Determination of peracetic acid and hydrogen peroxide in the mixture

Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2) in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A). Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV=3.4% for peracetic acid, 0.6% for H2O2). The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV=2,5% for peracetic acid, 0,45% for H2O2).

Coprecipitation of Sr, Ni and U with CaCO3: An Experimental Study

At the Finnish candidate sites for a nuclear waste repository, calcite (CaCO3) is a common fracture mineral that may participate in coprecipitation processes. The objective of this preliminary work was to study the coprecipitation of the trace elements Sr, Ni, and U with CaCO3 under controlled conditions. The experiments were made in a titration vessel at room temperature under pure N2 or a 0.1 % CO 2/N2 mixture. The water phase contained CaCl2 (0.01M) and NaCl (0.05 M) to which trace amounts of Ni2+, Sr2+ and UO22+ were initially added. CaCO3 was precipitated by the addition of Na2CO3 and the use of CaCO3 seed crystals. When about 10−4 mol of precipitate had formed, the solution and solid phases were analysed with ICPMS. The results seem to indicate that Ni coprecipitated with CaCO3 under the experimental conditions, while U did not. In the case of Sr, further data are needed in order to make any conclusions from the experiments.

Determination of Water in Compound Fertilizers

A method is proposed for determining the water content of nitrogen-potassium-phosphorus compound fertilizers. The method combines drying with methanol extraction, with or without ultrasonic comminution of the fertilizer. The total moisture content of the sample is calculated as a sum of1 that found by drying and that determined by the extraction method (residual moisture). Two methods of methanol extraction were used: extraction of the uncomminuted fertilizer sample directly in the titration vessel, or extraction of the comminuted sample by ultrasonic vibration. Water contents determined by the proposed method ranged from 0.3 to 1.7%. Standard deviations for extraction without and with comminution were 0.015 and 0.018%, respectively. Moreover, ultrasonic comminution of fertilizer increased the amount of residual water extracted by about 20% compared with other methods.