導電高分子奈米複合材料塗佈金屬有機骨架薄膜用於太陽能水純化

Abstract

隨著工業的發展和現代科技的進步，世界面臨著水污染和水資源匱乏的問題。近年來，太陽能蒸汽生成、太陽能純化水因其不會額外耗能的優點而備受關注。不同於傳統的淨水方式，其利用太陽能轉化為熱能，通過蒸發後獲得純水，在這個過程中，所有的鹽和雜質都會從蒸汽中分離，蒸汽被冷凝成純水並收集。水純化過程中不會產生污染物、脫鹽膜可以重複使用等優勢，提供了環境友善的水純化方法。純化薄膜或脫鹽膜必須滿足兩項主要性質：1.可吸收太陽光並轉化成熱能，提供水蒸發的吸收熱。2.多孔隙、具有連續的微孔結構，提供水分子藉由毛細現象向上傳輸的途徑。另外，熱能須集中在表面，避免熱傳導分散到膜內及底下的水，以達到最高的水蒸發、純化水效率。在此研究中，我們利用三氧化二鈦(Ti2O3)及羥基官能化聚(3,4-亞乙基二氧噻吩) (PEDOT-OH)作為光熱轉換材料，並在親水的官能化聚四氟乙烯(polytetrafluoroethylene, PTFE)過濾薄膜上合成原位生長(in-situ)的金屬有機骨架(metal-organic framework, MOF) CAU-10-H，藉由PTFE基材的孔洞吸收下方的鹽水，再經由MOF中的結構孔洞及晶隙傳輸至吸光層，吸收熱能並蒸發。研究中，探討了PEDOT-OH和不同比例的PEDOT-OH包覆Ti2O3奈米複合材料的光吸收量及光熱轉換效果，而重量比例1:1的PEDOT-OH包覆Ti2O3複合材料能良好塗佈在MOF薄膜上又具有最高的吸光量、光熱轉換量。同時，我們合成不同晶體厚度的in-situ CAU-10-H，晶體厚度不但影響水傳輸路徑長短，也會造成絕熱效果的改變。研究結果以厚度13 μm的CAU-10-H達到兩種機制的平衡，其塗佈薄膜具有最高的水蒸發速率，達2.17 kg.m-2.h-1，而光熱轉換要率達98%。有別於其他太陽能純化水的發表，緻密in-situ CAU-10-H 的低熱傳導率有利於熱能集中在表面，而此裝置中的脫鹽膜也無須額外的隔熱層以避免熱能分散至水體。結果證明，PEDOT-OH包覆Ti2O3奈米複合材料塗佈CAU-10-H薄膜在太陽能蒸氣生成及海水淡化等永續能源領域具有巨大的優勢。

With the advancement of modern technology, the world is facing the issues of water pollution and scarcity of water resources. Solar steam generation and desalination have attracted much attention due to their intrinsic advantages. In the purification process, salts and impurities are separated from the steam, which is condensed into pure water and collected. Moreover, no pollutants are produced during the water purification process. Desalination membranes are also repeatable, providing an environmentally friendly water purification method. In this research, we successfully fabricated titanium trioxide coated with poly(hydroxymethyl EDOT) (Ti2O3@PEDOT-OH) nanocomposites as a photothermal conversion material, and well synthesized in-situ metal-organic framework (MOF), CAU-10-H based membranes. Ti2O3@PEDOT-OH coating 13 μm CAU-10-H self-floating on the water achieves the highest water evaporation rate of 2.17 kg.m-2.h-1 with an efficient thermal insulating ability and an evaporation efficiency of 98%. Also, the ion concentrations of collected water tremendously decrease and are much lower than drinkable water standards by WHO. The results have shown that Ti2O3@PEDOT-OH nanocomposites on CAU-10-H films possess excellent potential in the fields of sustainable energy such as solar steam generation and seawater desalination.