Dual-functional metal-organic frameworks-based hydrogel micromotor for uranium detection and removal.

Self-propelled micro/nanomotors have attracted great attention for environmental remediation, however, their use for radioactive waste detection and removal has not been addressed. Engineered micromotors that are able to combine fast detection and highly adsorptive capability are promising tools for radioactive waste management but remain challenging. Herein, we design self-propelled micromotors based on zeolite imidazolate framework (ZIF-8)-hydrogel composites via inverse emulsion polymerization and show their potential for efficient uranium detection and removal. The incorporation of magnetic ferroferric oxide nanoparticles enables the magnetic recycling and actuation of the single micromotors as well as formation of swarms of worm-like or tank-treading structure. Benefited from the enhanced motion, the micromotors show fast and high-capacity uranium adsorption (747.3 mg g-1), as well as fast uranium detection based on fluorescence quenching. DFT calculation confirms the strong binding between carboxyl groups and uranyl ions. The combination of poly(acrylic acid-co-acrylamide) with ZIF-8 greatly enhances the fluorescence of the micromotor, facilitating the high-resolution fluorescence detection. A low detection limit of 250 ppb is reached by the micromotors. Such self-propelled micromotors provide a new strategy for the design of smart materials in remediation of radioactive wastewater.

Co-MOF-74 based Co3O4/cellulose derivative membrane as dual-functional catalyst for colorimetric detection and degradation of phenol.

Smart nanomaterials that can simultaneously detect and eliminate contaminants in water environment are significant for health protection. To achieve such goal, Co-MOF-74 was in-situ assembled on regenerated cellulose membranes followed by calcination process, thus achieving dual-functional Co3O4/cellulose derivative membrane (Co3O4/CDM) catalyst. The Co3O4 morphology was readily controlled by further recrystallization of the deposited MOF precursor. Combining the high enrichment ability of cellulose membrane and outstanding peroxidase-active of Co3O4, the fast color reaction for phenol was accomplished within 10 min by Co3O4/CDM with the assistance of H2O2 and 4-aminoantipyrine (4-AAP). Moreover, the Co3O4/CDM also portrayed an excellent degradation property for phenol elimination via sulfate radical-advanced oxidation processes (SR-AOPs). The degradation efficiency of phenol reached 93% in 20 min, and the possible mineralization mechanism was proposed based on the XPS and LC-MS analysis. Thus, Co-MOF-74 derived Co3O4/CDM shows excellent properties in aiding the colorimetric detection and degradation of phenol in aqueous solutions.

Efficient degradation of perfluorooctanoic acid by electrospun lignin-based bimetallic MOFs nanofibers composite membranes with peroxymonosulfate under solar light irradiation.

Perfluorooctanoic acid (PFOA) has demonstrated potential toxicity to human health and has been detected in different environmental matrices due to its stable physical and chemical properties. To degrade PFOA under solar light irradiation, we fabricated a lignin/polyvinyl alcohol (PVA)/Co/Fe metal-organic frameworks (lignin/PVA/bi-MOFs) composite membrane via a typical electrospinning and in-situ solvothermal method for the catalytic degradation of PFOA. In the peroxymonosulfate (PMS)/membranes/solar light system, Electron paramagnetic resonance analysis (EPR) demonstrated the sulfate radicals (SO4-) and hydroxyl radicals (OH) were generated by activating PMS with transition metal and solar light irradiation. Lignin/PVA/bi-MOFs showed outstanding performance in that 89.6% of PFOA was degraded within 3 h under optimal conditions. Compared with that in solar light, only 59.6% PFOA was degraded in the dark, and the rate constant of PFOA degradation decreased from 0.0150 min-1 to 0.0046 min-1. Moreover, lignin/PVA/bi-MOFs were reused after simply rinsing with ultra-pure water and the degradation capacity of lignin/PVA/bi-MOFs remained at 77% after 4 cycles. The results might provide a new concept for the design of bimetallic MOFs for applications in organic pollutant removal.

Facile synthesis of a Co/Fe bi-MOFs/CNF membrane nanocomposite and its application in the degradation of tetrabromobisphenol A.

In this study, a sulfate radical-advanced oxidation process (SR-AOP) was proposed by utilizing a bimetallic Co/Fe metal-organic frameworks/cellulose nanofiber membrane (Co/Fe bi-MOFs/CNF) as a catalyst for TBBPA degradation. Sulfate radicals (SO4-) and hydroxyl radicals (OH·) were generated through the activation of peroxymonosulfate (PMS) by Co/Fe bi-MOFs/CNF. Co/Fe bi-MOFs/CNF was prepared by a facile solvothermal method and vacuum filtration. CNF acted as a natural substrates material to relieve the agglomeration of loaded MOFs. Additionally the composite membranes was easily separated from the reaction solution. The properties of the composite materials and the main factors that influenced TBBPA degradation were elucidated in detail, along with the TBBPA degradation intermediates, recyclability, and TBBPA degradation pathway. Almost 100 % of TBBPA was degraded within 30 min under optimal conditions, and the rate constant was determined to be 0.764 min-1. Furthermore, the degradation rate of the composite membrane was 60 % after 4 cycles.