Activation of peroxymonosulfate by natural molybdenite for dye degradation: Identification of reactive species and catalytic mechanism

2021 ◽  
Vol 22 ◽  
pp. 101403
Author(s):  
Guang-En Yuan ◽  
Yingzhi Qin ◽  
Mingyang Feng ◽  
Xiangli Ru ◽  
Xin Zhang
Keyword(s):  
Catalytic Mechanism ◽  
Dye Degradation ◽  
Reactive Species

scholarly journals Facile Preparation of CNT/Ag2S Nanocomposites with Improved Visible and NIR Light Photocatalytic Degradation Activity and Their Catalytic Mechanism

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 503 ◽  
Author(s):  
Lijing Di ◽  
Tao Xian ◽  
Xiaofeng Sun ◽  
Hongqin Li ◽  
Yongjie Zhou ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Dye Degradation ◽  
Average Particle Size ◽  
Hybrid Nanocomposites ◽  
Light Irradiation ◽  
Precipitation Method ◽  
Average Particle ◽  
Nir Light ◽  
Photocatalytic Activities ◽  
Ag2s Nanoparticles

In this work, a series of carbon nanotubes (CNT)/Ag2S hybrid nanocomposites were successfully prepared by a facile precipitation method. Transmission electron microscope (TEM) observation indicates that Ag2S nanoparticles with an average particle size of ~25 nm are uniformly anchored on the surface of CNT. The photocatalytic activities of the CNT/Ag2S nanocomposites were investigated toward the degradation of rhodamine B (RhB) under visible and near-infrared (NIR) light irradiation. It is shown that the nanocomposites exhibit obviously enhanced visible and NIR light photocatalytic activities compared with bare Ag2S nanoparticles. Moreover, the recycling photocatalytic experiment demonstrates that the CNT/Ag2S nanocomposites possess excellent photocatalytic stability. The photoelectrochemical and photoluminescence measurements reveal the efficient separation of photogenerated charges in the CNT/Ag2S nanocomposites. This is the dominant reason behind the improvement of the photocatalytic activity. Based on active species trapping experiments, the possible photocatalytic mechanism of CNT/Ag2S nanocomposites for dye degradation under visible and NIR light irradiation was proposed.

scholarly journals Oxidative degradation of Orange G in aqueous solution by persulfate activated with pyrite

2020 ◽  
Author(s):  
Xin Zhang ◽  
Yingzhi Qin ◽  
Weiting Zhang ◽  
Yali Zhang ◽  
Guang-En Yuan
Keyword(s):  
Aqueous Solution ◽  
Azo Dye ◽  
Dye Degradation ◽  
Oxidative Degradation ◽  
Reactive Species ◽  
Lower Solution ◽  
Solution Ph ◽  
Paramagnetic Resonance ◽  
Orange G ◽  
Electron Paramagnetic

Abstract Orange G (OG), a typical azo dye in textile wastewaters, has been the subject of intense investigations. This study investigated oxidative degradation of OG in aqueous solution by persulfate (PS) activated with pyrite. A complete destruction of OG was achieved within 60 min in the pyrite/PS system. Lower solution pH, smaller pyrite particles and higher pyrite dosage was beneficial for OG degradation. Higher PS concentration was also in favour of OG degradation, but excess PS would decrease the removal efficiency of OG. The addition of HCO3− and H2PO4− but Cl− had inhibitory effects on the destruction of OG. The results of quenching experiments and electron paramagnetic resonance tests proved that SO4•− and •OH were the dominant reactive species responsible for OG degradation in the pyrite/PS system. The azo bond, naphthalene ring and benzene ring of OG were all destroyed by the generated reactive species. The mineralization rate of OG reached 34.4% after 60 min of reaction. This work will provide information for understanding azo dye degradation by pyrite activated PS.

Carbonate anion photolyzed by solar radiation or combined with peracetic acid to form reactive species for dye degradation

2021 ◽  
pp. 113511
Author(s):  
Ana Paula Nogueira das Neves ◽  
Thayrine Dias Carlos ◽  
Leydiane Barbosa Bezerra ◽  
Whisley Durães Alceno ◽  
Renato Almeida Sarmentob ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Peracetic Acid ◽  
Dye Degradation ◽  
Reactive Species ◽  
Carbonate Anion

scholarly journals Ultrasound assisted Fenton-like degradation of dyes using copper doped graphitic carbon nitride

2021 ◽  
Author(s):  
Chongqing Wang ◽  
Rong Huang ◽  
Ruirui Sun ◽  
Hui Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Carbon Nitride ◽  
Catalytic Mechanism ◽  
Dye Degradation ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Order Kinetic ◽  
Acid Orange 7 ◽  
Solution Ph ◽  
X Ray

Abstract A novel copper doped graphitic carbon nitride (Cu-C3N4) was successfully synthesized and used as an effective Fenton-like catalyst. Cu-C3N4 was characterized by scanning electron microscopy, surface area analyzer, Fourier transform infrared spectroscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy. Effect of process parameters including catalyst dosage, hydrogen peroxide (H2O2) concentration, solution pH, and initial methylene blue (MB) concentration was investigated to evaluate catalytic performance. The pseudo first-order kinetic model was used to describe the catalytic process. The enhancement of MB degradation is observed assisted by ultrasound. MB degradation of 96% is obtained within 30 min in Cu-C3N4/H2O2/ultrasound system, and the corresponding rate constant is 0.099 min−1. Effective MB degradation is obtained over a broad pH range (3.3–9.9). The catalytic mechanism is examined by ultraviolet-visible spectra, quenching test, and electron spin resonance determination. The dominant mechanism of MB degradation is ascribed to the ultrasonic H2O2 activation by Cu-C3N4 for hydroxyl radical generation. Cu-C3N4 has good reusability and is effective to degrade rhodamine B and acid orange 7. This work not only contributes to the field of wastewater treatment, but also provides insights into the synthesis of Fenton-like catalysts. The results manifest that Cu-C3N4 is a promising Fenton-like catalyst for dye degradation in the field of environmental pollution remediation.

scholarly journals Structural and Optical Sensing Properties of Nonthermal Atmospheric Plasma-Synthesized Polyethylene Glycol-Functionalized Gold Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1678
Author(s):  
Linh Nguyen ◽  
Pradeep Lamichhane ◽  
Eun Choi ◽  
Geon Lee
Keyword(s):  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Dye Degradation ◽  
Particle Diameter ◽  
Plasma Jet ◽  
Reactive Species ◽  
Atmospheric Plasma ◽  
Average Particle ◽  
Functionalized Gold Nanoparticles ◽  
Gold Precursor

Polyethylene glycol-functionalized gold nanoparticles (Au@PEG NPs) were prepared by a simple plasma-assisted method without additional reducing chemicals. After irradiating tetrachloroauric acid (HAuCl4) and polyethylene glycol (PEG) in aqueous medium with an argon plasma jet, the gold precursor transformed into an Au@PEG NP colloid that exhibited surface plasma resonance at 530 nm. When the plasma jet entered the water, additional reactive species were induced through interactions between plasma-generated reactive species and aqueous media. Interaction of the gold precursor with the plasma-activated medium allowed the synthesis of gold nanoparticles (AuNPs) without reductants. The plasma-synthesized Au@PEG NPs had a quasi-spherical shape with an average particle diameter of 32.5 nm. The addition of PEG not only helped to stabilize the AuNPs but also increased the number of AuNPs. Au@PEG NP-loaded paper (AuNP-paper) was able to detect the degradation of rhodamine B, therefore, indicating that AuNP-paper can act as a surface-enhanced Raman scattering platform. Dye degradation by plasma treatment was investigated by optical absorption and Raman spectroscopy. The method proposed for the fabrication of Au@PEG NPs is rapid, low-cost, and environment-friendly and will facilitate the application of plasma-synthesized nanomaterials in sensors.

Structures of c-di-GMP/cGAMP degrading phosphodiesterase VcEAL: identification of a novel conformational switch and its implication

2019 ◽  
Vol 476 (21) ◽  
pp. 3333-3353 ◽  
Author(s):  
Malti Yadav ◽  
Kamalendu Pal ◽  
Udayaditya Sen
Keyword(s):  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Triosephosphate Isomerase ◽  
Catalytic Mechanism ◽  
Degradation Mechanism ◽  
Structural Basis ◽  
Conserved Residues ◽  
Phosphodiester Bond ◽  
Cyclic Dinucleotides

Cyclic dinucleotides (CDNs) have emerged as the central molecules that aid bacteria to adapt and thrive in changing environmental conditions. Therefore, tight regulation of intracellular CDN concentration by counteracting the action of dinucleotide cyclases and phosphodiesterases (PDEs) is critical. Here, we demonstrate that a putative stand-alone EAL domain PDE from Vibrio cholerae (VcEAL) is capable to degrade both the second messenger c-di-GMP and hybrid 3′3′-cyclic GMP–AMP (cGAMP). To unveil their degradation mechanism, we have determined high-resolution crystal structures of VcEAL with Ca2+, c-di-GMP-Ca2+, 5′-pGpG-Ca2+ and cGAMP-Ca2+, the latter provides the first structural basis of cGAMP hydrolysis. Structural studies reveal a typical triosephosphate isomerase barrel-fold with substrate c-di-GMP/cGAMP bound in an extended conformation. Highly conserved residues specifically bind the guanine base of c-di-GMP/cGAMP in the G2 site while the semi-conserved nature of residues at the G1 site could act as a specificity determinant. Two metal ions, co-ordinated with six stubbornly conserved residues and two non-bridging scissile phosphate oxygens of c-di-GMP/cGAMP, activate a water molecule for an in-line attack on the phosphodiester bond, supporting two-metal ion-based catalytic mechanism. PDE activity and biofilm assays of several prudently designed mutants collectively demonstrate that VcEAL active site is charge and size optimized. Intriguingly, in VcEAL-5′-pGpG-Ca2+ structure, β5–α5 loop adopts a novel conformation that along with conserved E131 creates a new metal-binding site. This novel conformation along with several subtle changes in the active site designate VcEAL-5′-pGpG-Ca2+ structure quite different from other 5′-pGpG bound structures reported earlier.

Heat Transfer in a Ferromagnetic Chemically Reactive Species

2020 ◽  
pp. 1-9
Author(s):  
Hassan Tahir ◽  
Umair Khan ◽  
Anwarud Din ◽  
Yu-Ming Chu ◽  
Noor Muhammad
Keyword(s):  
Heat Transfer ◽  
Reactive Species ◽  
Chemically Reactive Species

Rationalizing the pH-Activity Response for Escherichia Coli’s Glycinamide Ribonucleotidetransformylase Through Computational Methods

2019 ◽  
Author(s):  
Adrian Roitberg ◽  
Pancham Lal Gupta
Keyword(s):  
Transfer Reaction ◽  
Catalytic Mechanism ◽  
Ph Dependence ◽  
Ph Effects ◽  
Dependent Manner ◽  
E Coli ◽  
Gar Tfase ◽  
Activity Curve ◽  
Ph Dependent ◽  
Formyl Transfer

<div>Human Glycinamide ribonucleotide transformylase (GAR Tfase), a regulatory enzyme in the de novo purine biosynthesis pathway, has been established as an anti-cancer target. GAR Tfase catalyzes the formyl transfer reaction from the folate cofactor to the GAR ligand. In the present work, we study E. coli GAR Tfase, which has high sequence similarity with the human GAR Tfase with most functional residues conserved. E. coli GAR Tfase exhibits structural changes and the binding of ligands that varies with pH which leads to change the rate of the formyl transfer reaction in a pH-dependent manner. Thus, the inclusion of pH becomes essential for the study of its catalytic mechanism. Experimentally, the pH-dependence of the kinetic parameter kcat is measured to evaluate the pH-range of enzymatic activity. However, insufficient information about residues governing the pH-effects on the catalytic activity leads to ambiguous assignments of the general acid and base catalysts and consequently its catalytic mechanism. In the present work, we use pH-replica exchange molecular dynamics (pH-REMD) simulations to study the effects of pH on E. coli GAR Tfase enzyme. We identify the titratable residues governing the pH-dependent conformational changes in the system. Furthermore, we filter out the protonation states which are essential in maintaining the structural integrity, keeping the ligands bound and assisting the catalysis. We reproduce the experimental pH-activity curve by computing the population of key protonation states. Moreover, we provide a detailed description of residues governing the acidic and basic limbs of the pH-activity curve.</div>

Arylboronic Acids in Self-condensation of Glucosamines Forming Deoxyfructosazine, Catalysts or Reagents?

2019 ◽  
Author(s):  
Meifeng Wang ◽  
Gan Zhu ◽  
Yiqun Li ◽  
Liuqun Gu
Keyword(s):  
Molecular Recognition ◽  
Boric Acid ◽  
Boronic Acid ◽  
Catalytic Mechanism ◽  
Organic Transformations ◽  
Food Industries ◽  
Arylboronic Acids ◽  
Excess Amount ◽  
Phenyl Boronic Acid ◽  
Boron Acid

Arylboronic acids were widely used as efficient catalysts in direct amide formation and other organic transformations. Surprisingly, reports on their use as catalysts in carbohydrates synthesis are very rare even though boron acid-diol complexation was extensively investigated in molecular recognition for saccharides and so on. Here we developed an efficient arylboronic acids catalyzed dimerization of glucosamines forming deoxyfructosazine which is important compound in pharmaceutical and food industries, against a commonly held belief that excess amount of phenyl boronic acid (or boric acid) is a must. A catalytic mechanism was also proposed and arylboronic acids instead of their boronates was identified as catalysts.

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