scholarly journals Biomimetic Synthesis of Hydroxyapatite in Presence of Imidazole-4,5-dicarboxylic Acid Grafted Chitosan for Removing Chromium(VI)

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Zhangxu Chen ◽  
Baorong Wu ◽  
Xiaodan Huang ◽  
Xianxue Li ◽  
Yonglong Lin
Keyword(s):  
Dicarboxylic Acid ◽  
Removal Rate ◽  
Biomimetic Synthesis ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
X Ray ◽  
Natural Bone ◽  
Chromium Vi ◽  
Orthogonal Experiments ◽  
Novel Method

In order to biomimetic synthesize hydroxyapatite similar to natural bone. Hydroxyapatite (HAP) is biomimetic synthesized in simulated body fluid (SBF) by addition of imidazole-4,5-dicarboxylic acid grafted chitosan (IDACS). The effect of molar ratio of chitosan (CS) to imidazole-4,5-dicarboxylic acid (IDA) on preparation of HAP was investigated. The structure, size, and crystal phase of the obtained hydroxyapatite were observed by Fourier transform infrared spectroscopy, X-ray powder diffraction, and scanning electron microscopy. The results show that the molar ratio of CS to IDA is 1 : 3, the temperature is 37.0°C, the aging time is 48 h, the synthesized nanorod-like hydroxyapatite with diameter 20–30 nm, and length ranging from 75 to 120 nm presents excellent phase, which disperses well and is similar to the natural bone of HAP. The obtained HAP can be used to remove chromium(VI) by the orthogonal experiments, and the results indicated that the removal rate can reach 95.66% under the optimum conditions. These results suggest that the morphology of the obtained HAP is more affected by the material ratio of chitosan to imidazole-4,5-dicarboxylic acid than its structure, and the obtained HAP can effectively remove Cr(VI), which provides a novel method for biomimetic synthesis of other biomaterials and application in the water purification.

Preparation of xanthated bentonite and its removal behavior for Pb(II) ions

2010 ◽  
Vol 61 (5) ◽  
pp. 1235-1243 ◽  
Author(s):  
Y. F. He ◽  
F. R. Li ◽  
R. M. Wang ◽  
F. Y. Li ◽  
Y. Wang ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Removal Rate ◽  
Freundlich Isotherm ◽  
Particle Size Analysis ◽  
Lead Ions ◽  
Size Analysis ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir

Xanthate was successfully grafted onto bentonite by a relatively simple solution reaction. The obtained xanthated bentonite (XBent) was characterized by FT-IR spectrophotometer, thermogravimetric analysis (TG), particle size analysis, x-ray diffraction (XRD) and scanning electron microscopy (SEM). XBent acting as a type of environmentally friendly adsorbent was applied to remove lead ions from aqueous solutions. The optimum conditions were as follows: [Pb2 + ] = 500 mg L−1, [XBent] = 2 g L−1, pH = 5.0; oscillating 60 min under 200 rpm at 25°C. The removal rate of lead was up to 99.9%. It was found that the lead(II) ions—XBent adsorption isotherm model fitted well to the Freundlich isotherm. The adsorption mechanism was also investigated by SEM and XRD, which concluded that lead ions were complexed or chelated with XBent. XBent appears to have potential to be used later in water treatment as a type of inorganic polymer reagent.

Catalytic acetylation of (+)-cedrol with heterogeneous catalyst H2SO4/SiO2 under solvent free conditions

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Acetic Anhydride ◽  
Heterogeneous Catalyst ◽  
Silica Gel ◽  
Solvent Free ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solvent Free Conditions ◽  
Bet Method

Heterogeneous catalyst, H2SO4/SiO2 was synthesized by immobilizing sulfuric acid on silica gel as solid support. Silica gel was prepared from kaolin, originating from Belitung island Indonesia. The synthesized catalyst was characterized by various techniques such as X-ray diffraction, scanning electron microscopy, Fourier transform Infrared spectroscopy and BET method and was applied for the acetylation of (+)-cedrol compound using acetic anhydride under solvent free conditions. The optimum conditions for catalytic acetylation were found at 353 K for 20 h reaction period, the molar ratio (+)-cedrol/acetic anhydride 1:10 in the presence of 5%-w of catalyst converted 88,7% (+)-cedrol into cedryl acetate. Results revealed catalyst could possibly be used for cedryl acetate synthesis from (+)-cedrol.

Biomimetic Synthesis of Tooth-Like Hydroxyapatite under Organic Polymer Monolayer

2009 ◽  
Vol 610-613 ◽  
pp. 1054-1058
Author(s):  
Kun Tian ◽  
Hui Min Shuai ◽  
Xiao Min Yang
Keyword(s):  
Biomimetic Synthesis ◽  
Organic Polymer ◽  
Molar Ratio ◽  
Dentinal Tubule ◽  
Ftir Analysis ◽  
X Ray ◽  
Dentin Surface ◽  
Crosslinking Process ◽  
Protein Monolayer

Based on the basic theory of molecular recognition , we design a organic molecules model to induce the crystallization of hydroxyapatite to synthesized tooth-like calcium phosphate/hydroxyapatite under a controllable way in vitro. The cross-linking of collagen on the dentin surface and extraneous collagen was optimized by varying the molar ratio of N,N-(3-dimethylaminopropyl)- N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) at a constant EDC concentration. CaCl2 and Na3PO4-12H2O solutions were added after the crosslinking process. X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis of organic protein monolayer for samples. The obtained composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as energy dispersive X-ray (EDX). XPS and FTIR analysis showed the surface organic compositions in experimental group is higher than that of normal dentin and decalcified dentin surface. The results showed that the dentinal tubule were blocked by neonatal hydroxyapatite layer which has a continuous structure of columns crystal with size of 10-40nm. Furthermore, there were column crystal with parallel direction inside, similar to the crystal array in the top of enamel rod. This study showed that the specific organic molecule model can be used as a potential effective crystal growth modifier.

scholarly journals Fabrication of Surfactant-Enhanced Metal Oxides Catalyst for Catalytic Ozonation Ammonia in Water

2018 ◽  
Vol 15 (8) ◽  
pp. 1654 ◽  
Author(s):  
Yunnen Chen ◽  
Lin Guo ◽  
Chang Li
Keyword(s):  
Catalytic Activity ◽  
Metal Oxides ◽  
Metal Salt ◽  
Removal Rate ◽  
Catalytic Ozonation ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Gaseous Nitrogen ◽  
Solid State Method ◽  
X Ray

The new surfactant-enhanced metal oxides composite catalysts have been prepared using solid state method and characterized by the N2-adsorption-desorption, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), and X-ray diffraction (XRD) techniques. Catalytic activity of the synthesized powders has been investigated in the liquid-phase catalytic ozonation ammonia nitrogen (NH4+) (50 mg/L). Especially, the effect of parameters such as optimum molar ratio for metal salt, NaOH and surfactants, temperature, and time of calcinations was also considered. Leveraging both high catalytic activity in NH4+degradation and more harmless selectivity for gaseous nitrogen, the CTAB/NiO catalyst is the best among 24 tested catalysts, which was generated by calcining NiCl2·6H2O, NaOH, and CTAB under the molar ratio 1:2.1:0.155 at 300 °C for 2 h. With CTAB/NiO, NH4+ removal rate was 95.93% and gaseous nitrogen selectivity was 80.98%, under the conditions of a pH of 9, ozone flow of 12 mg/min, dosage of catalyst 1.0 g/L, reaction time 120 min, and magnetic stirring speed 600 r/min in room temperature.

Effects of Reverse Micelles-Complexation-Supercritical CO2 Extraction Conditions on Removal of Pb, Hg and as Ions in Lotus Leaf

2011 ◽  
Vol 233-235 ◽  
pp. 585-588 ◽  
Author(s):  
Jun Ji ◽  
Yao Ding ◽  
Chang Yan Yang ◽  
Hai Tao Huang ◽  
Yi Gang Ding
Keyword(s):  
Reverse Micelles ◽  
Loss Rate ◽  
Removal Rate ◽  
Orthogonal Experiment ◽  
Complexing Agent ◽  
Optimum Conditions ◽  
Leaf Extracts ◽  
Lotus Leaf ◽  
Orthogonal Experiments ◽  
Triton X

Removal rates of Pb, Hg and As ions in lotus leaf extracts obtained by Micelles- complexation-supercritical CO2 extraction through an orthogonal experiment(L16(45)) were investigated to get the best extraction conditions. The results of orthogonal experiments indicated that the removal rate of Pb, Hg and As ions trace heavy metal ions is high by complexaction and reverse micelles in supercritical carbon dioxide (Sc-CO2), and the removal rate of Pb, Hg, As from lotus leaf is 87.85%, 89.19% and 84.72% respectively with the loss rate of total flavonoids is 8.73% under the potential optimum conditions which are 50°C, 20 MPa, 1.5 h, the concentration of Triton X-100 of 0.15 mol.L-1, the mass of complexing agent is 0.1 g.

Crystallochemical formula as a tool for describing metal–ligand complexes – a pyridine-2,6-dicarboxylate example

2009 ◽  
Vol 65 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Viktor N. Serezhkin ◽  
Anna V. Vologzhanina ◽  
Larisa B. Serezhkina ◽  
Ekaterina S. Smirnova ◽  
Elena V. Grachova ◽  
...  
Keyword(s):  
Dicarboxylic Acid ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystallochemical Formula ◽  
Structural Database ◽  
Acidic Ligands ◽  
Metal Ligand ◽  
Crystallochemical Analysis ◽  
Pentadentate Ligand

Compounds (299) containing 494 symmetrically independent pyridine-2,6-dicarboxylate moieties have been investigated. Among them the structures of Na3[Nd(Pydc)3]·14H2O and Na3[Er(Pydc)3]·11.5H2O, where H2Pydc is pyridine-2,6-dicarboxylic acid, were determined by single-crystal X-ray diffraction, while the others were taken from the Cambridge Structural Database. The characteristics of any complex by means of the `method of crystallochemical analysis' are described, and the coordination types of all the Pydc ions and crystallochemical formulae of all the compounds were determined. Although the ion can act as a mono-, bi-, tri-, tetra- and pentadentate ligand, 96% of Pydc ions are coordinated to the central A atom in the tridentate-chelating mode. The dependence of the denticity and geometry of pyridine-2,6-dicarboxylate, as well as of the composition of Pydc-containing complexes, was studied as a function of the nature of the A atom, the molar ratio Pydc:A and the presence of neutral or acidic ligands in the reaction mixture.

Effect of Different Molar Ratios of Fenton Reagents on the Surface Modification of CNTs

2011 ◽  
Vol 236-238 ◽  
pp. 2036-2039
Author(s):  
Yin Qiang ◽  
Jian Hua Xin
Keyword(s):  
Carbon Nanotubes ◽  
Molar Ratio ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
Uv Treatment ◽  
X Ray ◽  
Molar Ratios ◽  
Fenton Reagents ◽  
Result Show ◽  
Novel Method

A novel method——Fenton/UV treatment, was used to modificate carbon nanotubes (CNTs) in our research. Effects of different molar ratios of Fenton reagents on the surface of CNTs were studied in our work. The purity of CNTs was investigated by TGA. The functional groups on the surface of CNTs were investigated by FTIR spectra, and the phase analysis of CNTs was investigated by X-ray diffraction analysis (XRD). The result show that it can introduce a great deal of hydroxyl groups onto the surface of carbon nanotubes, and almost never introduce impurities, when the molar ratio of Fe2+and H2O2 is 1:40.

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

Heterogeneous Fenton Catalytic Removal of Organic Pollutant in Aqueous Solution by using Coal Gangue as a Catalyst

2019 ◽  
Vol 12 (4) ◽  
pp. 312-325
Author(s):  
Jiwei Zhang ◽  
Jingjing Xu ◽  
Shuaixia Liu ◽  
Baoxiang Gu ◽  
Feng Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Removal Rate ◽  
Organic Pollutant ◽  
Coal Gangue ◽  
Ion Leakage ◽  
Heterogeneous Fenton ◽  
Solution Ph ◽  
X Ray

Background: Coal gangue was used as a catalyst in heterogeneous Fenton process for the degradation of azo dye and phenol. The influencing factors, such as solution pH gangue concentration and hydrogen peroxide dosage were investigated, and the reaction mechanism between coal gangue and hydrogen peroxide was also discussed. Methods: Experimental results showed that coal gangue has the ability to activate hydrogen peroxide to degrade environmental pollutants in aqueous solution. Under optimal conditions, after 60 minutes of treatment, more than 90.57% of reactive red dye was removed, and the removal efficiency of Chemical Oxygen Demand (COD) up to 72.83%. Results: Both hydroxyl radical and superoxide radical anion participated in the degradation of organic pollutant but hydroxyl radical predominated. Stability tests for coal gangue were also carried out via the continuous degradation experiment and ion leakage analysis. After five times continuous degradation, dye removal rate decreased slightly and the leached Fe was still at very low level (2.24-3.02 mg L-1). The results of Scanning Electron Microscope (SEM), energy dispersive X-Ray Spectrometer (EDS) and X-Ray Powder Diffraction (XRD) indicated that coal gangue catalyst is stable after five times continuous reuse. Conclusion: The progress in this research suggested that coal gangue is a potential nature catalyst for the efficient degradation of organic pollutant in water and wastewater via the Fenton reaction.

scholarly journals COVID-19 infection map generation and detection from chest X-ray images

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Aysen Degerli ◽  
Mete Ahishali ◽  
Mehmet Yamac ◽  
Serkan Kiranyaz ◽  
Muhammad E. H. Chowdhury ◽  
...  
Keyword(s):  
State Of The Art ◽  
Ground Truth ◽  
Clinical Use ◽  
X Ray ◽  
Learning Techniques ◽  
Map Generation ◽  
Severity Grading ◽  
Chest X Ray ◽  
Novel Method ◽  
Aided Diagnosis

AbstractComputer-aided diagnosis has become a necessity for accurate and immediate coronavirus disease 2019 (COVID-19) detection to aid treatment and prevent the spread of the virus. Numerous studies have proposed to use Deep Learning techniques for COVID-19 diagnosis. However, they have used very limited chest X-ray (CXR) image repositories for evaluation with a small number, a few hundreds, of COVID-19 samples. Moreover, these methods can neither localize nor grade the severity of COVID-19 infection. For this purpose, recent studies proposed to explore the activation maps of deep networks. However, they remain inaccurate for localizing the actual infestation making them unreliable for clinical use. This study proposes a novel method for the joint localization, severity grading, and detection of COVID-19 from CXR images by generating the so-called infection maps. To accomplish this, we have compiled the largest dataset with 119,316 CXR images including 2951 COVID-19 samples, where the annotation of the ground-truth segmentation masks is performed on CXRs by a novel collaborative human–machine approach. Furthermore, we publicly release the first CXR dataset with the ground-truth segmentation masks of the COVID-19 infected regions. A detailed set of experiments show that state-of-the-art segmentation networks can learn to localize COVID-19 infection with an F1-score of 83.20%, which is significantly superior to the activation maps created by the previous methods. Finally, the proposed approach achieved a COVID-19 detection performance with 94.96% sensitivity and 99.88% specificity.

Sign in / Sign up

Export Citation Format

Share Document