Designing of MOF@COF with enhanced removal performance for parabens: Fast adsorption plus built-in heterojunction facilitated photocatalysis

With the widespread use of parabens as preservatives, their increasing environmental concentration and potential adverse heathy effects have drawn considerable concern. Photodegradation represents a sustainable approach for paraben removal; however, developing photocatalysts that exhibit both efficient visible-light absorption and effective separation of photocarriers remains a challenge. Herein, a MOF@COF core-shell structure was fabricated to utilize the heterojunction for charge-hole spatial separation, generating sufficient reactive species for the photodegradation process. Under visible light, TPTi-0.225 (i.e., 0.225 g NH2-MIL-125 was added during COF synthesis) catalyzed highly efficient removal (∼99 %) of propylparaben within two hours. The degradation performance of TPTi-0.225 over a wide pH range and various real water matrices was also satisfactory. Theoretic calculation along with key reaction intermediate identification revealed parabens were degraded into low-toxicity products. This study not only offers insight into the design of novel visible photocatalysts but also presents a viable approach for detoxifying parabens in environmental waters.