Lithium Pyrene Squarate Covalent Organic Frameworks for Efficient Lithium and Magnesium Separation from Salt Water

Abstract

The increasing pressure for lithium resources from the electric vehicle and nuclear energy industries means that new technologies to separate Mg2+ from Li+ from salt water are in demand. To address this need, we fabricated lithium pyrene squarate covalent organic frameworks (Li-SQCOFs) to separate Mg2+/Li+ mixtures from salt water. We optimized the effect of the electrolyte and the amount of the adsorbent and then carried out a kinetics study on the adsorbent recovery at various pH levels using both batch and continuous flow adsorption methods. Li-SQCOF was found to have excellent selectivity for solutions containing a mixture of Mg2+/Li+ ions. This work represents a unique path for the separation of Mg2+/Li+ through direct adsorption using a covalent organic framework (COF). The COF-supported ultrafiltration bed made in this study gave a Mg2+ separation flux of 60.5 h–1 m–2.

Synthesis and Improving the Crystallinity of a Squaranine Covalent Organic Framework by Investigating the Co-Catalyst Effect and Using It as a green and Metal-Free Catalyst for the synthesis of enaminones

“…According to the results and optimizations, it seems that the presence of a catalytic amount of aqueous acetic acid can affect the synthesis process, so it can be said that the presence or absence of this catalyst was effective in the synthesis of SQCOF. Also, the addition of this cocatalyst reduced the synthesis time by 4 days, and also the PXRD pattern of the obtained product was closer to the simulated pattern that has been reported [25]. squaranine units in SQCOF can perform as Bronsted acid groups [25] that are placed on the framework through the bottom-up synthesis strategy, without the need for post-modi cation.…”

“…Also, the addition of this cocatalyst reduced the synthesis time by 4 days, and also the PXRD pattern of the obtained product was closer to the simulated pattern that has been reported [25]. squaranine units in SQCOF can perform as Bronsted acid groups [25] that are placed on the framework through the bottom-up synthesis strategy, without the need for post-modi cation. So, SQCOF can be a good candidate as a heterogeneous acidic catalyst.…”

“…Therefore, to investigate the catalytic role of acetic acid, the concentration and volume of the aquae solution of acetic acid as two effective key factors were optimized and the crystallinity of SQCOF was investigated by PXRD. according to previous studies, a sharp peak near 7.85 (in simulated PXRD) [25] is related to crystallinity quality. Therefore, in this study, we used the 8.4 peak, which was close to the mentioned value and is a symbol of the crystallinity of the structure, as the basis for optimization.…”

“…SQCOF was synthesized by condensation between squaric acid and TAPP under solvothermal conditions. The reported simulated powder x-ray diffraction (PXRD) pattern of SQCOF illustrates different peaks at 7.85, 9.58, 15.90, 21.87, 22.42, 23.33, and 24.02 degrees [25]. In the experimental PXRD pattern of SQCOF, a sharp peak near 8.4 degrees (Figure 2) can be related to (200) Miller indices that were closely matched with the reported simulation (7.85) [25].…”

“…Also, Ding and et.al synthesized many squaranine -linked COFs, utilizable in photothermal studies [22]. Recently, Abbaspourrad and coworkers synthesized and applied SQCOF as a high-performance membrane for water treatment [25]. In these reported methods, squaric acid has played the role of an acid catalyst and a monomer.…”