Prasetya, N. / Li, K. (2022)

Separation and Purification Technology, 2022,  301, 122024

Abstract

Diclofenac is one of the most popular non-steroidal anti-inflammatory drugs (NSAIDs) which has been widely
used worldwide. Despite its popularity, its accumulation in the environment poses danger to the aquatic lives and
its removal from the environment is paramount important. Although some conventional adsorbents such as
activated carbon can be readily used to address this issue, they usually suffer from low diclofenac adsorption
capacity (around 200 mg g 1), resulting in bulky adsorption systems. To overcome this problem, high perfor-
mance materials such as metal organic frameworks (MOFs) can be employed. Here, we report that we syn-
thesised defective MOF-801 for enhanced diclofenac adsorption via a simple and environmentally benign
approach. Differing from a conventional MOF synthesis that usually requires the use of organic solvents at high
temperature, the defective MOF-801 could be synthesised at room temperature and by changing the reaction
medium from dimethylformamide to water. In addition, we have also successfully shown in this study that the
defect concentration in MOF-801 can be rationally tuned by adjusting the modulator concentration (formic acid)
in the synthesis solution. The resulting defective MOF-801 can then be used for environmental remediation,
which we have shown here by employing them as an adsorbent for diclofenac removal from water streams. The
enhanced adsorption of defective MOF-801 in comparison to its non-defective counterpart is due to the pore
enlargement of the defective MOF-801 which provides a better pathway to access the adsorption sites. The
maximum diclofenac adsorption capacity in a highly defective MOF-801 can reach as high as 680 mg g 1, which
is almost 4 times higher than its non-defective counterpart. This study then opens possibilities to engineer the
MOF particles for environmental remediation.

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