Supercritical CO₂‐assisted formation of metal–organic framework‐loaded porous polystyrene membranes for dye removal

Abstract

Metal–organic frameworks (MOFs) are efficient adsorbents for the removal of hazardous materials. An MOF based on 1,3,5‐benzenetricarboxylic acid (BTC), Cu3(BTC)2, is prepared via phase separation using supercritical CO2 (scCO2) as a nonsolvent for the polymer solution. The prepared MOF is then loaded onto microporous polystyrene membranes. To evaluate the performance of Cu3(BTC)2‐loaded microporous polystyrene membranes for pollutant removal from water, they are tested for the separation of methylene blue (MB) dye from an aqueous solution. Prior to the preparation of the Cu3(BTC)2‐loaded microporous polystyrene membranes, Cu3(BTC)2 is activated with scCO2. After the activation with scCO2, the internal surface area of Cu3(BTC)2 and its MB adsorption increase. A toluene solution of polystyrene containing Cu3(BTC)2 particles is prepared, and scCO2 is introduced to induce the phase separation of the polymer solution. A Cu3(BTC)2‐loaded microporous polystyrene membrane is obtained without the collapse of the structure after the release of the CO2 pressure. MB can be readily and rapidly removed from aqueous solutions using Cu3(BTC)2‐loaded microporous polystyrene membranes. The removal efficiencies for aqueous MB solution were high, and removal efficiencies reached 92.8%.

PdRu Bimetallic Nanoparticles/Metal–Organic Framework Composite through Supercritical CO2–Assisted Immobilization

“… 31 Currently, drying with scCO 2 is used to improve the pore stabilities of the MOFs. 32 − 35 Recently, immobilization techniques using catalytically active bimetallic NPs assisted by scCO 2 have been considered for the preparation of porous carbon and silica materials. 36 − 38 …”

“…The morphology of the products could be improved by varying the operating temperature, pressure, contact time, and CO 2 volume rate. , ScCO 2 can surpass the diffusivity and mass transfer limitations of conventional solvents and load sufficient amounts of target materials, such as metal precursors, into the pores and MOF surfaces . Currently, drying with scCO 2 is used to improve the pore stabilities of the MOFs. − Recently, immobilization techniques using catalytically active bimetallic NPs assisted by scCO 2 have been considered for the preparation of porous carbon and silica materials. − …”

Synthesis, characterization, and photocatalytic activity for water remediation and hydrogen evolution of Zn(II) and Ni(II) bis(thiosemicarbazone) complexes

“…1,2 Currently, the approaches to dye removal mainly depend on traditional biological, physical, and chemical techniques, such as precipitation, coagulation, adsorption, filtration, membrane separation, or biodegradation, but they are far from satisfactory, mainly due to cost control and harmless processing. [3][4][5][6] To solve this problem, different photocatalytic approaches are being developed to remove pollutants from wastewater, due to their potential to degrade and mineralize toxic organic dyes into less harmful compounds such as H 2 O, CO 2 , and NO 3 À . [7][8][9] Among the different possible photocatalysts, transition metal-based coordination compounds have given rise to diverse and flexible ways of promoting photocatalytic efficiency.…”

“…Due to their extensive use in many types of industries, one of the most widespread water contaminants are organic dyes, which are reported to be responsible for respiratory toxicity and cancer 1,2 . Currently, the approaches to dye removal mainly depend on traditional biological, physical, and chemical techniques, such as precipitation, coagulation, adsorption, filtration, membrane separation, or biodegradation, but they are far from satisfactory, mainly due to cost control and harmless processing 3–6 . To solve this problem, different photocatalytic approaches are being developed to remove pollutants from wastewater, due to their potential to degrade and mineralize toxic organic dyes into less harmful compounds such as H 2 O, CO 2 , and NO 3 − 7–9 .…”