State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No.73, Huanghe Road, Harbin, 150090, People's Republic of China.
Environ Sci Pollut Res Int. 2019 Jun;26(16):16641-16651. doi: 10.1007/s11356-019-04691-4. Epub 2019 Apr 15.
In this paper, the application of ultrafiltration (UF) technology to treat cadmium (Cd) pollution in surface waters is investigated. The effect of the UF membrane molecular weight cut-off (MWCO), Cd ion (Cd) concentration, solution pH and ionic strength on the removal, and mass balance of Cd were explored. In addition, the effect of the solution pH on UF membrane fouling was analyzed. The results indicated that UF membranes with a low MWCO resulted in an improved Cd removal rate. In addition, as the Cd concentration in feedwater increased, the Cd removal rate decreased, while the Cd concentration in the permeate increased. Since the solution pH and ionic strength had a notable impact on the Cd removal rate, a high pH value and low ionic strength led to a higher removal rate of Cd. Under optimal Cd removal conditions, UF reduced the influent Cd concentration from 1.0 to 0.019 mg/L. For membrane fouling, increasing the solution pH led to more serious membrane fouling. This phenomenon was the result of Cd reacting with OH and forming a Cd (OH) precipitate. The precipitate and humic acid formed compact cakes on the membrane surface and blocked membrane pores. These results provided adequate evidence for the higher removal of Cd with increasing solution pH. In addition, SEM images under different pH conditions were in agreement with the conclusion mentioned above, which provided further support for the effect of the solution pH on Cd removal and membrane fouling.
本文研究了超滤（UF）技术在处理地表水中镉（Cd）污染的应用。探讨了 UF 膜的分子量截留（MWCO）、Cd 离子（Cd）浓度、溶液 pH 值和离子强度对 Cd 的去除率和质量平衡的影响。此外，还分析了溶液 pH 值对 UF 膜污染的影响。结果表明，MWCO 较低的 UF 膜可提高 Cd 的去除率。此外，随着进料水中 Cd 浓度的增加，Cd 的去除率降低，而透过液中的 Cd 浓度增加。由于溶液 pH 值和离子强度对 Cd 的去除率有显著影响，因此较高的 pH 值和较低的离子强度导致 Cd 的去除率更高。在最佳的 Cd 去除条件下，UF 将进水 Cd 浓度从 1.0 降低至 0.019mg/L。对于膜污染，增加溶液 pH 值会导致更严重的膜污染。这种现象是由于 Cd 与 OH 反应并形成 Cd(OH)沉淀所致。沉淀物和腐殖酸在膜表面形成致密的饼层并堵塞膜孔。这些结果为溶液 pH 值升高时 Cd 去除率提高提供了充分的证据。此外，不同 pH 值条件下的 SEM 图像与上述结论一致，进一步支持了溶液 pH 值对 Cd 去除和膜污染的影响。
