Multiwalled carbon nanotube (MWCNT) have a great potential for advanced oxidation process as a metal free catalyst. However, there catalytic activity is very low and needs to be appropriately tuned. ...Herein, we demonstrate a novel synthesis method for tuning the defect and surface functionality of MWCNT using azo dyes and the catalytic performance was tested for the degradation of different organic contaminates using PMS as an oxidant. The content, type of heteroatom functional groups, and the defect parameters were optimized by varying the pH and concentration of the organic dye. The quenching effect showed that singlet oxygen (1O2) is the primary reactive species generated by graphitic nitrogen, which can be boosted by the degree of graphitic structure disruption in MWCNT. The Linear sweep voltammetry (LSV) also confirmed that extrinsic doping enhanced the non-radical degradation by increasing the direct charge transfer rate from MB to PMS. Moreover, the designed catalyst showed a fast degradation performance with 35.1 kJ/mol activation energy and achieved the highest dye degradation rate and even surpassed some state-of-the-art metal-based and metal-free catalysts. The effect of inorganic anions study has also confirmed its industrial applicability.
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•Tuning structural defect of MWCNT using pH of congo red solution.•The doping of heteroatoms induced the Non-radical degradation path.•Structural defects generate the singlet oxygen.•The catalyst exhibits fast kinetics, high efficiency, and recyclability.
The removal of methyl blue (MB) from wastewater using graphene and its derivative is very successful due to their high aromaticity which drives adsorption via π-π and electron-donor-acceptor (EDA) ...interactions; however, graphene is expensive and difficult to synthesize, which limit its practical application. Meanwhile, low aromatic carbon materials (LACM) derived from farm-water and other materials are cheaper and easier to synthesize but have limited π-π and EDA interactions and low adsorption capacity. Herein, we demonstrate that LACM with oxidized-nitrogen (N–O-) functionality overcomes this limitation via chemisorption of MB through a combination of hydrophobic-hydrophobic interactions and EDA interactions. This is confirmed using XPS analysis of LACM/N–O- post MB adsorption. Consequently, a remarkable adsorption capacity of 3904 mg g−1 is achieved under batch condition which is the highest ever reported for any MB adsorbent. Furthermore, LACM/N–O- works equally well under continuous-flow adsorption conditions which shows its practicability. Amongst several LACM precursors tested, only Azo-dyes are able to generate LACM/N–O- implying that the NN moiety is key to N–O- formation. A carbonization temperature of 700 °C generates the highest N–O- sites hence the highest adsorption capacity. Characterization of LACM/N–O- is done mainly using BET, XPS, Raman, TGA, and FTIR analysis.
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•Oxidize nitrogen (N–O-) laden carbon sheets synthesized via Azo-dye carbonization.•Maximum adsorption capacity of 3904 mg g−1 achieved for Methyl blue (MB) dye.•Adsorption process governed by synergy between electrostatic and chemisorption.•N–O- interacts with MB via electron-donor-accepter reaction.•The adsorbent exhibits fast kinetics, high efficiency and recyclability.
Carbon-based adsorbents show high adsorption capacity towards caffeine due to their porosity and surface functionality. However, the main limiting factor for high performance has not been addressed; ...furthermore, the adsorption interaction with different active sites needs to be explored. In this study, we synthesized a hierarchical porous nitrogen-doped carbon with unique surface functionality by single-step calcination of coffee waste with KOH under N2. The porous structure, nitrogen content, and types are optimized by varying calcination temperature and KOH concentration. The result of the adsorption experiments shows that both the nitrogen type and the pore size distribution are the limiting factors to adsorption. In addition, the effect of acidic and basic functional groups is studied in detail. The adsorption of caffeine on CW-C is dominantly governed by EDA interaction between the resonance structure of pyridonic-N and the electron-withdrawing group of the caffeine, and the dispersive force caused by the oxidized-N and delocalized π electron of caffeine. Furthermore, we demonstrate that the surface of CW-C is not suitable for the formation of electrostatic and non-electrostatic interaction with caffeine. The maximum adsorption capacity of caffeine at 25 °C is 274.2 mg/g. Moreover, we demonstrate that the unique physio-chemical properties of CW-C are capable of adsorbing other emerging contaminants such as diclofenac, where maximum adsorption capacity of 242.3 mg/g diclofenac is recorded.
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•N doped carbon synthesized from coffee waste in the presence of KOH.•Maximum adsorption capacity of 274.2 mg/g achieved for caffeine.•High adsorption achieved by synergy of between pore texture and surface chemistry.•Surface interaction is governed by interaction of between EDA and dispersive force.•The adsorbent exhibits fast kinetics, high efficiency, and recyclability.
Graphitic carbon nitride has been proven to be a good candidate for using solar energy for photo-induced pollutant degradation. However, the high photo-induced holes-electron recombination rate, ...unfavorable morphology, and textural properties limited their application. In this study, we present a novel g-C
3
N
4
with a novel electronic structure and physiochemical properties by introducing a single nitrogen in the graphitic network of the g-C
3
N
4
through a novel method involving step-by-step co-polycondensation of melamine and urea. Through extensive characterization using techniques such as XPS, UPS-XPS, Raman, XRD, FE-SEM, TEM, and N
2
adsorption–desorption, we analyze the electronic and crystallographic properties, as well as the morphology and textural features of the newly prepared g-C
3
N
4
(N-g-C
3
N
4
). This material exhibits a lower C/N ratio of 0.62 compared to conventional g-C
3
N
4
and a reduced band gap of 2.63 eV. The newly prepared g-C
3
N
4
demonstrates a distinct valance band maxima that enhances its photo-induced oxidation potential, improving photocatalytic activity in degrading various organic pollutants. We thoroughly investigate the photocatalytic degradation performance of N-g-C
3
N
4
for Congo red (CR) and sulfamethoxazole (SMX), and removal of up to 90 and 86% was attained after 2 h at solution pH of 5.5 for CR and SMX. The influence of different parameters was examined to understand the degradation mechanism and the influence of reactive oxygenated species. The catalytic performance is also evaluated in the degradation of various organic pollutants, and it showed a good performance.
In this study, we demonstrate the preparation of laser-cum KOH-activated porous carbon with tunable ionic states, unique surface chemistry, and physical texture from renewable and environmentally ...friendly precursors (waste cardboard boxes). The adsorption performance of the engineered adsorbents is examined on the adsorption of methyl blue (MB, anionic) and methylene blue (MeB, cationic). The adsorption mechanism was determined using detailed batch adsorption, and the MB was adsorbed via the formation of ternary complexes, whereas the MeB was adsorbed through cation-π interaction. Furthermore, the non-activated laser-induced carbon (LIC100) and the KOH-activated carbon (KAC(L)) exhibit superior dye adsorption capacities of 9610 (MB) and 1882 mg g−1 (MeB), respectively. To the best of our knowledge, this is the highest ever reported at dye removal in the field of adsorptive dye removal. Langmuir isotherm model and pseudo-second-order are fitted well for both MB and MeB adsorption. Lastly, the carbons generated through this modern technique can be remodeled into a more secure device to obtain clean and microorganism-free water. This study showed the potential of laser-induced carbonization of KOH-activated substrate and provided unique insights into future development for universal dye adsorption and other possible applications.
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•Successful synthesis of waste-derived carbon via laser-induced carbonization.•Utilization of cardboard waste for environmental remediation.•Salt bridge and cation-π adsorption mechanism.•Superior adsorption capacity of 9610 (MB) and 1882 mg g−1 (MeB), respectively.•Ultrafast dye removal performance of LIC100 and KAC(L).
The oxidation state of an active metal is vital in the hydrolysis of NaBH4 for rapid hydrogen generation since the electron-rich and electron-deficient sites facilitate BH4− and H2O adsorption. ...Herein, we systematically design a tunable oxidation state of Co in Co3O4 by in situ N-doing using the combination of melamine (M) and urea (U) as nitrogen precursors during thermal treatment. The oxidation state of Co was tuned via electronic interaction between N and Co. This interaction was optimized by varying the amount of N doping and calcination temperature. The types of heterocyclic nitrogen, mainly pyridinic- and graphitic-N, and their carbon matrix content are critical in controlling the Co oxidation state. Various Co2+/Co3+ ratios showed a different catalytic performance, and the catalytic activity reached its peak at the highest ratio of 2.74 due to the synergetic effect of the maximum adsorption of BH4− and H2O by Co2+ and Co3+, respectively. Consequently, an excellent hydrogen generation rate (2042 mL g−1 min−1) was achieved with a low activation energy of 46.9 kJ mol−1 of M2.5U10Co3O4-400. Hence, N doping from a dual N source significantly enhanced the hydrogen performance compared to the reported cobalt-based catalyst. Furthermore, M2.5U10Co3O4-400 is highly recyclable, implying its stability and practical application.
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•Effect of N precursor on Co2+/Co3+ ratio in Co3O4.•Electrons reach and deficient active cobalt species.•Co2+/Co3+ ratio has a prominent effect on NaBH4 hydrolysis than conductivity.•Both Melamine and urea influence the growth of Co3O4.
Clays, valued for their versatility, serve as economical adsorbents. Recent studies show that physical, thermal, and chemical modifications can enhance their adsorption capacity. In this study, the ...synthesis of a functional bead comprising phosphoric acid-modified montmorillonite (PMMT) and coffee waste carbon (CWC) and its application for the efficient adsorption of methylene blue (MeB) dye is investigated. A highly flexible and low-cost phyllosilicate, montmorillonite clay, MMT was treated with phosphoric acid to enhance the ionic density, composited with CWC, resulting in improved surface properties thereafter was transformed into easily recoverable bead form through subsequent cross-linking steps. These functional composite beads were characterized using various characterization techniques. As a result, the existing tetrahedral sheets possessed by the MMT having weak bonds between the layers are improved in a way that they can allow molecule exchange for the efficient enhancement of the adsorption capacity of the composite material. Moreover, after the necessary modifications, the adsorbent was found to be mechanically stable, inhibiting secondary pollutions from the use in powder forms while allowing the interlayers favorable for not just cationic but also anionic exchange whilst increasing the specific surface area and pore volume. The surface area was enhanced to 9.93 m2 /g. Following this, maximum adsorption capacity of 489.9 mg/g was attained showing a superior removal efficiency for methylene blue dye (>80%). The adsorption equilibrium was analyzed using Freundlich and Langmuir models. The adsorption mechanism aligns with the Langmuir model which encompasses a monolayer adsorption. All in all, this study is anticipated to play a crucial role in the search for adsorbents with multiple functionalities and good structural stability during and after use.
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Summary
Peri‐operative SARS‐CoV‐2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had ...SARS‐CoV‐2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre‐operative SARS‐CoV‐2 infection were compared with those without previous SARS‐CoV‐2 infection. The primary outcome measure was 30‐day postoperative mortality. Logistic regression models were used to calculate adjusted 30‐day mortality rates stratified by time from diagnosis of SARS‐CoV‐2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre‐operative SARS‐CoV‐2 diagnosis. Adjusted 30‐day mortality in patients without SARS‐CoV‐2 infection was 1.5% (95%CI 1.4–1.5). In patients with a pre‐operative SARS‐CoV‐2 diagnosis, mortality was increased in patients having surgery within 0–2 weeks, 3–4 weeks and 5–6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3–4.8), 3.9 (2.6–5.1) and 3.6 (2.0–5.2), respectively). Surgery performed ≥ 7 weeks after SARS‐CoV‐2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9–2.1)). After a ≥ 7 week delay in undertaking surgery following SARS‐CoV‐2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2–8.7) vs. 2.4% (95%CI 1.4–3.4) vs. 1.3% (95%CI 0.6–2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS‐CoV‐2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay.
Genome-wide association studies (GWASs) have identified hundreds of loci associated with Crohn's disease (CD). However, as with all complex diseases, robust identification of the genes dysregulated ...by noncoding variants typically driving GWAS discoveries has been challenging. Here, to complement GWASs and better define actionable biological targets, we analyzed sequence data from more than 30,000 patients with CD and 80,000 population controls. We directly implicate ten genes in general onset CD for the first time to our knowledge via association to coding variation, four of which lie within established CD GWAS loci. In nine instances, a single coding variant is significantly associated, and in the tenth, ATG4C, we see additionally a significantly increased burden of very rare coding variants in CD cases. In addition to reiterating the central role of innate and adaptive immune cells as well as autophagy in CD pathogenesis, these newly associated genes highlight the emerging role of mesenchymal cells in the development and maintenance of intestinal inflammation.
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