软水中EPS对铜管/硅酸盐体系溶解性铜释放影响

以海藻酸钠模拟水体中的EPS,研究了软水体系中海藻酸钠对铜管,硅酸盐体系缓蚀效果的影响.结果表明,当有低浓度海藻酸钠存在时,体系中的溶解性铜浓度显著增加,且老化1 a的铜管溶解性铜释放浓度明显高于老化3 a和10 a的铜管,释放溶解性铜浓度大小顺序为c1a>c3a>c10a;但随着海藻酸钠浓度的增加,老化1 a的铜管的溶解性铜释放浓度增加,而3 a和10 a铜管的溶解性铜释放浓度减小,表明水体中EPS的存在降低硅酸盐对铜管的缓蚀效果.在pH值7.5和海藻酸钠为16mg/L条件下,不同停留时间溶解性铜释放呈现逐渐增加-降低-逐渐增加的趋势,表明海藻酸钠、硅酸盐、铜离子和管壁进行了复杂的相互作用.在低pH值条件下,海藻酸钠对铜管溶解性铜释放影响更加显著,随着pH值增加和铜管老化时间延长,其溶解性铜释放浓度降低,表明海藻酸钠对溶解性铜释放影响降低.

Influence of EPS on Silicate Corrosion Inhibition for Copper Pipe in Soft Water

The effects of sodium alginate on silicate corrosion inhibition for copper pipe in simulated soft water were investigated. The results showed that more soluble copper release was occurred when low concentration sodium alginate was in presence. The 1 a aged copper pipe released more soluble copper than the 3 a and 10 a aged copper pipe. The sequence of concentration of soluble copper release was c_1ac_3ac_10a. However, compared to the low concentration sodium alginate, soluble copper released from the 1 a aged copper pipe increased, and the 3 a and 10 a aged copper pipe were inverse when high level sodium alginate was in presence. These phenomena showed that the effect of silicate corrosion inhibition decreased when extracellular polymer substances was dissolved in soft water. Under the conditions of pH 7.5 and sodium alginate 16 mg/L, soluble copper release tend was gradually increase-decrease-gradually run-up which due to the absorption of sodium alginate on the surface of copper surface and the complex interaction between sodium alginate, silicate and copper ions. When the initial pH value was low, compared to the system of no sodium alginate, the soluble copper release distinctly increased in the presence of sodium alginate. The amount of soluble copper released from 1 a copper pipe is higher than that from 3 a and 10 a aged copper pipe, which due to the different components of copper corrosion by-products on the surface of different aged copper pipes and the different solubility of different corrosion by-products.