scholarly journals Synthesis of MCM-41 stabilized NZVI and its use in removal of Cr(VI) from aqueous solution

2014 ◽  
Vol 5 (2) ◽  
pp. 149-156 ◽  
Author(s):  
Mang Lu ◽  
Yue Cheng ◽  
Jian-min Pan ◽  
Wen-jing Fan ◽  
Chuang Jiao ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Removal Rate ◽  
Kinetic Equations ◽  
Order Kinetic ◽  
Phase Reaction ◽  
Solution Ph ◽  
Transmission Electron ◽  
Initial Ph ◽  
Nano Zero Valent Iron ◽  
Mcm 41

In this study, MCM-41 stabilized nano zero-valent iron (M-NZVI) is synthesized using the rheological phase reaction method. Characterization with transmission electron microscopy validates the hypothesis that the introduction of MCM-41 leads to a decrease in aggregation of iron nanoparticles. X-ray diffraction confirms the existence of Fe0 and the strong antioxidant activity of Fe0 nanoparticles. Batch Cr(VI) reduction experiments exhibit that solution pH, M-NZVI dosage, and reaction time have significant effects on Cr(VI) removal. A high removal efficiency of Cr(VI) (84.5%) is obtained within 60 min for 100 mg/L of Cr(VI) solution at an initial pH of 6.0 and M-NZVI dosage of 0.5 g/L at 35 °C. The Cr(VI) removal rates follow modified pseudo-first-order kinetic equations. The observed removal rate constant was 0.0168/min for the M-NZVI dosage of 1.0 g/L. Our study suggests that the introduction of an innocuous stabilizer such as MCM-41 can significantly improve the performance of Fe0 nanoparticles for environmental remediation applications.

Preparation of Coated CMC-nZVI Using Rheological Phase Reaction Method and Research on Degradation of Chloroform in Water

2016 ◽  
Vol 847 ◽  
pp. 230-233 ◽  
Author(s):  
Shu Zhen Yu ◽  
Yue Cheng ◽  
Xiao Feng Fan ◽  
Li Ping Xu
Keyword(s):  
Removal Rate ◽  
Reaction Rate Constant ◽  
Order Kinetic ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
Rheological Phase Reaction ◽  
Transmission Electron ◽  
Simulated Groundwater ◽  
Apparent Reaction Rate Constant

This study reported the synthesis of nanoscale zero-valent iron (nZVI) by rheological phase reaction method in the presence of sodium (CMC). The synthesized CMC coated nZVI (CMC-nZVI) was then characterized with x-ray diffraction (XRD) and transmission electron microscope (TEM) and was tested for the removal of chloroform from simulated groundwater. The investigated parameters in the uptake experiments included different adsorbents, initial concentrations of chloroform and different water flow. The results show that:(1) the prepared CMC-nZVI has good stability and dispersibility; (2) when the concentration of chloroform is 0.1 mg/L, the dosage of CMC-Fe0 is 0.01 g, the removal rate of chloroform is 91.2%;(3)The reaction follows the first-order kinetic reaction equation, and the apparent reaction rate constant increases with decreasing the concentration of chloroform.

scholarly journals Fabrication of the magnetic mesoporous silica Fe-MCM-41-A as efficient adsorbent: performance, kinetics and mechanism

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yige Guo ◽  
Bin Chen ◽  
Ying Zhao ◽  
Tianxue Yang
Keyword(s):  
Mesoporous Silica ◽  
Zero Valent Iron ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Environment And Health ◽  
Transmission Electron ◽  
Order Kinetic Model ◽  
Neutral Conditions ◽  
Magnetic Mesoporous Silica ◽  
Mcm 41

AbstractAntibiotics are emerging pollutants and increasingly present in aquaculture and industrial wastewater. Due to their impact on the environment and health, their removal has recently become a significant concern. In this investigation, we synthesized nano zero-valent iron-loaded magnetic mesoporous silica (Fe-MCM-41-A) via precipitation and applied the adsorption of oxytetracycline (OTC) from an aqueous solution. The effects of competing ions such as Na+, Ca2+ and Cu2+ on the adsorption process under different pH conditions were studied in depth to providing a theoretical basis for the application of nanomaterials. The characterization of the obtained material through transmission electron microscopy demonstrates that the adsorbent possesses hexagonal channels, which facilitate mass transfer during adsorption. The loaded zero-valent iron made the magnetic, and was thus separated under an applied magnetic field. The adsorption of OTC onto Fe-MCM-41-A is rapid and obeys the pseudo-second-order kinetic model, and the maximum adsorption capacity of OTC is 625.90 mg g−1. The reaction between OTC and Fe-MCM-41-A was inner complexation and was less affected by the Na+. The effect of Ca2+ on the adsorption was small under acidic and neutral conditions. However, the promotion effect of Ca2+ increased by the increase of pH. Cu2+ decreased the removal efficiencies continuously and the inhibitory effects decrease varied with the increase of pH. We propose that surface complexing, ion-exchange, cationic π-bonding, hydrogen bonding, and hydrophobicity are responsible for the adsorption of OTC onto Fe-MCM-41-A.

Preparation of Novel Ag–Si–TiO2 Composite and Research on Its Photocatalytic Degradation of Formaldehyde

2021 ◽  
Vol 13 (3) ◽  
pp. 371-380
Author(s):  
Yongjun Wu ◽  
Nina Xie ◽  
Lu Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Formaldehyde Concentration ◽  
Order Kinetic ◽  
Solution Ph ◽  
Visible Absorption ◽  
X Ray ◽  
Co Doped

A novel Ag–Si–TiO2 composite was prepared via sol–gel method for removing residual formaldehyde in shiitake mushroom. The structure of Ag–Si–TiO2 composite was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. Ultraviolet-visible absorption spectroscopy (UV-Vis) and N2 adsorption-desorption tests showed that Ag and Si co-doped decreased the band gap, the Brunauer-Emmett-Teller (BET) specific surface area of the samples increased and the recombination probability of electron-hole pairs (e--h+) reduced. Effect on removal rate of formaldehyde with different Ag-Si co-doped content, formaldehyde concentration and solution pH were investigated, and the results showed that 6.0 wt%Ag-3.0 wt%Si-TiO2 samples had an optimum catalytic performance, and the degradation efficiency reached 96.6% after 40 W 365 nm UV lamp irradiation for 360 min. The kinetics of formaldehyde degradation by Ag–Si–TiO2 composite photocatalyst could be described by Langmuir-Hinshelwood first-order kinetic model.

scholarly journals Photoreduction of Cr(VI) Ions in Aqueous Solutions by UV/ Photocatalytic Processes

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Chih Ming Ma ◽  
Yung Shuen Shen ◽  
Po Hsiang Lin
Keyword(s):  
Aqueous Solutions ◽  
Reaction Rate ◽  
Removal Rate ◽  
Experimental Results ◽  
Order Kinetic ◽  
Solution Ph ◽  
Relationship Of ◽  
The Relationship ◽  
Photocatalytic Processes ◽  
Order Kinetic Equation

This study discussed the photoreduction of Cr(VI) ions in aqueous solutions by UV/TiO2photocatalytic processes under various operational factors. Experimental results showed that the removal rate of Cr(VI) increased with decreasing solution pH values and with increasing dosages of organic compounds, indicating that the recombination rate of electrons and h+can be retarded in the reaction systems by the addition of the scavenger, thus raising the reaction rate of Cr(VI). The relationship of the chemical reaction rate of Cr(VI), TiO2dosage, and changes of Cr(VI) concentration was expressed by the pseudo-first-order kinetic equation. Comparing the experimental results of two different doping metals in modified TiO2photoreduction systems, the removal rate of Cr(VI) by the Ag/TiO2process is larger, possibly because the electron transferring ability of Ag is superior to that of Cu. However, the photoreduction rates of Cr(VI) by modified UV/TiO2processes are worse than those by a nonmodified commercial UV/TiO2process.

scholarly journals A novel nano zero-valent iron@chitosan for effective removal of Microcystin-LR: Kinetics and adsorption mechanism

2018 ◽  
Vol 53 ◽  
pp. 04004 ◽  
Author(s):  
Xiaofan Yang ◽  
Xueyu Wei ◽  
Xiaoping Xu ◽  
Zhigang Liu
Keyword(s):  
Low Cost ◽  
Spherical Shape ◽  
Step Method ◽  
Variable Parameters ◽  
Transmission Electron ◽  
Effective Removal ◽  
Initial Ph ◽  
Nano Zero Valent Iron ◽  
One Step ◽  
Kinetics Of

Microcystin-LR (MC-LR) is one of the most notorious toxins liberated from cyanobacteria in drinking water sources. In this study, a skillful method access to new nanozero-valent iron @chitosan (nZVIMC) was synthesized by a facile one step method. The as-prepared nZVIMC was employed as an adsorbent for the effective removal MC-LR from aqueous solution. Transmission electron microscopy (TEM) demonstrates that nZVIMC is in quasi-spherical shape with size of around 50 nm, effect of variable parameters such as pH, contact time, initial concentration of MC-LR and adsorption properties of nZVIMC on MC-LR was further investigated. Scanning electron microscope (SEM) reveals that the particles are nearly spherical in shape with agglomeration. The results indicated that good adsorption performance was achieved at an initial pH of 5. The adsorption kinetics of nZVIMC was better fitted by pseudo-secondorder kinetics. The adsorption isotherm data was fitted well to Langmuir isotherm and then to Freundlich model, with an adsorption capacity of 68.9 mg/g at 300K. Thus, we believe that nZVIMC can be used as a low cost material for efficient removal of MC-LR from water.

Performance of Nano Zero-Valent Iron Derived from the Decomposition of Siderite in the Removal of Phosphate

2021 ◽  
Vol 21 (1) ◽  
pp. 623-631
Author(s):  
Yueling Zhao ◽  
Haibo Liu ◽  
Tianhu Chen ◽  
Dong Chen ◽  
Chen Chen ◽  
...  
Keyword(s):  
Orthogonal Experiment ◽  
Zero Valent Iron ◽  
Raw Material ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
P Concentration ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Nano Zero Valent Iron

Natural siderite was selected as a raw material for preparing nano zero-valent iron (nZVI). The efficiency of the as-synthesized nZVI for PO3−4–P removal was investigated, and the effects of the annealing temperature, pH, initial PO3−4–P concentration, adsorption temperature and oxygen were investigated. The results indicated that after annealing at 550 °C, nZVI exhibited an average crystal size of 56.3 nm and a surface area of 14.1 m2/g. A decrease in pH and an increase in oxygen availability enhanced the removal efficiency. The adsorption process, which was spontaneous and exothermic according to the thermodynamic analysis, agreed well with the pseudo-second-order kinetic model. Based on the Langmuir equilibrium isotherms, the capacity of nZVI to adsorb phosphorus was determined to be 33.18 mg/L. The optimized conditions for the experimental conditions were defined by an orthogonal experiment as follows: initial P concentration 2 mg/L, initial pH 4, iron dose 2 g/L, adsorption time 60 min. The experimental results suggested that the as-prepared nZVI was a promising adsorbent for the removal of phosphate.

scholarly journals Preparation of wrapped nZVI particles and their application for the degradation of trichloroethylene (TCE) in aqueous solution

2015 ◽  
Vol 5 (3) ◽  
pp. 335-343 ◽  
Author(s):  
Wenjing Fan ◽  
Yue Cheng ◽  
Shuzhen Yu ◽  
Xiaofeng Fan ◽  
Yaqian Deng
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Methyl Cellulose ◽  
Order Reaction ◽  
Phase Reaction ◽  
Solution Ph ◽  
First Order ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Optimal Ph

Three types of wrappped nanoscale zero-valent iron (W-nZVI) with different coatings including agar, starch, and carboxyl methyl cellulose, were synthesized using a rheological phase reaction method. The structure and morphology of W-nZVI particles were characterized by scanning electron microscopy and transmission electron microscopy. Batch degradation experiments exhibited that W-nZVI dosage, initial trichloroethylene (TCE) concentration and solution pH had significant effects on TCE dechlorination. Experimental results proved that the highest dechlorination efficiency was obtained within 320 minutes for 10 mg/L of TCE at the optimal pH of 5.0 and W-nZVI dosage of 0.5 g/L. Kinetic study revealed that TCE dechlorination by W-nZVI in aqueous solution obeyed the quasi-first-order reaction kinetics. The product after the reaction could be easily separated by the permanent magnet for re-use.

Sorption of lead ions from aqueous solution onto Enterococcus faecium biomass

2013 ◽  
Vol 68 (7) ◽  
pp. 1550-1555 ◽  
Author(s):  
Meral Yilmaz Cankilic ◽  
R. Bengu Karabacak ◽  
Turgay Tay ◽  
Merih Kivanc
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacterium ◽  
Enterococcus Faecium ◽  
Lead Concentration ◽  
Lead Removal ◽  
Order Kinetic ◽  
Lead Uptake ◽  
Solution Ph ◽  
Initial Ph ◽  
Lead Sorption

This study reports kinetics and equilibrium of lead sorption onto the biomass of Enterococcus faecium. E. faecium is a lactic acid bacterium and was isolated from meat. Batch experiments were carried out to analyze the effects of the initial lead concentration, initial pH of the medium, agitation time and temperature on the biosorption. The lead sorption was found to increase with the increase in the solution pH, reaching a plateau value beyond pH 5, and the most favorable pH for removal was determined as 5.0. The highest lead uptake capacity of the biomass was obtained at the initial lead concentration of 300 mg L–1. The Langmuir and Freundlich adsorption models were applied to determine the biosorption isotherm, and the equilibrium data correlated well with the Langmuir model. The pseudo-second-order kinetic model was more suitable to fit the experimental data. The results were promising that the biomass of this lactic acid bacterium can be successfully used as a convenient adsorbent for lead removal from aqueous solutions.

Catalytic Activity of Argentum-loaded MCM-41 for Ozonation of p- Chlorobenzoic Acid (p-CBA) in Aqueous Solution

2015 ◽  
Vol 18 (1) ◽  
Author(s):  
Zhaoqi Pan ◽  
Junyu Zeng ◽  
Bingyan Lan ◽  
Laisheng Li
Keyword(s):  
Aqueous Solution ◽  
Nitrogen Adsorption ◽  
Hexagonal Structure ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Chlorobenzoic Acid ◽  
Transmission Electron ◽  
Initial Ph ◽  
Adsorption Desorption ◽  
Mcm 41

AbstractArgentum-loaded MCM-41 (Ag/MCM-41) was synthesized successfully by a hydrothermal method and used as a catalyst for the ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution. Ag/MCM-41 was characterized by low angle X-ray diffraction (XRD), nitrogen adsorption-desorption and transmission electron microscopy (TEM). Characterizations suggest that the prepared samples retained a highly regulated mesopores of hexagonal structure and a high BET surface area. The influences of argentum content, initial pH, reaction temperature on the catalytic ozonation were also evaluated. Ag/MCM-41/O

scholarly journals Adsorption of Ni2+ from aqueous solution by magnetic Fe@graphite nano-composite

2016 ◽  
Vol 18 (4) ◽  
pp. 96-103 ◽  
Author(s):  
Wojciech Konicki ◽  
Rafał Pelka ◽  
Walerian Arabczyk
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Diffraction Method ◽  
Chemical Vapor ◽  
Bet Surface Area ◽  
Order Kinetic ◽  
Solution Ph ◽  
Transmission Electron ◽  
Order Kinetic Model ◽  
Nanocrystalline Iron

Abstract The removal of Ni2+ from aqueous solution by iron nanoparticles encapsulated by graphitic layers (Fe@G) was investigated. Nanoparticles Fe@G were prepared by chemical vapor deposition CVD process using methane as a carbon source and nanocrystalline iron. The properties of Fe@G were characterized by X-ray Diffraction method (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), Fourier Transform-Infrared Spectroscopy (FTIR), BET surface area and zeta potential measurements. The effects of initial Ni2+ concentration (1–20 mg L−1), pH (4–11) and temperature (20–60°C) on adsorption capacity were studied. The adsorption capacity at equilibrium increased from 2.96 to 8.78 mg g−1, with the increase in the initial concentration of Ni2+ from 1 to 20 mg L−1 at pH 7.0 and 20oC. The experimental results indicated that the maximum Ni2+ removal could be attained at a solution pH of 8.2 and the adsorption capacity obtained was 9.33 mg g−1. The experimental data fitted well with the Langmuir model with a monolayer adsorption capacity of 9.20 mg g−1. The adsorption kinetics was found to follow pseudo-second-order kinetic model. Thermodynamics parameters, ΔHO, ΔGO and ΔSO, were calculated, indicating that the adsorption of Ni2+ onto Fe@G was spontaneous and endothermic in nature.

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