MOF-808 and its hollow fibre adsorbents for efficient diclofenac removal

The popularity of diclofenac, one of the highly effective non-steroidal anti-inflammatory drugs (NSAIDs), has led to its excessive consumptions. Consequently, its presence in water bodies is continually increasing and poses serious threats to ecosystems. Adsorption processes have been employed to address this issue. However, most of the commercially available adsorbents such as activated carbon, zeolite, etc. suffer from relatively low diclofenac adsorption capacity (100–200 mg g−1) and slow kinetics. Herein, we explore the potential of MOF-808 as a superior adsorbent for diclofenac removal. Benefitting from its high specific surface area and large pore aperture, the maximum diclofenac adsorption capacity achieved in this study reaches 833 mg g−1 with almost 95% removal within first hour. This performance is one of the highest reported adsorbents for diclofenac removal so far and has led us to have further commercial exploitation by employing a yttria-stabilised zirconia (YSZ) hollow fibre support where the MOF-808 adsorbent is deposited on its outer surface. Such a configuration is beneficial from a practical point-of-view, as it eliminates the requirement of separation of powdered adsorbents from treated water once the adsorption process finishes. Also, the hollow fibre configuration not only substantially increases the surface-area-to-volume ratio of adsorption systems, but also reduces the maldistribution of flows commonly unavoidable in conventional packed bed adsorption columns. The high-efficiency of the MOF-808 hollow fibre adsorbent is exhibited by retainment of its equilibrium adsorption capacity of 796 mg g−1. More importantly, the MOF-808 hollow fibre adsorbent can withstand at least 4 adsorption-regeneration cycles without any significant reduction in the adsorption performances, indicating the potential for possible commercialisation of the MOF-808 adsorbent for diclofenac removal from water.