Zeolite Y was synthesised, for the first time, using Nigerian Ahoko kaolin. In addition, a novel metakaolinization technique was used to produce the necessary reactant phase. The first step involves the refining of the raw kaolin sample, which removes a substantial amount of quartz, a major impurity present in all kaolin including Ahoko kaolin. The second step, metakaolinization, was carried out at a significantly lower temperature and for a shorter time than in previous studies. The method for the production of metakaolin, based on rapidly exposing a sample of refined kaolin to elevated temperature was investigated in this work. Metakaolin was obtained after 6 min of exposure at 600 C. The metakaolin produced was then used to synthesis zeolite Y and ZSM-5 using conventional hydrothermal treatment and the shortened thermal treatment cycle was shown to be effective for commercial kaolin as demonstrated by the synthesis of zeolite A.

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The efficient removal of toxic metals ions from chemical industry wastewater is considered problematic due to the existence of pollutants as mixtures in the aqueous matrix, thus development of advanced and effective treatment method has been identified as a panacea to the lingering problems of heavy metal pollution. In this study, KIAgNPs decorated MWCNTs nano adsorbent was developed using combination of green chemistry protocol and chemical vapor deposition techniques and subsequently characterized using UV–Vis, HRTEM, HRSEM, XRD, FTIR and XPS. The adsorptive efficiency of MWCNTs-KIAgNPs for the removal of Cr(VI), Ni(II), Fe(II), Cd(II) and physico-chemical parameters like pH, TDS, COD, BOD, nitrates, sulphates, chlorides and phosphates from chemical industrial wastewater was examined in both batch and fixed bed systems. The result exhibited successful deposition of KIAgNPs on the surface of MWCNTs as confirmed by the microstructures, morphology, crystalline nature, functional groups and elemental characteristics of the MWCNTs-KIAgNPs. Optimum batch adsorption parameters include; pH (3 for Cr(VI) and 6 for Ni(II), Fe(II) and Cd(II) ions), contact time (60 min), adsorbent dosage (40 mg) and temperature (318 K). The binding capacities were obtained as follows; Cr6+ (229.540 mg/g), Ni2+ (174.784 mg/g), Fe2+ (149.552) and Cd2+ (121.026 mg/g), respectively. Langmuir isotherm and pseudo-second order kinetic model best described the experimental data in batch adsorption, while the thermodynamic parameters validated the chemisorption and endothermic nature of the adsorption process. In continuous adsorption, the metal ions were effectively removed at low metal influent concentration, low flow rate and high bed depth, whereby the experimental data were designated by Thomas model. The high physico-chemical parameters in the wastewater were successfully treated in both batch and fixed bed systems to fall within WHO permissible concentrations. The adsorption/desorption study illustrated over 80% metal removal by MWCNTs-KIAgNPs even after 8th adsorption cycle. This study demonstrated excellent performance of MWCNTs-KIAgNPs for chemical industry wastewater treatment.

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The use of kaolin as a silica source in the synthesis of zeolites has been achieved using a novel synthetic approach. The technique reported allows the use of impure kaolin as a starting material to produce pure ZSM-5 zeolite. This is important as it is extremely difficult and time consuming to remove all impurities from natural kaolin. This is also the first report of the direct synthesis of a high silica zeolite from kaolin without the use of an external silica source.

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Here we demonstrate the conversion of a Nigerian Kaolin, straight from the source without any form of pre-treatment, directly into pure zeolite-A. The method involves a rapid and low temperature meta-kaolinization step followed by chemical conversion directly into pure zeolite-A. The synthesis step acts as the purification step removing the 80% quartz impurity simultaneously with zeolite growth. The whole process is designed to be both economical and straightforward to facilitate commercialisation.