scholarly journals Size Distribution and Phosphate Removal Capacity of Nano Zero-Valent Iron (nZVI): Influence of pH and Ionic Strength

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2939
Author(s):  
Dantong Lin ◽  
Liming Hu ◽  
Irene M. C. Lo ◽  
Zhigang Yu
Keyword(s):  
Ionic Strength ◽  
Size Distribution ◽  
Environmental Conditions ◽  
Colloidal Stability ◽  
Removal Rate ◽  
Phosphate Removal ◽  
Zero Valent Iron ◽  
Removal Capacity ◽  
Nano Zero Valent Iron ◽  
Ph Conditions

Nano zero-valent iron (nZVI) has been considered as a promising material for groundwater remediation in the past few decades. The size distribution of nZVI is one of the main factors that influences its transport capability and remediation capacity. However, studies on the size distribution of nZVI under different environmental conditions are still limited. In this study, the influence of the pH (pH = 5, 7, 9) and ionic strength (IS = 0, 15, 30, 45 mM) on the size distribution of nZVI are investigated. The dynamic light scattering (DLS) method is used to study the variation of the size distribution of nZVI aggregate with time, and batch tests are performed to evaluate the efficiency of phosphate removal. Meanwhile, the phosphate removal capacity of nZVI with different size distribution was examined. Experimental results show that under low IS and high pH conditions, nZVI aggregate exhibited a stable, narrow and one-peak size distribution. By contrast, under high IS and low pH conditions, nZVI exhibited a wide and complicated size distribution with multiple peak values. This different pattern in size distribution was further explained by the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The phosphate removal rate of nZVI under acidic and neutral conditions is higher than 98% but is only 68% under alkaline conditions. The phosphate removal capacity is insensitive to the variation of IS since the removal rate is higher than 97% for different IS conditions. Favorable environmental conditions for colloidal stability and removal capacity of nZVI can be different, which needs comprehensive consideration in the application.

scholarly journals The Influence of Pluronic F-127 Modification on Nano Zero-Valent Iron (NZVI): Sedimentation and Reactivity with 2,4-Dichlorophenol in Water Using Response Surface Methodology

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 412 ◽  
Author(s):  
Yajun Li ◽  
Yongxiang Zhang ◽  
Qi Jing ◽  
Yuhui Lin
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Colloidal Stability ◽  
Removal Rate ◽  
Zero Valent Iron ◽  
Quadratic Model ◽  
Biphasic Model ◽  
Sedimentation Behavior ◽  
Nano Zero Valent Iron ◽  
The Stability

Nano zero-valent iron (NZVI) is widely used for reducing chlorinated organic pollutants in water. However, the stability of the particles will affect the removal rate of the contaminant. In order to enhance the stability of nano zero-valent iron (NZVI), the particles were modified with F-127 as an environmentally friendly organic stabilizer. The study investigated the effect of the F-127 mass ratio on the colloidal stability of NZVI. Results show that the sedimentation behavior of F-NZVI varied at different mass ratios. A biphasic model was used to describe the two time-dependent settling processes (rapid sedimentation followed by slower settling), and the settling rates were calculated. The surface morphology of the synthesized F-NZVI was observed with a scanning electron microscope (SEM), and the functional groups of the samples were analyzed with Fourier Transform Infrared Spectroscopy (FTIR). Results show that the F-127 was successfully coated on the surface of the NZVI, and that significantly improved the stability of NZVI. Finally, in order to optimize the removal rate of 2,4-dichlorophenol (2,4-DCP) by F-NZVI, three variables were tested: the initial concentration 2,4-DCP, the pH, and the F-NZVI dosage. These were evaluated with a Box-Behnken Design (BBD) of response surface methodology (RSM). The experiments were designed by Design Expert software, and the regression model of fitting quadratic model was established. The following optimum removal conditions were determined: pH = 5, 3.5 g·L−1 F-NZVI for 22.5 mg·L−1 of 2,4-DCP.

scholarly journals Preparation of Activated Carbon Supported Bead String Structure Nano Zero Valent Iron in a Polyethylene Glycol-Aqueous Solution and Its Efficient Treatment of Cr(VI) Wastewater

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 47 ◽  
Author(s):  
Chunlei Jiao ◽  
Xiao Tan ◽  
Aijun Lin ◽  
Wenjie Yang
Keyword(s):  
Activated Carbon ◽  
Polyethylene Glycol ◽  
Removal Rate ◽  
Zero Valent Iron ◽  
Efficient Treatment ◽  
Removal Capacity ◽  
Oxidation Reduction ◽  
String Structure ◽  
Nano Zero Valent Iron ◽  
Reduction Effect

Nanometer zero-valent iron (nZVI) has been widely used in the treatment of heavy metals such as hexavalent chromium (Cr(VI)). A novel composite of bead string-structured nZVI on modified activated carbon (nZVI–MAC) is prepared here, using polyethylene glycol as the stable dispersant rather than traditional ethanol during the loading process. The microstructure characterization shows that nZVI particles are loaded on MAC with a bead string structure in large quantity and stably due to the addition of hydroxyl functional groups on the surface by polyethylene glycol. Experiments on the treatment of Cr(VI) in wastewater show that the reaction process requires only 20 min to achieve equilibrium. The removal rate of Cr(VI) with a low concentration (80–100 mg/L) is over 99% and the maximum saturation removal capacity is up to 66 mg/g. The system converts Cr(VI) to trivalent chromium (Cr(III)) through an oxidation-reduction effect and forms an insoluble material with iron ions by coprecipitation, which is then adsorbed on the surface of the nZVI–MAC. The process conforms to the quasi-second order adsorption kinetics equation (mainly chemical adsorption process).

scholarly journals Removal of selected pesticides by nano zero-valent iron

2015 ◽  
Vol 8 (2) ◽  
pp. 152-155 ◽  
Author(s):  
Karol Šimkovič ◽  
Ján Derco ◽  
Mária Valičková
Keyword(s):  
Iron Nanoparticles ◽  
Removal Rate ◽  
Zero Valent Iron ◽  
Experimental Measurements ◽  
Nano Zero Valent Iron ◽  
Removal Efficiencies ◽  
Rate Evaluation

Abstract This paper is focused on the possibility of using iron nanoparticles (nZVI - nano zero-valent iron) to remove selected specific synthetic substances, such as hexachlorobutadiene, pentachlorobenzene, hexachlorobenzene, lindane and heptachlor. Experimental measurements were performed in order to evaluate the effectiveness of the removal of substances and their specific removal rate. Evaluation of the results shows that nanoiron NANOFER 25 is a convenient reactant for the removal of heptachlor, lindane and hexachlorobenzene; while for pentachlorbenzene and hexachlorobutadiene removal, longer contact times are necessary to achieve significant removal efficiencies.

scholarly journals Mechanism of Stability and Transport of Chitosan-Stabilized Nano Zero-Valent Iron in Saturated Porous Media

2021 ◽  
Vol 18 (10) ◽  
pp. 5115
Author(s):  
Dan Huang ◽  
Zhongyu Ren ◽  
Xiaoyu Li ◽  
Qi Jing
Keyword(s):  
Porous Media ◽  
Colloidal Stability ◽  
Transport Model ◽  
Transport Coefficients ◽  
Point Of View ◽  
Zero Valent Iron ◽  
Column Experiments ◽  
Saturated Porous Media ◽  
Sand Column ◽  
Nano Zero Valent Iron

Chitosan-stabilized nano zero-valent iron (CTS-nZVI) prepared by the liquid-phase reduction method has been shown to achieve a good dispersion effect. However, there has been little analysis on the mechanism affecting its stability and transport in saturated porous media. In this paper, settling experiments were conducted to study the stabilization of CTS-nZVI. The transport of CTS-nZVI in saturated porous media at different influencing factors was studied by sand column experiments. The stability mechanism of CTS-nZVI was analyzed from the point of view of colloidal stability by settling experiments and a zeta potential test. The theoretical model of colloidal filtration was applied for the calculation of transport coefficients on the basis of the column experiments data. Considering attachment–detachment effects, a particle transport model was built using HYDRUS-1D software to analyze the transport and spatial distribution of CTS-nZVI in a sand column.

scholarly journals Bisphenol A degradation by a new acidic nano zero-valent iron diatomite composite

2016 ◽  
Vol 6 (15) ◽  
pp. 6066-6075 ◽  
Author(s):  
Lingya Ma ◽  
Hongping He ◽  
Runliang Zhu ◽  
Jianxi Zhu ◽  
Ian D. R. Mackinnon ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Removal Efficiency ◽  
Zero Valent Iron ◽  
Nano Zero Valent Iron ◽  
Acidic Conditions ◽  
Ph Conditions ◽  
Iron Material

A new nano zero-valent iron material that generates acidic conditionsin situexhibits a high removal efficiency of BPA under natural pH conditions.

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