添加硫酸亞鐵降低國產水泥六價鉻含量研究

Study on Reduction of Chromium (VI) Content in Domestic Cement by Addition of Ferrous Sulfate

泥水業作業人員常見的過敏性皮膚病與暴露於水泥中水溶性六價鉻有密切相關。西歐工業先進國家，如德國、丹麥、瑞典等，對水泥中水溶性六價鉻勞工暴露容許值為2ppm。本研究針對台灣地區14家水泥廠所生產之水泥，嘗試以硫酸亞鐵降低其水溶性六價鉻含量至安全程度以下。研究中利用1,5-二苯基二氨與六價鉻鹽基螯合，再以分光光度計檢測540nm波長之吸收度以定量六價鉻含量。本分析方法每樣品之偵測極限為0.017ppm。在國內14家水泥廠所生產水泥水溶性六價鉻含量分布範圍為2.33~27.49ppm。在添加0.15%硫酸亞鐵之後六價鉻含量分布範圍為1.02~12.15ppm，其中有10家水泥樣品六價鉻含量降至2ppm以下。在添加0.30%硫酸亞鐵之後六價鉻含量分布範圍為0.97~7.91ppm，其中水泥六價鉻含量降至2ppm以下之廠家增為11家。而在添加0.6%硫酸亞鐵之後六價鉻含量分布範圍在0.45~6.17ppm，六價鉻含量降至2ppm以下之廠家增為12家。在水泥製造過程中添加0.35%及0.70%的硫酸亞鐵，在一週後水泥中六價鉻含量皆高於2ppm，而水泥樣品六價鉻含量有隨儲存時間增加而增家的現象。以上結果說明，由於台灣的氣候溼熱，硫酸亞鐵有效儲存期限太短，在製作過程中添加硫酸亞鐵以降低六價鉻含量的做法似乎不太適宜。

Allergenic dermatitis among cement workers is closely related to the exposure to water-soluble hexavalent chromium (WSHC) of wet cement. To prevent workers from over exposure to the allergen, WSHC content in cement is regulated below 2ppm in countries like Germany, Denmark, Sweden and Finland. In this study, we investigated the feasibility by the addition of ferrous sulfate to cement manufactured in Taiwan to reduce WSHC levels to less than 2ppm. The determination of cement WSHC content was performed with an UV-Uis spectrophotometer at 540nm. This analytical method had a detection limit of 0.017ppm. Without adding ferrous sulfate, the WSHC content was between 2.33 and 27.49ppm. After treated with 0.15% ferrous sulfate, the WSHC levels reduced to between 1.02 and 12.15ppm, where 10 out of 14 samples was below 2ppm. Whereas, the addition of 0.30% and 0.60% ferrous sulfated showed slightly further reducing of WSHC to 0.97~7.91ppm and 0.45~6.17ppm, respectively, and the number of samples with WSHC below 2ppm increased to 11 and 12, respectively. 0.35% and 0.7% of ferrous sulfate were added during cement producing process, where WSHC level were found above 2ppm after one week of storage, and the WSHC levels increased with prolong storage. With limited effetive storage period, cement treated with ferrous sulfate during manufacture is inadequate due to hot and humid climate in Taiwan.