复合溶液膜吸收CO_2的性能及其对膜孔润湿的影响

Effect of complex solution on CO_2 absorption and wettability of membrane

利用自行搭建的CO_2膜吸收实验台,采用聚丙烯(PP)膜组件,以质量分数10%的N-甲基二乙醇胺(MDEA)作为主体胺溶液,添加不同配比的哌嗪(PZ)、乙醇胺(MEA)、甘氨酸钾(PG),考察CO_2脱除效率和传质速率的变化,比较不同复配比的复合溶液表面张力以及对PP膜的浸润性,并以10%MDEA+10%PG混合溶液作为吸收液进行长时间实验。结果表明:添加少量的添加剂对MDEA溶液膜吸收CO_2均有显著的促进作用,当配比小于0.2时,促进作用大小为PZ>MEA>PG;当配比大于0.2时,促进作用大小为PZ>PG>MEA;PZ和MEA均随着添加配比的增加,溶液表面张力减小,而PG相反;表面张力小的溶液对膜浸润性较强,容易造成膜润湿;添加剂质量分数均为10%时,对膜溶胀性和疏水性以及膜孔结构影响大小为PZ>MEA>PG;在20天内,PG/MDEA混合溶液作用下的CO_2脱除效率从89.56%下降为83.09%,对PP的疏水性影响较小,膜组件可以稳定运行。吸收液表面张力对膜吸收法脱除CO_2性能的影响显著。所得结果可为膜吸收CO_2吸收剂复配提供依据,并可为揭示膜吸收CO_2过程中膜润湿导致膜失效的机理以及抑制膜润湿提供实验数据。

Using 10% MDEA as the main amine solution and different proportions of piperazine(PZ),ethanolamine(MEA) and glycine potassium(PG) were used as absorption solutions to compare the change of CO2 removal efficiency and mass transfer rate by polypropylene(PP) hollow fiber member contactor in self built CO2 membrane absorption test platform. The surface tension of different complex ratio mixed solution and the wettability of PP films were compared.Long-term experimental runs were carried out using 10%MDEA+10%PG mixed solution as the absorption solution.The results showed that the addition of a small amount of additives can significantly promote the MDEA solution.When the ratio is less than0.2, the promotion effect is PZ>MEA>PG, when the ratio is greater than 0.2, the promotion effect is PZ>PG>MEA. The surface tension of PZ and MEA decreases with the increase of the addition ratio, but the PG is the opposite. The solution with small surface tension is more infiltrating to the membrane, which can easily cause the wetting of the membrane.when the additive concentration is 10%.The effect on membrane swellability and hydrophobicity and membrane pore structure is:PZ>MEA>PG.The CO2 removal efficiency under MDEA/PG mixed solution decreases from 89.56% to 83.09% during 20 days of operation, which has little effect on the hydrophobicity of PP. The surface tension of absorption liquid has a significant effect on the removal of CO2 with membrane gas absorption method. The results can provide a basis for the formulation of CO2 absorber, and also provide experimental data for revealing the mechanism of membrane failure caused by membrane wetting and inhibition of membrane wetting.