M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / The presence of tires in open fields, households and landfills is a great threat to the wellbeing of the ecosystem around them. Tire creates an ideal breeding ground for disease carrying vermins and their possible ignition threatens the surrounding air quality due to the harmful gases produced during combustion. Pyrolysis of tires produces four valuable products namely; char, steel, tire pyrolytic oil (TPO) and noncondensable gases. TPO has been reported to have similar properties to commercial diesel fuel. The biggest challenge faced by TPO to be used directly in combustion engines is the available sulfur content of about 1.0% wt. Considering the stringent regulations globally for allowable sulfur content in liquid fuels, TPO therefore, requires deep desulfurization before commercialization. In this study, different desulfurization techniques were applied to reduce the sulfur content in TPO. A novel study on combination of adsorptive and air-assisted oxidative desulfurization (AAOD) was developed for desulfurization of TPO. Different carbon materials were employed as catalyst and/or adsorbent for the AAOD system. The effect of operating conditions; catalyst/adsorbent dosage, H2O2/HCOOH ratio, reaction time, temperature and air flowrate were studied. Oxidation equilibrium was reached at 80 °C for both commercial activated carbon (CAC) and activated tire char (ATC) at a reaction time of 50 min. With a total oil recovery of more than 90% and the initial sulfur content of 7767.7 ppmw, the presence of air at a flow rate of 60 l/hr increased oxidation from 59.2% to 64.2% and 47.4% to 53% for CAC and ATC, respectively. The use π-complexation sorbent was also applied to study the selectivity of such sorbents to organosulfur compounds (OSC) found in liquid fuels. The π-complexationbased adsorbent was obtained by ion exchanging Y-zeolite with Cu+ cation using liquid phase ion exchange (LPIE). Batch adsorption experiments were carried out in borosilicate beakers filled with modified Cu(I)-Y zeolite for both TPO and synthesized model fuels. For model fuels (MF), the selectivity for adsorption of sulfur compounds followed the order dibenzothiophene (DBT)> benzothiophene (BT)> Thiophene.

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Selon la European Tyre Recycling Association (ETRA), plus de 3 millions de tonnes de pneus en fin de vie sont à traiter en Europe chaque année et sont directement concernés par les mesures législatives visant le réemploi et la valorisation de 95 % de la masse totale des véhicules hors d'usage. Malgré les différentes possibilités de valorisation des pneus usagés (applications dans le secteur du bâtiment et travaux publics, valorisation matière, valorisation énergétique), une partie du gisement français n’est pas répertorié, ni valorisé, et aucune des voies citées auparavant ne s’intéresse à la récupération du noir de carbone, qui est un constituant essentiel du pneu. Ce produit, à forte valeur ajoutée, est principalement utilisé comme charge de renfort dans l'industrie du caoutchouc et des plastiques. Il existe deux types de procédés thermiques industrialisés permettant de récupérer le noir de carbone d’un pneumatique en fin de vie : la pyrolyse et la vapo-thermolyse. La vapo-thermolyse, actuellement industrialisée par Alpha Recyclage Franche Comté (ARFC), est une variante innovante de la pyrolyse, qui utilise la vapeur d’eau surchauffée à pression atmosphérique. La solution qui consiste à substituer un noir de carbone issu d’un procédé de fabrication conventionnel par un noir de carbone issu de vapo-thermolyse de pneus repose sur la qualité du noir de carbone récupéré et, en particulier, sur ses propriétés physico-chimiques intrinsèques et de surface. L'objectif de ce travail de thèse est de proposer et mettre en place une méthodologie adéquate afin de récupérer et caractériser les propriétés physico-chimiques du noir de carbone recupéré (rCB) par vapo-thermolyse à partir d'une formulation de pneu, d'évaluer l'impact des conditions de fonctionnement du procédé sur les propriétés du rCB, et enfin de valoriser le rCB en tant que charge de renfort alternative pour l'élaboration d'un produit final. / According to the European Tyre Recycling Association (ETRA), more than 3 millions tonnes of waste tires are to be treated in Europe each year and are subject to legislation and regulation policies for the re-use and recycling of 95 % of the total mass of end-of-life vehicles. Despite the various opportunities for recycling used tires (civil engineering applications, material recovery, energy recovery), a part of the French available resource remains unvalued and none of the applications just mentioned focuses specifically on the recovery of carbon black, which is one of the main component of a tire. This high added value product is mainly used as reinforcing filler in the rubber and plastics industries. There are two types of industrialized thermal processes for recovering the carbon black from an end-of-life tire : pyrolysis and steam thermolysis. Steam thermolysis, currently industrialized by Alpha Recyclage Franche Comté (ARFC), is an efficient pyrolysis alternative which uses superheated steam at atmospheric pressure. The substitution of carbon blacks produced from a conventional manufacturing process by carbon blacks recovered from the steam thermolysis treatment is based upon the quality of the recycled product, especially regarding its physicochemical properties (intrinsic and surface). The objective of this work is to propose and implement an adequate methodology to recover and characterize the physicochemical properties of recovered carbon black (rCB) from steam thermolysis of a tire, to assess the impact of the process operating conditions on the properties of the rCB, and finally to valorize the rCB as an alternative reinforcing filler for the elaboration of a final product.

M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / The generation of waste tires is one of the most serious environmental problems in the modern world due to the increased use of auto mobiles all over the world. Currently there is a problem with the disposal of waste tires generated since there are strict regulations concerning their disposal through landfill sites. Therefore, there is a need to find ways of disposing these waste tires which pose serious health and environmental problem. The pyrolysis of the waste tires has been recognised as the most promising method to dispose the waste tires because it can reduce the weight of the waste tires to 10% of its original weight and produce products such as pyrolysis oil, pyrolysis char, and pyrolysis char. These products can be further processed to produce value added products. The char produced from the pyrolysis of waste tires can be further activated to produce activated carbon. This study is based on the chemical activation of waste tire pyrolysis char to produce activated carbon for the removal of lead ions from aqueous solution. This was done by impregnating the waste tire pyrolysis char with Potassium hydroxide and activating it inside a tube furnace under inert conditions to produce waste tire activated carbon. Adsorbent characterisation techniques (SEM, FTIR, TGA, XRF, XRD, BET, and Proximate analysis) were performed on the waste tire pyrolysis char and the activated carbon produced to make a comparison between the two samples. The results showed that the waste tire activated carbon produced has better physical and chemical properties compared to the raw waste tire pyrolysis char. Adsorption results revealed that waste tire activated carbon achieves higher removal percentages of lead ions from aqueous solution compared to waste tire pyrolysis char. The results also showed the effect of various process variables on the adsorption process. Adsorption isotherms, kinetics, and thermodynamics were also studied. The adsorption of lead ions agreed with the Freundlich isotherm model for both the waste tire pyrolysis char and waste tire activated carbon. In terms of adsorption kinetics, the experimental data provided best fits for the pseudo-first order kinetic model for both the waste tire pyrolysis char and the waste tire activated carbon. The adsorption thermodynamics study revealed that the process is an exothermic process and spontaneous in nature. Response surface methodology was used to determine the combined effect of process variables on the adsorption of lead ions onto waste tire activated carbon and to optimise the process using numerical optimisation. The optimum conditions were found to be adsorbent dosage = 1g/100ml, pH = 7, contact time = 115.2 min, initial meta concentration = 100 mg/l, and temperature = 25°C to achieve a maximum adsorption capacity of 93.176 mg/l.

Made available in DSpace on 2014-12-17T15:03:29Z (GMT). No. of bitstreams: 1 KarisiaLBF_DISSERT.pdf: 5553904 bytes, checksum: bd332662da6ffbc4e0c2609d1d3928c7 (MD5) Previous issue date: 2012-01-27 / A technological alternative for the correct disposal of tires is the use in the construction of embankment with soil and shredded tires. The use of waste tires in tropical soils requires prior knowledge of the properties and limitations of these materials. In this work, the results of an experimental program was devised to characterize the behavior of mixtures of waste tires and a lateritic soil. The residue used in this study is classified as tire buffings with an average size of 1.4 mm. The laboratory program included testing of particle size analysis, Atterberg limits, compaction, direct shear tests, permeability and confined compression tests with pure soil, pure tire and the mixtures. Proportions of 0% (pure soil), 10%, 20%, 40%, 50 % and 100% (pure tire) by weight were used. For the confining stress levels used in the study, the presence of tire residue provided a considerable increase in shear strength of the mixture. The maximum shear strength was obtained for a residue content of 40% by weight. Permeability tests on samples of waste under a confining stress of 100 kPa showed that the permeability increases significantly with increasing residue content until a residue content of 20%. The increase in permeability after that value showed to be negligible. Confined compression tests showed that the soil mixed with tire residue becomes more compressible than the pure soil. The secant constrained modulus (Msec) for the same vertical stress decreases with increasing percentage of residue. / Dentre as alternativas tecnol?gicas para a destina??o correta de pneus est? o uso na constru??o de aterros de misturas de solo e res?duo de pneus triturados. A utiliza??o de res?duo de pneus em solos tropicais requer o conhecimento pr?vio das propriedades e limita??es desses materiais. Nesta disserta??o, apresentam-se os resultados de um programa experimental para caracteriza??o de misturas de res?duo de pneus em um solo later?tico. O res?duo utilizado neste estudo ? classificado como desbastes de pneus, com tamanho m?dio de 1,4 mm. O programa laboratorial incluiu ensaios de an?lise granulom?trica, limites de consist?ncia, compacta??o, cisalhamento direto, permeabilidade e compress?o confinada com as misturas de solo res?duos de pneus. Foram utilizadas propor??es de 0% (solo puro), 10%, 20%, 40%, 50% e 100% (res?duo puro) em peso. Para os n?veis de tens?o confinantes utilizados no estudo, a presen?a do res?duo de pneu proporcionou um aumento consider?vel da resist?ncia ao cisalhamento da mistura. A m?xima resist?ncia ao cisalhamento foi obtida para um teor de res?duo de 40% em peso. Os ensaios de permeabilidade em amostras de res?duos sob uma tens?o confinante de 100 kPa revelaram que a permeabilidade cresce significativamente com o aumento do teor de res?duo at? um teor de 20%, estabilizando-se em seguida. Os ensaios de compress?o confinada evidenciaram que o solo misturado ao res?duo de pneus torna-se mais compress?vel que o solo puro. O estudo demonstra que o m?dulo de compress?o confinada secante (Msec) para uma mesma tens?o vertical diminui com o aumento da porcentagem de res?duo.

The research work critically analyzed the factors responsible for imprudent waste tyre management in South Africa. As an approach to determine the complexity of the problem, questionnaires were sent to one hundred and sixty (160) respondents in conjunction with interviews. Perusal of literature and interaction with industry involved in waste tyre processing to further gain knowledge of the problem and possible solutions that can be solicited to address the problem. Findings revealed that, lack of clear, focused legislation that guide the handling, disposal and processing of waste tyres remain the challenge. It is also deduced that recycling of waste tyres can provide economic benefits and opportunities. It is recommended that South Africa develop appropriate legislation that deals with handling, treatment and disposal of waste tyres, develop an incentive programme to set up initiatives as well as developing skilled and capacitated enforcement agency. / Environmental Sciences / M.A. (Environmental Management)

The research work critically analyzed the factors responsible for imprudent waste tyre management in South Africa. As an approach to determine the complexity of the problem, questionnaires were sent to one hundred and sixty (160) respondents in conjunction with interviews. Perusal of literature and interaction with industry involved in waste tyre processing to further gain knowledge of the problem and possible solutions that can be solicited to address the problem. Findings revealed that, lack of clear, focused legislation that guide the handling, disposal and processing of waste tyres remain the challenge. It is also deduced that recycling of waste tyres can provide economic benefits and opportunities. It is recommended that South Africa develop appropriate legislation that deals with handling, treatment and disposal of waste tyres, develop an incentive programme to set up initiatives as well as developing skilled and capacitated enforcement agency. / Environmental Sciences / M.A. (Environmental Management)