The removal of organophosphorus (OP) herbicides from
water has
been studied using adsorptive removal, chemical oxidation, electrooxidation,
enzymatic degradation, and photodegradation. The OP herbicide glyphosate
(GP) is one of the most used herbicides worldwide, leading to excess
GP in wastewater and soil. GP is commonly broken down in environmental
conditions to compounds such as aminomethylphosphonic acid (AMPA)
or sarcosine, with AMPA having a longer half-life and similar toxicity
to GP. Metal–organic frameworks (MOFs) are excellent materials
for purifying OP herbicides from water due to their ability to combine
adsorption and photoactivity within one material. Herein, we report
the use of a robust Zr-based MOF with ameta-carborane
carboxylate ligand (mCB-MOF-2) to examine
the adsorption and photodegradation of GP. The maximum adsorption
capacity ofmCB-MOF-2for GP was determined
to be 11.4 mmol/g. Non-covalent intermolecular forces between the
carborane-based ligand and GP within the micropores ofmCB-MOF-2are thought to be responsible for strong
binding affinity and capture of GP. After 24 h of irradiation with
ultraviolet–visible (UV–vis) light,mCB-MOF-2selectively converts 69% of GP to sarcosine and orthophosphate,
following the C–P lyase enzymatic pathway and biomimetically
photodegrading GP. Circumventing the production of AMPA is desirable,
as it has a longer half-life and similar toxicity to GP. The exceptional
adsorption capacity of GP bymCB-MOF-2and its biomimetic photodegradation to non-toxic sarcosine make
it a promising material for removing OP herbicides from water.