A Ligand‐Doped Silver Triazolate MOF on the Removal of Diclofenac Sodium via Anion Exchange

Abstract

A ligand-doped silver triazolate MOF{[Ag 8 (Ph 2 tz) 5.6 (tBu 2 tz) 0.4 ] (BF 4) 2 (H 2 O) 6 } (AgTz-1/2, Ph 2 tzH = 3,5-di-phenyl-1,2,4-triazole; tBu 2 tzH = 3,5-di-tert-butyl-1,2,4-triazole), was successfully synthesized by the use of solid solution approach and characterized by different techniques. The obtained material featuring good thermal and chemical stability is isostrutural with an earlier reported MOF {[Ag 8 (Ph 2 tz) 6 ](BF 4) 2 (H 2 O) 3 } (AgTz-1). The study on the diclofenac sodium (DCF) adsorption from water by AgTz-1/2 at higher pH value (pH = 10) shows better efficiency in comparison with the parent MOF AgTz-1. Especially, using AgTz-1/2 as the adsorbent, the adsorption capacity at low concentration as well as the reaction rate is remarkable among those reported traditional and MOF materials. Anion-exchange between BF 4 À and anionic DCF play a vital role on the adsorption. More importantly, the used AgTz-1/2 adsorbent can be well regenerated and reused for the next four cycles of DCF adsorption while maintaining the structural integrity and the removal efficiency.

One‐pot Economic Synthesis to the Functional Copper Mixed‐triazolate MOF Materials Towards an Enhanced Adsorptive Removal of Diclofenac Sodium

“…Especially, an enhancement of 117 % was achieved CuMtz‐3b in comparison to that observed over CuTz‐1. which is also quite comparable with the reported MOF adsorbents [19,22a] …”

“…These results demonstrate that doping of tzH into the structure of CuTz‐1 plays a significant role on improving the adsorption of DCF over CuMtz‐3b. In addition, although the adsorption capacity of DCF over CuTz‐1 is lower than that of AgTz‐1 (i. e., 44 vs. 91 mg ⋅ g −1 ), the apparent enhanced adsorption capacity was achieved by the incorporation of tzH into CuTz‐1 [19] . CuMtz‐3b with 18 % incorporation amount of tzH exhibit higher adsorption capacity than AgTz‐1/2 with 7 % incorporation amount of 3,5‐ t Bu 2 ‐tzH.…”

“…In order to get deeper understanding on the adsorption process of DCF over CuMtz‐3b, the adsorption mechanism was also investigated. Since CuMtz‐3b is a cationic MOF, anion exchange between DCF and BF 4 − is usually considered as one of the mechanisms during adsorption [19,25] . Hence, the concentration of BF 4 − in the solution at equilibrium was tested by ion chromatography.…”

“…[18] It was also found that, via introducing a second ligand into the framework, a functional mixed-ligand MOF AgTz-1/2 {[Ag 8 (3,5-Ph 2 -tz) 5.6 (3,5-tBu 2tz) 0.4 ](BF 4 ) 2 (H 2 O) 6 ; 3,5-tBu 2 -tz = 3,5-di-tert-butyl-1,2,4-triazolate} was designed and showed enhanced adsorption property on the removal of DCF in comparison with the pristine MOF AgTz-1-BF 4 {[Ag 8 (3,5-Ph 2 -tz) 6 ](BF 4 ) 2 (H 2 O) 3 }. [19] However, from the economic perspective, the synthesis of Ag-MOFs involves the utilization of silver salts as the reactants, which may hinder the industrial application as adsorbents in practice due to the high cost. On this regards, the copper(I) analogue of AgTz-1, namely, CuTz-1({[Cu 8 (3,5-Ph 2 -tz) 6 ](BF 4 ) 2 (CH 3 OH) 3 }), featuring the similar framework, is supposed to be a good candidate for the adsorption of hazardous materials.…”

“…Our previous work reported that AgTz‐1{[Ag 8 (3,5‐Ph 2 ‐tz) 6 ](NO 3 ) 2 , 3,5‐Ph 2 ‐tz=3,5‐diphenyl‐1,2,4‐triazolate}, a 3D cationic MOF with nanoscale channels constructed by trigonal bipyramidal clusters [Ag 5 (3,5‐Ph 2 ‐tz) 6 ] − and Ag centers, was very efficient on the adsorptive removal of Cr(VI) from aqueous solution via anion exchange [18] . It was also found that, via introducing a second ligand into the framework, a functional mixed‐ligand MOF AgTz‐1/2 {[Ag 8 (3,5‐Ph 2 ‐tz) 5.6 (3,5‐ t Bu 2 ‐tz) 0.4 ](BF 4 ) 2 (H 2 O) 6 ; 3,5‐ t Bu 2 ‐tz=3,5‐di‐tert‐butyl‐1,2,4‐triazolate} was designed and showed enhanced adsorption property on the removal of DCF in comparison with the pristine MOF AgTz‐1‐BF 4 {[Ag 8 (3,5‐Ph 2 ‐tz) 6 ](BF 4 ) 2 (H 2 O) 3 } [19] . However, from the economic perspective, the synthesis of Ag‐MOFs involves the utilization of silver salts as the reactants, which may hinder the industrial application as adsorbents in practice due to the high cost.…”