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Pulp, paper and paperboard - Determination of calcium content

Abstract: 本文介绍了测定纸浆、纸和纸板中钙含量的标准滴定法。首先，将样品与醋酸反应生成醋酸钙沉淀，然后添加醋酸钠指示剂使溶液呈红色。使用0.05 M的EDTA溶液进行滴定，直到溶液变为蓝色，记录所用EDTA体积。对空白样品进行相同操作以获得对照值。通过公式计算样品中钙的含量。文章强调了滴定前EDTA溶液的标定及样品处理中的注意事项，以确保准确性和避免干扰。

Calcium content in pulp, paper and board can be determined by standard titration as follows:

  1. Take a certain amount of pulp, paper or cardboard sample and add a certain amount of acetic acid to convert the calcium ions in the sample into calcium acetate precipitates.

  2. The sample was mixed with acetic acid solution, and sodium acetate indicator was added to make the solution red.

  3. Titrate with 0.05 M EDTA solution until the solution turns blue, record the volume V1 of EDTA used.

  4. In the same way, titrate the blank sample and record the volume V0 of EDTA used.

  5. Calculate the calcium content in the sample according to the following formula:

Calcium content (%) = [(V1-V0)×C×1000]/m

Among them, V1 is the volume of EDTA used in the titration of the sample, V0 is the volume of EDTA used in the titration of the blank sample, C is the concentration of the EDTA solution, and m is the mass of the sample.

Note: Before titration, the EDTA solution needs to be calibrated. In addition, various factors that may introduce interference, such as carbonates in the air, should be strictly controlled during sample preparation and processing.

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