질산태 질소 정량을 위한 환원 증류법에서 Devarda’s Alloy의 입자크기 및 함량이 미치는 영향

We analyzed the particle size distributions of three commercially available Devarda’s alloy (DA) products, tested the nitrate recoveries of each particle size category, and examined the amounts of DA required for 100% recovery by varying NO 3 ?N concentration from 0.5 to 10 mg. We observed that use of DA coarser than 200 mesh resulted in poor analytical recovery ( 90% of the particles were less than 100 mesh), the recovery dramatically declined from 80% to 10% in a high concentration range (4 to 10 mg N). Satisfactory recovery was obtained by increasing the amount of finer DA (less than 300 or 450 mesh). However, there was no quantitative relationship between the amount of fine DA and nitrate recovered. Generally, the amount of nitrate reduced per unit DA decreased as the recovery efficiency declined. These results suggest that a sufficient amount of DA must be determined based on particle size distribution, and that treatment of at least two levels of DA and comparison of the subsequent change in nitrate recovery is required for soils containing high levels of nitrate. In addition, further studies are encouraged to account for the observed stoichiometric dis-equivalence of recovered nitrate N per unit mass of DA.