Zeolites and zeolite membranes are two important advanced chemical materials which are widely used in chemical processes. The manufacture of these materials usually involves the use of expensive chemicals. This study involves the use of Ahoko Nigerian kaolin (ANK) as precursor material for the development of zeolites and zeolite membranes. The synthesis of zeolite A, Y and ZSM-5 was successfully obtained following a sequence, collection of the raw clay from Nigeria, metakaolinization, dealumination and actual hydrothermal synthesis of the zeolites. Raw ANK was refined using sedimentation technique and about 97% kaolin was recovered from the raw sample. A novel metakaolinization technique was developed to convert kaolin into a reactive metastable phase. Amorphous metakaolin was obtained at a temperature of 600°C and exposure time of 10 min. This is a significant result because previous studies use higher temperatures and longer exposure times for the metakaolinization step. The metakaolin was used to prepare a number of different zeolites under various conditions. Highly crystalline zeolite A was obtained at an ageing time of 12 h, crystallization time of 6 h and crystallization temperature of 100oC. Zeolite Y was obtained at an ageing time of 3 h, crystallization time of 9 h and crystallization temperature of 100oC. Zeolite Y was also synthesised by using a dealuminated kaolin and highly crystallized zeolite Y with Si/Al ratio of 1.56 and BET surface area was obtained of 630 m2/g. ZSM-5 was synthesised using an ageing period of 36 h, crystallization time of 48 h and temperature of 140oC. The results obtained from zeolite powder synthesis from ANK were then used as guide to prepare supported zeolite films and membranes by a hydrothermal method. The effect of the support surface (stainless steel) was investigated using two synthesis methods namely modified in-situ and secondary (seeded) growth. Zeolite A, Y and ZSM-5 films were successfully prepared from ANK for the first time and on two modified supports, etched and oxidised. The zeolite films and membranes developed showed complete coverage on the two supports with the oxidised showing better adhesion and intergrowth. The separation performance of the three developed zeolite membrane was tested by pervaporation of water/ethanol mixture. The results of pervaporation of ethanol/water mixture showed that zeolite A membrane is highly selective towards water mainly because of hydrophilic properties occasioned by the high aluminium content. Zeolite Y membrane show a similar response when their separation performance was evaluated but with less selectivity because of reduced aluminium content. ZSM-5 showed selectivity towards ethanol because of it hydrophobicity allowing only ethanol to permeate. In all the zeolite membranes, the flux is lower in comparison to commercial zeolite membranes due mainly to the thickness of the zeolite layer. Oxidised support membranes showed better performance because of their better interaction between the oxide surface and the aluminosilicate gel. The results show that ANK can successfully be used to prepare zeolites and zeolite membrane.

Submitted by Rafael Santana (rafael.silvasantana@ufpe.br) on 2017-07-10T19:30:23Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao - Pedro Negrão.pdf: 2417925 bytes, checksum: 563fc37dbb3bf794487bc4e3c8fc102a (MD5) / Made available in DSpace on 2017-07-10T19:30:23Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao - Pedro Negrão.pdf: 2417925 bytes, checksum: 563fc37dbb3bf794487bc4e3c8fc102a (MD5) Previous issue date: 2016-03-29 / CAPES / As argilas compõem um grupo de matérias-primas muito importante devido a suas múltiplas funções industriais. Em especial o caulim, possui propriedades físicas e químicas que possibilitam a sua utilização no processo industrial de uma grande gama de produtos, desde matéria-prima para a indústria cerâmica, de carga e cobertura de papel, entre outras. Esta pesquisa objetivou descrever, através da caracterização mineralógica, análise química, análise granulométrica, ensaios tecnológicos e de plasticidade, as características do material arenocaulinítico sondado no município de Igarassu – PE, ocorrência localizada próxima ao bairro de Nova Cruz 2. O material foi coletado através de sondagem a trado, tendo as amostras passado por análise mineralógica por difração de raios X, análise química por fluorescência de raios X, análise granulométrica, ensaios de plasticidade e foram confeccionados corpos de prova para a realização de ensaios tecnológicos. Os resultados obtidos foram comparados com as características de caulins de outros jazimentos descritos na literatura e com as especificações dos caulins aproveitados industrialmente. / Clays form a group of so important raw materials due to its multiple industrial functions. In particular, the kaolin has physical and chemical properties which allow its use at the industrial process a wide range of products from a raw material for ceramic industry, filler and paper coating, among others. This research aimed to describe through mineralogical characterization, chemical analysis, particle size analysis, technological tests and plasticity characteristics of sandy-kaolinitic materials collected in the city of Igarassu - PE, occurrence located near the Nova Cruz 2. The material was got by auger boring, the samples submitted to a mineralogical analysis through X ray diffraction, chemical analysis through X ray fluorescence, particle size analysis, plasticity tests and was prepared specimens to be performed for the technological tests. The results obtained were compared with the characteristics of kaolin of other deposits described in the literature and with the specifications of kaolin exploited industrially.

Este trabalho objetivou estudar a síntese de zeólita NaA sob condições hidrotérmicas e aplicála na adsorção de metais pesados. Para a síntese de zeólita NaA, caulim do município de Ipixuna, Pará, foi calcinado a 700 °C por 3 horas para obtenção de metacaulim e usado como fonte de sílica e alumina. Para efeito de comparação, cloreto de alumínio e metassilicato de sódio também foram utilizados na síntese de zeólitas como precursores de Si e Al. A influência da alcalinidade na síntese dos produtos zeolíticos foi avaliada utilizando-se diferentes concentrações de NaOH. Todas as sínteses foram realizadas a 110 °C em autoclaves. Visando à compreensão da influência do tempo na quantidade e tipo de fase formada, foram realizadas sínteses com diferentes tempos de cristalização. Os produtos de reação foram caracterizados por difração de raios X, espectroscopia na região do infravermelho, análise termogravimétrica, análise térmica diferencial, microscopia eletrônica de varredura e adsorção de nitrogênio para cálculo de área específica pelo método BET. A amostra que apresentou maior proporção de zeólita NaA foi utilizada como adsorvente em soluções de Cu2+, Ni2+ e Cd2+ com concentrações iniciais de 25 a 400 mg/L. A concentração de equilíbrio desses metais, após remoção pela zeólita NaA, foi determinada por espectrofotometria de absorção atômica. Os resultados mostraram que o aumento da alcalinidade e do tempo de cristalização favoreceu a obtenção de sodalita, uma fase zeolítica concorrente à Zeólita A, nos produtos de síntese. A zeólita NaA provou ser um excelente adsorvente para remoção dos metais analisados, apresentando uma capacidade de adsorção máxima de aproximadamente 79, 65 e 32 mg/g para Cd2+, Cu2+ e Ni2+, respectivamente. O modelo de isoterma de adsorção que melhor descreveu a remoção de metais pela zeólita NaA foi o de Langmuir. / The aim of this work was to study the synthesis of zeolite NaA under hydrothermal conditions and use it as adsorbent of heavy metals. To synthesize zeolite NaA, kaolin from the city of Ipixuna, Pará, was calcined at 700 °C for 3 hours and used as source of silica and alumina. For comparison purposes, aluminum chloride and sodium metasilicate were also used in the synthesis of zeolites as precursors of Si and Al. The influence of alkalinity on the synthesis of the zeolitic products was evaluated using different NaOH concentrations. All the syntheses were performed at 110 °C by autoclaving. To understand the influence of time on the type and relative amount of the obtained phases, syntheses with different crystallization times were carried out. The reaction products were characterized by means of X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, thermal differential analysis, scanning electron microscopy and nitrogen adsorption for calculating surface area by the BET method. One of the samples, which exhibited the highest content of zeolite NaA, was used as adsorbent of Cu2+, Ni2+ and Cd2+ solutions with initial concentrations ranging from 25 to 400 mg/L. The equilibrium concentration of these heavy metals, after removal by zeolite NaA, was determined by atomic absorption spectrophotometry. The results showed that increasing alkalinity of the reaction medium led to the formation of sodalite, a concurrent zeolitic phase, in the products. Zeolite NaA turned out to be an excellent adsorbent for removing heavy metals, with an adsorption capacity of 79, 65 and 32 mg/g for Cu2+, Cd2+ and Ni2+, respectively. The Langmuir isotherm model was the most appropriate to describe the removal of metals by zeolite A.

Content: Sustainability is a key factor which control future leather manufacture. Developing several new technologies is one of the primary agenda for sustainability. However, developing countries are facing several challenges which not only limited to best practice technologies but also finding self sustainability in maximizing the available resources. In the present study, an attempt has been made to explore the potential resource of aluminium from kaolin of Pugu hills, Tanzania for combination tanning. Though, extraction of aluminium from several resources are available, there is limited literature pertaining to Tanzania resources. Moreover, the extracted aluminium is basified and studied for its tanning efficiency. Diffraction and vibrational spectroscopic studies were carried out to assess the confirmation of extracted aluminium. Combination tanning has been carried out with vegetable tannins and dialdehyde starch tanning chemicals, which are from natural resources. Leathers tanned with aluminum and wattle resulted with a shrinkage temperature of 118ºC as compared to Al-Dialdehyde starch leathers showed around 90-100ºC. Physical strength characteristics such as tensile, tear and grain crack strength met the standard norms. Grain surface of leathers are found to be smooth which has been confirmed through microscopic studies. The study provides a new insight on accomplishing self sustainability through available resources and manufacture of eco-friendly system. Take-Away: 1. Tanzania is endowed with massive kaolin rich in aluminium, which is potential for application in leather industry for sustainable development of leather industry 2. The combination tanning system using aluminium from Tanzania kaolin with wattle tannins or Dialdehyde starch imparts leather with both physical and organoleptic properties that meet the stipulated norms 3. This new tanning system provides new insight on ecofriendly tanning system for the sustainability of leather industry.

Throughout the past decade an increased amount of attention has been drawn to the water contamination problems that affect the world. As a result, a variety of purification methods targeted at communities in developing countries have surfaced and, although all have contributed to the effort of improving water quality, few have been accepted and sustained for long term usage. Case studies indicate that the most beneficial methods are those which use indigenous resources, as they are both abundant and readily accepted by the communities. In an attempt to make a contribution to the search for water purification methods that can serve in both developed and developing countries, two fractions of mucilage gum, a Gelling (GE) and a Non-Gelling (NE) Extract, were obtained from the Opuntia ficus-indica cactus and tested as a flocculating agent against sediment and bacteria suspended in surrogate ion-rich waters. Diatonic ions are known to influence both cell binding and mucilage properties, causing CaCl2 to be tested as a flocculating agent alone and in conjunction with mucilage. Column tests were utilized to determine the settling rates of contaminant removal from the waters and the precipitated flocs were then evaluated. In columns employing Kaolin as a model for sediment removal, settling rates as high as 13.2 cm/min were observed using GE versus a control (suspensions with no treatment) settling at 0.5 cm/min. B. cereus tests displayed flocculation initiation up to 10 minutes faster than columns treated with calcium chloride (CaCl2) when using less than 10 ppm (GE) and 5 ppm (NE) of mucilage in addition to CaCl2. B. cereus removal rates between 95 and 98% have been observed in high concentration tests (> 108 cells/mL). Tests on E. coli flocculation differed slightly from those seen using B. cereus with control columns requiring 5 to 10 minutes longer to begin flocculation and mucilage treated columns displaying signs of flocculation much earlier. Mucilage is an ideal material for water purification and contaminant flocculation because it grows abundantly, is inexpensive and offers communities a sustainable technology.

The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring montmorillonite with silica followed by the grafting of a chelate ligand onto its surface. Its structure was studied by the Brunauer, Emmett, and Teller Method adsorption of N2, Dynamic Light Scattering, and Scanning Electron Microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin soil samples and by analysis of heavy metal contents in leachate. The adsorbent was efficient in immobilization of heavy metals in both neutral aqueous and acidic media. In addition, the adsorbent was efficient in environmental samples reducing the concentration of iron in all samples in aqueous and acidic media. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites.

This thesis focuses on the use of scaled physical experiments to better understand the development and long-term evolution of fault systems that are otherwise impossible to observe directly. The document is divided into three chapters. The first chapter documents the implementation of an inexpensive stereo vision method for acquiring high resolution three-dimensional strain data for table-top experiments. The second chapter applies the stereo vision method to a tectonic problem—the development of slip partitioning in obliquely loaded crustal systems. Slip partitioned fault systems accommodate oblique convergence with different slip rake on two or more faults and are well documented in the crust. In this chapter, we simulate oblique convergence using blocks with 30° dipping contacts under wet kaolin clay. The experiments reveal three styles of slip partitioning development—contingent upon convergence angle and the presence or absence of a pre-existing vertical fault. Across all experiments, the slip rates along slip-partitioned faults vary temporally suggesting that the faults continuously adjust to conditions produced by the other fault. The lack of steady state in the experiments suggests that slip-partitioned crustal systems may also evolve with oscillating behavior rather than developing a single efficient active fault structure to accommodate oblique convergence. The third chapter documents rheological tests of wet kaolin for applications to crustal deformation experiments. This chapter investigates thixotropy in the clay as well as the role of grain size distribution and water content on its shear strength.

Dielectric constant is a physical property of soil that is often measured using non-invasive geophysical techniques in subsurface characterization studies. A proper understanding of dielectric responses allows investigators to make measurements that might otherwise require more invasive and/or destructive methods. Previous studies have suggested that dielectric models could be refined by accounting for the contributions of different types of mineral constituents that affect the ratio and properties of bound and bulk water. This study tested the hypothesis that the dielectric responses of porous materials are mineral-specific through differences in surface area and chemistry. An experimental design was developed to test the dielectric behavior of pure quartz sand (Control), quartz sand/kaolin clay mixtures and ferric oxyhydroxide coated quartz sand. Results from the experiments show that the dielectric responses of quartz-clay and iron oxyhydroxide modified samples are not significantly different from the pure quartz Control. Increasing clay content in quartz sands leads to a vertical displacement between fitted polynomials. The results suggest that the classic interpretation for the curvature of dielectric responses appears to be incorrect. The curvature of dielectric responses at low water contents appears to be controlled by unknown parameters other than bound water. A re-examination of the experimental procedure proposed in this study and past studies shows that a properly designed study of bound water effects on dielectric responses has not yet been conduct / Master of Science

Cette thèse présente une étude expérimentale visant à caractériser les propriétés hydrauliquesd'écoulements à surface libre de fluides complexes: fluides viscoplastiques et mélangesfluides viscoplastiques-grains. Ce travail est motivé par la nécessité d'améliorer lesconnaissances sur les propriétés des écoulements de laves torrentielles, dans un contexte deprotection contre les risques naturels en montagne. Nous avons développé un dispositif delaboratoire original, un canal à fond mobile, permettant de générer des coulées gravitaires quisont globalement stationnaires dans le référentiel du laboratoire. Les coulées présentent unfront très raide, suivi à l'amont d'une zone d'épaisseur uniforme. Les fluides viscoplastiquesutilisés (carbopol et kaolin) ont été choisis de manière à modéliser la matrice des couléesboueuses naturelles en prenant en compte les critères de similitude adaptés. Ces fluidessuivent une loi de comportement de Herschel-Bulkley, et leurs propriétés rhéologiques ont étédéterminées au moyen d'un rhéomètre de laboratoire en accordant un soin particulier àl'établissement des incertitudes associées. Nous présentons des mesures précises de l'évolutionde l'épaisseur des coulées dans la zone uniforme en fonction de la vitesse du fond du canal etde la pente. Ces résultats sont comparés à des prédictions théoriques correspondant à unécoulement permanent et uniforme d'un fluide de Herschel-Bulkley, et nous montrons quel'accord est satisfaisant moyennant les incertitudes sur les mesures rhéologiques. Nous avonségalement analysé la forme du front des coulées et, là-aussi, l'accord avec des modèleshydrauliques (modèles de type Saint-Venant) est bon. Ces deux études permettent de validerles prédictions hydrauliques obtenues à partir de lois de comportement mesurées aurhéomètre. Enfin, dans une dernière partie, nous présentons une étude préliminaire de ladynamique de particules rigides isolées placées au sein de la coulée, en nous intéressant auxvitesses longitudinales et aux vitesses de chute pour différentes tailles et différentes densitésde particules. / This thesis presents an experimental study dedicated to characterise the hydraulic propertiesof free surface flows of complex fluids : viscoplastic fluids and mixtures made of viscoplasticfluids and grains. This study is motivated by the need to improve knowledge on properties ofthe flow of debris flows in a context of protection against natural hazards in the mountains.We have developed an original laboratory device - a channel with a mobile bottom - togenerate gravitary flows that are globally stationary in the laboratory frame. The flows have avery steep front followed upstream by a zone of uniform thickness. Viscoplastic fluids used(carbopol and kaolin) were selected so to model the matrix of natural mud flows, taking intoaccount the criteria of similarity adapted. These fluids follow a behavior law of Herschel-Bulkley, and their rheological properties were determined using a laboratory rheometer byproviding a particular care to the establishment of the associated uncertainties. We presentaccurate measurements of the evolution of the thickness of the flow in the uniform zone withthe the velocity speed of channel belt. These results are compared with theoretical predictionscorresponding to a steady uniform flow of a fluid of Herschel-Bulkley, and we show that theagreement is satisfactory through the uncertainties on the rheological measurements. We alsoanalyzed the shape of front, and here too, the agreement with hydraulic models (models likeSaint-Venant) is good. Both of the studies allowed to validate the hydraulic predictionsobtained from behavior laws measured with the rheometer. Finally, in a last section, wepresent a Preliminary study about the dynamics of isolated rigid particles placed in the flow,by paying attention to longitudinal velocities and falling velocities for different particle sizesand densities.

PhD (Geology) / Department of Mining and Environmental Geology / Cretaceous-Tertiary Periods marked the break-up of Gondwana, a large landmass composed of most of the present-day southern continents. In understanding the events of the supercontinental break-up, paleoenvironmental studies need to be carried out. In such studies, kaolinites could be used as paleoenvironmental proxies due to their small particle sizes and large surface area. It is in this context that this research sought to reconstruct the paleoenvironments in which selected Cretaceous-Tertiary kaolin deposits in the Douala Sub-Basin in Cameroon formed. To achieve this objective, mineralogical and geochemical characterisations were carried out using x-ray diffractometry, scanning electron microscopy, Fourier transform infrared spectrometry, thermal analyses and x-ray fluorescence spectroscopy. Trace elements and stable isotopes were analysed using mass spectrometries. Ages of zircons in the kaolins were determined using laser ablation magnetic sector-field inductively coupled plasma mass spectrometry (LA-SF-ICP-MS) U-Pb geochronology. Diagnostic evaluation for industrial applications of the kaolins were carried out using particle size distribution, texture, moisture content, pH, and electric conductivity. Six kaolin deposits from Cretaceous-tertiary Formations of the Douala Sub-Basin were studied; namely, Bomkoul (Tertiary), Dibamba (Tertiary), Ediki (Cretaceous), Logbaba (Cretaceous), Missole (Tertiary) and Yatchika (Cretaceous). The nature and occurrences of these kaolin deposits in Cameroon were determined through thorough mineralogical and geochemical characterisations of bulk (< 2 mm size fraction), silt (2-63 μm size fraction) and clay samples (< 2 μm size fraction). By quantifying the mineral phases present, the morphology and the functional groups in the kaolins are presented as the mineralogical characteristics of kaolins of each study site; whereas, the major oxides geochemistry and the micro-elemental composition constitute the geochemical characteristics of these kaolins. The minerals’ geneses were also determined and the prevailing paleoenvironmental and paleoclimatic conditions in which they were formed were reconstructed using trace elements and stable isotopes of oxygen and hydrogen in kaolinite. The maximum age of the kaolins were determined using U-Pb LA-SFICP-MS dating of zircons in the kaolin deposits. Diagnostic evaluation of the kaolins was carried out, and involved the determination of physical characteristics (particle size, texture, colour and moisture content) and physico-chemical characteristics (pH and electrical conductivity). Results showed that kaolinite and quartz (as major phases), smectite and/or illite (as minor phases), anatase and rutile (as minor or trace phases), goethite and hematite (as trace viii phases) were the mineral phases present in bulk and silt samples. Whereas, in the < 2 μm fractions, the mineral phases are made up of kaolinite and smectite (as major phases), smectite and/or illite (as minor phases), anatase and rutile (as minor or trace phases), goethite and hematite (as trace phases). The kaolins are mostly made up of thin platy or pseudo-hexagonal particles or flakes, books or stacks of kaolinite. The Dibamba, Logbaba and Missole II kaolins have well-ordered structures. Exothermic peak temperatures were generally between 943-988oC. The most abundant major oxides are silica and alumina, followed by iron oxide and titania; though Logbaba and Missole II had higher titania than iron oxide. 85% of the kaolins, portrayed extreme silicate weathering (chemical index of alteration > 80%) and are compositionally mature (index of compositional variability > 0.78). The geochemical composition of the kaolins showed that source rocks of these kaolins vary between rhyolite/granite and rhyolite/granite + basalt. The geochemistry also suggested that the kaolins formed in a marine environment (except Logbaba samples). Trace elements results revealed that Cretaceous-Tertiary kaolins in the Douala Sub-Basin are mainly enriched in rare earth elements compared to the upper continental crust, and have negative Eu anomaly. Large ion lithophiles (mainly Rb and U) were highly enriched in samples, high field strength elements (Y and Nb) were enriched in studied samples of all fractions; and transition trace elements generally had concentrations quite similar to upper continental crust values. Stable isotopes showed that the kaolins were formed in a supergene environment; and temperatures of kaolinitisation (assuming equilibrium with the global meteoric water line) were 26.58oC ± 9.65oC for Cretaceous kaolins and 29.40oC ± 7.22oC for Tertiary kaolins. Assuming equilibrium with the local (Douala) meteoric water line, the temperatures of kaolinitisation were 24.64oC ± 9.48oC for Cretaceous and 27.42oC ± 7.08oC for Tertiary kaolins. Four main zircon populations were identified from radiogenic dating: the 1st between 550 and 650 Ma, the 2nd between 950 and 1050 Ma, the 3rd around 1600 Ma and the 4th between 2800-3200 Ma. These four zircon populations belong to the Proterozoic (Neo-, Meso- and Paleoproterozoic) and the Archean. The maximum depositional ages of the kaolins, reflected by the youngest weighted averages of zircon populations varied between 588 ± 2 Ma and 612 ± 2 Ma, all belonging to the Ediacaran Period (Neoproterozoic). The diagnostic evaluation of the kaolins revealed that the kaolins are very sandy, with 50% of the samples having a sandy loamy clay or sandy loam texture. The colour of the samples varied considerably from white to darker colours (dark grey); with 15% of the kaolins being light reddish brown. The moisture content was generally very low (< 2 wt %) in all size fractions, except in Yatchika samples (moisture content > 2 wt %). The kaolins are generally acidic, with ix a pH(KCl) varying between 3.06 and 3.81, except in Missole I samples, which had a pH (KCl) < 2. The electrical conductivity (EC) generally varied between 20 to ~ 50 μS/cm, except Dibamba and MSL II 01 samples which had EC values in the interval 50 μS/cm < EC < 80 μS/cm; and Missole I samples having an EC > 7500 μS/cm. In conclusion, no great distinction was found between Cretaceous and Tertiary kaolins of the Douala Sub-Basin based on their mineralogy and geochemistry. The best kaolins in terms of these characteristics, and in comparison with the Georgia Kaolins (known for their high kaolinite quality), were the Dibamba (Tertiary), Logbaba (Cretaceous) and Missole II (Tertiary) kaolins. Based on their compositional maturity and mineralogical characteristics, these three kaolins are considered to be second cycle sediments; unlike Bomkoul, Yatchika and Ediki kaolins, which are believed to be first cycle sediments. Based on the trace elements and stable isotopes composition, Cretaceous and Tertiary kaolins of the Douala Sub-Basin were derived from felsic rocks. However, Cretaceous kaolins were formed in a cooler anoxic reducing environment; whereas the Tertiary kaolins were formed in a warmer oxidising environment, with higher precipitation. Ages of zircons in Cretaceous-Tertiary kaolins suggested that the zircon formed during two main tectonic events: the Eburnean orogeny, during which older zircons crystallised and the Pan-African orogeny, during which younger zircons crystallised. The maximum depositional ages of the kaolins varied between 588 ± 2 Ma and 612 ± 2 Ma. The main identified sources of these zircons are the Archean Ntem Complex, the Paleoproterozoic Nyong Group and the Neoproterozoic Yaounde Group. The diagnostic evaluation indicated that the particle size greatly influences the mineralogy and geochemistry of the kaolins because the finer particles (< 2 μm) have higher amounts of kaolinite and Al2O3. The moisture content of the kaolins makes them suitable as paint fillers and in soap production. Paper coating, paper filler, ceramics, pharmaceutics and cosmetics are potential applications for the kaolins, though particle size reduction and beneficiation will give them a higher quality. However, because these kaolin deposits are not big and extensive, they cannot be recommended for large scale industrial applications; but they can be used for bricks, pottery and stoneware manufacturing.