Developing new materials and novel
technologies for the highly
efficient treatment of toxic organic pollutants is highly desirable.
Chemical reduction based on heterogeneous substrate/noble metal catalysts
and the reducing agent NaBH4 has become an effective method
in recent years. Here, a spherical covalent organic framework (SCOF)
was designed to provide basic sites for Ag ions, by which small Ag
NPs were immobilized on the SCOF to form Ag NPs@SCOF microspheres.
The prepared microspheres exhibited a high catalytic reduction ability
toward 4-nitrophenol (4-NP). An optimized permeation flux of 2000
L m–2 h–1 (LMH) and a more than
99% 4-NP reduction efficiency were obtained with flow-through experiments,
which are far better than the reported results (below 200 LMH). Moreover,
the microspheres could maintain stable catalytic performance under
a continuous flow-through process. Our work provides an efficient
material and technology that can be applied to easily treat toxic
organic pollutants.
Water-soluble organic carcinogenic pollutants have become a serious threat to both health and environment. Here, porous ternary spherical montmorillonite/exfoliated graphitic carbon nitride nanosheets/gold nanoparticles (SMt/g-C 3 N 4 /Au NPs) heterostructures were facile and green synthesized through a polydopamine chemistry method. These involved the coating of porous SMt with exfoliated g-C 3 N 4 nanosheets and in situ growth of Au NPs. The prepared heterostructures exhibited a universal catalytic ability toward organic dyes, such as methylene blue (MB), rhodamine 6G, and Congo red, in the presence of sodium borohydride (NaBH 4 ). The catalytic activity would improve under high SMt/g-C 3 N 4 /Au NPs concentration, high temperature, and high pH values. For example, the apparent reduction rate constant (k app ) and turnover frequency (TOF) toward MB can reach 5.91 min −1 and 302 h −1 , respectively, at 35 °C and pH values of 11. Furthermore, the influences of the pH values on the catalytic performance were investigated, and the reason can be attributed to the strong enhanced adsorption capacity of SMt/g-C 3 N 4 /Au NPs heterostructures toward organic dyes under the high pH values for facilitating electron transfer from NaBH 4 to organic dyes. Moreover, the SMt/g-C 3 N 4 /Au NPs heterostructures were quite stable, being recycled at least 10 times with almost unchanged k app . The excellent catalytic performance and recyclability recommend our synthesized SMt/g-C 3 N 4 /Au NPs heterostructures for a wide range of applications in environment and wastewater treatment.
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