scholarly journals Preparation of magnetic carbon/Fe3O4 supported zero-valent iron composites and their application in Pb(II) removal from aqueous solutions

2017 ◽  
Vol 76 (10) ◽  
pp. 2680-2689 ◽  
Author(s):  
Kaixuan Ma ◽  
Qiu Wang ◽  
Qianyun Rong ◽  
Dapeng Zhang ◽  
Shihai Cui ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Zero Valent Iron ◽  
Solution Ph ◽  
Environmental Friendliness ◽  
X Ray ◽  
Transmission Electron ◽  
Reduction Methods ◽  
Magnetic Carbon

Abstract Nanoscale zero-valent iron (NZVI) was first assembled on magnetic carbon/Fe3O4 (CM) with a combination of hydrothermal and liquid phase reduction methods. The novel NZVI@CM magnetic nanocomposites have the merits of large surface area, unique magnetic property, low cost and environmental friendliness. They can be used for Pb(II) removal in aqueous solution. The materials were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) adsorption. The various parameters, such as reaction time, dosage of catalyst, solution pH and acid ions concentrations were studied. The removal efficiency of Pb(II) can be obviously increased by the combination of appropriate CM and NZVI. The removal efficiency of Pb(II) is 99.7% by using 60 mg of NZVI@CM at pH 7. The kinetics study indicates that the Pb(II) removal accords to pseudo-second-order kinetics model.

A Facile Strategy to Fabricate Nanoscale Zero-Valent Iron Decorated Graphene Oxide Composite for Dechloridation of Trichloroacetic Acid in Water

2018 ◽  
Vol 18 (12) ◽  
pp. 8252-8257 ◽  
Author(s):  
Huixuan Zhang ◽  
Xinyi Zhang ◽  
Ruonan Guo ◽  
Qingfeng Cheng ◽  
Xiuwen Cheng
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Sewage Treatment ◽  
Reduction Process ◽  
Zero Valent Iron ◽  
Chlorinated Organic Compounds ◽  
X Ray ◽  
Transmission Electron ◽  
Nanoscale Zero Valent Iron ◽  
Adsorption Desorption

In this study, nanoscale zero-valent iron decorated graphene oxide (NZVI/GO) composite was fabricated through a reduction process in the presence of sodium borohydride (NaBH4) solution. Subsequently, physicochemical properties of the NZVI/GO composites were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transformation infrared spectroscopy (FT-IR) and Raman spectra. Results indicated that Fe species existed in the form of Fe0, which uniformly dispersed on the surface of GO. Furthermore, the performance of NZVI/GO was evaluated by the degradation of tichloroacetic acid (TCAA). TCAA can be rapidly degraded by NZVI/GO. This paper provides a promising strategy to synthesize versatile catalyst which would be potentially applied in sewage treatment to degrade chlorinated organic compounds.

scholarly journals Removal Efficiency and Mechanism of Cr(VI) from Aqueous Solution by Maize Straw Biochars Derived at Different Pyrolysis Temperatures

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 781 ◽  
Author(s):  
Wang ◽  
Zhang ◽  
Lv
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
X Ray ◽  
Removal Capacity ◽  
Maize Straw ◽  
Efficient Adsorbent ◽  
Positively Charged ◽  
Maximum Removal

The removal efficiency and mechanism of Cr(VI) removal from aqueous solution on semi-decomposed maize straw biochars pyrolyzed at 300 to 600 °C were investigated. The removal of Cr(VI) by the biochars decreased with pyrolysis temperature increasing from 300 to 600 °C, and the maximum removal capacity of Cr(VI) for maize straw biochar pyrolyzed at 300 °C was 91 mg/g at pH 2.0. The percentage removal of Cr(VI) rapidly decreased with pH increasing from 2.0 to 8.0, with the maximum (>99.9%) at pH 2.0. The variation of Cr(VI) and Cr(III) concentrations in the solution after reaction showed that Cr(VI) concentration decreased while Cr(III) increased and the equilibrium was reached after 48 h, while the redox potential after reaction decreased due to Cr(VI) reduction. X-ray photoelectron spectroscopy (XPS) semi-quantitative analysis showed that Cr(III) accounted for 75.7% of the total Cr bound to maize straw biochar, which indicated reductive adsorption was responsible for Cr(VI) removal by the biochars. Cr(VI) was firstly adsorbed onto the positively charged biochar surface and reduced to Cr(III) by electrons provided by oxygen-containing functional groups (e.g., C=O), and subsequently part of the converted Cr(III) remained on the biochar surface and the rest released into solution. Fourier transform infrared (FTIR) data indicated the participation of C=O, Si–O, –CH2 and –CH3 groups in Cr(VI) removal by the biochars. This study showed that maize straw biochar pyrolyzed at 300 °C for 2 h was one low-cost and efficient adsorbent for Cr(VI) removal from aqueous solution.

scholarly journals Studies on phenol removal from wastewater with CTAB-modified bentonite supported KMnO4

2013 ◽  
Vol 3 (3) ◽  
pp. 204-216 ◽  
Author(s):  
Jing Wang ◽  
Hongzhu Ma ◽  
Jie Yu ◽  
Shanshan Wang ◽  
Wenyan He ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Solid Phase ◽  
Phenol Degradation ◽  
Cod Removal ◽  
Phenol Removal ◽  
Solution Ph ◽  
Modified Bentonite ◽  
X Ray ◽  
Cod Removal Efficiency

Cetyltrimethylammonium bromide (CTAB) modified bentonite supported KMnO4 (KMnO4/CTAB-bent) was prepared by solid-phase grinding method, and applied to phenol removal from wastewater. Factors affecting efficiency, such as activated temperature, initial solution pH, KMnO4/CTAB-bent dosage, phenol initial concentration and reaction temperature on degradation were investigated. It was found that pH significantly affected the degradation and chemical oxygen demand (COD) removal efficiency. The results show that over 92% degradation and 60.58% COD removal efficiency can be obtained in 30 min. The surface properties and structure of KMnO4/CTAB-bent were measured by X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, and Fourier transform infrared spectroscopy. However, it was demonstrated that the KMnO4/CTAB-bent was deactivated quickly during phenol degradation after the second cycle, indicating that the stability of KMnO4/CTAB-bent needs to be further improved.

scholarly journals Non-precious Melamine/Chitosan Composites for the Oxygen Reduction Reaction: Effect of the Transition Metal

2020 ◽  
Vol 7 ◽  
Author(s):  
B. Aghabarari ◽  
M. V. Martínez-Huerta ◽  
M. C. Capel-Sánchez ◽  
M. J. Lázaro
Keyword(s):  
Transition Metal ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Reduction Reaction ◽  
X Ray ◽  
Transmission Electron ◽  
Electrode Cell ◽  
C And N

The development of active and low-cost electrocatalysts for the oxygen reduction reaction (ORR) is crucial for the sustainable commercialization of fuel cell technologies. In this study, we have synthetized Me/Mo2C (Me = Fe, Co, Cu)-based composites embedded in N- and P-dual doped carbon by means of inexpensive industrial materials, such as melamine and chitosan, as C and N sources, and the heteropolyacid H3PMo12O40 as P and Mo precursor. The effect of the transition metal (Fe, Co, and Cu) on the ORR in alkaline medium has been investigated. The physicochemical properties of the electrocatalysts were performed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM). Activity towards ORR was carried out in a three-electrode cell using a ring-disk electrode in 0.1M NaOH. The results obtained clearly show the important role played by each transition metal (Fe, Co, and Cu) in the electrochemical activity. Among them, Fe gives rise to the best performing composite in carrying out the oxygen reduction reaction. The formation Fe3C/Mo2C species embedded in N- and P-dual doped carbon seems to be the determining role in the increase of the ORR performance.

Co(OH)2 ELECTROCATALYST DECORATED ON TiO2 FILM FOR ENHANCED PHOTOELECTROCATALYTIC WATER OXIDATION

2020 ◽  
Vol 27 (11) ◽  
pp. 2050003
Author(s):  
HONGXIA LI ◽  
CHAO YANG ◽  
JIAN ZHANG ◽  
XIANGUO LIU ◽  
XUEFENG ZHANG
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Water Splitting ◽  
Transmission Electron Microscope ◽  
Photoelectron Spectroscopy ◽  
Water Oxidation ◽  
Low Cost ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Recently, Co(OH)2 has gained much attention as a promising electrocatalyst. Herein, we synthesized Co(OH)2-decorated TiO2 film for electrocatalytic water splitting by a facile and low-cost electrochemistry method, which possessed enhanced performance for oxygen evolution reaction. The results of X-ray diffractometry, transmission electron microscope, scanning electron microscope and X-ray photoelectron spectroscopy verify the successful decoration of Co(OH)2 electrocatalysts onto the surface of TiO2. Moreover, photoelectrocatalytic measurements illustrate that the Co(OH)2-decorated TiO2 shows higher current density than pure TiO2 sample. The results obtained in this work give deep insights into the development of photoelectrochemical water splitting.

scholarly journals A low-cost, low-density, and corrosion resistant AlFeMnSi compositionally complex alloy

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
S. P. O’Brien ◽  
J. Christudasjustus ◽  
L. Esteves ◽  
S. Vijayan ◽  
J. R. Jinschek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Surface Film ◽  
Low Cost ◽  
Incongruent Dissolution ◽  
Complex Alloy ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractA compositionally complex alloy was designed, consisting of equiatomic concentrations of four low-cost commodity elements (Al, Fe, Mn, and Si). The alloy was characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The corrosion of the AlFeMnSi alloy, as evaluated using potentiodynamic polarization tests and electrochemical impedance spectroscopy in 0.6 M NaCl solution, was comparable with that of stainless steel (SS) 304L. Detailed X-ray photoelectron spectroscopy analysis was carried out, including the determination of high-resolution spectra and surface sputtering. In addition, scanning transmission electron microscopy was also used to study the surface film(s) developed after constant immersion. The AlFeMnSi alloy exhibited a unique form of ‘passivity’ that arises from the development of a silicon-rich surface film from dynamic incongruent dissolution.

scholarly journals Role of Ag+ in the Bioleaching of Arsenopyrite by Acidithiobacillus ferrooxidans

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 403
Author(s):  
Yan Zhang ◽  
Qian Li ◽  
Xiaoliang Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Acidithiobacillus Ferrooxidans ◽  
Large Scale ◽  
Low Cost ◽  
Xrd Analysis ◽  
Green Technology ◽  
Environmental Friendliness ◽  
X Ray ◽  
Pre Treatment

Arsenopyrite (FeAsS) is often associated with gold, but pre-treatment is necessary prior to gold leaching, mainly due to the gold encapsulation in the matrix of FeAsS. Bio-oxidation is attractive and promising, largely due to its simplicity, low cost and environmental friendliness. A critical problem that still impedes the large-scale applications of this green technology is its slow leaching kinetics. Some metal ions such as Ag+ have previously been found to expedite the bioleaching process. In this paper, the role of Ag+ in the arsenopyrite bioleaching by Acidithiobacillus ferrooxidans was investigated in detail by bioleaching experiments and a series of analyses including thermodynamics, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Experimental results suggested that addition of 5 mg/L Ag+ to the leaching system could significantly improve the final As leaching efficiency from 30.4% to 47.8% and shorten the bioleaching period from 19 days to 15 days. Thermodynamic analysis indicates that Ag+ destabilises As2S2, As2S3 and S0 via forming Ag2S, which is confirmed by the XRD analysis on the phase transformation during bioleaching. SEM and XPS analyses further showed that Ag+ removed the passivating film consisting mainly of As2S2, As2S3 and S0 because Ag2S formed on the arsenopyrite surface from the start bioleaching of 36 h. In the presence of Fe3+, Ag2S could easily be dissolved to Ag+ again, likely leading to the establishment of the Ag+/Ag2S cycle. The bacteria utilised the two synergistic cycles of Fe3+/Fe2+ and Ag+/Ag2S to catalyse the bioleaching of arsenopyrite.

scholarly journals Removal of Zn(II), Mn(II) and Cu(II) by adsorption onto banana stalk biochar: adsorption process and mechanisms

2020 ◽  
Vol 82 (12) ◽  
pp. 2962-2974
Author(s):  
Hua Deng ◽  
Qiuyan Li ◽  
Meijia Huang ◽  
Anyu Li ◽  
Junyu Zhang ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Photoelectron Spectroscopy ◽  
Heavy Metal Ions ◽  
Metal Removal ◽  
Low Cost ◽  
Heavy Metal Removal ◽  
Order Kinetic ◽  
Solution Ph ◽  
X Ray

Abstract Low-cost banana stalk (Musa nana Lour.) biochar was prepared using oxygen-limited pyrolysis (at 500 °C and used), to remove heavy metal ions (including Zn(II), Mn(II) and Cu(II)) from aqueous solution. Adsorption experiments showed that the initial solution pH affected the ability of the biochar to adsorb heavy metal ions in single- and polymetal systems. Compared to Mn(II) and Zn(II), the biochar exhibited highly selective Cu(II) adsorption. The adsorption kinetics of all three metal ions followed the pseudo-second-order kinetic equation. The isotherm data demonstrated the Langmuir model fit for Zn(II), Mn(II) and Cu(II). The results showed that the chemical adsorption of single molecules was the main heavy metal removal mechanism. The maximum adsorption capacities (mg·g−1) were ranked as Cu(II) (134.88) > Mn(II) (109.10) > Zn(II) (108.10)) by the single-metal adsorption isotherms at 298 K. Moreover, characterization analysis was performed using Fourier transform infrared spectroscopy, the Brunauer-Emmett-Teller method, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results revealed that ion exchange was likely crucial in Mn(II) and Zn(II) removal, while C-O, O-H and C = O possibly were key to Cu(II) removal by complexing or other reactions.

scholarly journals Simultaneous adsorption and reduction of hexavalent chromium on biochar-supported nanoscale zero-valent iron (nZVI) in aqueous solution

2020 ◽  
Vol 82 (7) ◽  
pp. 1339-1349
Author(s):  
Fengfeng Ma ◽  
Bakunzibake Philippe ◽  
Baowei Zhao ◽  
Jingru Diao ◽  
Jian Li
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Zero Valent Iron ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Nanoscale Zero Valent Iron ◽  
Pseudo Second Order

Abstract Flax straw biochar (FSBC)-supported nanoscale zero-valent iron (nZVI) composite (nZVI-FSBC) combining the advantages of nZVI and biochar was synthesized and tested for Cr(VI) removal efficiency from aqueous solution. Surface morphology and structure of FSBC and nZVI-FSBC were characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller techniques, which help to clarify the mechanism of Cr(VI) removal from aqueous solution. The adsorption of Cr(VI) onto FSBC and nZVI-FSBC was best described by the pseudo-second-order and the Sips model. Compared with FSBC, nZVI-FSBC remarkably improved the performance in removing Cr(VI) under identical experimental conditions. Due to the collaborative effect of adsorption and reduction of nZVI-FSBC, the adsorption capacity of nZVI-FSBC for Cr(VI) is up to 186.99 mg/g. The results obtained by XPS, XRD, and FTIR confirmed that adsorption and reduction dominated the processes of Cr(VI) removal by nZVI-FSBC. As a supporter, FSBC not only improved the dispersion of nZVI, but also undertook the adsorption task of Cr(VI) removal. The surface oxygen-containing functional groups of nZVI-FSBC mainly participated in the adsorption part, and the nZVI promoted the Cr(VI) removal through the redox reactions. These observations indicated that the nZVI-FSBC can be considered as potential adsorbents to remove Cr(VI) for environment remediation.

scholarly journals Hybrid Veil-Like Co(OH)2/rGO Nanocomposites Towards Electrochemical Hydrogen Storage Properties

NANO ◽  
2017 ◽  
Vol 12 (11) ◽  
pp. 1750133 ◽  
Author(s):  
Keda Wang ◽  
Jing Yu ◽  
Lijun Liu ◽  
Lin Hou ◽  
Fengyou Jin
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Storage ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
High Capacity ◽  
X Ray ◽  
Design And Synthesis ◽  
Transmission Electron ◽  
Electrochemical Hydrogen Storage ◽  
New Type

The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today’s development of a hydrogen economy. As a new type hydrogen storage material, Co(OH)2/rGO nanocomposites were successfully obtained through a facile method in this study. Through the measurements of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry and galvanostatic charge/discharge, it indicated that Co(OH)2/rGO nanocomposites showed a veil-like microstructure, consisting of interlaced nanorods with a diameter of 4–8[Formula: see text]nm on rGO nanosheets. The hydrogen storage capacity was up to 400[Formula: see text]mAh/g at room temperature, higher than those of graphene and Co(OH)2.

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