In a study published in the Journal of Hazardous Materials, nanoparticles of manganese(III) oxide (Mn2O3) were anchored to the pores of attapulgite (APT) nanoscale fibers by an embedding and on-site precipitative process to form catalyst ceramic nanofiber membranes (Mn@CNMs) for the degradation of water contaminants.
Study: Ceramic nanofiber membrane anchoring nanosized Mn2O3 catalytic ozonation of sulfamethoxazole in water. Image Credit: Christos Georghiou/Shutterstock.com
The Threat Posed by Sulfamethoxazole
Water shortage has been identified as a worldwide concern due to population expansion and economic growth. A broad range of emerging contaminants (ECs) have been discovered in diverse bodies of water thus far.
Sulfamethoxazole (SMX), a common example of ECs, is widely found in aquatic environments, endangering human wellbeing and water ecosystems. Unfortunately, typical water treating systems are inefficient in removing ECs. As a result, it is critical to create successful EC removal technology.
Breaking Down Contaminants with AOPs
Advanced oxidative processes (AOPs) are frequently employed to break down emerging pollutants by creating highly reactive species of oxygen such as ⋅OH, O2-, and SO4-. Among the AOPs, the non-uniform catalyzed ozonation procedure has received much interest in its ability to destroy emerging contaminants.
Several metallic oxide particles (Fe3O4, Al2O3, TiO2, CeOx, and MnOx) have been extensively researched in the non-uniform catalyzed ozonation procedure to date. Owing to manganese ions' high oxidation reduction capacity, MnOx has been shown to be an excellent catalyst.
Strengths and Weaknesses of Ceramic Membranes for Catalytic Ozonation
The agglomeration of MnOx nanoparticles (NPs) regrettably leads to a decrease in accessible active spots and a reduction in catalytic performance. Furthermore, the reuse of nanoscale catalysts in suspension takes a while and limits practical uses.
Lately, non-uniform catalyzed ozonation combined with ceramic membrane filtering has been described as a viable approach for overcoming the above-mentioned problems.
The high porosity ceramic layer is ideal for supporting catalytic NPs, eliminating the need for NP reuse while also improving mass transference. The traditional ceramic layer comprised of Al2O3 particles, on the other hand, is comparatively less porous.
Furthermore, catalyst ceramic membranes were often made by impregnation with predecessors or co-sintering with a combination of catalytic particles and innocuous substrates. Under heat stress, catalytic NPs tend to agglomerate and expand to a larger size during the procedure, which is detrimental to catalytic performance.
Attapulgite can Overcome Limitations of Catalytic Ceramic Membranes
Attapulgite (APT), an organic fibrous clay, was utilized to create a ceramic nanofiber membrane (CNM) with excellent permeability and porosity. APT also has a great number of nanoscale pits on its exterior. These pits may act as physical barriers and anchorage points to limit the development of catalytic NPs.
Highlights of the Study
Catalyst ceramic nanofibrous membranes (Mn@CNMs) were created and used in an integrative catalyzed ozonation/membrane filtering procedure by attaching manganese(III) oxide NPs to the pits of APT nanoscale fibers.
The developed 0.05Mn@CNM-500 demonstrated better SMX removing ability, with up to 81.3 percent of SMX eliminated in seven hours of uninterrupted running. The quenching studies and electron paramagnetic resonance data supported the involvement of 1O2, ⋅OH, and O2- in the catalyst setup, and 1O2 may serve a major role in the breakdown of SMX.
Salient Features of Prepared Ceramic Nanofiber Membranes
Mn@CNM demonstrated a broad application for natural water systems, with the complete elimination of several ECs in actual hospital sewage water reaching 98.5 percent. The enhanced effectiveness of Mn@CNM may be attributed to the following important synergistic factors.
APT nanoscale pits successfully inhibited the agglomeration and development of Mn2O3 NPs, improved reaction site access, and improved catalyzed ozonation.
The interwoven APT nanofibers generated nanoscale network topologies in which reactive oxygen species (ROS) and SMX molecules were trapped in close proximity, increasing the likelihood of ROS attacking SMX.
The improved Mn(III)/Mn(IV) oxidation reduction cycles induced by engagement among Mn2O3 catalysts and APT targets gave Mn@CNM higher catalysis stability and allowed for the long-term elimination of SMX throughout continuous filtering.
Conclusions
The use of nanoscale pits on attapulgite nanofibers as anchorage points for catalytic NPs in this study is a unique technique for producing remarkably effective catalyst ceramic membranes.
This technique may be used to create various catalyst ceramic films built on cost-effective and organic mineral resources with nanoconfinement architectures. This inspirational work encourages the use of ceramic films in water filtration.
Reference
Yang, Y., Fu, W., Chen, X., Chen, L., Hou, C., Tang, T., & Zhang, X. (2022). Ceramic nanofiber membrane anchoring nanosized Mn2O3 catalytic ozonation of sulfamethoxazole in water. Journal of Hazardous Materials, 436. Available at: https://doi.org/10.1016/j.jhazmat.2022.129168
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