湿式催化氧化/膜过滤组合工艺膜过滤机理

采用湿式催化氧化/膜过滤组合工艺,以Mo-Zn-Al-O粉末作为催化剂降解阳离子红GTL模拟染料废水,探讨在膜过滤过程中平均孔径为0.1 μm的微滤和0.022 μm的超滤聚偏氟乙烯(PVDF)中空纤维膜的过滤机理。实验结果表明,两种膜过滤组合工艺对染料的降解效果均优于单独湿式催化氧化,0.01 MPa恒压条件下运行120 min后微滤和超滤的膜通量分别衰减了26.63%和16.48%,其原因是粉末催化剂可在微滤膜孔内部沉积形成中间阻塞过滤,后在表面形成滤饼层;而在超滤膜表面仅形成滤饼层。通过实验结果对膜阻力进行计算,可知在相同反应过程后微滤膜产生的不可逆阻力大于超滤膜。在不同反应条件下,催化剂的沉积量与膜阻力呈现线性相关。

Filtration mechanism of membranes in combination of catalytic wet air oxidation and membrane filtration

The treatment of simulated cationic red GTL dye wastewater was conducted by coupling technology of catalytic wet air oxidation(CWAO)with membrane filtration, using Mo-Zn-Al-O as catalyst.The filtration mechanism of polyvinylidene fluoride hollow fiber microfiltration(MF)membranes with average pore size 0.1 μm and ultrafiltration(UF)membranes with average pore size 0.022 μm was investigated.It was found that the degradation efficiency of hybrid system was superior to CWAO with single process.Under 0.01 MPa pressure for 120 min the fluxes of MF and UF declined 26.63% and 16.48%, respectively.The reason for flux decline of microfiltration membrane was considered to be the blocking of pores and the formation of cake layer on the membrane surface by deposited catalyst powder, while that of ultrafiltration was dominated by cake layer formation.The experimental results showed that the irreversible resistance in microfiltration was larger than that in ultrafiltration after the same process.Under different operation conditions, a linear relationship could be obtained between the filtration resistance and specific deposit.