Characterisation of the adsorption and regeneration behaviour of a commercial activated alumina adsorbent when separating 1-hexanol and 1-decanol from n-decane

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dc.contributor.advisorBurger, Andries Jacobusen_ZA
dc.contributor.authorKhalifa, Muzafar Tagelsir Hamzaen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering.en_ZA
dc.date.accessioned2023-03-03T12:05:53Zen_ZA
dc.date.accessioned2023-05-18T07:14:45Zen_ZA
dc.date.available2023-03-03T12:05:53Zen_ZA
dc.date.available2023-05-18T07:14:45Zen_ZA
dc.date.issued2023-03en_ZA
dc.descriptionThesis (MEng)--Stellenbosch University, 2023.en_ZA
dc.description.abstractENGLISH ABSTRACT: Paraffins produced in industry are usually associated with impurities such as oxygenates, and adsorption is commonly used to remove these oxygenates (e.g. alcohols). However, the recyclability of such adsorbents has rarely been studied. In this study, the reusability of activated alumina adsorbent used to adsorb 1-alcohols from a paraffin solvent was investigated. The objectives of this study included: (I) the measurement and investigation of single and binary-component adsorption data; (II) the modelling of equilibrium adsorption isotherms and adsorption kinetics; and (III) the measurement and investigation of the efficiency of adsorbent throughout consecutive adsorption/thermal regeneration cycles. One type of commercialized activated alumina adsorbent was used in this study. 1-hexanol and 1-decanol were used as adsorbates, while n-decane was used as the solvent. The effect of initial adsorbate concentration and alcohol carbon chain length on the adsorption and desorption were also briefly investigated. A bench-scale batch adsorption set-up was used for adsorption experiments. Schott bottles containing 1-alcohols + n-alkane solutions (at various initial concentrations of adsorbates) and adsorbents (10g of fresh adsorbent at first experiment) were immersed in a water bath, where the water temperature was maintained at 65 °C. The regeneration experiments were carried out at 205 °C, 185 °C and 165 °C using thermal regeneration columns. Heated purging carrier gas (nitrogen) was used to sweep through the adsorbent for the full duration of regeneration. For both single-component and binary systems, the total equilibrium adsorbent loading was found to increase when increasing the adsorbates’ initial concentration. For single-component solutions, the total adsorption capacity increased systematically as the initial concentration of adsorbates increased up to 2.5 mass%, but at even higher initial concentrations the capacity remained relatively constant. For the binary system, the equilibrium adsorbent loading began to plateau at initial concentrations higher than 2.0 mass%. The effect of carbon chain length exhibited different behaviour for single-component and binary systems. The adsorbent proved a slightly higher affinity to adsorb more of the 1-decanol in the single-component system, whereas in the binary system it was inclined to adsorb more of the 1-hexanol. At similar 1-alcohol initial concentrations in single and binary systems, it was found that the adsorption of a specific 1-alcohol from the binary systems was remarkably poorer than the adsorption of the same 1-alcohol from the corresponding singlecomponent systems. Equilibrium studies showed that the Freundlich and Sips isotherms are suitable for the single 1-hexanol and single 1-decanol adsorption systems, respectively. However, for the binary system, poor correlation was exhibited between the date and the Extended Langmuir, Extended Freundlich and Extended Sips models. Both single-component and binary systems can be described by Elovich kinetics and the Intra-Particle Diffusional Model. As expected, higher efficiencies were achieved for the respective single-component systems than for the binary system. As far as regeneration behaviour is concerned, the activated alumina adsorbent exhibited an adverse response to the highest regeneration temperature (205 °C). For both single-component and binary systems, the adsorbent offered a better efficiency at the regeneration temperature of 185 °C than at 205 °C and 165 °C. BET analysis showed a notable reduction in the total surface area of the regenerated adsorbent at 165 °C, indicating incomplete regeneration at such low temperature, was also confirmed by a systematic drop in adsorption efficiency down to 40% at the final regeneration cycle. en_ZA
dc.description.abstractAFRIKAANS OPSOMMING: Paraffiene wat in die industrie geproduseer word, word gewoonlik geassosieer met onsuiwerhede soos suurstofgebonde komponente (e.g. alkohole). Hierdie komponente word in die algemeen deur middel van adsorpsie verwyder. Gepubliseerde inligting oor die gebruik en regenerasie van die betrokke adsorbente in sulke toepassings is egter skaars. Hierdie studie het die regenerasie en hergebruik van 'n geaktiveerde alumina adsorbent waarmee 1- alkohole uit 'n paraffienoplosmiddel geadsorbeer is, ondersoek. Die doelwitte van die studie was: (I) die meting en bestudering van enkel- en binêre komponent adsorpsie data; (II) die modellering van ewewigsadsorpsie-isoterme en adsorpsie-kinetika; en (III) die meting van en ondersoek na die doeltreffendheid van die adsorbent deur opeenvolgende adsorpsie/termiese regenerasie-siklusse. Een tipe gekommersialiseerde geaktiveerde alumina adsorbent is vir hierdie studie gebruik. 1- heksanol en 1-dekanol is as adsorbate getoets, terwyl n-dekaan as die oplosmiddel gebruik is. Die effek van die aanvanklike adsorbaatkonsentrasie asook alkohole se koolstofkettinglengte op adsorpsie en desorpsie is ondersoek. 'n Laboratorium-skaal enkellading-adsorpsie opstelling is gebruik vir adsorpsie eksperimente. Schott-bottels bevattende 1-alkohole + n-alkaanoplossings (met verskillende aanvanklike konsentrasies van adsorbate) en adsorbente (10g vars adsorbent by die eerste eksperiment) is in 'n waterbad geplaas, waar die watertemperatuur konstant by 65 °C gehou is. Die regenerasie eksperimente is uitgevoer by 205 °C, 185 °C en 165 °C in termiese regenerasie kolomme. Verhitte spoelgas (stikstof) is gebruik om desorberende komponent mee te sleur vir die volle duur van regenerasie. By beide enkelkomponent en binêre stelsels is gevind dat die totale ewewigsadsorpsiebelading toeneem wanneer die aanvanklike konsentrasie van adsorbate toeneem. In enkelkomponent oplossings het die totale adsorpsiekapasiteit stelselmatig toegeneem namate die aanvanklike konsentrasie van adsorbate toegeneem het tot 2.5 massa%, maar by nog hoër aanvanklike konsentrasies het die kapasiteit relatief konstant gebly. In die binêre stelsel het die ewewigsadsorpsiebelading afgeplat by aanvanklike konsentrasies hoër as 2.0 massa%. Die effek van die koolstofkettinglengte was verskillend in enkelkomponent en binêre stelsels. Die adsorbent het in die enkel-komponent stelsel effens hoër affiniteit getoon vir 1-dekanol adsorpsie, terwyl dit in die binêre stelsel geneig was om meer van die 1-heksanol te adsorbeer. By soortgelyke aanvanklike 1-alkohol konsentrasies in enkel- en binêre stelsels is bevind dat die adsorpsie van 'n spesifieke 1- alkohol uit die binêre stelsels opmerklik swakker was as die adsorpsie van dieselfde 1-alkohol uit die ooreenstemmende enkelkomponent stelsels. Ewewigsstudies het getoon dat die Freundlich- en Sips-isoterme geskik is vir onderskeidelik enkel 1-heksanol en enkel 1-dekanoöl adsorpsie stelsels. Vir die binêre stelsel het die Extended Langmuir, Extended Freundlich en Extended Sips modelle egter 'n swak korrelasie met die data getoon. Beide enkel-komponent en binêre stelsels kan beskryf word deur Elovich-kinetika en die Intrapartikeldiffusie Model. Soos verwag, is hoër doeltreffendheid behaal in die onderskeie enkelkomponent stelsels as in die binêre stelsel. Wat herwinninggedrag betref, het die geaktiveerde alumina adsorbent 'n nadelige reaksie getoon by die hoogste herwinningstemperatuur (205 °C). Vir beide enkelkomponent en binêre stelsels was die adsorbent meer doeltreffend by 'n herwinningstemperatuur van 185 °C as by 205 °C en 165 °C. BET-analise het 'n merkbare afname in die totale oppervlakte van die naregenerasie adsorbent by 165 °C getoon, wat dui op onvolledige regenerasie by so 'n lae temperatuur. Hierdie waarneming is ook bevestig deur 'n sistematiese afname in adsorpsie doeltreffendheid tot by 40% in die finale herwinningsiklus. af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxv, 143 pages : illustrations.en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/127298
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshAluminum oxideen_ZA
dc.subject.lcshSeparation (Technology)en_ZA
dc.subject.lcshAdsorptionen_ZA
dc.titleCharacterisation of the adsorption and regeneration behaviour of a commercial activated alumina adsorbent when separating 1-hexanol and 1-decanol from n-decaneen_ZA
dc.typeThesisen_ZA
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