Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.
Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.
J Hazard Mater. 2020 Dec 5;400:123212. doi: 10.1016/j.jhazmat.2020.123212. Epub 2020 Jun 17.
This study investigated the potential for reducing scaling during chemical cleaning of polyvinylidene fluoride membranes by optimizing preoxidation dose and pH. Membranes were fouled by a solution containing inorganic foulants (aluminum, iron, and manganese), humic acid, and kaolin at a Ca strength of 0.5 mM and varying the preoxidation dose. Energy-dispersive spectroscopy was used to verify the presence of inorganic foulants after cleaning. Fourier-transform infrared spectroscopy revealed changes in CCl and C-F functional groups, with bond vibrations at 542 cm and 1199 cm, respectively. Minimum irreversible fouling of 5.4% and maximum flux recovery of 88.8% of the initial value were associated with a preoxidation dose of 1.5 mg/L and pH 8.5. A decrease in amount of aluminum from 5.79 ± 0.021 mg to 3.85 ± 0.054 mg in the presence of humic acid with a removal efficiency greater than 60% was due to alteration of the feed solution, as revealed by mass-balance analysis. Membrane characterization and fouling reversibility analysis confirmed that preoxidation of the feed solution produced less scaling during chemical cleaning. The cake layer fouling contribution was determined by fitting results of Hermia's fouling model analysis, with 1.34-1.85 times lower total fouling indices and 3-5.5 times lower chemically irreversible fouling indices at pH 8.5 and a preoxidation dose of 1.5 mg/L.
本研究通过优化预氧化剂量和 pH 值，考察了在聚偏二氟乙烯膜化学清洗过程中减少结垢的潜力。采用含有无机污染物（铝、铁和锰）、腐殖酸和高岭土的溶液对膜进行污染，Ca 强度为 0.5mM，并改变预氧化剂量。采用能谱分析验证清洗后无机污染物的存在。傅里叶变换红外光谱显示 CCl 和 C-F 官能团发生变化，键振动分别在 542cm 和 1199cm 处。当预氧化剂量为 1.5mg/L、pH 值为 8.5 时，不可逆污染最小为 5.4%，初始通量恢复最大为 88.8%。在腐殖酸存在的情况下，铝的量从 5.79±0.021mg 减少到 3.85±0.054mg，去除效率大于 60%，这是由于进料溶液的变化，通过质量平衡分析可以看出。膜特性和污染可逆性分析证实，进料溶液的预氧化在化学清洗过程中产生的结垢较少。通过拟合 Hermia 污垢模型分析的结果，确定了滤饼层污垢的贡献，在 pH 值为 8.5 和预氧化剂量为 1.5mg/L 时，总污垢指数降低了 1.34-1.85 倍，化学不可逆污垢指数降低了 3-5.5 倍。
