CO Groups Research Articles

A redox-active HybG-HypD scaffold complex is required for optimal ATPase activity during [NiFe]-hydrogenase maturation in Escherichia coli.

Four Hyp proteins build a scaffold complex upon which the Fe(CN)2 CO group of the [NiFe]-cofactor of hydrogenases (Hyd) is made. Two of these Hyp proteins, the redox-active, [4Fe-4S]-containing HypD protein and the HypC chaperone, form the basis of this scaffold complex. Two different scaffold complexes exist in Escherichia coli, HypCD, and the paralogous HybG-HypD complex, both of which exhibit ATPase activity. Apart from a Rossmann-fold, there is no obvious ATP-binding site in HypD. The aim of this study, therefore, was to identify amino acid motifs in HypD that are required for the ATPase activity of the HybG-HypD scaffold complex. Amino acid-exchange variants in three conserved motifs within HypD were generated. Variants in which individual cysteine residues coordinating the iron-sulfur ([4Fe-4S]) cluster were exchanged abolished Hyd enzyme activity and reduced ATPase activity, but also destabilized the complex. Two conserved cysteine residues, C69 and C72, form part of HypD's Rossmann-fold and play a role in HypD's thiol-disulfide exchange activity. Substitution of these two residues individually with alanine also abolished hydrogenase activity and strongly reduced ATPase activity, particularly the C72A exchange. Residues in a further conserved GFETT-motif were exchanged, but neither hydrogenase enzyme activity, nor ATPase activity of the isolated HybG-HypD complexes was significantly affected. Together, our findings identify a strong correlation between the redox activity of HypD, ATPase activity, and the ability of the complex to mature Hyd enzymes. These results further highlight the important role of thiol residues in the HybG-HypD scaffold complex during [NiFe]-cofactor biosynthesis.

Enhanced catalytic degradation of antibiotics by peanut shell-derived biochar-Co3O4 activated peroxymonosulfate: An experimental and mechanistic study

A peanut shell-derived biochar-Co3O4 (Bio-Co3O4) catalyst prepared by chemical bath deposition (CBD) method exhibited excellent ofloxacin (OFL) degradation ability through a broad pH range for peroxymonosulfate (PMS) activation. The excellent properties and behavior of catalyst were studied by characterization and degradation experiments. Benefiting from the synergy of adsorption and degradation, Bio-Co3O4 composite showed much higher removal efficiency (97.3%) and larger reaction rate constant (k = 0.1411 min−1) than that of biochar or Co3O4 in presence of PMS. Mechanisms exploration suggested that dual active pathways, including singlet oxygen-dominated non-radical pathway and sulfate radical-dominated radical pathway were involved in the reaction mechanism. The graphitized structure, stable redox cycle of Co2+/Co3+ and CO groups in catalyst were mainly responsible for the generation of reactive species. Furthermore, a total of ten main intermediates were detected and OFL degradation pathways as well as catalytic mechanisms were identified and proposed in detail. Overall, our study provides a potential way to activate PMS for the effective removal of abusive antibiotics from aqueous environments.

A co-solvent in aqueous electrolyte towards ultralong-life rechargeable zinc-ion batteries

Severe Zn dendrite and H2 evolution reaction (HER) derived from high activity of free H2O hinder the commercialization of aqueous Zn-ion batteries (AZIBs). Regulating the Zn2+ solvation structure is a straightforward way to solve the above issues. Herein, a polar solvent, tetramethylurea (TMU), is designed as a co-solvent in the aqueous electrolyte, which can form strong interactions with Zn2+ and H2O via the -CO group, conducing to reshape the Zn2+-solvation structure and interrupt the intrinsic hydrogen-bonds (H-bonds) of H2O. Furthermore, the steric-repulsion effect of -N(CH3)2 prevents H2O from entering the primary solvation structure. Such synergistic effects decrease the H2O activity, and hence suppress Zn dendrite and HER. As a result, Zn||Cu cells with TMU-based electrolyte can stably run over 6000 cycles with 99.8% Columbic efficiency at a current density of 10 mA cm−2, and the cumulative capacity of Zn||Zn cell reaches up to 5 Ah cm−2, exceeding most of the reported works involving co-solvent. The Zn||NH4V4O10 battery, under an N/P ratio of 4, can run for 300 cycles with 68% capacity retention, much better than that without TMU (3.9%). Our work reveals that rationally designing the electrolyte components at the molecular level is essential in stabilizing the Zn anode and achieving high-performance AZIBs.

Characterization of tautomeric forms of anti-cancer drug gemcitabine and their interconversion upon mechano-chemical treatment, using ATR-FTIR spectroscopy and complementary methods

Gemcitabine is a widely used anti-cancer drug of pyrimidine structure, which can exist as a free base molecular form in crystals. Tautomers are structural isomers of molecules, which interconvert via proton transfer. Mechano-chemistry studies reactions of solids under mechanical impact. We investigated gemcitabine free base for the presence of specific molecular tautomers, using ATR-FTIR spectroscopic analysis, powder XRD, optical microscopy and HPLC. The amino-keto tautomer has the characteristic infrared (IR) peak of the amino group at 3390 cm−1. For the first time, the imino-keto tautomer of gemcitabine free base was detected. The imino-keto tautomer has the characteristic IR peak of the =N–H group, and its peak due to the CO group in pyrimidine ring is shifted vs. that of the amino-keto tautomer. This serves as the unique spectroscopic “fingerprints” of these tautomers. The ATR-FTIR spectroscopic analysis shows that gemcitabine free base can be enriched with the amino-keto or the imino-keto tautomer. Further, we studied the transformation of gemcitabine free base in crystals between its tautomers under conditions of liquid-assisted grinding (LAG). The imino-keto tautomer undergoes tautomerization to the amino-keto tautomer, while the amino-keto tautomer remains stable. No destruction of molecules of gemcitabine free base, when present as either tautomer, occurs during LAG as was verified by the HPLC-UV analysis. LAG is a new, straightforward, facile and fast method to interconvert tautomers in crystals, and ATR-FTIR spectroscopy is a method of choice to study tautomerization reactions of pharmaceuticals. The presented approach is promising for analysis of crystals of drugs containing one or more than one tautomer, and the knowledge-driven design of composite materials, which contain specific tautomeric molecular forms of pyrimidines, purines and other biologically active heterocyclic compounds.

Effect of anions in ionic liquids on microstructure and oxidation characteristics of lignite

There is an urgent need for a green and efficient inhibitor to inhibit coal spontaneous combustion (CSC). Ionic liquids (ILs) have led to a growing interest because of eco-friendliness, sustainability, and excellent designable properties. Herein, we report some ILs, which are composed of [EMIM]+ cations and different anions (Cl–, [BF4]–, [OAC]–, [OTf]–). Anions show the characteristics of increased chain length and enhanced electronegativity of acid radical. The effect of the chain volume of anions and the strength of acidity on the microstructure of coal were measured by analyzing and comparing the changes of element morphology, Fourier Transform infrared spectroscopy structure parameters, and microcrystalline in this work. The results illustrate that with the increase of the anionic chain volume and the electronegativity of acid radical, the ILs appear the outstanding ability to destroy the lamellar diameter microcrystals and the structural abundance of aliphatic hydrocarbons of coal. With the enhancement of the electronegativity of anionic acid radical, the degree of reduction of CO and COO functional groups of coal and the ability of desulfurization rate are enhanced. The thermodynamic process demonstrates that the dry cracking temperature and ignition temperature can increase by 19.3 °C and 10.0 °C, respectively, resulting in coal may be inhibited during the oxidation. In additional, the thermal kinetic behaviors of samples were investigated by Starink models. Results indicated that the apparent activation energy of the inhibited samples can be increased from 51.96 kJ mol−1 of Un-tc to [EMIm][BF4]-tc 60.52 kJ mol−1 in the stages of thermal decomposition and combustion. The regular destruction characteristics of anions and cations on coal molecules to suggest hopeful prospects ILs as a novel and designable materials in the field of prevention CSC fire.

Efficient delivery of anticancer 5-fluorouracil drug by alkaline earth metal functionalized porphyrin-like porous fullerenes: A DFT study

Finding and developing effective targeted drug delivery systems has emerged as an attractive approach for treating a wide range of diseases. In the present study, the potential of alkaline earth metal functionalized porphyrin-like porous C24N24 fullerenes for delivering 5-fluorouracil (5FU) anticancer drug is assessed using density functional theory calculations. The goal is to evaluate how the addition of alkaline earth metals to C24N24 enhances the adsorption capabilities of this system towards 5FU drug. The adsorption energies and charge transfers are determined in order to evaluate the strength of the interaction between the 5FU and fullerene surfaces. According to the results, adding alkaline earth metals increases the drug's adsorption energy on the C24N24 fullerene. In all cases, the drug molecule interacts with the metal atom through its CO group. Furthermore, the adsorption strength of the 5FU increases with metal atom size (Ca > Mg > Be), which is connected to the polarizability of these atoms. The adsorption energies of 5FU are shown to be highly sensitive on solvent effects and the acidity of the environment. The adsorption strength of 5FU decreases within the solvent (water), allowing it to be released more easily. The moderate adsorption energies and short desorption times of 5FU imply that it is reversibly adsorbed on the functionalized fullerenes.

Design and construction of poly(benzoquinone-diamine)/Ti3C2TX hybrid electrode toward advanced aqueous zinc-ion batteries

Owing to the virtues of low cost, high security, and flexible structure design, zinc-ion batteries (ZIBs) have arisen widespread focus as a rising star in the application of energy-storage devises. Unfortunately, the further advancement of aqueous ZIBs is restricted by the unsatisfactory conduction of electron and structural instability of electrodes. Herein, a new organic-inorganic hybrid material, poly(benzoquinone-diamine)/Ti3C2TX (PBD/Ti3C2TX), has been conceived and fabricated as a cathode of ZIBs for the first time. The abundant CC and CO groups of PBD resulted in improved charge transfer and insolubility, which attributed to various hydrogen bonds and π-π packing interactions. Meanwhile, the Ti3C2TX can improve the electronic conductivity of the hybrid electrode effectively. In addition, the rich functional groups on the surface of Ti3C2TX are propitious to form a tight junction between PBD and Ti3C2TX (such as hydrogen bonds), which is conducive to strengthening the stability of electrode structure. With the synergistic effort of these measures, the PBD/Ti3C2TX composite delivers excellent long-term cycle stability (90 mAh g−1 at 1 A g−1 after 2000 cycles) with high-capacity retention of 78%.

Chest CT Scan In Patients With Contusion and COVID 19 A Comparative Study With Pure Lung Contusion

Resource allocation for traumatic patients who are positive/negative for COVID-19 challenges the diagnosis. This study aims to compare the chest CT of COVID-19 associated with lung contusion versus those with lung contusion only. CT-scans of 9 RT-PCR positive patients with lung contusion due to MVA (CC group) and 16 patients with lung contusions from pre-COVID-19 (CO group) were revaluated. The distribution and characteristics of presenting CT-scan findings; including presence, shape, distribution of GGO, consolidations, subpleural sparing, crazy-paving and Atoll sign. Presence of effusions and cavities were compared. Time course of the opacities was compared. Bilateral distribution of opacities was noted in 100% of CC and 87.5% of CO group. There was no significant difference between GGO or consolidation shapes (P=0.44 and P=0.66). Both GGO and consolidations were more diffusely distributed in CC, a predominantly peripheral distribution was more commonly seen in the CO group (P=0.03 and P=0.01). Subpleural sparing was noted in 93.8% of CO as compared to 44% of CC group (p=0.04). Time to resolution was significantly longer in CC (15±6days) comparing to CO patients (P=0.02). 'Typical' chest CT findings including bilateral peripheral GGO and consolidations, crazypaving, Atoll signs and also less typical findings e.g. subpleural sparing is seen in lung contusion and COVID-19 pneumonitis. Lesion Time course might be a better radiologic discriminator between the two entities.

Comparison of high-flow nasal cannula and conventional nasal cannula during sedation for endoscopic submucosal dissection: a retrospective study.

The high-flow nasal cannula (HFNC) is a relatively recent method that provides high-flow, heated, humidified gas delivery. We compared HFNC (group HF) and conventional nasal cannula (NC) (group CO) during deep sedation with propofol and remifentanil for endoscopic submucosal dissection (ESD). Single-center, retrospective observational cohort study. In this study, a total of 159 cases were analyzed (group CO, 71 and group HF, 88). We collected the data from electronic medical records from September 2020 to June 2021. The lowest oxygen saturation (SpO2), incidence of hypoxia (SpO2 < 90%), rescue interventions, and adverse events between the two groups were investigated. There were significant differences between the two groups in lowest SpO2 and incidence of hypoxia [group CO versus group HF; 90.3 ± 9.7% versus 95.7 ± 9.0%, 25 (35.2%) versus 10 (11.4%); p < 0.001, p < 0.001; respectively]. Among the rescue interventions, the number of jaw thrust, patient stimulation, O2 flow increase, and nasal airway insertion were significantly higher in the CO group than in the HF group. However, postprocedural chest X-ray showed higher rates of abnormal findings (atelectasis, aspiration, and pneumoperitoneum) in group HF than in group CO [group CO: 8 (11.3%) versus group HF: 26 (29.5%), p = 0.005]. In multivariable analysis, besides group CO, difficult type of lesion was the risk factor for hypoxia. Compared to the conventional NC, HFNC provided adequate oxygenation and a stable procedure without significant adverse events during sedation for ESD. However, caution is needed to avoid complications associated with deep sedation and difficult type of lesions.

ANALYSIS OF DENSITY, BIODEGRADATION, AND MORPHOLOGY OF BIOPLASTIC COMPOSITES

The purpose of this study was to analyze the effect of adding polypropylene (PP) to sago starch thermoplastic (TPPS) combination of polypropylene grafting maleic anhydrous (PP-g-MA) on density values, degradation tests, and morphological analysis. The thermoplastic mixture of sago starch/polypropylene/polypropylene maleic anhydrous was carried out using the blending method using an internal mixer. Based on the research results, the addition of polypropylene can reduce the density value, and the rate of degradation in freshwater, seawater, and soil storage media. The surface morphology indicates the presence of the dispersed phase (Polypropylene) which is evenly distributed over the entire surface of the matrix (TPPS). there was a shift in wave number in the O-H and CO groups on the bioplastic composite in the FTIR test.

Дослідження хімічно-фізичних особливостей похідних бурого вугілля для оцінки потенціалу їх гібридної функціональності

STUDY OF CHEMICAL AND PHYSICAL FEATURES OF LIGNITE DERIVATIVES FOR EVALUATION OF THEIR HYBRID FUNCTIONALITY POTENTIAL © V.V. Lebedev, PhD in technical sciences, D.V. Miroshnichenko, Doctor of Technical Sciences, D.O. Savchenko, E.I. Lytvynenko, PhD in technical sciences (National Technical University «Kharkiv Polytechnic Institute», 2 Kyrpychova Str., Kharkiv, 61002, Ukraine)) The article shows that despite the existence of studies on the modification of various types of polymeric materials with lignite and its derivatives (in particular, it has been proven that the addition of lignite to polymers can affect their biodegradation), there is a further need to study the physicochemical features of the hybrid functionality of these materials in relation to a wide range of materials. The paper analyzes lignite and its derivatives in the form of humic acids in terms of their use for hybrid modification of multifunctional materials. The subject of the study is related to the non-energy and non-fuel use of fossil coal. This area is one of the most promising, as it allows to obtain marketable products of high demand, the cost of which is much higher than the cost of the raw materials. By performing qualitative, quantitative, and spectroscopic analyses of humic acids of different types of lignite, it has been proved that they have a significant hybrid functionality due to the presence of a large number of different functional groups in their composition. It has been shown that the most characteristic functional groups of lignite humic acids include phenolic hydroxyl -OH groups, carboxyl COO-, NH2 deformation groups, aliphatic CO groups, etc. This determines the ability of lignite humic acids to act as hybrid modifiers in relation to a wide range of substances through the following mechanisms: chemical interaction, dipole-dipole interaction in the form of hydrogen bond systems, and configuration changes in the structure of various materials and substances. It has also been found that the high hybrid functionality of lignite humic acids is determined by their polarity, which significantly increases the reactivity of active peripheral groups. Keywords: coal, humic acids, hybrid functionality, modification, properties. Corresponding author Denys V. Miroshnychenko, e-mail: dvmir79@gmail.com

트레드밀 운동이 알코올 섭취로 유도된 쥐의 간 손상에 미치는 영향

Purpose: The purpose of this study is to investigate the liver function improvement effect of treadmill exercise on liver damage in rats induced by alcohol consumption.&#x0D; Method: Fifteen male Sprague Dawley (SD) rats were randomly assigned to CO (control group, n=5), AC (alcohol consumption, n=5) ACE (alcohol consumption + exercise, n=5). The treadmill exercise consisted of five times a week for five days and lasted 60 minutes (5 min for warm-up, 50 min for the main exercise, and 5 min for cool-down). Blood samples were taken after 5 weeks of exercise, and serum alanine transaminase (ALT) and aspartate transaminase (AST) were measured using an ELISA kit. The data were analyzed using one-way ANOVA to verify between-group differences in weight and liver damage index. If there was a statistically significant difference, Tukey's post-hoc was performed.&#x0D; Results: There was no weight change after five weeks of exercise intervention. However, ALT and AST were statistically significantly higher in the AC group than in the CO group and the ACE group(p&lt;0.001).&#x0D; Conclusion: In conclusion, treadmill exercise for 5 weeks improves liver function and reduces ALT and AST against alcohol-induced liver damage.

Antimalarial and Antimicrobial Activities of some Heteroleptic Metal(II) Complexes of Sulfadiazine–Vitamin C: Synthesis and Spectroscopic Studies

Some new Ni(II), Zn(II), Co(II), Cu(II), and Cd(II) of mixed Sulphadiazine and Vitamin C complexes have been synthesized and characterized by different spectroscopic techniques such as FT-IR, elemental analysis, molar conductivity, and magnetic measurements. Both ligands used for this research work act as bidentate ligands towards the central metal ions coordinating through the nitrogen atoms of &gt;C=N-, NH2 groups of Sulphadiazine and oxygen atoms of OH, CO groups of Vitamin C. Tetrahedral and square-planar geometries have been proposed for the complexes. The complexes are stable under atmospheric conditions. The ligands and their complexes were screened for antimicrobial activities against some isolated organisms: Klebsiella pneumoniae, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis to evaluate their microbial inhibiting potential. The derived complexes were found to exhibit an increased inhibitory action against the organisms when compared to the free ligands. The percentage reduction in parasitaemia for the compounds was also evaluated against Plasmodium berghei. In this realm, [Cd(Su)(Vit)]Cl2 showed the highest activity (89%) as compared to other compounds: Sulphadiazine, Ni(II), Zn(II), Co(II), and Cu(II) complexes are 70, 50, 81, 76, and 77%, respectively, Vitamin C showed no activity.&#x0D; Keywords: Sulfadiazine, Antimalarial, Vitamin C, Physicochemical, Metal-drug complexes, Antimicrobial

Effect of Storage of Yellow Pigment from Halophilic Bacillus clausii J1G-0%B on Antioxidant Activity

Oxidative stress is a state of excess free radicals in the body, which results in increased oxidation processes in the body’s cells and causes damage. In previous studies, one way to neutralize this situation was found, namely with halophilic bacteria. Halophilic bacteria can live at a salt content of 2% to 30%. These bacteria can produce various kinds of pigments for self-defense from extreme environments, which function as immunomodulatory compounds and have antioxidant activity. The antioxidant activity of the yellow pigment halophilic bacteria Bacillus clausii J1G-0%B using the DPPH method showed that the effect of light and air on antioxidant activity was 17.88% inhibition in the crude extract and 14.24% inhibition at 1600 ppm. Antioxidant activity decreased by 17.13% under the influence of air, 1.89% under the influence of light, and 28.58% under the influence of air and light. FTIR analysis under the influence of air experienced a decrease in the peak of the CO carbonyl group of 1739.29 cm-1 and an increase in the alkane C-H group of 1369.52 cm-1, while under the influence of light and open conditions, the carbonyl CO group experienced an increase of 1739.50 cm-1 and 1739.46 cm-1 and the increase in alkane C-H groups 1371.41 cm-1 and 1369.53 cm- 1.

Melatonin improves the removal and the reduction of Cr(VI) and alleviates the chromium toxicity by antioxidative machinery in Rhodobacter sphaeroides

Bioremediation with photosynthetic bacteria (PSB) is thought to be a promising removal method for hexavalent chromium [Cr(VI)]-containing wastewater. In the present study, Rhodobacter sphaeroides (R. sphaeroides) SC01 was used for the investigation of Cr(VI) removal in Cr(VI)-contaminated solution in the presence of melatonin. It was found that exogenous melatonin alleviated oxidative damage to R. sphaeroides SC01, increased Cr (VI) absorption capacity of cell membrane, and improved the reduction efficiency of Cr(VI) via the activation of chromate reductants. The results showed that melatonin could further promote the increase in Cr(VI) removal efficiency, reaching up to 97.8%. Furthermore, melatonin application resulted in 296.9%, 44.4%, and 69.7% upregulation of ascorbic acid (AsA), glutathione (GSH), and cysteine (Cys) relative to non-melatioin treated R. sphaeroides SC01 at 48 h. In addition, the resting cells, cell-free supernatants (CFS), and cell-free extracts (CFE) with melatonin had a higher Cr(VI) removal rate of 18.6%, 82.0%, and 15.2% compared with non-melatonin treated R. sphaeroides SC01. Fourier transform infrared spectroscopy (FTIR) revealed that melatonin increased the binding of Cr(III) with PO43− and CO groups on cell membrane of R. sphaeroides SC01. X-ray diffractometer (XRD) analysis demonstrated that melatonin remarkably bioprecipitated the production of CrPO4·6H2O in R. sphaeroides SC01. Hence, these results indicated that melatonin plays the important role in the reduction and uptake of Cr(VI), demonstrating it is a great promising strategy for the management of Cr(VI) contaminated wastewater in photosynthetic bacteria.

Oxidation of Alcohols into Carbonyl Compounds Using a CuO@GO Nano Catalyst in Oxygen Atmospheres

In this article, the oxidation of alcohols into carbonyl compounds was studied in oxygen atmospheres using a copper oxide on graphene oxide (CuO@GO) nano composites catalyst, synthesized by the wet chemistry method. CuO@GO nano composites were prepared from GO, and CuO NPs by the sol-gel method. The transformation of aromatic alcohols into corresponding carbonyl compounds in good-to-high yields were observed using the CuO@GO catalyst under an oxygen atmosphere. Synthesized CuO@GO was confirmed by FT-IR, XRD, XPS, TEM, FE-SEM, TEM, and SEM analyses, and revealed intercalation of CuO-NPs on/in GO nano sheets through the chelation of Cu+2 ions with CO, COOH, and OH groups presenting on the GO nano sheets. The catalytic activity of CuO@GO nano composites for the conversion of alcohols into carbonyl compounds were evaluated through TOF (2.56 × 10−3 mol g−1 min−1). The use of CuO@GO has shown catalytic activity and recyclability with a high conversion of alcohols to ketones. We assume that the proposed CuO@GO catalyst can be used for other key organic transformations and will be evaluated in the future.

In situ preparation of highly graphitized N-doped biochar geopolymer composites for efficient catalytic degradation of tetracycline in water by H2O2

Advanced oxidation processes (AOPs) hold great prospects for the treatment of antibiotic wastewater. N-doped biochar (NB) has received increasing attention as a catalyst for AOPs because of its green nature, abundant biomass resources, and low cost. However, NB catalysts are complicated to prepare and difficult to recover, limiting their practical application. In this study, an N-doped biochar geopolymer composite (NBGC) was synthesized via in situ doping, simultaneous carbonization, and activation (ISCA) of lignin and urea in the porous geopolymer flake, without additional activators. The ISCA process used a low-cost geopolymer flake that not only served as a carrier to immobilize NB and facilitate the recovery, but also applied its inherent strong alkalinity to activate NB. The composite catalyst obtained at 600 °C (NBGC-600) exhibited excellent activity in activating H2O2 to degrade tetracycline (∼100%, 50 mg/L). The EPR results indicated that NBGC-600 had a strong ability to activate and decompose H2O2 to •OH, which could be attributed to its rich persistent radicals, graphitized N and CO groups, as well as the high degree of graphitization of biochar. The degradation pathway and intermediates of tetracycline in the NBGC-600-H2O2 system were also discussed according to the HPLC-MS results. Moreover, NBGC-600 had excellent reusability and showed great potential for continuous treatment of tetracycline in water. This work paves a new way for the synthesis of cost-effective N-doped biochar composite catalysts for AOPs.

The molecular structure effects of starches and starch phosphates in the reverse flotation of quartz from hematite

Native starches and their phosphates with various molecular structures was introduced as the depressant to realize the flotation of quartz from hematite in this study. The present starch phosphates (WSP, NSP, GSP) were modified by the reaction between phosphate and three different corn starches (WS, NS, G50). The synthesis and characterization of starch phosphates found that starch with high amylopectin content was easily modified into starch phosphates. Microflotation tests showed that starch phosphates exhibited stronger depressing abilities of hematite flotation than native starches. Zeta potential measurement showed that both starches and starch phosphates could positively shift the zeta potential of hematite, while starch phosphates had more effects than starches. XPS and MDS indicated that the chemisorption occurred between Fe of hematite surface and CO groups of starch-based depressants. In addition, starch phosphates could adsorb onto the hematite surface through PO groups. MDS also presented that the adsorption strength of starch phosphate was mainly determined by the type and number of generating chelating rings, and the molecular structure of starch significantly affected the formation of chelate rings. The proposed adsorption model insights will significantly promote the development of starch-based depressants for iron ore flotation and other mineral processing applications.

Coupled adsorption and non-radical dominated mechanisms in Co, N-doped graphite via peroxymonosulfate activation for efficiently degradation of carbamazepine

A ZIF-derived Co, N-doped graphitic carbon prepared by calcination exhibited excellent carbamazepine (CBZ) removal ability over a broad pH range for peroxymonosulfate (PMS) activation. The impact of calcining temperature on catalyst constitution and catalytic behavior were studied through characterization and performance experiments. Benefiting from the synergy of adsorption and catalysis, CZIF-1000/PMS (with a 1000 °C pyrolysis temperature) system demonstrated outstanding catalytic capability, with 96.8 % removal efficiency supported by optimum parameters (catalyst dosage, 50 mg/L, PMS dosage, 0.4 mM, CBZ concentration, 5 ppm, and initial pH, 5.8). The graphitic N, pyrrolic N, CO group, Co3+ and Co0 were revealed to be the activation centers by X-ray photoelectron spectroscopy (XPS). Mechanisms exploration suggested that dual active pathways, including singlet oxygen-dominated non-radical pathway and sulfate radical-dominated radical pathway were involved in the reaction mechanism. Besides, a total of ten intermediates were detected and CBZ degradation pathways were derived subsequently.

Fe2P/N-doped biocarbon composite derived from mycelial pellet for bisphenol AF removal through peroxymonosulfate activation

In this work, microorganism of Phanerochaete chrysosporium with iron-tolerating and accumulating abilities was cultivated and harvested as mycelial pellets, which could serve as a sustainable and environmental-friendly precursor for iron phosphide/N-doped biocarbon composite preparation. Through one-step pyrolysis process, the inherent Fe and P elements in mycelial pellet enabled the formation of well crystallized Fe2P particles, loading on N-doped biocarbon matrix. Benefiting from the porous structure, high specific surface area, N doping-induced defects and CO groups of biocarbon, as well as the good electron-donating property of Fe2P, the as-obtained Fe2P/BC composite performed well for bisphenol pollutant (e.g., BPAF) removal through peroxymonosulfate (PMS) activation. Specifically, almost complete BPAF removal was achieved within 30 min adsorption and 10 min catalysis process with an apparent reaction rate constant of 0.486 min−1. The good crystallinity and protective carbon layer wrapping on Fe2P enabled the wide pH adaptability and low iron leaching of Fe2P/BC in catalytic reaction. Inorganic anions and humic acid brought only slight inhibition for BPAF removal, which could be overcome by prolonging reaction time to 30 min. Further mechanism studies indicated that reactive oxygen species, e.g., SO4-•, •OH and 1O2 were generated through both radical and non-radical pathways and contributed to BPAF degradation. After treatment by Fe2P/BC-PMS system, the total organic carbon (TOC) of original BPAF solution (20 mg L−1) was reduced by 51.6%. Fortunately, the residual degradation intermediate products showed much reduced ecotoxicity in both predicted (ECOSAR program) and experimental results (growth inhibition test using Raphidocelis subcapitata as ecological indicator).