Activated PDS of Single-Atom-Fe(III): Nonradical Oxidation of Pollutants

Prof. Jiang et al., from (1. Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China; 2. University of Chinese Academy of Sciences, Beijing, China, 3. Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, China) and their research collaboration team have reported on the single-atom Fe(III)- and nitrogen doped carbon (Fe−N−C) which can eﬃciently activate peroxydisulfate (PDS) to selectively remove some organic pollutants following an unreported nonradical pathway.

Generally, PDS is used as an oxidant for the degradation of polluted water/soil, it generates sulfate radical intermediate for the degradation pollutants, and this radical unselectively reacts with most of the substances in water/soil. PDS can be activated by base, heat, UV, low valent transition metal ions (e.g., Co^2+, Fe^2+, Cu^2+, and Ag⁺), and zero valent iron to produce a sulfate radical (SO₄^•−). All these PDS activation processes consume extensive energy or chemicals. Also, it is found that PDS is much cheaper and does not significantly reduce water pH upon addition. Sulfate radical is not preferred for purification of water. Therefore, recent research focus on the PDS activation without generating radicals is preferred to maximize its oxidation capacity for targeted pollutants.

This research work was published in Environmental Science & Technology on October 23, 2020 [1]. They find a new pathway for the degradation of pollutants without sulfate radicals, particularly, the coordinated Fe(III) is readily converted to Fe(V) through two-electron abstraction by PDS, and Fe(V) is responsible for the selective degradation of organic pollutants. The selectivity of the PDS/Fe−N−C oxidation process was examined with various pollutants, the PDS activation clearly follows a nonradical pathway. The highly dispersed Fe(III) sites on the Fe−N−C were proposed and converted to Fe(V) for pollutant degradation. This new approach is more effective than sulfate radical formation and also other reported nonradical oxidation like PDS/CuO under the same experimental conditions. This approach is also used to selectively degrade some organic pollutants through PDS activation.

Figure 1. Mechanism of nonradical oxidation of pollutants by single-atom-Fe(III) activated PDS [1].

If we use chlorinated water for purification process, chloride consumes a sulfate radical to produce a chlorine radical (Cl₂^•−), which not only reduces the oxidation potential toward pollutants but also produces hazardous chlorinated by-products [2]. Therefore, to avoid sulfate radical formation approach, a new approach is needed for water purification system with PDS. Lee et al., proposed similar approach that PDS can be attached to carbon nanotubes (CNTs) and react with phenolic compounds [3]. CNTs posses a high specific surface area (200−500 m²g⁻¹), however, their effectiveness for PDS activation still needs to be improved further.

Single-atom catalysts (SACs), with active metal sites dispersed in the single-atom state, have attracted a greater attention and wide interest in recent years for catalytic reactions. Some of the SACs were reported for the catalytic application with good efficiency. Particularly, a single cobalt-atom catalyst (Co−N−C), metal and nitrogen co-doped carbon materials [M−N−Cs (M = Fe, Co, Mn, etc.,)] and Fe(III)-doped g-C₃N has been successfully prepared, which showed good activity in peroxymonosulfate (PMS) activation. Also, the SACs have utilized its metal sites, that shows an excellent catalytic activity, structural stability and becomes a frontier in catalysis, especially for hydrogen evolution, oxygen reduction, and CO₂ conversion. These results inspired us to search for an appropriate M−N−C to activate for the cheaper PDS.

As an ﬁrst attempt, Jiang et al. and his team have apply a single atom Fe(III) for eﬀective PDS activation without generating radicals. Further, they have prepared single atom site of Fe−N−C characterized by Aberration-corrected high-angle annular dark-ﬁeld scanning transmission electron microscopy, X-ray adsorption spectra (XAS) including X-ray adsorption near-edge structure (XANES) and extended X-ray adsorption ﬁne structure (EXAFS).

Oxidation of pollutants was tested with batch reactions. They used phenol, bisphenol A, chlorophenols, sulfamethoxazole, atrazine, benzoic acid, EDTA, p-chloro benzoic acid, and benzothiazole to test the selectivity of the PDS/Fe−N−C-coupled oxidation. Further, they observed that all the compounds were degraded in this process except for benzothiazole, p-chloro benzoic acid, and benzoic acid. Benzoic acid and p-chloro benzoic acid have low reactivity possibly because of no substituent group existing at their α-C, which is not favorable for Fe(V) attack. Because of the high stability of the thiazole ring, benzothiazole was barely degraded here. The selectivity also shows that PDS/Fe−N−C has lower oxidation power as compared with sulfate and hydroxyl radicals.

Important points regarding environmental significance of this research work:

The single-atom Fe(III) material, Fe−N−C, can eﬃciently activate PDS to degrade some organic pollutants.
The PDS activation follows a nonradical pathway with Fe(V) as the possible intermediate oxidant for pollutant removal.
This reported SACs were used for the remediation of polluted groundwater and soil, and the treatment of drinking water and some industrial wastewater without any toxicity.
A low dosage of the Fe−N−C can achieve relatively high eﬃciency in pollutant degradation.

Our SNB team recommended this research article to enrich our viewer’s knowledge to know about the single-atom Fe(III)- and nitrogen doped carbon (Fe−N−C) can eﬃciently activate PDS to selectively remove some organic pollutants followed with an unreported nonradical pathway. The research studies showed that PDS can be activated while not generating radicals, that is, the pollutants can be degraded just through electron transfer to PDS. Hence, the future work is needed to develop an low cost approaches to obtain a large amount of single-atom Fe−N−C materials (e.g., through pyrolysis of biosolids) and to investigate the selectivity of the PDS/Fe−N−C oxidation and the transformation pathway of pollutants.

References

N. Jiang, et al., Environ. Sci. Technol. (2020) https://dx.doi.org/10.1021/acs.est.0c04867.
T. Zhang, et al., Environ. Sci. Technol. 48, 5868 (2014).
H. Lee, et al., Chem. Eng. J. 266, 28 (2015).

Blog Written By

Dr. A. S. Ganeshraja

Assistant Professor

National College, Tiruchirappalli

Tamil Nadu, India

Author Profile

Editors

Dr. K. Rajkumar

Dr. S. Chandrasekar

Reviewers

Dr. Y. Sasikumar

Dr. S. Thirumurugan

Dr. K. Vaithinathan

Comments

Electro-Organic Synthesis: Next Emerging Technique

Industrial developments, excessive energy consumption, sustainable technologies, environmental cleaning processes are major topics of political and social discourse. Current innovations are rated not only focusing on their benefit and utility but also concerning their eco-friendly approaches. The development of green technological processes is becoming more important and requires harmless energy sources. Particularly over the past decade, the severe limitations of fossil resources intensify the movement towards sustainable synthesis techniques with a strict cutback in the ecological footprint [ 1 ]. Electro-organic synthesis belongs to the synthetic organic chemistry discipline that facilities the direct use of electricity to generate valuable compounds. Hence, it is possible to transfer green aspects of sustainable energy sources to the whole production process [ 2 ]. Since the Kolbe’s discoveries of using electricity as a reagent for organic transformations over 170 years ago, ...

Designing of Corrosion Resistant Alloys via Percolation Theory

Canada and USA Scientists have reported on designing of corrosion-resistant alloys via percolation theory and published in Nature Materials on 01 February 2021. Nickel–chromium, Iron–chromium binary alloys can serve as the prototypical corrosion-resistant metals owing to its presence of a nanometre-thick protective passive oxide film. The main key criterion for good passive behavior is the passive film should be compromised via a scratch or abrasive wear that can be reformed with a little metal dissolution. This could be a principal reason for the stainless steels and other chromium containing alloys that are used for critical applications which ranges from nuclear reactor components to biomedical implants. A long-standing unanswered question in corrosion science is the unravelling of the compositional dependence of the electrochemical behavior of the alloys [ 1, 2 ]. The discovery of the family of these alloys were increased its rate with the advent of artificial intelligence, da...

AN ACT OF FACE MASK MATERIAL USED TO PROTECT US FROM SARS-COV-2

“ In the absence of a vaccine, or effective antiviral, one of our only remaining strategies for controlling COVID-19 is to physically block the spread of SARS-CoV-2 in the community ” On 11 March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a global pandemic [1] . In the absence of a vaccine, or effective antiviral, one of our only remaining strategies for controlling COVID-19 is to physically block the spread of SARS-CoV-2 in the community. Given that COVID-19 is a respiratory illness, the most effective physical defense likely involves widespread public use of face coverings, in conjunction with other control measures [ 2 ] . Face coverings (also variously referred to as face masks, nonmedical masks, community masks or barrier masks ) function primarily in source control; capturing droplets expelled by an infected individual [3] . Figure 1. DIY masks to protect against from viruses sounds like a crazy idea. source click here In the absence of an...

Electric Vehicle: Public Health and Climate Benefits

A research team led by Daniel Peters at Northwestern University has investigated that if we introducing electrifying vehicles in the streets of the United States could annually prevent hundreds-to-thousands of premature accidental deaths.This work highlights the potential of a synergistic solution to reduce CO 2 emissions by hundreds to millions of tons annually. The estimate of economic damages induced by introducing electrifying vehicles (EV) adoption is substantial. With current infrastructure, about 25% of electrifying vehicles adoption in the US can save approximately $16.8 billion annually, has been told in the study entitled"Public Health and Climate Benefits and Trade offs of U.S. Vehicle Electrification," in GeoHealth on 13 th August 2020 [1] . Vehicle electrification in the United States could prevent hundreds to thousands of premature deaths annually while reducing carbon emissions by hundreds of millions of tons. This highlights the potential of co-beneficial...

Novel Approach of Plastic Waste to Flash Graphene

Prof. Algozeeb and his research collaboration team have investigated an novel approach of upcycling plastic waste (PW) products to flash graphene (FG). This method relies on Flash Joule Heating (FJH) to convert PW into FG. A sequential direct current (DC) and alternating current (AC) flash is used in order to make a high-quality graphene. In this FJH process, they established without catalyst and works for PW mixtures that can make the process suitable for handling landfill PW. In 21 st century, PW pollution is considerable one among the various environmental issues. A very large fraction of PW ends up in the ocean, which leads to the formation of micro- and nanoplastics that threaten marine life, micro-organisms, useful bacteria, and humans. From the intense carbon footprint process, most of these synthesized plastics are used only once before dumping into landfills or water ways that terminate in the oceans. Hence, upcycling PW to higher value materials and chemicals is econ...

PROSPECTS ON PHOTOBIOREFINERY

Very recently, Prof. Dr. K. Faungnawakij and his research group have summarized a mini review report on an emerging renewable technique of Photobiorefinery . This is one of the beyond technique of Artificial Photosynthesis (AP) [1] . Despite great promises, AP technologies for solar H2 production and CO2 reduction are far uncompetitive to other promising technologies at the current stage . However, despite an enormous effort, time, and budget paid on AP-related researches throughout several decades, AP technologies have struggled to strive beyond laboratory demonstration except a very few exceptions [2] . This bitter reality makes the translation of this excellent science to practical application questionable [3] . Technoeconomic analysis shows that without achieving the aggressive technology targets, this technology will not be commercially viable. This has directed the research community towards the development of highly efficient yet expensive devices. While tremendous p...

Electromagnetic Field: Non-Chemical Water Treatment Technology

An interesting review report on “A critical review of the application of electromagnetic fields for scaling control in water systems: mechanisms, characterization, and operation” was reported by Lu Lin, Wenbin Jiang, Xuesong Xu and Pei Xu published in Nature Partner Journals Clean Water published on June 2020 [1] . Water is the precious matter in the world. source U.S. General Services Administration has interested on non-chemical water treatment technologies. It has mentioned following important points: n on-chemical technology promises to increase the period between required blow-down cycles, thus reducing water consumption , minimizes associated issues of chemical storage, handling, and disposal, and may permit on-site re-use of cooling-tower “blow-down” water as “grey water” , it promises to be life cycle cost effective based solely on the reduction in chemical costs , this technology may reduce or eliminate chemical costs, it may not reduce other contractor costs ...

Single-Atom Catalysis in Chemistry World

The recent interest on the heterogeneous single-atom catalysts (SACs) were composed of atomically dispersed active metal cen ters in catalyst research field, because of the increased atom utilization and unique catalytic properties of such materials, which differ greatly from those of conventional nano or subnano counter parts. In this case, the fabrication of SACs are challenging, especially in the case of noble metal based catalysts and many researches are ongoing in this field for the development of improved catalysts. Many chall enges have faced for the hybridization of controlling of single atoms in suitable host materials, but it has also equally opened with unique opportunities for catalyst design. SACs with atomically dispersed active metal centers on supports represent an intermediary between heterogeneous and homogeneous catalysis. Therefore, understanding the homogeneous catalysis prototype creates a great opportunity for designing SACs and developing related applications....

A Novel Green Synthesis of Au/TiO2 Nanocomposites

Prof. Lahiru A. Wijenayaka, Sri Lanka Institute of Nanotechnology (SLINTEC), Mahenwatte, Pitipana, Homagama, Sri Lanka and his collaboration team has reported on the interesting materials for effective environmental alternative remediation via nontoxic, low cost and eco-friendly methods dedicated to the scientific community. Here, a novel, facile, and green synthetic approach to synthesize gold nanoparticle decorated over TiO 2 (Au/TiO 2 ) nanocomposites for sustainable environmental development has been discussed [ 1 ] . Based on various metal oxide semiconductor (MOS) photocatalysts, titanium dioxide (TiO 2 ) is the most widely used, owing to its effective and excellent results in optical transmittance, high refractive index, chemical stability, concurrently being stable, nontoxic, and inexpensive [ 2 ]. They are highlighted with the following points: (i) Synthesis of the Au/TiO 2 nanocomposite, (ii) Microscopic characterization, (iii) Dye adsorption on Au/TiO 2 and (iv) Photoca...

Postdocs Crisis: The "Last Generation" of Scientists

Postdoctoral Researchers play a vital role in the research productivity of several countries and serving as leaders, mentors, guides, teachers, and scientists. These researchers have developed their own skills and preparing themself for their scientific research careers with various research groups worldwide. Even performing in a short term, they need to spend additional years in some special cases for succession in their research careers. Senior research investigators or leaders who have promised to their younger colleagues or students for a long term contract in the academics should find a new pathway to make it possible to stay and plan for their long-term career. Also, these investigators should be more flexible, patience, and supportive for everyone in their research groups. But the main key point which they should focus on that was the researchers who want to pursue fulfilling careers in science elsewhere need to be supported in all means, whatever matters, whoever may be, the ta...

Search This Blog