PAM-PDA-PEG改性气凝胶的光热转换性能研究

Photothermal conversion performance of PAM-PDA-PEG modified aerogels

气凝胶具有高孔隙率和低热导率,能够吸收太阳光并转换为热能加热液态水,因此被广泛应用于太阳能驱动水蒸发领域,可以实现高效的海水淡化和污水处理。为了提高气凝胶的水蒸发速率,选择吸水性好的聚丙烯酰胺(PAM)为基底,聚多巴胺(PDA)为亲水改性材料,聚乙二醇(PEG)为分散剂,通过冷冻干燥法制备PAM-PDA-PEG(PG-PAM)改性气凝胶。利用扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)、紫外/可见/近红外分光光度计(UV-vis-NIR)、水接触角和拉曼光谱(Raman)对改性气凝胶的微观形貌、化学组成、光学性质、亲水性及水状态进行了表征。还利用模拟蒸发系统测试了PAM-PDA-PEG的光热转换性能。结果表明,纯PAM的光热转换性能较弱,但经过改性后的PAM-PDA-PEG气凝胶不仅具有良好的吸光性和亲水性,还蕴含大量的中间水,可以有效地降低蒸发所需要的能量。经过测试,PAM-PDA-PEG在1 kW·m^(-2)的光强下蒸发速率达到2.40 kg·m^(-2)·h^(-1),是纯PAM的5倍。此外,脱盐和染料去除实验证明了PAM-PDA-PEG实际应用能力。

Aerogels with high porosity and low thermal conductivity can absorb sunlight and convert them into thermal energy to heat water,thus are widely used in the field of solar vapor generation to achieve efficient desalination and sewage treatment.In order to improve the evaporation rate of aerogels,PAM-PDA-PEG modified aerogels were prepared by freeze-drying using polyacrylamide(PAM)with good absorbency as substrate,polydopamine(PDA)as hydrophilic modification material and polyethylene glycol(PEG)as dispersant.Scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),ultraviolet/visible/near-infrared spectrophotometer(UV-vis-NIR),water contact angle and Raman spectroscopy(Raman)were used to characterize the micromorphology,chemical composition,optical properties,hydrophilicity and water state of the modified aerogels.The photothermal conversion performance of PAM-PDA-PEG were also tested by simulated evaporation system.The results show that the photothermal conversion performance of pure PAM is weak,but the modified PAM-PDA-PEG aerogels not only have good absorbance and hydrophilicity,but also contain a large amount of intermediate water which can effectively reduce the energy required for evaporation.Under the light intensity of 1 kW·m^(-2),the evaporation rate of PAM-PDA-PEG reaches 2.40 kg·m^(-2)·h^(-1),which is five times that of pure PAM.In addition,desalination and dye removal experiments proved the practical application ability of PAM-PDA-PEG.