Microrespirometric assessment of the metal–organic framework [Co2(btec)(bipy)(DMF)2]n (“MOF-Co”) to prevent inhibition by arsenic in activated sludge

Abstract

Metal–organic frameworks (MOFs) are a new class of hybrid porous materials built from organic linkers and inorganic metals, and have been used as adsorbent materials for the removal of heavy metals present in wastewater. While MOFs reduce the toxicity of wastewater by removing heavy metals, it has been reported that they can present some inhibitory effects, intrinsically or through the release of their metal cluster, although these aspects have only rarely been reported. In this work, the toxicity of [Co₂(btec)(bipy)(DMF)₂]_n (MOF-Co), as well as its impact on the toxicity exerted by As(III), was examined using activated sludge in the treatment of synthetic wastewater as an experimental model. Toxicity was assessed through microrespirometry using a wide range of MOF-Co and As(III) concentrations in different configurations. In each case, inhibition was quantified, and the main kinetic parameters were determined. The obtained results confirmed the noncompetitive inhibitory effect of As(III), as well as a significant reduction (by up to 98%) in this inhibitory effect in the presence of MOF-Co. It is concluded that MOF-Co has no effect on activated sludge and might be an efficient material for the removal of heavy metals in wastewater, although further studies are required to establish efficient application and recovery methods.