Ordered mesoporous materials for water pollution treatment:Adsorption and catalysis

To meet the growing emission of water contaminants,the development of new materials that enhance the efficiency of the water treatment system is urgent.Ordered mesoporous materials provide opportunities in environmental processing applications due to their exceptionally high surface areas,large pore sizes,and enough pore volumes.These properties might enhance the performance of materials concerning adsorption/catalysis capability,durability,and stability.In this review,we enumerate the ordered mesoporous materials as adsorbents/catalysts and their modifications in water pollution treatment from the past decade,including heavy metals(Hg^(2+),Pb^(2+),Cd^(2+),Cr^(6+),etc.),toxic anions(nitrate,phosphate,fluoride,etc.),and organic contaminants(organic dyes,antibiotics,etc.).These contributions demonstrate a deep understanding of the synergistic effect between the incorporated framework and homogeneous active centers.Besides,the challenges and perspectives of the future developments of ordered mesoporous materials in wastewater treatment are proposed.This work provides a theoretical basis and complete summary for the application of ordered mesoporous materials in the removal of contaminants from aqueous solutions.

Different Synthesis Methods for Ordered Mesoporous Silicas And Their Characteristics Comparison

Ordered mesoporous silica were synthesized under different conditions:hydrothermal synthesis in basic medium,room temperature synthesis in acid medium and sol gel synthesis in neutral medium,and pore structure,specific surface area and pore size distribution of samples were studied and compared in detail by means of SAXRD,HRTEM,BET,FT IR.The results show that the mesopores in the samples obtained via above three methods all possess uniform hexagonal arrays in short range.Mesoporous silica obtained in acid medium possesses narrow pore size distribution centered around 1.24nm with specific surface area of 1220 m 2·g -1 ;Mesoporous silica obtained in basic medium by hydrothermal synthesis at 160℃ possesses narrow pore size distribution centered around 1.90nm with specific surface area of 542.8 m 2·g -1 ;and mesoporous silica obtained in neutral medium by sol gel synthesis possesses broader pore size distribution centered around 4.01nm,specific surface area of 485.0 m 2·g -1 .Therefore,ordered mesoporous silicas with different pore sizes can be prepared using various synthetic methods and conditions.After heat treatment,Si O Si bending vibration strengthens and the adsorption peak of asymmetrical Si O Si stretching vibration broadens,and the crosslinking and condensation reaction of silica skeleton strengthen, meanwhile the amount of active centers of hydroxyl group on the surface of mesopores may be influenced,thus chemical assembly activity of mesopores may also be influenced.

Single-atom catalysts supported on ordered porous materials:Synthetic strategies and applications

Single-atom catalysts(SACs)are attracting extensive attention due to their incredibly catalytic activity and selectivity,high utilization of metal atoms,and obvious cost reduction.The unique ordered porous materials(OPMs)are promising carriers for stabilizing single atoms due to their large surface areas and uniformly tunable pore sizes.Meantime,the geometric and electronic structures of single-atom metals can be tuned by the interaction between the single-atoms(SAs)and OPMs to enhance the catalytic activity of SACs.The SACs based on OPMs,such as zeolites,metal-organic frameworks,and ordered mesoporous materials,have been developing fast recently.Herein,we review recent advancements on structural feature,synthetic strategy,characterization technique,and catalytic applications of OPMs-based SACs.The opportunities and challenges about SAs/OPMs are also provided to develop the novel catalysts with superior catalytic performances in the future.