Synthesis And Adsorption Properties Of Metal-Organic Frameworks(Zr,Fe,Al) And Their Composites

In recent years,a large amount of phosphorus-containing wastewater has been released into the water environment system due to large-scale production and excessive use of pesticides,detergents and fertilizers.Excessive phosphate accelerates the eutrophication of the water,worsens water quality and destroys the local ecological balance and hinders social and economic development.Water pollution caused by excessive discharge of heavy metals poses a serious threat to the entire ecosystem and public health.Adsorption is one of the most effective methods to solve the problems of eutrophication and heavy metal ions pollution.Therefore,the development of efficient and feasible adsorbents is the key to solve water pollution.However,existing adsorbents such as biological adsorbents,activated carbon,mineral materials,etc.have the disadvantages of poor adsorption selectivity,small adsorption capacity,difficult to recycle and may cause secondary pollution,etc.,which cannot solve the increasingly serious water pollution problem.Based on the above analysis,we need to rationally design the adsorbent material to significantly improve its sewage treatment capacity and achieve economic,healthy and sustainable development.In summary,Zr-based MOFs(UiO-66)with reasonable structural design and size control are prepared for practical eutrophication.The phosphate adsorption performance and adsorption mechanism are explored.Besides,bimetallic Fe/Mg-MOFs with controlled morphology(Fe/Mg-MIL-88B)are prepared for arsenate removal,meanwhile the adsorption performance and mechanism of arsenate are explored.Furthermore,NH2-MIL-53/wood-carbon hybrid membrane(NH2-MIL-53/WC)and lignosulfonate functionalized g-C3N4/carbonized wood sponge(LS-C3N4/CWS)are prepared for lead,cadmium and copper removal.The adsorption performance as well as adsorption mechanism of NH2-MIL-53/WC and LS-C3N4/CWS on the heavy metals are investigated.Finally,bacterial cellulose-based composite filters are synthesized for multiple pollutants remove.The main results are concluded as follows:1.Eutrophication of water bodies caused by the excessive phosphate discharge has constituted a serious threat on a global scale.It is imperative to exploit new advanced materials featuring abundant binding sites and high affinity to achieve highly efficient and specific capture of phosphate from polluted waters.Herein,water stable Zr-based metal-organic frameworks(UiO-66)with rational structural design and size modulation have been successfully synthesized based on a simple solvothermal method for effective phosphate remediation.Impressively,the size of the resulting UiO-66 particles can be effectively adjusted by simply altering reaction time and the amount of acetic acid with the purpose of understanding the crucial effect of structural design on the phosphate capture performance.Representatively,UiO-66 particles with a size of 30-70 nm demonstrate 415 mg/g of phosphate uptake capacity,outperforming most of the previously reported phosphate adsorbents.Meanwhile,the developed absorbents can rapidly reduce highly concentrated phosphate to below the permitted level in drinking water within a few minutes.More significantly,the current absorbents display remarkable phosphate sorption selectivity against the common interfering ions,which can be attributed to strong affinity between Zr-OH groups in UiO-66 and phosphate species.Furthermore,the spent UiO-66 particles can be readily regenerated and reused for multiple sorption-desorption cycles without obvious decrease in removal performance,rendering them promising sustainable materials.Hence,the developed UiO-66 adsorbents hold significant prospects for phosphate sequestration to mitigate the increasingly eutrophic problems.2.The rational design of metal-organic frameworks with tailored components and structural features is crucial for achieving the desired functions and expanding the emerging applications.Herein,water-stable bimetallic Fe/Mg bimetallic metal-organic frameworks(Fe/Mg-MIL-88B)have been successfully fabricated through a facile and effective one-step strategy to access the exceptional arsenic decontamination.Notably,the obtained bimetallic Fe/Mg-MIL-88B architectures are demonstrated to possess a well-defined spindle-like morphology.Interestingly,the Fe/Mg molar ratios within the resultant Fe/Mg-MIL-88B frameworks can be flexibly modulated on demand,leading to the variation of the structural features associated with length/diameter ratio and unit cell parameters along with surface areas.Thanks to the unique structural and compositional merits as well as the synergetic contribution from two active metal centres,the fabricated Fe/Mg-MIL-88B nanospindles exhibit enhanced decontaminant performance toward arsenate in terms of ultrafast sorption kinetics and high sorption capacities,compared to the monometallic Fe-MIL-88B.Impressively,an extraordinary arsenate uptake capacity up to 303.6 mg/g is achieved in the optimized Fe/Mg-MIL-88B with Fe/Mg feeding ratio of 0.5,which is substantially superior to most of the reported arsenic absorbents.More significantly,these Fe/Mg-MIL-88B absorbents possess exceptional regenerative ability and stability during multiple sorption-desorption cycles,as reflected by the negligible drop in arsenic removal efficiency and excellent maintenance of the crystalline structure and morhttps phology integrity.All these satisfactory results prefigure that the designed bimetallic Fe/Mg-MIL-88B absorbents hold a great promise for the in-depth purification of arsenic-contaminated water.3.Designing the desirable architecture for highly efficient sequestration of heavy metal ions is of paramount importance to ensure water safety.Herein,highly dense cuboid-like NH2-MIL-53 crystals have been in-situ immobilized on porous wood-carbon(WC)substrate(denoted as NH2-MIL-53/WC)based on a self-sacrificial template strategy.Benefiting from the perfect integration of unique 3D hierarchical pore structures,abundant binding sites and specific sorption affinity of amino functional groups in NH2-MIL-53 toward Pb2+,the resulting NH2-MIL-53/WC hybrid membrane exhibits exceptional Pb2+ decontamination capability in terms of high uptake capacity,fast removal kinetics and superior selectivity in the presence of competing ions.Meanwhile,the macroscopic-sized monolithic shape is competent for facile separation,overcoming the inherent limitations of conventional nanosorbents.Furthermore,the as-fabricated monolithic membrane can be further assembled into a home-made filter system for continuous-flow wastewater purification,accompanied by an efficient treatment capacity of 2200 kg wastewater(spiked with 10 ppm Pb2+)per kg sorbent,while restricting the Pb2+ level in the effluent below the World Health Organization limit(10 ppb).Such intriguing Pb2+ sequestration performance in both static and flowing states render the proposed NH2-MIL-53/WC hybrid membrane to hold huge prospects for the practical wastewater remediation.4.Wood-based absorbents possess important engineering significance in removing toxic heavy metals from wastewater due to their natural abundance,sustainability and biodegradability together with superior sorption performance.Herein,a novel adsorbent,lignosulfonate functionalized g-C3N4/carbonized wood sponge(denoted as LS-C3N4/CWS)has been successfully fabricated through pyrolysis of urea impregnated wood sponge under argon atmosphere,followed by subsequent modification by lignosulfonate(LS).As expected,the resulting LS-C3N4/CWS shows excellent decontaminant capability toward Pb2+,Cd2+and Cu2+with high uptake capacity of 659.6,329.1 and 173.5 mg/g,respectively,outperforming most of previously reported wood-based adsorbents and other nanomaterials.Moreover,the spent LS-C3N4/CWS can be readily recovered and maintain high removal efficiency after ten absorption-regeneration cycles,displaying excellent recyclability.Significantly,LS-C3N4/CWS can be directly utilized as the ultrafiltration membrane to continuously treat large volumes of simulated wastewater to below the permitted level in drinking water.The superior decontamination performance coupled with facile separation,cost-effectiveness and no secondary pollution underscores huge potential of LS-C3N4/CWS in removing effectively heavy metals from polluted waters.5.Bacterial cellulose has a resistant network structure,strong hydrogen bonding strength,excellent film-forming performance,high tensile strength and elastic modulus,and strong hydration.It is widely used in adhesives,thickeners,high-strength paper,etc.Here,the prepared bacterial cellulose slurry was fully mixed with nanomaterials(UiO-66,Fe-MIL-88B,MoS2,MnO2,MgO)after the cultured bacterial cellulose wet film was beaten and dispersed.The results showed that the prepared bacterial cellulose-based composite membrane retains the adsorption properties of pure nanomaterials.Therefore,the hydrogen bond of the hydroxyl groups on the cellulose macromolecules is used to form a functional thin membrane by simple vacuum filtration.Based on above the analysis,bacterial cellulose-based membrane has extremely strong development prospects.