which exist over much wider ranges of temperature and pressure: the liquid state arises from a delicate balance between packing of molecules and cohesive forces or, more formally, between entropy and energy. The importance of a full quantitative understanding of liquids is only obvious. Following research in simple liquids, a new area of complex liquids emerged for the study of systems which exhibit ow, but whose liquid-like behaviour cannot be explained by the standard one-body picture used in simple liquids, as interatomic forces are significantly different from the hard-sphere type. The term complex liquid can be interchangeably used with complex fluid or soft matter - following P.G. de Gennes. Many examples of complex liquids involve the mixing of different phases, be they fluid or not in their own right, such as solid and liquid (to make up gel or sol), liquid and gas (to make up foam or liquid aerosol), and solid and gas (to make up solid foam or solid aerosol). Under appropriate conditions, these complex liquid examples, known as colloids, will exhibit fluid-like behaviour on the macroscopic scale. Further examples of complex fluids include polymers and liquid crystals. This Thesis focuses on polymers. Specifically, it researches polymers from a theoretical and a computer simulation perspective, in particular their interaction with surfaces in such a way that they become adsorbed. Setting out with a definition, examples of polymers, and a brief discussion of the practical applications of this work, the General Introduction gives an overview of the theoretical progress in the area of polymer adsorption. This sets the context for a subsequent description of the objectives of this Thesis. The General Introduction closes with an outline of the remainder of the chapters that follow.