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liulp2008木虫 (小有名气)
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[求助]
求助翻译英文文献。谢谢
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| As the membrane thickness increases, the distance that water needs to go through and the resistance that water needs to overcome both increase. Correspondingly, the duration increases and the water flux decreases. However, thicker self-supporting NaA zeolite membranes have high strength and good ion % rejection based on the salt rejection process in NaCl solutions. The salt rejection mechanism [1] of these membranes can be summarized as follows. First, the positively charged metal species, specifically sodium ions, are adsorbed onto the NaA zeolite surface, which makes the surface positively charged. Then, the positive surface charge prevents the hydrated cations from approaching the openings of the non-zeolitic pores, whereas the hydrated anions accelerate toward the openings. In other words, the charge exclusion mechanism and the size exclusion mechanism are cooperative [1]. The hydrated anions and cations can be adsorbed onto the surface or the interior of the zeolite, even if they diffuse and enter the membrane through the non-zeolitic pores. If the adsorbed ions reach equilibrium within a small quantity of non-zeolitic pores in the membrane, the pores cannot absorb additional ions due to concentration polarization. The salt rejection experiment demonstrated that a small quantity of non-zeolitic pores in the membrane does not influence the ion rejection but that the membrane thickness approaches specific thresholds. When the thickness of self-supported zeolite membrane arrived at the thresholds value, the influences of mesopores and macropores defects would be reduced and omitted. |
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baoshanqiu
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liulp2008: 金币+30, 翻译EPI+1, ★★★★★最佳答案 2015-06-18 15:12:51
liulp2008: 金币+30, 翻译EPI+1, ★★★★★最佳答案 2015-06-18 15:12:51
| 随着膜厚度的增加，水通过需要的距离和需要克服的阻力都增加。相应地，持续时间增加而水流量减小。然而，根据NaCl溶液的盐排除过程所知，较厚的NaA 沸石膜具有高强度和良好的离子%排除率。这些膜的盐排除机理[1] 可总结如下。首先，正电荷的金属类，特别是钠离子，被吸附在NaA 沸石表面，使该表面带正电荷。这样，正电荷的表面避免水合阳离子接近非沸石孔的开口，而水合阴离子则加速靠近这些开口。换句话说，电荷排斥机制和尺寸排阻机制是相互协同的[1]。水合阴离子和阳离子即使通过非沸石孔扩散进入膜内，也被吸附在沸石的表面或内部。如果在膜内少量的非沸石孔吸附的离子达到平衡，这些孔因浓度极化不能再吸附更多的离子。盐排除实验表明只要膜厚度达到特定的阈值，膜中少量的非沸石孔不会影响离子排除。当自身支持的沸石膜厚度达到阈值的时候，间孔和大孔隙不利的影响即减少可忽略。 |
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