Sulfamethoxazole (SMX) is a broad-spectrum antibiotic and was largely used in breeding industry. The reaction rate of SMX with KMnO4 is slow, and the adsorption efficiency of biochar for SMX was ...inferior (less than 11% in 30 min). By adding biochar powder into SMX solution with the addition of permanganate, the oxidation ratio of SMX surged to 97% in 30 min, and over 58% of the total organic carbon (TOC) was simultaneously removed. KMnO4 interacted with biochar and resulted in the formation of highly oxidative intermediate manganese species, which transformed SMX into hydrolysis products, oxygen-transfer products, and self-coupling products. Brunauer–Emmett–Teller (BET) analysis showed that surface area, total pore volume, and micropore volume of biochar increased by 32.1%, 36.4%, and 80.6%, respectively, after reaction process. This in situ activation of biochar with KMnO4 enhanced its adsorption capacity and led to great improvement of TOC removal. Besides KMnO4 oxidation, biochar also enhanced TOC removal in Mn(III) oxidation (KMnO4+ bisulfite) and ozonization of SMX. Considering that KMnO4 could react with biochar and result in the formation of intermediate manganese species, while biochar can be simultaneously activated and exhibit high capacity for organic adsorption, the combination of biochar with the chemical/advanced oxidation could be a promising process for the removal of environmental pollutants.
•Ferrate self-decomposition is also a self-activation process forming Fe(V) species•Fe(V) species was the major oxidant during excess ferrate oxidation•Fe(VI) oxidation is not influenced by phosphate ...while Fe(V) oxidation was inhibited•Both in situ formed and external Fe(III) promoted the Fe(V) oxidation
To reveal the role of ferrate self-decomposition and the fates of intermediate iron species Fe(V)/Fe(IV) species during ferrate oxidation, the reaction between ferrate and methyl phenyl sulfoxide (PMSO) at pH 7.0 was investigated as a model system in this study. Interestingly, the apparent second-order rate constants (kapp) between ferrate and PMSO was found to increase with ferrate dosage in the condition of excess ferrate in borate buffer. This ferrate dosage effect was diminished greatly in the condition of excess PMSO where ferrate self-decomposition was lessened largely, or counterbalanced by adding a strong complexing ligand (e.g. pyrophosphate) to sequester Fe(V) oxidation, demonstrating that the Fe(V) species derived from ferrate self-decomposition plays an important role in PMSO oxidation. A mechanistic kinetics model involving the ferrate self-decomposition and PMSO oxidation by Fe(VI), Fe(V) and Fe(IV) species was then developed and validated. The modeling results show that up to 99% of the PMSO oxidation was contributed by the ferrate self-decomposition resultant Fe(V) species in borate buffer, revealing that ferrate self-decomposition is also a self-activation process. The direct Fe(VI) oxidation of PMSO was impervious to presence of phosphate or Fe(III), while the Fe(V) oxidation pathway was strongly inhibited by phosphate complexation or enhanced with Fe(III). Similar ferrate dosage effect and its counterbalance by pyrophosphate as well as the Fe(III) enhancement were also observed in ferrate oxidation of micropollutants like carbamazepine, diclofenac and sulfamethoxazole, implying the general role of Fe(V) and promising Fe(III) enhancement during ferrate oxidation of micropollutants.
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Ferrate (K2FeO4) is a powerful oxidant and up to 3 mol of electrons could be captured by 1 mol of ferrate in the theoretical conversion of Fe(VI)–Fe(V)–Fe(IV)–Fe(III). However, it is reported ...that the utilization efficiency of the ferrate oxidation capacity is quite low because of the rapid autodecomposition of intermediate iron species, which negatively influences the potential of ferrate on organic pollutants control. We accidentally found that for the ferrate oxidation of carbamazepine (CBZ), bisphenol S (BPS), diclofenac (DCF), and ciprofloxacin (CIP), the determined reaction rate constants were 1.7–2.4 times lower in phosphate buffer than those in borate buffer at pH 8.0. For the reaction of ferrate with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) at pH 7.0, the determined reaction stoichiometries were 1:1.04 in 100 mM phosphate buffer, 1:1.18 in 10 mM phosphate buffer, and 1:1.93 in 10 mM borate buffer, respectively. The oxidation ability of ferrate seems depressed in phosphate buffer. A kinetic model involving the oxidation of ABTS by Fe(VI), Fe(V) and Fe(IV) species was developed and fitted the ABTS•+ formation kinetics well under different buffer conditions. The results showed that phosphate exhibited little influence on the oxidation ability of Fe(VI) and Fe(IV) species, but decreased the specific rate constants of ABTS with Fe(V) species by 1–2 orders of magnitude, resulting in the outcompeting of Fe(V) autodecomposition pathway. The complexation between phosphate anions and Fe(V) species may account for the inhibition effect of phosphate buffer. Considering that many studies regarding ferrate oxidation were carried out in phosphate buffer, the actual oxidation ability of ferrate may be underestimated.
Manganese ion Mn(II) is a background constituent existing in natural waters. Herein, it was found that only 59% of bisphenol A (BPA), 47% of bisphenol F (BPF), 65% of acetaminophen (AAP), and 49% of ...4-tert-butylphenol (4-tBP) were oxidized by 20 μM of Fe(VI), while 97% of BPA, 95% of BPF, 96% of AAP, and 94% of 4-tBP could be oxidized by the Fe(VI)/Mn(II) system 20 μM Fe(VI)/20 μM Mn(II) at pH 7.0. Further investigations showed that bisphenol S (BPS) was highly reactive with reactive iron species (RFeS) but was sluggish with reactive manganese species (RMnS). By using BPS and methyl phenyl sulfoxide (PMSO) as the probe compounds, it was found that reactive iron species contributed primarily for BPA oxidation at low Mn(II)/Fe(VI) molar ratios (below 0.1), while reactive manganese species Mn(VII)/Mn(III) contributed increasingly for BPA oxidation with the elevation of the Mn(II)/Fe(VI) molar ratio (from 0.1 to 3.0). In the interaction of Mn(II) and Fe(VI), the transfer of oxidation capacity from Fe(VI) to Mn(III), including the formation of Mn(VII) and the inhibition of Fe(VI) self-decay, improved the amount of electron equivalents per Fe(VI) for BPA oxidation. UV–vis spectra and dominant transformation product analysis further revealed the evolution of iron and manganese species at different Mn(II)/Fe(VI) molar ratios.
Bisphenol S (BPS), as a main alternative of bisphenol A for the production of industrial and consumer products, is now frequently detected in aquatic environments. In this work, it was found that ...free chlorine could effectively degrade BPS over a wide pH range from 5 to 10 with apparent second-order rate constants of 7.6–435.3 M−1s−1. A total of eleven products including chlorinated BPS (i.e., mono/di/tri/tetrachloro-BPS), 4-hydroxybenzenesulfonic acid (BSA), chlorinated BSA (mono/dichloro-BSA), 4-chlorophenol (4CP), and two polymeric products were detected by high performance liquid chromatography and electrospray ionization-tandem quadrupole time-of-flight mass spectrometry. Two parallel transformation pathways were tentatively proposed: (i) BPS was attacked by stepwise chlorine electrophilic substitution with the formation of chlorinated BPS. (ii) BPS was oxidized by chlorine via electron transfer leading to the formation of BSA, 4CP and polymeric products. Humic acid (HA) significantly suppressed the degradation rates of BPS even taking chlorine consumption into account, while negligibly affected the products species. The inhibitory effect of HA was reasonably explained by a two-channel kinetic model. It was proposed that HA negligibly influenced pathway i while appreciably inhibited the degradation of BPS through pathway ii, where HA reversed BPS phenoxyl radical (formed via pathway ii) back to parent BPS.
•BPS could be effectively degraded by chlorine over pH of 5–10 (kapp 7.6–435.3 M−1s−1).•A total of eleven products were detected by HPLC/ESI-QTOF-MS.•Two parallel pathways (electrophilic substitution & electron transfer) were proposed.•Inhibitory effect of HA on degradation was explained by a two-channel kinetic model.•HA had negligible effect on product species in chlorination of BPS.
With the development of artificial intelligence, neural network provides unique opportunities for holography, such as high fidelity and dynamic calculation. How to obtain real 3D scene and generate ...high fidelity hologram in real time is an urgent problem. Here, we propose a liquid lens based holographic camera for real 3D scene hologram acquisition using an end-to-end physical model-driven network (EEPMD-Net). As the core component of the liquid camera, the first 10 mm large aperture electrowetting-based liquid lens is proposed by using specially fabricated solution. The design of the liquid camera ensures that the multi-layers of the real 3D scene can be obtained quickly and with great imaging performance. The EEPMD-Net takes the information of real 3D scene as the input, and uses two new structures of encoder and decoder networks to realize low-noise phase generation. By comparing the intensity information between the reconstructed image after depth fusion and the target scene, the composite loss function is constructed for phase optimization, and the high-fidelity training of hologram with true depth of the 3D scene is realized for the first time. The holographic camera achieves the high-fidelity and fast generation of the hologram of the real 3D scene, and the reconstructed experiment proves that the holographic image has the advantage of low noise. The proposed holographic camera is unique and can be used in 3D display, measurement, encryption and other fields.
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•Reaction of ABTS with equimolar amounts of Fe(VI) produced Fe(V) as the only high valent iron intermediate.•Reaction of ABTS with excess Fe(VI) underwent a two-stage oxidation via ...the ABTS+ intermediate.•H2FeVIO4 species was responsible for the further oxidation of the generated ABTS+ to ABTS2+ via one-electron transfer.•HFeVIO4 species resulted in the oxidative degradation of the formed ABTS+.
This work investigated the reaction of 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) with Fe(VI) in phosphate buffer, in a wide concentration range of Fe(VI), to ascertain the potential influence of Fe(VI) on the type and fate of the high valent iron intermediate. The reaction of ABTS with equimolar amounts of Fe(VI) stopped at the formation of ABTS+, accompanied by the complete reduction of Fe(VI) to produce Fe(V) as the only high valent iron intermediate, thereby providing a model system involving Fe(V) alone. Even in the presence of the target compound (propranolol, methyl phenyl sulfoxide and carbamazepine), Fe(VI) was also completely transformed to Fe(V) rather than to oxidize the target compound. Thus, the observed degradation of the target compound was caused by Fe(V) alone, confirming the feasibility of the reaction as a model system involving Fe(V) only. Comparatively, the formation of ABTS+ (Stage I) and its further oxidation by Fe(VI) (Stage II) was found in the reaction of ABTS with excess Fe(VI). Stage II produced one-electron transfer product (i.e., ABTS2+) only in the case of pH ≤ 5 (k = 2.55 × 105 M−1s−1, pH = 4) while proceeded oxidative degradation rather than one-electron transfer in the pH range of 6–8 (k = 2.33 × 103 M−1s−1, pH = 7). Based on the distribution of the speciation of Fe(VI) species, H2FeO4 was confirmed to be the active species for one-electron transfer path while HFeO4- species was responsible for the oxidative degradation. Correspondingly, Fe(VI) was transformed to Fe(V) or Fe(IV), which did not react with other intermediates (i.e., ABTS+ and ABTS2+).
Reducing nosocomial transmission within health care facilities is important, but the number of negative-pressure airborne infection isolation rooms for SARS-CoV-2 (severe acute respiratory syndrome ...coronavirus 2) is limited. It is a daunting challenge to cope with a surge of suspected infectious patients in hospitals. We installed air exhaust fans on the windows to change the pressure direction within the wards rapidly. The best location for the fans was 90 cm from the floor and 90 cm from the edge of bed whether the indoor air conditioners were on or off. The noise level should be <60 dB(A) as per government regulations. General wards can be transformed into makeshift negative-pressure rooms easily and effectively within 24 hours, which is really the simple, fast, and effective way for the transformation being applied.
The chromogenic reaction between 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and ferrate Fe(VI) has long been utilized for Fe(VI) content measurement. However, the presence of ...electron-rich organic compounds has been found to significantly impact Fe(VI) detection using the ABTS method, leading to relative errors ranging from ∼88 to 100%. Reducing substances consumed ABTS•+ and resulted in underestimated Fe(VI) levels. Moreover, the oxidation of electron-rich organics containing hydroxyl groups by Fe(VI) could generate a phenoxyl radical (Ph•), promoting the transformation of Fe(VI) → Fe(V) → Fe(IV). The in situ formation of Fe(IV) can then contribute to ABTS oxidation, altering the ABTS•+:Fe(VI) stoichiometry from 1:1 to 2:1. To overcome these challenges, we introduced Mn(II) as an activator and 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic agent for Fe(VI) detection. This Mn(II)/TMB method enables rapid completion of the chromogenic reaction within 2 s, with a low detection limit of approximately 4 nM and a wide detection range (0.01-10 μM). Importantly, the Mn(II)/TMB method exhibits superior resistance to reductive interference and effectively eliminates the impact of phenoxyl-radical-mediated intermediate valence iron transfer processes associated with electron-rich organic compounds. Furthermore, this method is resilient to particle interference and demonstrates practical applicability in authentic waters.The chromogenic reaction between 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and ferrate Fe(VI) has long been utilized for Fe(VI) content measurement. However, the presence of electron-rich organic compounds has been found to significantly impact Fe(VI) detection using the ABTS method, leading to relative errors ranging from ∼88 to 100%. Reducing substances consumed ABTS•+ and resulted in underestimated Fe(VI) levels. Moreover, the oxidation of electron-rich organics containing hydroxyl groups by Fe(VI) could generate a phenoxyl radical (Ph•), promoting the transformation of Fe(VI) → Fe(V) → Fe(IV). The in situ formation of Fe(IV) can then contribute to ABTS oxidation, altering the ABTS•+:Fe(VI) stoichiometry from 1:1 to 2:1. To overcome these challenges, we introduced Mn(II) as an activator and 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic agent for Fe(VI) detection. This Mn(II)/TMB method enables rapid completion of the chromogenic reaction within 2 s, with a low detection limit of approximately 4 nM and a wide detection range (0.01-10 μM). Importantly, the Mn(II)/TMB method exhibits superior resistance to reductive interference and effectively eliminates the impact of phenoxyl-radical-mediated intermediate valence iron transfer processes associated with electron-rich organic compounds. Furthermore, this method is resilient to particle interference and demonstrates practical applicability in authentic waters.
A tunable guided-mode resonant (GMR) reflection filter based on dielectric elastomer actuators (DEA) is designed. Simulating the characteristics of the filter with rigorous coupled wave analysis, it ...is shown that the resonant wavelength of the kind of GMR filter can be tuned from 1442.8nm to 1644.6nm by applying voltage on the dielectric elastomer actuators which changes the period of the grating layer of the GMR filter conveniently. Furthermore, there is an almost perfect linear relationship of resonant wavelength tuned and the period varied with negligible effect on the linewidth.
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