Towards mass production of Au nanoparticles supported on montmorillonite microspheres for catalytic reduction of 4-nitrophenol

Abstract

Noble metals supported on substrates have been proven as highly efficient catalysts for the reduction of nitrocompounds. However, their large-scale applications are still limited by the problems of fouling and transport during the mass production process. Herein, we first fabricated a spherical montmorillonite (Mt) substrate via spray drying technique, followed by the deposition of Au NPs through polydopamine chemistry to synthesize spherical Au nanoparticles supported Mt (Au@Mt) microspheres. The Au loading is 14.5 wt%, whereas the specific surface area of the Au@Mt microspheres is 47.3 m 2 g −1 , endowing the prepared Au@Mt microspheres with excellent catalytic activity to the reduction of 4-nitrophenol (4-NP) in the presence of NaBH 4 with the optimized apparent reduction rate constant higher than 1.05 min −1. Furthermore, the microspheres can be easily recycled with self-sedimentation without any devices involved and showed excellent stability and recyclability for at least 20 cycles without almost unchanged spherical morphology and catalytic performance. Our straightforward strategy to solve the issue of the mass production process through granulation of amorphous nanomaterial substrate facilitates the practical application of these catalysts in the reduction of nitro-compounds.

Spherical montmorillonite-supported molybdenum disulfide nanosheets as a self-sedimentary catalyst for organic pollutants removal

“…The stacked Mt forms a porous structure and provides abundant surface areas to support active sites. In addition, the granular treatment can obviously enhance the transport ability during the productive process, facilitating mass prodution of these kinds of catalysts [36]. Furthermore, the density of the prepared granular Mt microsphere is much higher than the mixture, which can be self-sedimentary and easy recovered from the bottom.…”

Exfoliated Graphitic Carbon Nitride Nanosheets/Gold Nanoparticles/Spherical Montmorillonite Ternary Porous Heterostructures for the Degradation of Organic Dyes

“…As shown in Figure 4d, the catalytic process can be finished within 30 s and k app can reach 5.91 min −1 at a catalyst concentration of 250 mg•L −1 , a pH value of 11, and a temperature of 35 °C, which is much higher than those reported for other systems, e.g., Au-based catalyst (1.05 min −1 for SMt and 1.80 min −1 for Fe 3 O 4 and MgAlCe-LDH, respectively; Table 2). 29,39,40 In addition, the TOF of the SMt/g-C 3 N 4 /Au NPs heterostructures toward MB degradation was calculated as 302 h −1 , according to the moles of MB catalytically reduced per mole of Au NPs, which is also much higher than that reported for SMt (13.2 h −1 ) and Fe 3 O 4 (115 h −1 ), demonstrating the high catalytic performance of the synthesized 3D SMt/g-C 3 N 4 /Au NPs heterostructures. 29,39 3.4.…”

“…SMt was prepared using our previously reported method. 29 The synthesis of g-C 3 N 4 nanosheets was performed via calcination and ultrasonication from dicyandiamide. Typically, 10 g of dicyandiamide was introduced into a muffle furnace, and the temperature was raised to 550 °C within 4 h. The organic was calcined at this temperature for 4 h to obtain bulk g-C 3 N 4 .…”

“…Then the suspension was subjected to an ultrasound treatment for at least 2 h using an ultrasonic cell disruptor at 25 °C to obtain a canary-yellow suspension. Pyridinedithioethylamine (PDA)-coated SMt prepared by our previously reported method 29 was introduced to the canary-yellow suspension to obtain a mixture with a PDA-coated SMt concentration of 20 g•L −1 . After being shaken for 6 h, the product (SMt/g-C 3 N 4 ) was washed at least five times, respectively, with deionized (DI) water and DI water containing 25 wt % isopropyl alcohol.…”

Towards mass production of a spherical montmorillonite@covalent organic framework@gold nanoparticles heterostructure as a high-efficiency catalyst for reduction of methylene blue

“…In our previous work, porous spherical montmorillonite (SMt) prepared with the granulation of Mt. through spraydrying technology owning the characteristics of large surface area, strong adsorption ability, and outstanding acid-base stability (Wang et al, 2020;Xiao et al, 2018). Different from the pristine Mt.…”