چكيده به لاتين
The main objective of this study was to find procedures to extract silica from natural kaolin. In order to optimize the kaolin into raw material for the preparation of zeolites, by different methods such as acid treatment, Leaching by the inorganic and organic base. In the acid treatment, kaolin was refluxed with sulphuric acid of different concentrations 1M, 3M, 5M and 10M at 110◦C for 4h followed by calcination at 500◦C for 1h. The results indicate that acid treatment under reflux conditions leads to the removal of the octahedral Al3+ cations along with other impurities. Leaching of Al3+ ions increased progressively with severity of the acid treatment. For modification with inorganic base, beneficiated kaolin clay was calcined at 1000°C for 1 hour to activate the silica content in the clay. The silica was extracted from the clay in an alkaline medium using 5, 10, 20, 30 and 40 %w/w NaOH and a contact time of 20 minutes.The amount of alumina leached by different concentrations of NaOH increased with increase in concentrations of NaOH but the solubility of the alumina in the alkaline solution was less than that of the silica at any specific contact time studied. At the end similarities between the treatment mediated by organic hydroxides and the conventional NaOH leaching comprised. Silicon dissolution in TPAOH was much slower than in NaOH, making the demetallation process highly controllable. The treatment in the organic base was less selective for silicon extraction, i.e. a higher amount of aluminum was leached to the solution compared to the NaOH treatment. Physico-chemical characteristics of leached kaolin clay were studied by XRF, XRD and SEM techniques.
