scholarly journals Degradation of Azo Dyes with Different Functional Groups in Simulated Wastewater by Electrocoagulation

Water ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 123
Author(s):  
Yang Liu ◽  
Chenglong Li ◽  
Jia Bao ◽  
Xin Wang ◽  
Wenjing Yu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Azo Dyes ◽  
Current Intensity ◽  
Hydroxyl Groups ◽  
Time Saving ◽  
Alizarin Yellow ◽  
Energy Conserving ◽  
Carcinogenic Effects ◽  
Simulated Wastewater ◽  
Hydroxyl Free Radicals

Increasing attention has been paid to the widespread contamination of azo dyes in water bodies globally. These chemicals can present high toxicity, possibly causing severe irritation of the respiratory tract and even carcinogenic effects. The present study focuses on the periodically reverse electrocoagulation (PREC) treatment of two typical azo dyes with different functional groups, involving methyl orange (MO) and alizarin yellow (AY), using Fe-Fe electrodes. Based upon the comparative analysis of three main parameters, including current intensity, pH, and electrolyte, the optimal color removal rates for MO and AY could be achieved at a rate of up to 98.7% and 98.6%, respectively, when the current intensity is set to 0.6 A, the pH is set at 6.0, and the electrolyte is selected as NaCl. An accurate predicted method of response surface methodology (RSM) was established to optimize the PREC process involving the three parameters above. The reaction time was the main influence for both azo dyes, while the condition of PREC treatment for AY simulated wastewater was time-saving and energy conserving. According to the further UV–Vis spectrophotometry analysis throughout the procedure of the PREC process, the removal efficiency for AY was better than that of MO, potentially because hydroxyl groups might donate electrons to iron flocs or electrolyze out hydroxyl free radicals. The present study revealed that the functional groups might pose a vital influence on the removal efficiencies of the PREC treatment for those two azo dyes.

scholarly journals Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Xu Xu ◽  
Zeping Zhang ◽  
Wenjuan Yao
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Grain Boundaries ◽  
Functional Groups ◽  
Oxygen Content ◽  
Tensile Fracture ◽  
Hydroxyl Groups ◽  
Molecular Configuration ◽  
Spatial Design ◽  
Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

Diffusion coefficients and viscosities of organic aerosol components through equilibrium and non-equilibrium molecular dynamics simulations

2021 ◽  
Author(s):  
Katerina S. Karadima ◽  
Vlasis G. Mavrantzas ◽  
Spyros N. Pandis
Keyword(s):  
Molecular Dynamics ◽  
Functional Groups ◽  
Organic Compounds ◽  
Diffusion Coefficients ◽  
Amorphous Solid ◽  
Good Effect ◽  
Hydroxyl Groups ◽  
Chemical Structures ◽  
Organic Particles ◽  
Non Equilibrium

<p>Organic aerosols have been typically considered to be liquid, with equilibration between gas and aerosol phase assumed to be reached within seconds. However, Virtanen et al. (Nature, 2010) suggested that particles in amorphous solid state may also occur in the atmosphere implying that mass transfer between the atmospheric particulate and gas phases may be much slower than initially thought. Experimentally, the direct measurement of the diffusion coefficients of different compounds inside atmospheric organic particles is challenging. Thus, an indirect approach is usually employed, involving viscosity measurements and then estimation of diffusion coefficients via the Stokes-Einstein equation, according to which the diffusion coefficient is inversely proportional to the medium viscosity. However, the corresponding diffusion estimates are highly uncertain, especially for highly viscous aerosols which is the most important case. Molecular simulation methods, such as molecular dynamics (MD), can be an alternative method to determine directly the diffusion rates and the viscosity of the constituents of atmospheric organic particles. MD also provides detailed information of the exact dynamics and motion of the molecules, thus offering a deeper understanding on the underlying mechanisms and interactions.</p><p>In the present work, we use equilibrium and non-equilibrium MD simulations to estimate the viscosity and diffusion coefficients of bulk systems of representative organic compounds with different chemical structures and physicochemical characteristics. Hydrophilic and hydrophobic compounds representative of primary and secondary oxidized organic products and of primary organic compounds emitted by various sources are considered. The viscosity and self-diffusion coefficients calculated by our simulations are in good agreement with available experimentally measured values. Our results confirm that the presence of carboxyl and hydroxyl groups in the molecule increases the viscosity. The number of carboxyl and hydroxyl groups, in particular, seems to have a good effect on diffusivity (the diffusivity decreases as the number of these functional groups increase), and to a lesser extent on the viscosity. We also discuss the role of the hydrogen bonds formed between these functional groups.</p>

Effect of Acid on Surface Hydroxyl Groups on Kaolinite and Montmorillonite

2018 ◽  
Vol 232 (3) ◽  
pp. 409-430 ◽  
Author(s):  
Sarah K. Sihvonen ◽  
Kelly A. Murphy ◽  
Nancy M. Washton ◽  
Muhammad Bilal Altaf ◽  
Karl T. Mueller ◽  
...  
Keyword(s):  
Functional Groups ◽  
Acid Treatment ◽  
Atmospheric Transport ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Magic Angle ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Angle Spinning

AbstractMineral dust aerosol participates in heterogeneous chemistry in the atmosphere. In particular, the hydroxyl groups on the surface of aluminosilicate clay minerals are important for heterogeneous atmospheric processes. These functional groups may be altered by acidic processing during atmospheric transport. In this study, we exposed kaolinite (KGa-1b) and montmorillonite (STx-1b) to aqueous sulfuric acid and then rinsed the soluble reactants and products off in order to explore changes to functional groups on the mineral surface. To quantify the changes due to acid treatment of edge hydroxyl groups, we use19F magic angle spinning nuclear magnetic resonance spectroscopy and a probe molecule, 3,3,3-trifluoropropyldimethylchlorosilane. We find that the edge hydroxyl groups (OH) increase in both number and density with acid treatment. Chemical reactions in the atmosphere may be impacted by the increase in OH at the mineral edge.

Reaction pathways of hydroxyl groups during coal spontaneous combustion

2016 ◽  
Vol 94 (5) ◽  
pp. 494-500 ◽  
Author(s):  
Xuyao Qi ◽  
Haibo Xue ◽  
Haihui Xin ◽  
Cunxiang Wei
Keyword(s):  
Activation Energy ◽  
Free Radicals ◽  
Hydrogen Abstraction ◽  
Enthalpy Change ◽  
Reaction Pathways ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Typical Structure ◽  
Self Heating ◽  
Hydroxyl Free Radicals

Hydroxyl groups are one of the key factors for the development of coal self-heating, although their detailed reaction pathways are still unclear. This study investigated the reaction pathways in coal self-heating by the method of quantum chemistry calculation. The Ar–CH2–CH(CH3)–OH was selected as a typical structure unit for the calculation. The results indicate that the hydrogen atoms in hydroxyl groups and R3–CH are the active sites. For the hydrogen atoms in hydroxyl groups, they are directly abstracted by oxygen. For hydrogen atoms in R3–CH, they are abstracted by oxygen at first and generate peroxy-hydroxyl free radicals, which abstract the hydrogen atoms in hydroxyl groups later. The reaction of R3–CH contains three elementary reactions, i.e., the hydrogen abstraction of R3–CH by oxygen, the conjugation reaction between the R3C■ and oxygen atom, and the hydrogen abstraction of –OH by hydroxyl free radicals. Then, the microstructure parameters, IRC pathways, and reaction dynamic parameters were respectively analyzed for the four reactions. For the hydrogen abstraction of –OH by oxygen, the enthalpy change and activation energy are 137.63 and 334.44 kJ/mol, respectively, which will occur at medium temperatures and the corresponding heat effect is great. For the reaction of R3–CH, the enthalpy change and the activation energy are −3.45 and 55.79 kJ/mol, respectively, which will occur at low temperatures while the corresponding heat influence is weak. They both affect heat accumulation and provide new active centers for enhancing the coal self-heating process. The results would be helpful for further understanding of the coal self-heating mechanism.

Effects of metal ions on the interaction between polyethylenimine and azo dyes carrying hydroxyl groups

1985 ◽  
Vol 23 (1) ◽  
pp. 255-259 ◽  
Author(s):  
Toru Takagishi ◽  
Kiyoaki Yoshikawa ◽  
Sadatsugu Okuda ◽  
Nobuhiko Kuroki ◽  
Hiroshi Kozuka
Keyword(s):  
Metal Ions ◽  
Azo Dyes ◽  
Hydroxyl Groups

Construction and surface/interface behavior of bio-functional surface layer by microwave-excited Ar/H2O plasma-induced polyethylene glycol polymerization

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744093
Author(s):  
Z. Shao ◽  
A. Ogino ◽  
M. Nagatsu
Keyword(s):  
Surface Layer ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Optical Emission ◽  
Aging Effect ◽  
Hydroxyl Groups ◽  
Functional Surface ◽  
Interface Behavior ◽  
Water Contact ◽  
Spacer Layer

Ar/H2O microwave-excited surface-wave plasma-induced grafting-polymerization and crosslinking technique was presented to construct a bio-functional surface layer. Optical emission spectroscopy was used to diagnose Ar/H[Formula: see text]O plasma. The surface/interface behavior especially the aging effect of hydroxyl groups over the grafted PEG spacer layer was investigated by measuring water contact angle and X-ray photoelectron spectroscopy. The results demonstrate that the addition of water vapor into Ar plasma can optimize the concentration of hydroxyl functional groups on surface; grafted PEG spacer layer can provide a long-term hydrophilicity of PU films, and alleviate the aging effect of hydroxyl functional groups.

A novel amino acid analysis method using derivatization of multiple functional groups followed by liquid chromatography/tandem mass spectrometry

The Analyst ◽  
2015 ◽  
Vol 140 (6) ◽  
pp. 1965-1973 ◽  
Author(s):  
Yohei Sakaguchi ◽  
Tomoya Kinumi ◽  
Taichi Yamazaki ◽  
Akiko Takatsu
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Functional Groups ◽  
Amino Acid Analysis ◽  
Hydroxyl Groups ◽  
Tandem Mass ◽  
Analysis Method ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Phenolic Hydroxyl Groups

We have developed a novel amino acid analysis method using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups).

scholarly journals Terminal Groups Dependent Near-Field Enhancement Effect of Ti3C2Tx Nanosheets

2020 ◽  
Author(s):  
Ying-Ying Yang ◽  
Wen-Tao Zhou ◽  
Wei-Long Song ◽  
Qing-Quan Zhu ◽  
Hao-Jiang Xiong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Oxidation Resistance ◽  
Functional Groups ◽  
Near Field ◽  
Field Enhancement ◽  
Electron Injection ◽  
Enhancement Effect ◽  
Hydroxyl Groups ◽  
Physical And Chemical

Abstract Both multilayered (ML) and few-layered (FL) Ti3C2Tx nanosheets with different dominant terminal groups have been prepared through a typical etching and delaminating procedure. Various characterizations confirm that the physical and chemical performance of the nanosheets are dependent on the dominant functional groups. It has been demonstrated that ML-Ti3C2Tx has been mainly terminated by O-related groups, which result in better oxidation resistance and stronger near-field enhancement effect. As for FL-Ti3C2Tx, which is mainly terminated by hydroxyl groups, it can be better dispersed in aqueous solution and could confine stronger near-field after coupling to Ag nanostructures by electron injection.

scholarly journals Biobased Hyperbranched Poly(ester)s of Precise Structure for the Release of Therapeutics

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Bob Howell ◽  
Tracy Zhang ◽  
Patrick Smith
Keyword(s):  
Sustained Release ◽  
Functional Groups ◽  
Active Agent ◽  
Monomer Conversion ◽  
Single Type ◽  
Hydroxyl Groups ◽  
Naturally Occurring ◽  
Hyperbranched Poly ◽  
The Difference ◽  
Smith Model

Hyperbrached poly(ester)s derived from naturally-occurring biomonomers may serve as excellent platforms for the sustained-release of therapeutics. Those generated from glycerol are particularly attractive. Traditionally, the difference in reactivity of the hydroxyl groups of glycerol has precluded the formation of well-defined polymers at high monomer conversion without gelation. Using the Martin-Smith model to select appropriate monomer ratios (ratios of functional groups), polymerization may be carried out to high conversion while avoiding gelation and with the assurance of a single type of endgroup. Various agents may be attached via esterification, amide formation or other process. Sustained release of the active agent may be readily achieved by enzyme-catalyzed hydrolysis.

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