Study on the Optimum Preparation Process Conditions of Iron Oxide Coated Sand

The Iron Oxide Coated Sands (IOCS) are prepared with ordinary quartz sands and the modifier- FeCl3. By using the orthogonal test method, morphological properties analysis and semi-quantitative analysis method by EDS, effects of different factors on surface loading and adherent strength on the surface of IOCS are analyzed: stirring frequency N, dosage ratio of FeCl3 to NaOH, calcination temperature T and time t, appearance of IOCS and etc. The optimum preparation conditions of IOCS are investigated. Results are obtained: (1)Stirring had better not be taken when drying IOCS at 110°C before calcination, (2) At high temperature, calcining conditions should be controlled: t ≥ 3 h and T ≈ 300°C; (3) The optimal dosing ratio of FeCl₃ (2mol/L) to Raw Quartz Sand(RQS) is 0.33 mL FeCl₃/g RQS. The surface loading of iron oxide is up to the maximum with dosing ratio of NaOH to RQSis 0.3 mL NaOH/g RQS. However, if dosing ratio is too high, the surface loading will decrease markedly, and the adherent strength will be weak. (4) As compared with IOCS-0 prepared by the alkaline deposition method at low temperature(T ≤ 110°C), IOCS-1 which is prepared by calcining IOCS-0 at high temperature (T ≈ 300°C), whose surface loading will be increased by 3~5 times, and desorption rate will decrease by more than 90%. (5) The content of α-FeOOH (Goethite) on surface loading of IOCS affects adherent strength strongly. The particle size of α-Fe₂O₃ (Hematite) attached on the surface of IOCS-1 can be changed by controlling the calcining temperature. The prepared IOCS-1 can efficiently adsorb pollutants in the same size as that of IOCS-1 particles.