聚乙烯醇/海藻酸钠复合气凝胶的制备及其高效海水淡化应用

李萌; 王甜; 侯宪广; 张宪胜

doi:10.13801/j.cnki.fhclxb.20230310.003

聚乙烯醇/海藻酸钠复合气凝胶的制备及其高效海水淡化应用

doi: 10.13801/j.cnki.fhclxb.20230310.003

青岛大学　纺织服装学院，青岛 266071

基金项目: 国家自然科学基金(52003131)

详细信息

通讯作者:
张宪胜，博士，副教授，硕士生导师，研究方向为功能防护与能量转换材料　E-mail: xshzhang@qdu.edu.cn

中图分类号: TB332
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出版历程
- 收稿日期: 2022-11-10
- 修回日期: 2023-02-15
- 录用日期: 2023-03-03
- 网络出版日期: 2023-03-11
- 刊出日期: 2023-10-15

Preparation of polyvinyl alcohol/sodium alginate composite aerogel and its application in efficient seawater desalination

College of Textiles and Clothing, Qingdao University, Qingdao 266071, China

Funds: National Natural Science Foundation of China (52003131)

摘要

摘要: 基于太阳能界面水蒸发技术的海水淡化蒸发器可以实现海水的淡化提纯，但目前蒸发器的蒸发速率较低。本文通过定向冷冻的方法制备了聚乙烯醇与海藻酸钠的复合气凝胶，同时采用碳纳米管作为光吸收材料，探索了复合气凝胶组分、比例和光吸收材料含量等因素对蒸发器水蒸发性能的影响。结果发现该复合气凝胶蒸发器有高达97%的光吸收率和优异的海水淡化性能，一个太阳光下的水蒸发速率能够达到2.7 kg·m⁻²·h⁻¹，并且在长期的光照和黑暗的交替过程中，蒸发器表面积累的盐晶体会自动融化消失，起到自清洁的效果，可以实现长期的可持续蒸发，在海水淡化领域具有广阔的应用前景。
- 气凝胶 /
- 定向冷冻 /
- 海水淡化 /
- 水蒸发 /
- 自清洁 /
- 海藻酸钠 /
- 碳纳米管 /
- 聚乙烯醇
Abstract: The desalination evaporator based on the solar interface water evaporation technology can realize the desalination and purification of seawater, but the evaporation rate of the evaporator is low at present. In this work, the composite aerogel of polyvinyl alcohol and sodium alginate was prepared by directional freezing. At the same time, carbon nanotubes were used as light absorbing material. The effects of the composition, proportion and content of light absorbing material of the composite aerogel on the evaporation performance of evaporator water were explored. The results show that the composite aerogel evaporator has a light absorption rate of up to 97% and excellent seawater desalination performance. The water evaporation rate under a sun light can reach 2.7 kg·m⁻²·h⁻¹.In the long-term alternating process of light and darkness, the salt crystals accumulated on the surface of the evaporator will automatically melt and disappear, playing a self-cleaning effect, and can achieve long-term sustainable evaporation. It has broad application prospects in the field of seawater desalination.
- aerogel /
- directional freezing /
- seawater desalination /
- water evaporation /
- self-cleaning /
- sodium alginate /
- carbon nanotubes /
- polyvinyl alcohol

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图 1 CNT/PVA-SA复合气凝胶蒸发器的制备过程示意图

Figure 1. Schematic diagram of preparation process of CNT/PVA-SA composite aerogel evaporator

CNT—Carbon nanotube; PVA—Polyvinyl alcohol; SA—Sodium alginate; KH560—Silane coupling agent

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图 2 CNT10/PVA-SA(6) (a)、CNT10/PVA-SA(7) (b)、CNT10/PVA-SA(8) (c)、CNT10/PVA-SA(9) (d)、CNT10/PVA-SA(10) (e) 的SEM图像；(f) 复合气凝胶的宏观图像

Figure 2. SEM images of CNT10/PVA-SA(6) (a), CNT10/PVA-SA(7) (b), CNT10/PVA-SA(8) (c), CNT10/PVA-SA(9) (d), CNT10/PVA-SA(10) (e); (f) Macro photo of composite aerogel

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图 3 PVA、PVA-SA、CNT10/PVA-SA(6)的接触角测试图

Figure 3. Contact angle test diagrams of PVA, PVA-SA and CNT10/PVA-SA(6)

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图 4 ((a)~(d)) CNT10/PVA-SA(6)在热板上的红外图像；(e) 干态CNT10/PVA-SA(6)在1~5个太阳光照射(1~5 sun)下的红外图像； (f) 湿态CNT10/PVA-SA(6)在1~5 sun下的红外图像

Figure 4. ((a)-(d)) Infrared image of CNT10/PVA-SA(6) on hot plate; (e) Infrared image of dry CNT10/PVA-SA(6) under 1-5 sun; (f) Infrared image of wet CNT10/PVA-SA(6) under 1-5 sun

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图 5 (a) PVA-SA和CNT10/PVA-SA的吸收光谱；(b) 在1 sun下CNT(5~20)/PVA-SA的表面温度变化曲线；(c) 在1 sun下CNT(5~20)/PVA-SA的水蒸发质量变化；(d) 在1 sun下不同比例CNT10/PVA-SA(1~5)的水蒸发质量变化

Figure 5. (a) Absorption spectra of PVA-SA and CNT10/PVA-SA; (b) Surface temperature change curves of CNT(5-20)/PVA-SA under 1 sun; (c) Water evaporation mass change of CNT(5-20)/PVA-SA under 1 sun; (d) Water evaporation mass change of CNT10/PVA-SA(1-5) with different proportions under 1 sun

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图 6 (a) 在3 kW·m⁻²太阳光下产生的水蒸气的图像(左)和在2D蒸发下的红外图像(右)；(b) 3D水蒸发测试示意图(左)和在3D蒸发下的红外图像(右)；(c) 在1 sun下不同浓度CNT10/PVA-SA(6~10)的2D水蒸发质量变化；(d) 在1 sun下不同浓度CNT10/PVA-SA(6~10)的3D水蒸发质量变化

Figure 6. (a) Photo of water vapor generated under the sunlight of 3 kW·m⁻² (left), infrared image under 2D evaporation (right); (b) Schematic diagram of 3D water evaporation test (left), infrared image under 3D evaporation (right); (c) Change of 2D water evaporation quality with different concentrations of CNT10/PVA-SA(6-10) under 1 sun; (d) Change of 3D water evaporation quality with different concentrations of CNT10/PVA-SA(6-10) under 1 sun

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图 7 (a) 脱盐前后，真实海水(中国黄海)中4种主要阳离子的浓度；(b) CNT10/PVA-SA蒸发器表面模拟自然环境的盐沉积/自清洁照片

Figure 7. (a) Concentrations of four main cations in real seawater (Yellow Sea, China) before and after desalination; (b) Photos of salt deposition/self-cleaning on the surface of CNT10/PVA-SA evaporator simulating the natural environment

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表 1 不同CNT含量和PVA与SA不同比例的复合气凝胶

Table 1. Composite aerogels with different CNT content and different proportions of PVA and SA

Sample	3wt%PVA/mL	3wt%SA/mL	CNT/g
PVA	20	—	—
PVA-SA	10	10	—
CNT5/PVA-SA	10	10	5
CNT10/PVA-SA	10	10	10
CNT15/PVA-SA	10	10	15
CNT20/PVA-SA	10	10	20
CNT10/PVA-SA(1)	10	10	10
CNT10/PVA-SA(2)	6.66	13.3	10
CNT10/PVA-SA(3)	5	15	10
CNT10/PVA-SA(4)	15	5	10
CNT10/PVA-SA(5)	13.3	6.66	10

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表 2 不同PVA与SA浓度的复合气凝胶

Table 2. Composite aerogels with different PVA and SA concentrations

Sample	5 mL PVA/wt%	15 mL SA/wt%	CNT/g
CNT10/PVA-SA(6)	1	1	10
CNT10/PVA-SA(7)	2	2	10
CNT10/PVA-SA(8)	3	3	10
CNT10/PVA-SA(9)	4	4	10
CNT10/PVA-SA(10)	5	5	10

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