Investigation Of Alkoxy Functionalized UiO-66 For The Adsorptive Removal Of Acetic Acid From Dilute Aqueous Solution

Every year,a large amount of low-concentration acetic acid wastewater was produced in China,which was very acidic and corrosive.The wastewater could not be directly discharged and required efficient treatment methods.In recent years,metal-organic framework materials with unique properties had attracted people’s attention,and had certain application potential in the fields of catalysis,membrane separation,and adsorption.A series of alkoxy groups are introduced to the UiO-66 structure to enhance its adsorption performance toward acetic acid in water.The adsorption kinetics,isotherm,thermodynamics,and regeneration of these adsorbents have been investigated,and the excellent adsorption capacity of n-propyloxy-substituted adsorbent(UiO-66-3)was illustrated.The kinetic results could be fitted well to the pseudo-second-order model.The adsorption isotherm followed the Langmuir isotherm,which indicated that the adsorption process involved a strong interaction between adsorbate and adsorbent.The thermodynamic parameters(ΔG,ΔH,and ΔS)had also been calculated,which verified that acetic acid adsorption on UiO-66-3 was a spontaneously endothermic process.In this paper,with the help of molecular simulation and various characterization methods,we explored the mechanism of the adsorption process,and it is proved that the introduction of alkoxy groups can effectively increase the adsorption capacity of acetic acid.The adsorption of acetic acid on UiO-66-3 was a complex multistep process,and the close contact between O of the ether bond of the adsorbent and H of the carboxyl group of acetic acid played an important role in adsorption.The adsorbent exhibited good stability under specified experimental conditions,which consolidated its potential as a solution to wastewater containing dilute acetic acid.