Abatement Of Contaminants Research Articles

Possible formation of long-lived photo-oxidants by photolysis of organic matter phenols in sunlit waters

AbstractPhotodegradation in sunlit waters is a major process of contaminant abatement, yet underlying chemical processes in the presence of dissolved organic matter are poorly known. Long-lived photo-oxidants are reactive species formed when the chromophoric dissolved organic matter absorbs sunlight, and they are involved in the degradation of contaminants. Previous works identified long-lived photo-oxidants with phenoxy radicals, which could be formed upon oxidation of natural phenols by the excited triplet states of chromophoric dissolved organic matter. Here, we generated reactive phenoxy radicals by direct ultraviolet-A photolysis of 2-nitrophenol and 4-nitrophenol. We measured the second-order rate constants for reaction of these phenoxy radicals with 2,4,6-trimethylphenol, a model electron-rich phenol. Results show rate constants of 9.39 × 108(M−1s−1) for the 2-nitrophenoxyl radical, and 1.56 × 108(M−1s−1) for the 4-nitrophenoxyl radical. These values are slightly lower than the typical rate constant of the reaction between 2,4,6-trimethylphenol and the excited triplet states of chromophoric dissolved organic matter, of 3 × 109(M−1s−1). This means that 2,4,6-trimethylphenol would not be degraded to comparable extents by the excited triplet states of chromophoric dissolved organic matter and by long-lived photo-oxidants, if long-lived photo-oxidants were generated solely by the triplet states of chromophoric dissolved organic matter. Overall, findings suggest the occurrence of new pathway involving the direct photolysis of organic matter phenols that generates long-lived photo-oxidants.

Ceramics as potential materials in pollution prevention and control

AbstractThe social progress, economic growth, and meteoric urbanization prompt the exploitation of available resources triggering the contagion of the biological and physical elements of the atmosphere irrationally causing global environmental pollution. Environmental contamination monitoring is a dire necessity. Although a number of technologies find mention in the literature for environmental remediation, however, environmental catalysis is an advanced steadily growing technique for pollution abatement. In this dimension, ceramic materials have turned heads due to their wide‐scale application areas. Hitherto, research is being done on advanced ceramics to fabricate novel modules for energy storage applications, in designing green buildings, pollution rheostats, and environmental engineering. This article deals with the abatement of environmental contaminants by adopting various methodologies such as aerobic and anaerobic biological treatments, adsorption, chemical oxidation, membrane separation, photocatalysis, ozonation using the ceramic as precursor materials. The ceramic membranes are cost‐effective, ecofriendly, efficacious, and green approach to obliterate toxins and harmful gases released in environment. Even though, limited literature is available on the abolition of harmful contaminants from air and soil using ceramic materials, an attempt has been made to present currently available data with best of our knowledge. This article will sensitize researchers to refabricate novel materials for environment sustainability.

Constructing Co3O4 nanosheet arrays anode as durable and efficient electrocatalyst for simultaneous chlorine evolution and carbamazepine degradation in the marine environment

The electrochemical chlorine evolution reaction (CER) is an essential and valuable technology for converting Cl− to Cl2 in industrial-scale applications. However, under the background of freshwater scarcity, seawater electrolysis for Cl2 generation becoming highly demanded. Meanwhile, pollutant degradation in the ocean is still challenging, especially in coastal and offshore seawaters. Herein, we provide a facile approach for constructing a highly efficient system for simultaneous Cl2 evolution and organic contaminant abatement utilizing Co3O4 nanosheet arrays decorated carbon cloth (Co3O4/CC) anode in the marine environment. The fabricated Co3O4/CC electrode achieved a considerably low potential of 1.55 V to reach a current density (j) of 10 mA cm−2 and long-term stability of 12 h at 100 mA cm−2 in seawater (pH = 2). Meanwhile, the practical environmental remediation results attested that the Co3O4 nanosheet arrays possess an outstanding Carbamazepine (CBZ) degradation efficiency of 100 % within 6 min accompanied with a k value of 0.358 min−1 in real seawater, demonstrating the integrity and reusability. The overall findings offer new insight into designing highly active CER catalysts with efficient pollutant degradation in the marine environment.

Confinement effect of FeMOFs glass enhances the proton coupled electron transfer reaction for the organic pollutants polymerization toward sustainable water purification

Polymerization-driven removal of pollutants in advanced oxidation processes (AOPs) offers a sustainable way for the simultaneous achievement of contamination abatement and resource recovery, supporting a low-carbon water purification approach. In this work, metal–organic frameworks (MOFs) glass complexes (g-ZIF-62@8) were used as a platform to enhance proton transfer through the confinement effect of nanopores, modulating proton coupled electron transfer (PCET) reaction to promote organic pollutant polymerization. The results show that the confinement effect of nanopores in ZIF-62 glass can significantly improve the proton and electron transfer behavior, the proton diffusion coefficient is increased by 4.9 times (2.91*10−3 to 1.43*10−2), the energy barrier of the PCET reaction can be reduced by 1.9 eV, and the reaction kinetic rate constant is increased from 0.0198 min−1 to 0.20118 min−1. Photogenerated holes and Fe(IV = O), as the main reactive oxygen species (ROS), undergo PCET reaction with Bisphenol A (BPA) to convert them into phenoxy radicals, which are then polymerized into macromolecular organic compounds. PCET with proton-electron synergy was identified as a key driver of pollutant polymerization. This enables low-carbon purification and organic carbon recovery in wastewater. Our work provides new insights into the application of confinement effects to enhance proton and electron behavior to regulate pollutant polymerization toward sustainable water purification.

Cu-optimized long-range interaction between Co nanoparticles and Co single atoms: Improved Fenton-like reaction activity

The interplay between multi-atom assembly configurations and single atoms (SAs) has been gaining attention in research. However, the effect of long-term range interactions between SAs and multi-atom assemblies on the orbital filling characteristics has yet to be investigated. In this context, we introduced copper (Cu) doping to strengthen the interaction between cobalt (Co) nanoparticles (NPs) and Co SAs by promoting the spontaneous formation of Co–Cu alloy NPs that tends toward aggregation owing to its negative cohesive energy (−0.06454), instead of forming Cu SAs. The incorporation of Cu within the Co–Cu alloy NPs, compared to the pure Co NPs, significantly expedites the kinetics of peroxymonosulfate (PMS) oxidation processes on Co SAs. Unlike Co NPs, Co–Cu NPs facilitate electron rearrangement in the d orbitals (especially dz2 and dxz) near the Fermi level in Co SAs, thereby optimizing the dz2–O (PMS) and dxz–O (SO5−) orbital interaction. Eventually, the Co–Cu alloy NPs embedded in nitrogen-doped carbon (CC@CNC) catalysts rapidly eliminated 80.67% of 20 mg L−1 carbamazepine (CBZ) within 5 min. This performance significantly surpasses that of catalysts consisting solely of Co NPs in a similar matrix (C@CNC), which achieved a 58.99% reduction in 5 min. The quasi in situ characterization suggested that PMS acts as an electron donor and will transfer electrons to Co SAs, generating 1O2 for contaminant abatement. This study offers valuable insights into the mechanisms by which composite active sites formed through multi-atom assembly interact at the atomic orbital level to achieve high-efficiency PMS-based advanced oxidation processes at the atomic orbital level.

The potential of coupled water electrolysis with electrochemical wastewater treatments

The coupled water electrolysis is a promising strategy for green hydrogen production. Pollutants are attractive feedstocks for the fungible anode reactions of the sluggish oxygen evolution reaction, with the advantages of trash-to-treasure and cost reduction. There is an urgent need for real waste sample tests from the view of both contaminant abatement and electrochemical hydrogen production. This work offers a systematic evaluation of the coupled water electrolysis with real wastewater, where four real wastewater with sulfur element compounds in different states are taken as examples. The technical and economic potentials are evaluated particularly based on the coupled water electrolysis performances, including cell voltage, current density, hydrogen production rate, hydrogen electricity consumption, and pollution abatement. The coupled water electrolysis with the refractory wastewater, e.g. the desulfurization wastewater from coal-fired power plants and the H acid wastewater, does not show advantages from the view of hydrogen production, due to the high overpotential and limited current density. Nevertheless, hydrogen is a high-value-added byproduct for operation cost reduction from the view of wastewater treatment. The readily oxidizable pollutants, e.g. sulfite and sulfide, exhibit notable potentials for anodic depolarization and electricity consumption reduction of hydrogen production. However, the coupled water electrolysis adopting the sulfide spent caustic stream may suffer a low hydrogen production rate for sulfide to sulfur. The coupled water electrolysis adopting sulfite wastewater indicates excellent potential for both space-time yield and electricity consumption for hydrogen production. This work may offer a reference for the systematic evaluation and selection of coupled water electrolysis with real wastewater.

Electrochemical processes for simultaneous sulfur and energy recoveries from sulfide-containing wastewater

Hydrogen sulfide and dissolved sulfide are notorious and lethal contaminants. The electrochemical process adopting the two-electron sulfide anodic oxidation reaction is an attractive strategy, which can simultaneously recycle and convert the chemical energy and sulfur resources into valued products. Sulfide pollutants are promising electron donors to reduce the electrochemical production cost, which is demonstrated in a sulfide/air fuel cell and a sulfide depolarized electrolyser. Sulfide oxidation behaviors are investigated on the developed IrxRu1-xO2 catalyst. A sulfide/air fuel cell is applied to evaluate the self-driven abilities of sulfur recovery and electricity generation. The sulfide/air fuel cell exhibits a notable discharge current density of > 120 mA cm−2 for 1.0 mol/L Na2S solution and 42.43 ± 1.94 mA cm−2 for the sulfide spent caustic stream. The potentials of sulfide anodic depolarization for electrochemical cost reduction are evaluated in a sulfide depolarized electrolyser for hydrogen production. Its open cell voltage is −0.33 V. For sulfur recovery, the cell can achieve about 20 mA cm−2 at 1.0 V, where the average energy cost of hydrogen production is about 2.39 kWh Nm−3. The sulfide removal rate is 0.26 ± 0.04 kgS m-2h−1, with an average current efficiency of 152.47 ± 28.59 %. This work may shed light on the potential of the incorporation of sulfide contaminants abatement and electrochemical productions.

Positive profile of natural small molecule organic matters on emerging antivirus pharmaceutical elimination in advance reduction process: A deep dive into the photosensitive mechanism of triplet excited state compounds

Natural small molecular organic matter (NSOM), ubiquitous in natural waters and distinct from humic acid or fulvic acid, is a special type of dissolved organic matter (DOM) which is characterized as strong photosensitivity and simple molecular structure. However, little study had been directed on the role of NSOM in eliminating emerging contaminants in advanced reduction process (ARP). This study took three small molecular isomeric organic acids (p−hydroxybenzoic acid, pHBA; salicylic acid, SA; m−hydroxybenzoic acid, mHBA) as the representative substances of NSOM to explore these mechanisms on promoting Ribavirin (RBV, an anti COVID−19 medicine) degradation in ultraviolet activated sulfite (UV/Sulfite) process. The results demonstrated that the observed degradation rate constant of RBV (kobs-RBV) was 7.56 × 10−6 s−1 in UV/Sulfite process, indicating that hydrated electron (eaq−) from UV/Sulfite process could not effectively degrade RBV, while it increased by 178 and 38 times when pHBA and SA were introduced into UV/Sulfite process respectively, suggesting that pHBA and SA strongly promoted RBV degradation while mHBA had no promotion on RBV abatement in UV/Sulfite process. Transient absorption spectra and reactive intermediates scavenging experiment indicated that the triplet excited state pHBA and SA (3pHBA* and 3SA*) contributed to the degradation of RBV through non−radical process. Notably, eaq− played the role of key initiator in transforming pHBA and SA into their triplet states. The difference of kobs-RBV in UV/Sulfite/pHBA and UV/Sulfite/SA process was attributed to different generation pathways of 3pHBA* and 3SA* (high molar absorptivity at the wavelength of 254 nm and photosensitive cycle, respectively) and their second order rate constants towards RBV (kRBV-3pHBA* = 8.60 × 108 M−1 s−1 and kRBV-3SA* = 6.81 × 107 M−1 s−1). mHBA could not degrade RBV for its lack of intramolecular hydrogen bond and low molar absorptivity at 254 nm to abundantly transform into its triplet state. kobs-RBV increased as pH increased from 5.0 to 11.0 in UV/Sulfite/SA process, due to the high yield of eaq− in alkaline condition which promoted the generation of 3SA* and the stable of the absorbance of SA at 254 nm. By contrast, kobs-RBV underwent a process of first increasing and then decreasing in UV/Sulfite/pHBA process as the increase of pH, and its highest value achieved in a neutral condition. This lied in the exposure of eaq− increased as the increase of pH which promoted the generation of 3pHBA*, while the molar absorptivity of pHBA at 254 nm decreased as the increase of pH in an alkaline condition which inhibited the yield of 3pHBA*. The RBV degradation pathways and products toxicity assessment indicated that UV/Sulfite/pHBA had better detoxification performance on RBV than UV/Sulfite/SA process. This study disclosed a novel mechanism of emerging contaminants abatement through non-radical process in NSOM mediated ARP, and provide a wide insight into positive profile of DOM in water treatment process, instead of only taking DOM as a quencher of reactive intermediates.

Pro-Environmental Transformation of Cultural Institutions through Sustainable Infrastructural Projects: A Case Study of Poznan

The aim of the article is to elucidate pro-environmental solutions and activities, consonant with the tenets of sustainability and enduring developmental paradigms, implemented within the infrastructural purview of the cultural institutions situated in Poznan—a municipality located in western Poland. A diagnostic scrutiny was executed encompassing the entirety of municipal cultural entities, constituting a cumulative assemblage of 15 establishments, all of which were extended invitations to participate in this investigation. Interrogations were directed towards ascertaining their strategic, environmentally conscientious determinations vis à vis the construction, renovation, or modernization of edifices during the temporal expanse of 2021 and 2022. Ultimately, responses germane to the posed inquiries were proffered by 7 institutions, as the remaining entities refrained from financial investments during the stipulated timeframe. The discerned outcomes illuminate the manifold pro-environmental measures and endeavors embraced by these institutions within the domain of infrastructural initiatives. These initiatives pertain to ecological considerations, safeguarding the natural milieu, and fortifying sustainability, encompassing facets such as energy and water conservation, the abatement of water and air contaminants, recycling endeavors, the utilization of renewable materials, the afforestation of vicinities, and the mitigation of the ostensibly designated “heat island effect”, among sundry others. These initiatives are not only significant for the current ecological situation worldwide, but they also appear to be crucial for the better future of the next generations.

Kinetic Model for Predicting Perfluoroalkyl Acid Degradation During UV-Sulfite Treatment.

Hydrated electron (eaq-) treatment processes show great potential in remediating recalcitrant water contaminants, including perfluoroalkyl and polyfluoroalkyl substances (PFAS). However, treatment efficacy depends upon many factors relating to source water composition, UV light source characteristics, and contaminant reactivity. Here, we provide critical insights into the complex roles of solution parameters on contaminant abatement through application of a UV-sulfite kinetic model that incorporates first-principles information on eaq- photogeneration and reactivity. The model accurately predicts decay profiles of short-chain perfluoroalkyl acids (PFAAs) during UV-sulfite treatment and facilitates quantitative interpretation of the effects of changing solution composition on PFAS degradation rates. Model results also confirm that the enhanced degradation of PFAAs observed under highly alkaline pH conditions results from changes in speciation of nontarget eaq- scavengers. Reverse application of the model to UV-sulfite data collected for longer chain PFAAs enabled estimation of bimolecular rate constants (k2, M-1 s-1), providing an alternative to laser flash photolysis (LFP) measurements that are not feasible due to the water solubility limitations of these compounds. The proposed model links the disparate means of investigating eaq- processes, namely, UV photolysis and LFP, and provides a framework to estimate UV-sulfite treatment efficacy of PFAS in diverse water sources.

Tailoring d-band center of high-valent metal-oxo species for pollutant removal via complete polymerization

Polymerization-driven removal of pollutants in advanced oxidation processes (AOPs) offers a sustainable way for the simultaneous achievement of contamination abatement and resource recovery, supporting a low-carbon water purification approach. However, regulating such a process remains a great challenge due to the insufficient microscopic understanding of electronic structure-dependent reaction mechanisms. Herein, this work probes the origin of catalytic pollutant polymerization using a series of transition metal (Cu, Ni, Co, and Fe) single-atom catalysts and identifies the d-band center of active site as the key driver for polymerization transfer of pollutants. The high-valent metal-oxo species, produced via peroxymonosulfate activation, are found to trigger the pollutant removal via polymerization transfer. Phenoxyl radicals, identified by the innovative spin-trapping and quenching approaches, act as the key intermediate in the polymerization reactions. More importantly, the oxidation capacity of high-valent metal-oxo species can be facilely tuned by regulating their binding strength for peroxymonosulfate through d-band center modulation. A 100% polymerization transfer ratio is achieved by lowering the d-band center. This work presents a paradigm to dynamically modulate the electronic structure of high-valent metal-oxo species and optimize pollutant removal from wastewater via polymerization.

Molybdenum nitride(γ-Mo2N) as a novel co-catalyst to enhance Fe(III)/Fe(II) cycle for homogeneous and heterogeneous peroxymonosulfate activation: Performance and mechanism

In this work, molybdenum nitride (γ-Mo2N) was investigated for the first time as a co-catalyst to accelerate the activation of PMS by enhancing iron cycling for the treatment of acid orange 7. γ-Mo2N/PMS/Fe3+ system showed excellent performance: 95% of acid orange 7 were highly degraded within 9 mins, and the γ-Mo2N proved to be stable and reusable after a 4-cycles experiment. The homogeneous Fe2+-activated PMS process was determined by testing the change in the concentration of iron species during the experiments. In addition, the heterogeneous activation of PMS by the iron retained on the catalyst surface was further determined by ICP-OES and the degradation effect of the *γ-Mo2N (used γ-Mo2N)/PMS system. In addition, the main active species for the homogeneous and heterogeneous activation of the PMS process were identified as hydroxyl radicals(⋅OH), sulfate radicals (SO4·-) and singlet oxygen (1O2) by EPR tests. Based on XPS, TEM and FT-IR analyses, a possible mechanism was proposed: Mo(III) and Mo(IV) play the role in the reduction of Fe3+, and γ-Mo2N forms Mo-N-O-Fe as well as Mo-N-Fe electron-transfer processes with iron in the reaction, which correspond to heterogeneous and homogeneous activation for PMS to achieve efficient degradation of the target. In summary, this work clarifies that γ-Mo2N can act as an efficient co-catalyst in the γ-Mo2N/PMS/Fe3+ system to accelerate the Fe(III)/Fe(II) cycle and thus promote homogeneous and heterogeneous PMS activation, which provides a promising γ-Mo2N co-catalyzed AOPs for rapid and efficient abatement of organic contaminants.

The efficient abatement of contaminants of emerging concern by LED-UV275nm/electrochemical chlorine for wastewater reuse: kinetics, degradation pathways, and cytotoxicity

Treating wastewater to augment surface water can be a practicable solution to water scarcity, while the residual contaminants of emerging concern (CECs) and inorganic ions put forward new requirements to the treatment methods. Electrochemical chlorine process (EC/Cl2) utilizes the remaining Cl− in wastewater to generate free chlorine and radicals, which could be further improved in conjunction with LED UV275nm irradiation (UV-EC/Cl2). Compared to UV only and EC/Cl2, UV-EC/Cl2 could effectively decompose the selected CECs at higher rates due to the much higher yield of reactive chlorine species (Cl•, ClO•, and Cl2•−). A MATLAB R2021a programming method was developed to estimate the order of magnitude of these radicals, and Cl2•− was the most abundant radical. In the UV-EC/Cl2 system, CECs with phenolic or aniline moieties were mainly degraded by electrochemical oxidation (EC), ClO•, and Cl2•−; and the CECs with weakly electron-donating moieties were predominately decomposed by EC, •OH, and Cl•. The degradation pathways of levofloxacin, diclofenac, carbamazepine (CBZ), and ibuprofen were proposed according to the transformation products (TPs) detected by LC/Q-TOF-MS. Moreover, the cytotoxicity of spiked CBZ in real water samples, that were discharged to surface water, was significantly reduced by UV-EC/Cl2. Interestingly, the electrical energy per order (EE/O) for CBZ decomposition by LED UV275nm-EC/Cl2 (1.46 kWh m−3 order−1) is lower than that by UV/Cl2, EC/Cl2, and UV254nm-EC/Cl2. The results indicate that UV-EC/Cl2 could be used as a promising method to remediate CECs during the tertiary treatment and reuse of wastewater for augmenting surface water.

Abatement of Nitrophenol in Aqueous Solution by HOCl and UV/HOCl Processes: Kinetics, Mechanisms, and Formation of Chlorinated Nitrogenous Byproducts

HOCl and UV activated HOCl (UV/HOCl) have been applied for water disinfection and abatement of organic contaminants. However, the production of toxic byproducts in the HOCl and UV/HOCl treatment should be scrutinized. This contribution comparatively investigated the elimination of 4-nitrophenol and the generation of chlorinated byproducts in HOCl and UV/HOCl treatment processes. 61.4% of 4-nitrophenol was removed by UV/HOCl in 5 min with HOCl dose of 60 μM, significantly higher than that by UV (3.3%) or HOCl alone (32.0%). Radical quenching test showed that HO• and Cl• played important roles in UV/HOCl process. 2-Chloro-4-nitrophenol and 2,6-dichloro-4-nitrophenol were generated consecutively in HOCl process; but their formation was less in the UV/HOCl process. Trichloronitromethane (TCNM) was only found in the UV/HOCl process, and its production increased with increasing HOCl dosage. Besides chlorinated products hydroxylated and dinitrated products were also identified in the UV/HOCl process. Transformation pathways involving electrophilic substitution, hydroxylation, and nitration were proposed for 4-nitrophenol transformation in the UV/HOCl process. Wastewater matrix could significantly promote the transformation of 4-nitrophenol to 2-chloro-4-nitrophenol in UV/HOCl process. Results of this study are helpful to advance the understanding of the transformation of nitrophenolic compounds and assess the formation potential of chlorinated byproducts in HOCl and UV/HOCl disinfection processes.

Using the inherent elements in yeast biomass to produce Ni2P/N-doped biocarbon composites for efficient hexavalent chromium reduction.

The heterogeneous catalytic reduction of Cr(VI) to Cr(III) is an effective strategy for aqueous Cr(VI) contamination abatement, which requires the development of highly efficient, low-cost, and recyclable catalysts. Herein, Ni2P/N-doped biocarbon composites (Ni2P/N-BC) were fabricated through an anoxic pyrolysis process using NaCl and KCl as activators. A precursor of yeast biomass provided the essential C, N, and P elements for Ni2P/N-BC formation. When adopted for Cr(VI) reduction in the presence of oxalic acid as a reductant, the fabricated Ni2P/N-BC performed superior catalytic activity with a 100% Cr(VI) reduction efficiency within 10 min (Ni2P/N-BC-5 = 0.2 g L-1, oxalic acid = 0.4 g L-1, Cr(VI) = 20 mg L-1). Typical affecting parameters, e.g., catalyst dosage, oxalic acid loading, reaction temperature, initial solution pH, and water matrix, were investigated. Ni2P/N-BC exhibited good applicability in a broad pH range from 3.0 to 9.0 and in actual aquatic systems. Cr(VI) reduction efficiency remained 92.7% after five recycle runs. Such promising catalytic activity may originate from the well-crystallized Ni2P, N-doped biocarbon framework and high specific surface area of the materials. Preliminary reaction mechanism analysis indicated that the favorable charge state of Ni2P, fast hydrogen transfer, affinity of oxalic acid to Cr(VI), and inherent electron transfer in the biocarbon matrix contributed to effective Cr(VI) reduction. This work not only provides a facile and low-cost strategy to construct Ni2P/N-doped biocarbon nanosheet composite using environmentally benign biomass but also brings new insights for the remediation of Cr(VI) contamination.

Cobalt(II) mediated calcium sulfite activation for efficient oxidative decontamination in waters: Performance, kinetics and mechanism

To overcome the drawback that excess SO32− from soluble Na2SO3 captures the generated reactive intermediates in sulfite (S(IV))-based advanced oxidation processes (AOP), CaSO3 of the ability to slowly release SO32− is selected as an alternative S(IV) source to establish an enduring S(IV)-based AOP with Co(II). Herein, the Co(II)/CaSO3 process triggers a much better ofloxacin (OFL) degradation than the Co(II)/Na2SO3 process (degradation rate constant: 12.1 > 3.18 mM−1 min−1). The mechanism investigation corroborates that the Co(II) mediated CaSO3 activation follows a Fenton-like process (complexation followed by intramolecular electron transfer). Apart from the conventional sulfate radical (SO4•−), Co(IV) species and singlet oxygen (1O2) are also certifiably involved in Co(II)/CaSO3 process, and their role and formation mechanisms are elucidated comprehensively. Further, the proposed Co(II)/CaSO3 process exhibits an excellent tolerance to complex water matrices (e.g., background ions and humic acid), suggesting its practical application potential for various contaminants abatement in actual wastewater.

Carbon nitride exfoliation for photocatalysis and photocatalytic ozonation over emerging contaminants abatement

The production of graphitic carbon nitride was studied with the addition of a following exfoliation step using ultrasounds, at different times. The treatment produced catalysts with much higher surface areas, from 2.18 m2 g−1 with no treatment to 28.34 m2 g−1 after 36 h of exfoliation. During exfoliation, melem was also produced, and may further enhance the photoluminescence and photocatalytic properties. The photocatalytic reaction also indicated the improved performance of exfoliated g-C3N4 towards the degradation of a mixture of parabens, enhancing their removal from 20% to up to 65% in 2 h under UVA radiation. The combination of ozone and g-C3N4 photocatalysis was able to completely remove the parabens in under 8 min and with a 20% lower consumption of ozone compared to photolytic ozonation. The main reactive species were identified, and the by-products formed during parabens degradation were detected. The efficiency of the combined system was also attested by using a mixture of parabens and other common drugs, maintaining its better performance.

High efficiency 2D/0D/3D Z-scheme rGO@g-C3N4/TiO2 nanobelt-tubes heterojunction for tetracycline degradation under visible light: Electrochemical synthesis, performance, and mechanisms

Photocatalytic water treatment is drawing attention for the abatement of organic contaminants with solar energy. Herein, an immobilized rGO@g-C3N4/TiO2 nanobelt-tubes (GCTs) heterojunction photocatalyst coating on titanium plates was fabricated via implementable anodizing and electrodeposition technology and systematically investigated their morphologies and photoelectrochemical properties. The GCTs held the unique 2D/0D/3D sandwich-like nanobelt-tubes arichitecture, perfect visible light absorption (400–500 nm) performance, and high charge transfer capacity, which contributed to the enhancement photocatalytic activity and recyclability for tetracycline degradation, particularly under visible light irradiations. The optimal GCTs photocatalyst showed higher photocatalytic degradation efficiency (81.46 %) compared to pure TiO2 (62.77 %). Photocatalytic activity of GCTs only suffered a small decrease in tetracycline degradation efficiency after 6 operation cycles, from 81.46 % to 76.06 %. Z-scheme interfacial charge transfer mechanism operates for the GCTs during photocatalytic degradation, as authenticated by in situ X-ray photoelectron spectroscopy, quenching tests and electron spin resonance spectra. The tetracycline degradation efficiency was enhanced under alkaline conditions from 35.17 % to 71.11 %. The degradation pathways were also clarified based on HPLC/MS analysis, and the overall toxicity of tetracycline was effectively mitigated after photodegradation. The GCTs photocatalyst provide an effective strategy for the photocatalytic degradation of antibiotics in natural waters.

Can a UV-C box help the cinema industry by disinfecting video cameras?

UV-C has proven to be an effective virucide and microbicide, and its cost-effectiveness allowed it to spread as a disinfecting procedure in different environments. The study aims to determine the microbicide activity on Staphylococcus aureus, Escherichia coli and SARS-CoV-2 of the UV-C Boxer by Cartoni S.p.A. Three separate experiments were performed to assess the effectiveness of the UV-C disinfection device on different materials, directly on surfaces of a video camera and on a specific carrier for SARS-CoV-2. In all three experiments, a significant abatement of bacterial and viral contamination was reached after 60 seconds on carriers and after 3 minutes on all examined surfaces of the video camera, with a higher reduction on glass carriers. UV-C devices may be a valuable tool to implement in the working routine to achieve a higher level of safety in work environments.

Enhanced tetracycline abatement by peracetic acid activation with sulfidation of nanoscale zerovalent iron.

Iron-based heterogeneous catalysts due to the environmental friendliness have been widely studied for activation of peracetic acid (PAA) for abatement of organic contaminants in the water and wastewater treatment. However, the slow reduction from Fe(III) to Fe(II) of the iron-based catalysts as the rate-limiting step results in the low PAA activation efficiency. With regard to the excellent electron-donating capability of the reductive sulfur species, sulfidized nanoscale zerovalent iron is proposed for PAA activation (simplified as the S-nZVI/PAA process) and the tetracycline (TC) abatement efficacy and mechanism of this process are elucidated. The optimal sulfidation ratio (S/Fe) of S-nZVI is 0.07, which exhibits superior performance in PAA activation for TC abatement with the efficiency of 80-100% in the pH range of 4.0-10.0. The radical quenching experiments and oxygen release measurements confirm that acetyl(per)oxygen radicals (CH3C(O)OO•) are the main radical contributing to TC abatement. The influence of sulfidation on the crystalline structure, hydrophobicity, corrosion potential, and electron transfer resistance of S-nZVI is evaluated. The main sulfur species on the S-nZVI surface are identified as ferrous sulfide (FeS) and ferrous disulfide (FeS2). The analysis by X-ray photoelectron spectroscopy (XPS) and Fe(II) dissolution suggest that the reductive sulfur species can accelerate the conversion from Fe(III) to Fe(II). In summary, the S-nZVI/PAA process exhibits application prospects for the abatement of antibiotics in the aquatic environments.