High-Efficiency and Sustainable Desalination Using Thermo-regenerable MOF-808-EDTA: Temperature-Regulated Proton Transfer,ACS Applied Materials & Interfaces

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High-Efficiency and Sustainable Desalination Using Thermo-regenerable MOF-808-EDTA: Temperature-Regulated Proton Transfer
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-05-11 , DOI: 10.1021/acsami.1c05204
Chenghan Ji ₁ , Hang Yu ₁ , Junhe Lu ₂ , Yi Ren ₁ , Lu Lv _{1,

3} , Weiming Zhang _{1,

3,

4}

Affiliation

Adsorption as a desalination approach has the advantages of energy efficiency, low cost, and operational convenience, but its practical application is limited by low desalination capacity, consumption/disposal of strong acids/bases as regeneration reagents, and poor reusability. Herein, we synthesized a thermo-regenerable salt absorbent by grafting ethylenediaminetetraacetic acid (EDTA) onto a metal–organic framework (MOF), MOF-808-EDTA, which could rapidly adsorb NaCl within 30 min from saline water at 25 °C with a desalination capacity as high as 9.4 mmol/g. Moreover, the saturated adsorbent could be facilely regenerated in 80 °C water. Fourier transform infrared spectroscopy and derivative thermogravimetry revealed that temperature-regulated proton transfer between amino and carboxyl groups was the mechanism of thermo-regeneration. EDTA on MOF-808-EDTA appears in a zwitterionic state in water at room temperature, which allowed simultaneous adsorption of Na⁺ and Cl^–. At elevated temperature, it returned to a nonionic state accompanied by the desorption of ions. A similar temperature-dependent adsorption–regeneration process was also observed for other salts, including LiCl, KCl, CaCl₂, and MgCl₂. Column experiments of brackish groundwater showed that 1 g of MOF-808-EDTA could produce ∼106 mL of fresh water (total dissolved solids < 600 mg/L) without significant capacity loss after 10 successive adsorption–regeneration cycles. This study is the first to propose an EDTA-based MOF for desalination and indicates the potential of MOF-808-EDTA as a green adsorbent for sustainable water desalination.

中文翻译：

使用可热再生的MOF-808-EDTA进行高效，可持续的脱盐：温度调节的质子转移

作为脱盐方法的吸附具有能量效率高，成本低和操作方便的优点，但是其实际应用受到脱盐能力低，作为再生试剂的强酸/碱的消耗/处置以及可重复使用性差的限制。在这里，我们通过将乙二胺四乙酸（EDTA）接枝到金属有机骨架（MOF）MOF-808-EDTA上合成了一种可热再生的盐吸收剂，该吸收剂可以在25°C的盐水中30分钟内迅速吸附NaCl。脱盐能力高达9.4 mmol / g。此外，饱和吸附剂可以在80°C的水中轻松再生。傅立叶变换红外光谱和导数热重分析表明，温度调节的质子在氨基和羧基之间的转移是热再生的机理。⁺和Cl ^–。在升高的温度下，它返回到非离子状态，并伴随着离子的解吸。对于其他盐，包括LiCl，KCl，CaCl ₂和MgCl ₂，也观察到了类似的温度依赖性吸附-再生过程。苦咸水的色谱柱实验表明，经过10个连续的吸附-再生循环，1 g的MOF-808-EDTA可以产生约106 mL的淡水（总溶解固体<600 mg / L），而容量没有明显损失。这项研究是第一个提出基于EDTA的MOF进行脱盐的研究，并表明MOF-808-EDTA作为绿色吸附剂可持续进行水脱盐的潜力。

更新日期：2021-05-26

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