Fernando G. Colina

Bio: Fernando G. Colina is an academic researcher from University of Barcelona. The author has contributed to research in topics: Calcination & Specific surface area. The author has an hindex of 6, co-authored 8 publications receiving 119 citations.

High-Temperature Reaction of Kaolin with Sulfuric Acid

Abstract: A new procedure is described in which kaolin and a small amount of concentrated sulfuric acid are heated in a furnace at temperatures between 150 and 1000 °C. Parameters studied were reaction temperature and time, proton to alumina molar ratio, calcination temperature and time, and amount of water in the reaction medium. Al yield grew sharply until reaching a maximum at a reaction temperature of 700 °C and decreasing sharply beyond this temperature. Ti reaction yield values were lower than the Al reaction yield, showing a maximum at 200 °C and decreasing steadily as the reaction temperature was increased. Fe reaction yield showed a maximum in the same range of reaction temperature as Al. Previous calcination of kaolin produced only slight increases in reaction yields. Brunauer−Emmett−Teller (BET) surface area tests indicated an increase of the BET surface area for short reaction times, reaching values above 100 m2/g. Products of the reaction were mostly Al2(SO4)3.

High temperature reaction of kaolin with inorganic acids

Abstract: A new method is described in which raw materials prepared by mixing kaolin and concentrated acid are heated in a furnace at temperatures between 100 and 700°C. Experiments with HCl, HNO3, H3PO4, an...

A new extraction procedure for simultaneous quantitative determination of water-soluble metals in reaction products of clays and inorganic salts

Abstract: Kaolin, a possible source of Al, may be reacted with inorganic acids or salts to form different Al salts that can be further processed to prepare metallic Al. Although the reaction of kaolin and acid in aqueous solution can be monitored by chemical analysis of Al, the Al salts must be extracted from any unreacted kaolinite. Also, the lixiviation of Ti or Fe species present in kaolin should be monitored. A simple extraction procedure is reported to determine, quickly and quantitatively, water-soluble Al, Ti and Fe metals present in products of reaction of kaolin (85 wt.% kaolinite, 12 wt.% mica, 2 wt.% feldspar, 1 wt.% quartz) with inorganic salts, such as sodium hydrogensulfate, using conventional glassware for the glass reaction tubes. Optimum results are obtained with 250 mL glass reaction tubes. The best operating conditions found for this piece of equipment are: (1) sample weight of 0.05 g, (2) lixiviation time of 1 h, and (3) lixiviating agent, 50 mL of an aqueous solution of pH = 1 H2SO4 at its boiling point. Comparisons are made with soxhlet extraction and beaker and magnetic stirring methods.

High-Temperature Reaction of Kaolin with Ammonium Sulfate

Abstract: Reactions between kaolin and inorganic salts, such as sodium hydrogen sulfate and ammonium sulfate, or inorganic acids, such as hydrochloric acid and sulfuric acid, can be focused either on the production of Al or on the adjustment of the silica-to-alumina ratio of the kaolin. On the basis of adjusting the silica-to-alumina ratio, kaolin and ammonium sulfate [(NH4)2SO4] are mixed and heated in a furnace at temperatures between 200 and 1000 °C. The parameters studied were the reaction temperature and time, the proton-to-alumina molar ratio, the calcination temperature and time, and the reaction atmosphere. The products of the reaction between kaolin and (NH4)2SO4 were characterized by means of X-ray diffraction (XRD). The Al reaction yield grew until reaching a maximum at 600 °C and started to decrease sharply beyond this temperature. The Ti reaction yield values were lower than the Al reaction yield values, showing a maximum at 600 °C and decreasing smoothly as the reaction temperature was increased. The ...

Synthesis and characterization of zeolite Y and ZSM-5 from Nigerian Ahoko Kaolin using a novel, lower temperature, metakaolinization technique

Abstract: 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.