1. School of Civil Engineering and Architecture, Anhui University of Technology, Ma’anshan 243032, China
2. Key Laboratory of Metallurgical Emission Reduction & Resources Recycling, Ministry of Education (Anhui University of Technology), Ma’anshan 243002, China
Abstract：Building energy consumption occupies more than 30% of total energy consumption in China. Building energy conservation is an important part of China’s policy on energy conservation and emissions reduction. It is important to realize building energy conservation by improving its thermal and humidity regulation performance through the passive regulation performance of the building itself. Decylic acid and palmitic acid were used to prepare decylic acid-palmitic acid composite phase change material, which phase changes temperature within the comfort range of the human body. The decylic acid-palmitic acid composite phase change material, tetraethyl silicate and tetrabutyl titanate were used as raw materials to prepare decylic acid-palmitic acid /SiO2@TiO2 photocatalytic phase change microcapsules (D-T microcapsules) which have heat, humidity adjustment and air purification function. It is conducive to building energy saving and improving indoor air quality. In this study, the dosage of deionized water (the molar ratio of deionized water to tetraethyl silicate), pH value, the dosage of clecylic acid-palmitic acid composite phase change material (the molar ratio of decylic acid-palmitic acid composite phase change material to tetraethyl silicate), the dosage of tetrabutyl titanate (molar ratio of tetrabutyl titanate to tetraethyl silicate) and the dropping acceleration of tetrabutyl titanate, these five effects were analyzed to study the effects on the particle size, composition, morphology, air purification function, thermal and humidity regulation performance of D-T microcapsules. The laser particle size analysis results showed that the amount of deionized water and tetrabutyl titanate had important effects on the particle size distribution of D-T microcapsules. The excess water system can effectively disperse T-D microcapsules and prevent agglomeration. TiO2 generated by the hydrolysis of tetrabutyl titanate was wrapped on the surface of decylic acid-palmitic acid@SiO2. Thus the dosage of tetrabutyl titanate affected the particle size of D-T microcapsules. Scanning electron microscopy showed that excessive decylic acid-palmitic acid composite phase change material would cause leakage of phase change material. The rapid drop acceleration of tetrabutyl titanate affected the hydrolysis reaction rate and would led to TiO2 agglomeration. XRD analysis showed that pH value was the key factor for preparing anatase phase TiO2 with photocatalytic performance. Therefore, when the dosage of deionized water is 90∶1, the pH value is 2, the dosage of decylic acid-palmitic acid composite phase change material is 0.5, the dosage of tetrabutyl titanate is 0.8, and the dropping acceleration of tetrabutyl titanate is 20 min, the prepared D-T microcapsules have complete morphology, uniform particle size and anatase structure. After 6 hours of the formaldehyde degradation test, the degradation rate of formaldehyde can reach 67.87 %. There is an obvious phase transition temperature platform between 18~23 ℃, with a duration of 300 s. When the relative humidity is 84.34%, the equilibrium moisture content is 0.181 9 g·g-1, and the moisture capacity between 32.78%～84.34% is 0.161 3 g·g-1.
Key words：Phase change microcapsule; Photocatalytic; Heat-humidity adjust; Air purification; Formaldehyde
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