Manganese oxide integrated catalytic ceramic membrane for degradation of organic pollutants using sulfate radicals

Abstract

Membrane separation and advanced oxidation processes (AOPs) have been respectively demonstrated to be effective for a variety of water and/or wastewater treatments. Innovative integration of membrane with catalytic oxidation is thus expected to be more competing for more versatile applications. In this study, ceramic membranes (CMs) integrated with manganese oxide (MnO2) were designed and fabricated via a simple one-step ball-milling method with a high temperature sintering. Functional membranes with different loadings of MnO2 (1.67%, 3.33% and 6.67% of the total membrane mass) were then fabricated. The microstructures and compositions of the catalytic membranes were investigated by a number of advanced characterisations. It was found that the MnO2 nanocatalysts (10-20 nm) were distributed uniformly around the Al2O3 particles (500 nm) of the membrane basal material, and can provide a large amount of active sites for the peroxymonosulfate (PMS) activation which can be facilitated within the pores of the catalytic membrane. The catalytic degradation of 4hydroxylbenzoic acid (HBA), which is induced by the sulfate radicals via PMS activation, was investigated in a cross-flow membrane unit. The degradation efficiency slightly increased with a higher MnO2 loading. Moreover, even with the lowest loading of MnO2 (1.67%), the effectiveness of HBA degradation was still prominent, shown by that a 98.9 % HBA degradation was achieved at the permeated side within 30 min when the initial HBA concentration was 80 ppm. The stability and leaching tests revealed a good stability of the catalytic membrane even after the 6 th run. Electron paramagnetic resonance (EPR) and quenching tests were used to investigate the mechanism of PMS activation and HBA degradation. Both sulfate radicals (SO4˙−) and hydroxyl radicals (˙OH) were generated in the catalytic membrane process. Moreover, the contribution from non-radical process was also observed. This study provides a novel strategy for preparing a ceramic membrane with the 3 function of catalytic degradation of organic pollutants, as well as outlining into future integration of separation and AOPs.

Recent Manganese Oxide Octahedral Molecular Sieves (OMS–2) with Isomorphically Substituted Cationic Dopants and Their Catalytic Applications

“…In this review, we focus on cryptomelane, and from now on this material will be named as K-OMS-2. 8. Counter cations located in the tunnels (A) will compensate the charge imbalance of the system.…”

“…In this regard, it is important to note that it is extremely difficult to find pure Mn oxides with a single oxidation state, provided that as a general rule, different oxidation states will usually coexist in the same structure [2]. As informative data, the three most prominent manganese oxide forms (MnO, Mn 3 O 4 and MnO 2 ) have been applied in the fields of wastewater treatment [6][7][8], catalysis [9][10][11][12][13][14], supercapacitors [15][16][17], storage devices [18][19][20][21], medical agents [22][23][24], etc. Among these oxides, manganese oxide (IV), MnO 2 , is probably one of the most important oxides since it has important physical-chemical properties, such as an easily 2 of 34 exchangeable multiple oxidation state, a thermally stable structural form, a high grade of polymorphism and low cost and benignity with the environment [25][26][27][28].…”

Polysulfone Ultrafiltration Membrane Promoted by Brownmillerite SrCuxCo1–xO3−λ-Deposited MCM-41 for Industrial Wastewater Decontamination: Catalytic Oxidation and Antifouling Properties

“…The reactive oxygen species produced in the course of filtration are capable of mineralizing and partially oxidizing the recalcitrant organic pollutants into the small molecular compounds of less safety concern. , In this regard, soluble organic matter degradation and membrane fouling alleviation can be achieved in a single unit . Moreover, such a combination can immobilize the catalyst, thereby avoiding the tedious catalyst recycling process . Among the integrated AOPs, PMS-based AOPs have gained a growing attention for superiorities of mild reaction conditions and mighty oxidation property .…”

“…13 Moreover, such a combination can immobilize the catalyst, thereby avoiding the tedious catalyst recycling process. 14 Among the integrated AOPs, PMS-based AOPs have gained a growing attention for superiorities of mild reaction conditions and mighty oxidation property. 15 For example, Bao et al reported a catalytic ceramic membrane with impregnated Co 3 O 4 .…”

Pd Nanoparticles Loaded on Ceramic Membranes by Atomic Layer Deposition with Enhanced Catalytic Properties

“…Atomic layer deposition (ALD) for membrane-forming technology alternately pulses the vapor into the reaction chamber and allows the target species chemisorb on the surface of the carrier. , ALD has been widely used in microelectronics, − optoelectronics, − nanotechnology, , batteries, energy, organic electronic packaging, , separation membranes, , electrocatalysis, and organic pollutant degradation . In recent years, a large number of catalytic materials have been prepared by ALD.…”