Three radical scavengers (methanol (MA), tert-butanol (TBA), phenol) were used to determine the dominant active spices generated in the GAC/PS system. Since MA and TBA were hydrophilic compounds and ...it was easier for phenol to approach carbon surface, it was assumed that the course of AO7 degradation by the GAC/PS system possibly did not occur in the liquid phase, but the porous bulk or the boundary layer on the external surface of GAC granules. And, the active species which took part in the organic degradation by the GAC/PS combined system was SO4− or HO, generated near or at the surface of GAC. Display omitted
▶ The GAC/PS system can significantly induce AO7 degradation at ambient temperature. ▶ PS could be decomposed by GAC catalysis. ▶ Adsorption has an adverse effect on AO7 degradation. ▶ SO4− or HO, generated on or near the surface of GAC, plays a major role. ▶ The recovery performance of GAC is high.
Persulfate (PS) oxidative degradation of azo dye acid orange 7 (AO7) in an aqueous solution was studied in the presence of suspended granular activated carbon (GAC) at ambient temperature (e.g., 25°C). It was observed that there existed a remarkable synergistic effect in the GAC/PS combined system. Higher PS concentration and GAC dosage resulted in higher AO7 degrading rates. Near-neutral was the optimal initial pH. Adsorption had an adverse effect on AO7 degradation. AO7 had not only a good decolorization, but a good mineralization. The decomposition of PS followed a first-order kinetics behavior both in the presence and in the absence of AO7. Radical mechanism was studied and three radical scavengers (methanol (MA), tert-butanol (TBA), phenol) were used to determine the kind of major active species taking part in the degradation of AO7 and the location of degradation reaction. It was assumed that the degradation of AO7 did not occur in the liquid phase, but in the porous bulk and boundary layer on the external surface of GAC. SO4− or HO, generated on or near the surface of GAC, played a major role in the AO7 degradation. Finally, the recovery performance of GAC was studied through the GAC reuse experiments.
In this paper, the degradation of azo dye Acid Orange 7 (AO7) by three common peroxides (persulfate (PS), peroxymonosulfate (PMS) or hydrogen peroxide (H
2O
2)) under various activation conditions, ...i.e., heat (25–80
°C), UV light (254
nm), or anions (SO
4
2−, NO
3
−, CO
3
2−, HCO
3
−, HPO
4
2−, and Cl
−), was investigated. The order of AO7 degradation efficiencies by heat activation is PS
≫
PMS
>
H
2O
2. PS oxidation activated by heat (>50
°C) is an effective degradation technology, while PMS and H
2O
2 are hardly activated. When assisted by UV, peroxides could all be activated and degrade AO7 quickly. The order is PS
>
H
2O
2
>
PMS. We activated peroxides, for the first time, by using some anions and compared the subsequently degradation efficiencies of AO7. It was found that PMS could be activated by some anions, but PS and H
2O
2 cannot. The activation efficiencies of PMS by SO
4
2− and NO
3
− are negligible, whereas remarkable by HCO
3
−, HPO
4
2−, Cl
− and CO
3
2−. For HCO
3
−, HPO
4
2− and Cl
−, the activation efficiencies become higher with the increase of anion concentration. For CO
3
2−, however, the activation efficiency is higher at lower concentration.
•ACF can efficiently activate peroxymonosulfate to generate radicals.•AO7 can be effectively degraded in the ACF/PMS system.•Basic sites on the surface of ACF are possible catalytic active ...sites.•SO4− and HO are the mainly oxidizing species.•The degradation process of AO7 was initiated by cleavage of azo linkage.
Increasing attention has been paid to environmental friendly activation method of peroxymonosulfate (PMS) in the field of advanced oxidation processes (AOPs). In this work, activated carbon fiber (ACF) was utilized as an effective and green catalyst to activate peroxymonosulfate (PMS) for degradation of aqueous organic pollutant. As results indicated, a very low dosage of ACF (0.3gL−1) could efficiently activate PMS to eliminate Acid Orange 7 (AO7), a probe compound, and the degradation of AO7 followed first order kinetics. Surface chemistry analyses of ACF samples, including BET specific surface area, pH at the point of zero charge, Boehm titration and FTIR spectroscopy, suggested that the basic sites on ACF surface were likely to be the active sites inducing the decomposition of PMS and the generation of radicals. Quenching studies confirmed that sulfate radicals (SO4−) and hydroxyl radicals (HO), which formed on the surface of ACF, were the primary oxidizing species. A possible pathway for AO7 degradation was proposed by monitoring the temporal evolution of intermediates in the solution, with the use of GC–MS and ionic chromatography (IC). It is suggested that the degradation process of AO7 was initiated by cleavage of azo linkage and further undergoes ring-opening reactions.
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•ACF can efficiently activate peroxymonosulfate to degrade organic pollutants.•Basic functional groups may mainly increase the adsorption capacity of ACF.•C1, N1, N2 have promoting ...effect on the ACF catalyzed PMS oxidation.•Modification by heat after nitric acid is also a way of ACF regeneration.
A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N2 adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the −NO2 has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment.
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Baicalein is the main active compound of Scutellaria baicalensis Georgi, a medicinal herb with multiple pharmacological activities, including the broad anti-virus effects. In this ...paper, the preclinical study of baicalein on the treatment of COVID-19 was performed. Results showed that baicalein inhibited cell damage induced by SARS-CoV-2 and improved the morphology of Vero E6 cells at a concentration of 0.1 μM and above. The effective concentration could be reached after oral administration of 200 mg/kg crystal form β of baicalein in rats. Furthermore, baicalein significantly inhibited the body weight loss, the replication of the virus, and relieved the lesions of lung tissue in hACE2 transgenic mice infected with SARS-CoV-2. In LPS-induced acute lung injury of mice, baicalein improved the respiratory function, inhibited inflammatory cell infiltration in the lung, and decreased the levels of IL-1β and TNF-α in serum. In conclusion, oral administration of crystal form β of baicalein could reach its effective concentration against SARS-CoV-2. Baicalein could inhibit SARS-CoV-2-induced injury both in vitro and in vivo. Therefore, baicalein might be a promising therapeutic drug for the treatment of COVID-19.
•The SAOR, SNOR and SNRR in GSBR decreased as the salinity increased from 0% to 8%.•The SOUR in GSBR increased at 0–3% salinity and decreased at over 3% salinity.•The SVI showed linear correlations ...with LB-EPS and TB-EPS at different salinities.•The RH showed linear correlations with the PN/PS ratios in TB-EPS and LB-EPS.•The microbial community in GSBR obviously changed as the increase in salinity.
The effects of salinity on the performance, extracellular polymeric substances (EPS) and microbial community of granular sludge were evaluated in an aerobic granular sequencing batch reactor (GSBR). The chemical oxygen demand (COD) and NH4+–N removal efficiencies decreased from 92% and 93% to 25% and 21% at 0–8% salinity, respectively. The specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR), and specific nitrate reduction rate (SNRR) decreased from 4.6, 5.6 and 43.0mgNg−1MLSSh−1 to 0.5, 0.4 and 9mgNg−1MLSSh−1 at 0–8% salinity, respectively. The specific oxygen utilization rate (SOUR) of granular sludge increased from 30 to 42mgO2g−1MLSSh−1 at 0–3% salinity and subsequently decreased to 11mgO2g−1MLSSh−1 at 8% salinity. The protein (PN) and polysaccharide (PS) contents in loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) increased at 0–8% salinity. The relative hydrophobicity (RH) of granular sludge illustrated good positive linear correlations with the PN/PS ratios in TB-EPS and LB-EPS. The chemical structural changes of LB-EPS and TB-EPS at different salinities were analyzed by three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy. A good linear correlation was found between sludge volume index (SVI) and LB-EPS (or TB-EPS). The denaturing gradient gel electrophoresis (DGGE) profile revealed that Lactococcus sp. YM05004, Desulfopila sp. PR5_F09 and Demequina oxidasica were present at all the salinities, suggesting these bacteria were capable of tolerating 8% salinity. Some bacteria could utilize nitrate as an electron acceptor and was present at certain salinities, such as Arcobacter defluvii, Halomonas hydrothermalis and Paracoccus denitrificans.
It is well known that daidzein has various significant medicinal values and health benefits, such as anti-oxidant, anti-inflammatory, anti-cancer, anti-diabetic, cholesterol lowering, ...neuroprotective, cardioprotective and so on. To our disappointment, poor solubility, low permeability and inferior bioavailability seriously limit its clinical application and market development. To optimize the solubility, permeability and bioavailability of daidzein, the cocrystal of daidzein and piperazine was prepared through a scientific and reasonable design, which was thoroughly characterized by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Combining single-crystal X-ray diffraction analysis with theoretical calculation, detailed structural information on the cocrystal was clarified and validated. In addition, a series of evaluations on the pharmacogenetic properties of the cocrystal were investigated. The results indicated that the cocrystal of daidzein and piperazine possessed the favorable stability, increased solubility, improved permeability and optimized bioavailability of daidzein. Compared with the parent drug, the formation of cocrystal, respectively, resulted in 3.9-, 3.1-, 4.9- and 60.8-fold enhancement in the solubility in four different media, 4.8-fold elevation in the permeability and 3.2-fold in the bioavailability of daidzein. Targeting the pharmaceutical defects of daidzein, the surprising elevation in the solubility, permeability and bioavailability of daidzein was realized by a clever cocrystal strategy, which not only devoted assistance to the market development and clinical application of daidzein but also paved a new path to address the drug-forming defects of insoluble drugs.
Ligustrazine (TMP) is the main active ingredient extracted from
, which is used in the treatment of cardiovascular and cerebrovascular diseases, with the drawback of being unstable and readily ...sublimated. Cocrystal technology is an effective method to improve the stability of TMP. Three benzoic acid compounds including P-aminobenzoic acid (PABA), 3-Aminobenzoic acid (MABA), and 3,5-Dinitrobenzoic acid (DNBA) were chosen for co-crystallization with TMP. Three novel cocrystals were obtained, including TMP-PABA (1:2), TMP-MABA (1.5:1), and TMP-DNBA (0.5:1). Hygroscopicity was characterized by the dynamic vapor sorption (DVS) method. Three cocrystals significantly improved the hygroscopicity stability, and the mass change in TMP decreased from 25% to 1.64% (TMP-PABA), 0.12% (TMP-MABA), and 0.03% (TMP-DNBA) at 90% relative humidity. The melting points of the three cocrystals were all higher than TMP, among which the TMP-DNBA cocrystal had the highest melting point and showed the best stability in reducing hygroscopicity. Crystal structure analysis shows that the mesh-like structure formed by the O-H⋯N hydrogen bond in the TMP-DNBA cocrystal was the reason for improving the stability of TMP.
Drug combinations have been the hotspot of the pharmaceutical industry, but the promising applications are limited by the unmet solubility and low bioavailability. In this work, novel cocrystals, ...consisting of two antithrombotic drugs with poor solubility and low bioavailability in vivo, namely, apixaban (Apx) and quercetin (Que), were developed to discover a potential method to improve the poor solubility and internal absorption of the drug combination. Compared with Apx, the dissolution behavior of Apx–Que (1:1) and Apx–Que–2ACN (1:1:2) was enhanced significantly, while the physical mixture of the chemicals failed to exhibit the advantages. The dissolution improvements of Apx–Que–2ACN could be explained by the fact that the solid dispersion-like structure and column-shaped cage of Que accelerated the access of the solvent to the inner layer of Apx. The fracture of the hydrogen bonds of Apx, which was the joint of the adjacent Que chains, facilitated the break-up of the structures. Besides, the bioavailability of Apx–Que was increased compared with the physical mixture and Apx, and Apx–Que remained stable in high temperature and illumination conditions. Therefore, a drug–drug cocrystal of two antithrombotic agents with poor solubility was developed, which exhibited greatly improved solubility, bioavailability and superior stability, indicating a novel method to overcome the shortages of drug combination.
This article, for the first time, provides a novel advanced oxidation process based on sulfate radical （SO^4·-） to degrade organic pollutants in wastewater： microwave （MW）-activated persulfate ...oxidation （APO） with or without active carbon （AC）. Azo dye acid Orange 7 （AO7） is used as a model compound to investigate the high reactivity of MW-APO. It is found that AO7 （up to 1000 mg/L） is completely decolorized within 5-7 min under an 800 W MW furnace assisted-APO. In the presence of chloride ion （up to 0.50 mol/L）, the decolorization is still 100% completed, though delayed for about 1-2 min. Experiments are made to examine the enhancement by AC. It is exciting to find that the 100% decolorization of AO7 （500 mg/L） is achieved within 3 min by MW-APO using 1.0 g/L AC as catalyst, while the degradation efficiency maintains at 50% by MW energy without persulfate after about 5 min. Besides the destruction of visible light chromophore band of AO7 （484 nm）, during MW-APO, two bands in the ultraviolet region （228 nm and 310 nm） are rapidly broken down. The removal of COD is about 83%-95% for 500 mg/L AO7. SO^4·- is identified with quenching studies using specific alcohols. Both SO^4·- and ·OH could degrade AO7, but SO^4·- plays the dominant role. In a word, MW-APO AC is a new catalytic combustion technology for destruction of organic contamination even for high concentration.
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