Influence of Temperature on the Extraction of Amorphous Iron by the Acidic Ammonium Oxalate Method
Ying Jing · T'u Jang T'ung Pao · 2006
Xiashu Loess was utilized to study the influence of temperature on the extraction of amorphous iron by acidic ammonium oxalate method.The results showed that the content of extracted iron increased with the increase of temperature.The extracted iron at 30℃ was about 1.57 times of that at 20℃,and the extracted iron at 50℃ was about 4.43 times of that at 20℃.Magnetic susceptibility(χ)of the soil residue after extraction was reduced rapidly with the increase of temperature.χvalues of the residues after extraction at 20℃ were only slightly less than those of the original samples;but those at 30℃ and 50℃ were 93.6% and 65.3%,of the original sample,respectively.It implied that crystal iron such as magnetic minerals in soil samples could be dissolved when the extraction temperature incresed.Hence,as a matter of fact,the iron,extracted at higher temperature is no longer the single form of amorphous iron.Therefore,the extracting temperature should be controlled strictly at 20℃ when determining the content of amorphous iron in soil by this method.