Abstract Green tea (Camellia sinensis) leaves are particularly rich in polyphenols. Here we propose the clarification of green tea extract by an innovative process consisting of a two-stage filtration through asymmetric alumina (Al2O3) hollow fibers, which we specially designed for this application by the phase inversion technique. The fibers presented outer sponge like-layers, mainly responsible for the membrane selectivity (turbidity of green tea extract was reduced by 90%) and mechanical strength (135 MPa), and an inner finger-like layer that reduced the resistance to flux permeation (water permeability of 2.56 × 10−9 m3 s−1 m−2 Pa−1). In order to increase the membrane retention coefficient, we deposited a polyethersulfone (PES) coating layer on the fiber outer surface. This polymeric layer further reduced the green tea extract turbidity by 97.8% in the permeate. As a consequence, no team cream formed even after 30 days of refrigerated storage. Thus, the membranes that we conceived enabled to obtain a product with superior clarity and stability. Additionally, a mathematical description of flux decay during the filtration processes showed that cake formation and internal pore blockage models better described flux decay through Al2O3 and PES/Al2O3 hollow fibers, respectively.

中文翻译：

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用于绿茶提取物澄清的不对称 Al2O3 和 PES/Al2O3 中空纤维膜

摘要 绿茶 (Camellia sinensis) 的叶子特别富含多酚。在这里，我们建议通过创新工艺对绿茶提取物进行澄清，该工艺包括通过不对称氧化铝 (Al2O3) 中空纤维的两级过滤，我们通过相转化技术专门为此应用设计。纤维呈现外海绵状层，主要负责膜选择性（绿茶提取物的浊度降低90％）和机械强度（135 MPa），以及降低通量渗透阻力的内指状层（ 2.56 × 10−9 m3 s−1 m−2 Pa−1)。为了增加膜保留系数，我们在纤维外表面上沉积了聚醚砜（PES）涂层。该聚合物层进一步将绿茶提取物的浊度降低了 97。8% 的渗透液。因此，即使在冷藏 30 天后也没有形成团队奶油。因此，我们设想的膜能够获得具有卓越透明度和稳定性的产品。此外，过滤过程中通量衰减的数学描述表明，滤饼形成和内部孔堵塞模型分别更好地描述了通过 Al2O3 和 PES/Al2O3 中空纤维的通量衰减。