Chalita Ratanatawanate

Flexible and hydrophilic copolyamide (Co-PA) thin-film composite (TFC) membranes were fabricated as a selective layer on the outer surface of the polyvinylidene fluoride hollow fiber membrane substrate. The fabrication process was carried out by the dip-coating method to create three TFC membranes. The first layer is tannic acid and the second layer is (3-aminopropyl)triethoxysilane, which is followed by Co-PA as a final selective layer. The Co-PA TFC membrane was prepared through interfacial polymerization via the combination of various short-chain aliphatic diamines and conventional aromatic diamines with trimesoyl chloride. The influence of coating layers and total diamine concentration on the Co-PA TFC membrane was investigated in terms of the membrane’s physicochemical and mechanical properties, morphology, surface thickness and roughness, water contact angle, surface charge, and nanofiltration (NF) performance. The obtained Co-PA TFC membrane system was operated under low pressure (2 bar) with pure water flux in the range of 23.8–83.9 L m^–2 h^–1 and exhibited better hydrophilicity, flexibility, molecular weight cutoff, and NF performance compared to the conventional PA TFC membrane. The superior properties of Co-PA are due to the increased chain mobilities provided by short-chain aliphatic diamines in its structure. The best Co-PA TFC membranes, which were synthesized using diamines containing four carbon atoms, achieved a significant improvement in NF membrane performance and selectivity (pure water flux = 56.9 L m^–2 h^–1 and salt and dye rejection in the range of 46.2–99.2%). This Co-PA TFC membrane is a promising membrane for its high flexibility, hydrophilicity, and selectivity of the NF membrane.

Lead sulfide quantum dots-doped titanium dioxide nanotubes (PbS QDs-doped TNTs) were successfully prepared by the hydrothermal and impregnation methods. A thin layer of titanium dioxide (TiO2) comprising of PbS QDs-doped TNTs was applied as an electron transport layer (ETL) in order to improve the planar perovskite solar cell efficiency. The role of incorporating a high surface area of one-dimensional nanotube structure of TiO2 in the conventional TiO2 layer provided a special unidirectional charge transport and a high charge collection. Moreover, doping PbS QDs onto the surface of TNTs modified the electronic and optical properties of the ETL by downshifting the conduction band of TiO2 from −4.22 to −4.58 eV, therefore promoting the driving force of an electron injection to the transparent conductive electrode. By varying the concentration of PbS QDs-doped TNTs dispersed in 2-butanol from 0.1 to 0.9 mg/mL, a concentration of 0.3 mg/mL PbS QDs-doped TNTs was the optimum concentration to be mixed with TiO2 solution for the ETL deposition. The best perovskite solar cell performance with the optimum loading of PbS QDs-doped TNTs provided 14.95% power conversion efficiency, which was increased from 12.82% obtained from the cell with pristine TiO2 film as ETL.