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Lecture_5_Case Study_CCA_for_course_EESA10

Lecture_5_Case Study_CCA_for_course_EESA10 - Case Study...

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Case Study: CCA (Chromated Copper Arsenate) wood preservative “Protector” of forest vs. carcinogenic chemical Dr. Silvija Stefanovic Wood preservatives are used to protect wood products from decay and in that way to prolong their age in service. In the same time, wood preservatives reduce needs for forest cutting and support concept of Sustainable Forest Management. One of the preservatives with very effective protective characteristics is CCA (chromated copper arsenate). For that reason, 100% of residential lumber and 70% of all wood products were treated with CCA at last decade. Chromated Copper Arsenate (CCA), water borne preservative, was developed in 1933 and has been widely used throughout the world since then. During that period CCA has proven its ability to adequately protect wood from fungal and insect attack. The CCA- treated wood is used in applications such as utility poles (especially electric and telephone), wooden playground equipment, garden projects, marine piles etc. Depending on the relative proportion of metals, there are three waterborne formulations designated as CCA types A, B, and C. In North America, CCA-C is used almost exclusively. This type contains 47.5% Cr0 3 , 18.5% CuO, and 34% As 2 O 5 . When they are dissolved in water, the solution becomes very acidic with a pH of about 1.8. All of
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