Factors affecting the leaching behaviors of magnesium phosphate cement-stabilized/solidified Pb-contaminated soil, part II: Dosage and curing age

2017 ◽  
Vol 36 (5) ◽  
pp. 1351-1357 ◽  
Author(s):  
Ping Wang ◽  
Qiang Xue ◽  
Zhenning Yang ◽  
Jiangshan Li ◽  
Tingting Zhang ◽  
...  
Keyword(s):  
Contaminated Soil ◽  
Magnesium Phosphate ◽  
Factors Affecting ◽  
Curing Age

scholarly journals Application of nanoscale zero-valent iron in hexavalent chromium-contaminated soil: A review

2020 ◽  
Vol 9 (1) ◽  
pp. 736-750
Author(s):  
Xilu Chen ◽  
Xiaomin Li ◽  
Dandan Xu ◽  
Weichun Yang ◽  
Shaoyuan Bai
Keyword(s):  
Heavy Metal ◽  
Hexavalent Chromium ◽  
Contaminated Soil ◽  
Zero Valent Iron ◽  
Toxic Heavy Metal ◽  
Factors Affecting ◽  
Metal Pollutants ◽  
Nanoscale Zero Valent Iron ◽  
Low Toxicity ◽  
Heavy Metal Pollutants

AbstractChromium (Cr) is a common toxic heavy metal that is widely used in all kinds of industries, causing a series of environmental problems. Nanoscale zero- valent iron (nZVI) is considered to be an ideal remediation material for contaminated soil, especially for heavy metal pollutants. As a material of low toxicity and good activity, nZVI has been widely applied in the in situ remediation of soil hexavalent chromium (Cr(vi)) with mobility and toxicity in recent years. In this paper, some current technologies for the preparation of nZVI are summarized and the remediation mechanism of Cr(vi)-contaminated soil is proposed. Five classified modified nZVI materials are introduced and their remediation processes in Cr(vi)-contaminated soil are summarized. Key factors affecting the remediation of Cr(vi)-contaminated soil by nZVI are studied. Interaction mechanisms between nZVI-based materials and Cr(vi) are explored. This study provides a comprehensive review of the nZVI materials for the remediation of Cr(vi)-contaminated soil, which is conducive to reducing soil pollution.

scholarly journals Leaching characteristics and curing mechanism of magnesium phosphate cement solidified zinc-contaminated soil in an acid rain environment

2020 ◽  
Vol 26 (4) ◽  
pp. 200256-0
Author(s):  
Zhe Wang ◽  
Hangjun Zhu ◽  
Xuehui Wu ◽  
Binpin Wei ◽  
Hongli Zhou ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Acid Rain ◽  
Contaminated Soil ◽  
Water Glass ◽  
Ph Value ◽  
Strong Acid ◽  
Magnesium Phosphate ◽  
Leaching Characteristics ◽  
Curing Mechanism ◽  
Acid Environment

A semi-dynamic leaching test was used to simulate the erosion effect of acid rain on magnesium phosphate cement (MPC)-stabilized/solidified zinc-contaminated soil. The leaching characteristics and curing mechanism were studied with a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Influences of the initial pH value of the simulated acid rain, the ratio of the curing agent (MgO/KH2PO4, abbreviated M/P), and the mass of water glass on the leaching characteristics of Zn<sup>2+</sup> and conductivity in the leachate of the sample were studied. It is shown that the curing effect of the cement component on Zn<sup>2+</sup> is better for M/P = 6 when compared to M/P = 4 in a strong acid environment. While in a weak acid environment, it is observed that the curing effect is superior when M/P = 4. Also it is observed that 4% water glass content can effectively improve the cement curing effect of heavy metal Zn in an acid rain environment. These results indicate that water glass can be effectively applied to MPC solidified heavy metal Zn.

Utilisation of Magnesium Phosphate Cements to Facilitate Biodegradation within a Stabilised/Solidified Contaminated Soil

2010 ◽  
Vol 216 (1-4) ◽  
pp. 411-427 ◽  
Author(s):  
Reginald B. Kogbara ◽  
Abir Al-Tabbaa ◽  
Srinath R. Iyengar
Keyword(s):  
Contaminated Soil ◽  
Magnesium Phosphate

Red mud-enhanced magnesium phosphate cement for remediation of Pb and As contaminated soil

2020 ◽  
Vol 400 ◽  
pp. 123317 ◽  
Author(s):  
Lei Wang ◽  
Liang Chen ◽  
Binglin Guo ◽  
Daniel C.W. Tsang ◽  
Longbin Huang ◽  
...  
Keyword(s):  
Contaminated Soil ◽  
Red Mud ◽  
Magnesium Phosphate

scholarly journals Flexural Properties of Renewable Coir Fiber Reinforced Magnesium Phosphate Cement, Considering Fiber Length

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3692 ◽  
Author(s):  
Liwen Zhang ◽  
Zuqian Jiang ◽  
Hui Wu ◽  
Wenhua Zhang ◽  
Yushan Lai ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Waste Treatment ◽  
Bending Test ◽  
Magnesium Phosphate ◽  
Flexural Properties ◽  
Coir Fiber ◽  
X Ray Diffraction ◽  
Flexural Toughness ◽  
Three Point Bending ◽  
Curing Age

Coir fiber (CF), a renewable natural plant fiber, is more competitive in improving poor toughness and crack resistance of magnesium phosphate cement (MPC) than artificial fibers, due to its slight energy consumptions and low costs in production and waste treatment. In this paper, a typical three-point bending test was carried out to study the effects of CF length on MPC flexural properties. A total of forty-two cuboid specimens were employed to investigate the flexural strength, load-deflection behavior, and flexural toughness of MPC, with CF lengths varying from 0 to 30 mm at the curing age of 7 days and 28 days. Results showed that, at both two curing ages, MPC flexural strength first increased with CF length increasing, and then deceased when CF length exceeded the threshold. However, with the increase of CF length, MPC flexural toughness increased continuously, while MPC elastic modulus displayed a decreasing trend. Additionally, Modern micro testing techniques, such as scanning electron microscope (SEM) and X-ray diffraction (XRD), were also used to study the microstructure and phase compositions of specimens for further explaining the themicroscopic mechanism.

scholarly journals Leachability and Stability of Hexavalent-Chromium-Contaminated Soil Stabilized by Ferrous Sulfate and Calcium Polysulfide

2018 ◽  
Vol 8 (9) ◽  
pp. 1431 ◽  
Author(s):  
Ting-Ting Zhang ◽  
Qiang Xue ◽  
Ming-Li Wei
Keyword(s):  
Hexavalent Chromium ◽  
Contaminated Soil ◽  
Ferrous Sulfate ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
X Ray ◽  
Acid Buffering ◽  
Before And After ◽  
Calcium Polysulfide ◽  
Better Than

Ferrous sulfate (FeSO4) and calcium polysulfide (CaS5) stabilization are practical approaches to stabilizing hexavalent chromium (Cr(VI))-contaminated soil. The leachability and stability of Cr(VI) and Cr are important factors affecting the effectiveness of stabilized Cr(VI)-contaminated soil. This study compared the leachability and stability of Cr(VI) and Cr in Cr(VI)-contaminated soil stabilized by using FeSO4 and CaS5. The contaminated soil was characterized before and after stabilization, and the effectiveness of FeSO4 and CaS5 stabilization was assessed using leaching, bioaccessibility, alkaline digestion, sequential extraction, and X-ray diffraction tests. Results showed that FeSO4 and CaS5 significantly reduced the leachability and Cr(VI) content in the contaminated soil. The acid-buffering capacity and stability (leachability, bioaccessibility, speciation distribution, and mineral composition) of the Cr(VI)/Cr and Cr(VI) content of CaS5 were better than those of FeSO4. This study demonstrated that CaS5 had a better effect than FeSO4 on the stabilization of Cr(VI) in Cr(VI)-contaminated soil. The CaS5 significantly enhanced the stabilization and immobilization of Cr(VI) and reduced its leachability and toxicity.

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