scholarly journals Green Synthesis of Nanostructure CeO2 Using Tea Extract: Characterization and Adsorption of Dye from Aqueous Phase

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chengshun Liu ◽  
Xiyao Liu ◽  
Yilin Wu ◽  
Zhuotong Chen ◽  
Zhuanrong Wu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Fluorite Structure ◽  
Bulk Sample ◽  
Second Order ◽  
Raman Signal ◽  
Cerium Chloride ◽  
Adsorption Efficiency ◽  
Order Model ◽  
X Ray ◽  
Second Order Model

Nanostructure CeO2 powders were synthesized using tea waste extract as gel precursor. The as-prepared samples were characterized by thermogravimetric analyzer (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Based on the TGA/DTG analysis, the intermediates of cerium chloride hydrates (CeCl3.4H2O and CeCl3.H2O) and cerium anhydrous (CeCl3) were produced, and the formation temperature of CeO2 was estimated to be 773 K. The cubic fluorite structure of CeO2 was detected to be the predominant species and was completely formed at the calcination temperature of 773K–1073 K with a crystal size between 8.8 and 11.4 nm based on the XRD measurement. Moreover, the main chemical state of ceria on the surface of the synthesized samples was confirmed to be tetravalent ceria by XPS. All samples show a strong Raman signal at a well-defined chemical shift of 463 cm−1 and a significant symmetry feature was observed, suggesting that the tetravalent ceria is the dominant species throughout the bulk sample. All the synthesized CeO2 calcined at different temperatures showed higher adsorption efficiency for Congo red (CR) compared with commercial CeO2. The adsorption efficiency maintained a steady state of more than 95% when the concentration of CR and adsorption temperature were varied in this study. The kinetic analysis showed that the second-order model was the appropriate model to interpret the adsorption behavior of synthesized CeO2. The calculated adsorption capacity derived from the second-order model is in good agreement with the experimental data. The isotherm analysis revealed that the Freundlich and D-R models fit well for the synthesized CeO2 and represent physisorption with a multilayer mechanism. The thermodynamic parameters, including the changes in Gibb’s free energy, enthalpy, and entropy, suggested that the adsorption of CR on the synthesized CeO2 sample was a spontaneous and endothermic process.

Fluoride processing of oil hydrocarbon cracking catalyst with REE concentrate extraction

2021 ◽  
Vol 1 (1) ◽  
pp. 28-35
Author(s):  
A. O. Puzhel ◽  
V. A. Borisov ◽  
A. R. Osipov ◽  
I. V. Petlin ◽  
A. D. Kiselev ◽  
...  
Keyword(s):  
Rare Earth ◽  
Ir Spectroscopy ◽  
Phase Analysis ◽  
Second Order ◽  
Order Model ◽  
X Ray ◽  
Before And After ◽  
Aluminum Compounds ◽  
Oil Cracking ◽  
Second Order Model

It is proposed to use a spent cracking catalyst of petroleum hydrocarbons containing 1 wt.% of rare earth element (REE) oxides as an alternative REE feed source. The study covers the process of removing silicon in the form of ammonium hexafluorosilicate (NH4)2SiF6 by sintering an oil cracking catalyst sample with NH4F and subsequent (NH4)2SiF6 sublimation to produce an aluminum-containing concentrate of rare earth elements. The orthogonal central compositional planning of the experiment was used to study the effect of three factors: sublimation temperature (350 to 400 °С), duration (40 to 80 min), and weight of the catalyst fluorinated sintered mass (5 to 10 g) on the (NH4)2SiF6 sublimation completeness. Results obtained in the experiment were used to build a second-order model, which correlate with experimental data. The dynamics of (NH4)2SiF6 sublimation removal was determined for sublimation durations of τ = 10, 20, 40 and 80 min at processing temperatures of 350, 375 and 400 °C. The (NH4)2SiF6 removal degree values calculated based on the second-order model for τ = 44, 48, 52, 56, 60, 64, 68, 72, and 76 min fit well the experimental curves. Spectra of fluorinated catalyst samples before and after sublimation were studied using X-ray phase analysis and IR spectroscopy. The data of IR spectroscopy and X-ray phase analysis are in good agreement and show that (NH4)2SiF6, (NH4)3AlF6 and unreacted NH4F are present in the catalyst with NH4F sintered mass, and only aluminum compounds are detected – NH4AlF4 and AlF3 after sublimation. These data indicate the completeness of the sublimation removal of silicon from the catalyst and NH4F sintered mass with NH4AlF4 and AlF3 aluminum compounds only observed after sublimation. REE concentration is 15 % due to silicon removal.

Adsorption of Cu(II) from Aqueous Solutions by Ammoniated Cotton Fiber

2016 ◽  
Vol 11 (4) ◽  
pp. 155892501601100
Author(s):  
Chuanfeng Zang ◽  
Yu Ren ◽  
Fangfang Wang ◽  
Hong Lin ◽  
Yuyue Chen
Keyword(s):  
Aqueous Solutions ◽  
Cotton Fiber ◽  
Photoelectron Spectroscopy ◽  
Metal Ion ◽  
Second Order ◽  
Order Model ◽  
Amine Content ◽  
Pseudo Second Order ◽  
Adsorption Amount ◽  
Second Order Model

This study describes the preparation of a novel chelating cotton fiber adsorbent, ammoniated cotton fiber (ACF), which was prepared by modifying cotton fiber with amino-HBP using glutaraldehyde as a cross-linking agent. This new adsorbent was characterized and analyzed for amine content, and by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The capacity of ACF to adsorb Cu(II) from aqueous solution was evaluated at different pHs, contact times and initial metal ion concentrations. The results showed that ACF was effective in removing of Cu(II) from aqueous solutions and the adsorption amount of Cu(II) reached 16.7374 mg g-1. The adsorption isotherm and kinetics were well fitted to the Langmuir model and the pseudo-second-order model, respectively. The adsorption amount calculated using the pseudo-second-order model was in good agreement with the experimental data.

scholarly journals Application of Wasted Oolong Tea as a Biosorbent for the Adsorption of Methylene Blue

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Yunfei Hu ◽  
Yue Zhang ◽  
Yuqun Hu ◽  
Chen-Yao Chu ◽  
Jinke Lin ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Adsorption Process ◽  
Intraparticle Diffusion ◽  
Second Order ◽  
Adsorption Efficiency ◽  
Order Model ◽  
Oolong Tea ◽  
Adsorption Capacities ◽  
Pseudo Second Order ◽  
Second Order Model

Tea powder, a biosorbent prepared from wasted oolong tea, was collected as a prospective adsorbent for the adsorption of methylene blue (MB) from aqueous solution. The effect of factors on adsorption efficiency, isotherms, kinetics, and potential mechanism was carried out. Adsorption capacity of MB onto wasted tea powder increased with the MB concentration and contact time, whereas the increase in pH value and ion strength appeared to have a negative effect for the adsorption process. The adsorption efficiency increased rapidly and reached a stable state within 120 min. The optimal tea powder loading weight is suggested to be at 0.1 to 0.2 g, and the highest efficiency of 94.8% is achieved at 333 K. There were no significant changes in adsorption efficiency when the effect of temperature is considered. The Langmuir isotherm model was found to be the best isotherm models to elucidate the adsorption mechanism in this study. The maximum adsorption capacities calculated at different temperatures by the Langmuir model ranging from 312.5 to 333.3 mg·g−1 were much close to the experimental results. From the kinetic analysis, the pseudo--second-order model was found to be the best model to describe the adsorption behavior. The calculated adsorption capacities at different initial MB concentrations by the pseudo-second-order model ranging from 92.34 to 400 mg·g−1 were well close to the experimental data. The fitting results obtained from the intraparticle diffusion model suggested that the intraparticle diffusion was not the only rate-controlling step and some other mechanisms along with the intraparticle diffusion were probably involved. The intraparticle diffusion of MB molecules into pore structures of wasted tea powder is the rate-limiting step for the adsorption process in this study. The repetitive cycle experiments indicated that the wasted oolong tea powder was efficiently regenerated using NaOH and thus be used for many times.

scholarly journals Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Model ◽  
X Ray ◽  
Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

Adsorption Kinetics of Pb2+ Ions Using Chitosan Nanoparticles

2013 ◽  
Vol 367 ◽  
pp. 45-49
Author(s):  
Ying Hong ◽  
Ze Hui Zhong ◽  
You Shi Liu
Keyword(s):  
Adsorption Kinetics ◽  
Chitosan Nanoparticles ◽  
Second Order ◽  
Isotherm Model ◽  
Order Model ◽  
Adsorption Characteristics ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Second Order Model

Chitosan nanoparticles were prepared by crosslinkingusing TPP. SEM showed that chitosan nanoparticles were successfully obtained.The adsorption characteristics of chitosan nanoparticles were evaluated. Theresults demonstrated that chitosan nanoparticles were suitable for adsorbent toremoval Pb2+. The parameters for the adsorption of Pb2+by chitosan nanoparticles were also determined. It was shown that chitosannanoparticles were fit for Langmuir’s isotherm model and that the adsorptionkinetics of Pb2+ described by the pseudo-second-order model could bebest.

Polyaniline/ZnO nanocomposites for the removal of methyl orange dye from waste water

2018 ◽  
Vol 32 (19) ◽  
pp. 1840085 ◽  
Author(s):  
Neha V. Nerkar ◽  
Subhash B. Kondawar ◽  
Snehal Kargirwar Brahme ◽  
Yun Hae Kim
Keyword(s):  
Waste Water ◽  
Methyl Orange ◽  
Adsorption Mechanism ◽  
Second Order ◽  
Pure Pani ◽  
Time Interval ◽  
Order Model ◽  
Vis Spectroscopy ◽  
Pseudo Second Order ◽  
Second Order Model

In this paper, we report the safe removal of methyl orange (MO) dye from aqueous solution using chemical interaction of dye molecule with polyaniline/zinc oxide (PANI/ZnO) nanocomposite. PANI/ZnO nanocomposite has been prepared by in situ polymerization. PANI/ZnO nanocomposite was found to be the best promising candidate for adsorption of dyes due to more porosities compared to that of pure PANI. In the present investigation, PANI/ZnO nanocomposite was mixed in a solution of MO dye and used for adsorption process. Color removal was studied using UV-Vis spectroscopy and the spectra were recorded for specific time interval and validation of kinetic model has been applied. Absorbance of PANI/ZnO nanocomposite was found to be increased as compared to that of pure ZnO nanoparticles and pure PANI due to synergistic effect. Comparatively, the removal of dye was also found to be more by using PANI/ZnO nanocomposites. In order to evaluate kinetic mechanism the pseudo-first-order model, pseudo-second-order model and intraparticle diffusion models were verified by the linear equation analysis. Adsorption mechanism of pseudo-second-order model was systematically explained for removal of dye using PANI/ZnO nanocomposite. The results clearly demonstrated that the adsorption mechanism gives very novel and green method of removal of hazardous dyes from waste water.

scholarly journals Validating a second-order model for oil and gas projects’ investment climate scale

2017 ◽  
Vol 11 (1) ◽  
pp. 65-79 ◽  
Author(s):  
Abdulsalam Mas’ud ◽  
Nor Aziah Abd Manaf ◽  
Natrah Saad
Keyword(s):  
Goodness Of Fit ◽  
Oil And Gas ◽  
Second Order ◽  
Fit Indices ◽  
Investment Climate ◽  
Order Model ◽  
Content Type ◽  
Latent Construct ◽  
Climate Scale ◽  
Second Order Model

Purpose The investment climate is one of the key factors considered by foreign investors while deciding their investment destination. This paper aims to attempt at validating the second-order model of oil and gas projects’ investment climate. Examination of the relationship between the dimensions of oil and gas projects’ investment climate; strategy, participants/operating environment and risk/return; and the overall latent construct was conducted. The study also evaluates the goodness of fit of the second-order model using relevant fit indices. Design/methodology/approach Oil and gas experts in Malaysian marginal oil fields subsector were deployed, through whom responses were collected that formed the data set used in the analysis. Then, the data were used for confirmatory factor analysis, evaluation of the second-order model through path analysis and for model fit evaluation. Findings The finding revealed that the second-order model of oil and gas projects’ investment climate is valid and reliable. It also revealed that all the three dimensions, strategy, participants/operating environment and risk/return, have significant effects on the formation of the oil and gas projects’ investment climate. Finally, the goodness of fit of the second-order model satisfied the relevant fit indices. Research limitations/implications The findings present valuable insights to policymakers on the extent of the influence each of the dimensions has on the overall latent construct. The validity and reliability analysis suggests the measurements of the second-order model of oil and gas projects’ investment climate construct, and its dimensions are valid, reliable and fit for future empirical research. Thus, it calls for replication in other oil and gas settings. Originality/value The findings from the results of this study are pioneering. Extant literature falls short in attempting the validation of the second-order oil and gas projects’ investment climate scale, as well as relating each of the dimensions with the overall latent construct.

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