New insights into the underlying influence of bentonite on Pb immobilization by undissolvable and dissolvable fractions of biochar

ABSTRACTNon-radioactive ash was immobilized via microwave melting. The ash composed mainly of silica (SiO2), titania (TiO2), calcia (CaO), alumina (Al2O3), and carbon (C). The ash was melted with various additives, such as magnetite (Fe3O4), lithium carbonate (Li2CO3), sodium carbonate (Na2CO3), and boron oxide (B2O3) by using a 2.45 GHz, 750 W microwave oven. Samples with different ash and additive concentrations were melted when subjected to microwave radiation. Ease of melting was dependent on the carbon and magnetite concentrations. Melted samples were characterized by X-ray diffraction and scanning electron microscopy (SEM), and subjected to the Toxicity Characteristic Leaching Procedure in regard to lead (Pb) immobilization. Melted samples with more than 30 wt% additives has an undetectable leaching rate of less than 0.1 ppm of lead for TCLP test, which was found to be due to the reduction and evaporation of the lead during melting. More than 80 % of the lead was lost through evaporation leaving less than 0.1 wt% Pb in the melted glass.

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A porous biochar supported nanoscale zero-valent iron highly efficient for the remediation of cadmium and lead contaminated soil

10.21203/rs.3.rs-250897/v1 ◽

2021 ◽

Author(s):

Wei Qian ◽

Zeng-Hui Diao

Keyword(s):

Heavy Metals ◽

Clayey Soil ◽

Zero Valent Iron ◽

Nanoscale Zero Valent Iron ◽

Cadmium And Lead ◽

Concentration Levels ◽

Pb Immobilization ◽

Better Than ◽

Cd Species ◽

Simultaneous Immobilization

Abstract Risk associated with heavy metals in soil has been received widespread attention. In this study, a porous biochar supported nanoscale zero-valent iron (BC-nZVI) was applied to immobilize cadmium (Cd) and/or lead (Pb) in clayey soil. Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process, and about 80 % of heavy metals immobilization was obtained in BC-nZVI process. Addition of BC-nZVI could increase soil pH and organic matter (SOM). Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol (2,4-DCP), but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels. Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process, and both Cd and Pb availability significantly decreased. Stable Cd species inculding Cd(OH)2, CdCO3 and CdO were formed, whereas stable Pb species such as PbCO3, PbO and Pb(OH)2 were produced with BC-nZVI treatment. Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed. This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple metals in soil.

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A Biosorption-Pyrolysis Process for Removal of Pb from Aqueous Solution and Subsequent Immobilization of Pb in the Char

Water ◽

10.3390/w12092381 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2381

Author(s):

Yue Wang ◽

Jinhong Lü ◽

Dongqing Feng ◽

Sen Guo ◽

Jianfa Li

Keyword(s):

Heavy Metals ◽

Pyrolysis Temperature ◽

Acidic Solution ◽

Potential Solution ◽

Pyrolysis Process ◽

X Ray Diffraction ◽

X Ray ◽

Removal Of Heavy Metals ◽

Pretreated Biomass ◽

Pb Immobilization

The application of biosorption in the removal of heavy metals from water faces a challenge of safe disposal of contaminated biomass. In this study, a potential solution for this problem was proposed by using a biosorption-pyrolysis process featured by pretreatment of biomass with phosphoric acid (PA). The PA pretreatment of biomass increased the removal efficiency of heavy metal Pb from water by sorption, and subsequent pyrolysis helped immobilize Pb in the residual char. The results indicate that most (>95%) of the Pb adsorbed by the PA-pretreated biomass was retained in the char, and that the lower pyrolysis temperature (350 °C) is more favorable for Pb immobilization. In this way, the bioavailable Pb in the char was hardly detected, while the Pb leachable in acidic solution decreased to <3% of total Pb in the char. However, higher pyrolysis temperature (450 °C) is unfavorable for Pb immobilization, as both the leachable and bioavailable Pb increased to >28%. The reason should be related to the formation of elemental Pb and unstable Pb compounds during pyrolysis at 450 °C, according to the X-ray diffraction study.

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Enhanced immobilization of Prussian blue through hydrogel formation by polymerization of acrylic acid for radioactive cesium adsorption

Scientific Reports ◽

10.1038/s41598-019-52600-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 3

Author(s):

Daemin Oh ◽

Bokseong Kim ◽

Sungwon Kang ◽

Youngsug Kim ◽

Sungjong Yoo ◽

...

Keyword(s):

Acrylic Acid ◽

Radioactive Cesium ◽

Layer By Layer ◽

Freundlich Model ◽

Lbl Assembly ◽

Washing Process ◽

Ft Ir ◽

The Stability ◽

Potential Efficiency ◽

Pb Immobilization

Abstract In this study, a hydrogel impregnated with powder activated carbon (PAC), MAA-PAC, was synthesized through the polymerization of acrylic acid (AA) and PB was immobilized using the carboxyl group of AA. In this process, an adsorbent with an enhancement of PB content and stability of immobilization was developed through the additional supply of Fe3+ ions by the layer by layer (LBL) assembly. XRD, FT-IR, SEM (EDS), TEM (EDS, mapping), and TG analyzes of the LBL and non-LBL groups were performed to confirm the change of PB content in the adsorbent as the LBL assembly was applied. The stability of PB immobilization was confirmed during the washing process after the synthesis of the adsorbent. When the LBL assembly process was applied as a PB immobilization strategy, the PB content in the adsorbent was improved and PB leakage was not observed during the washing process. The maximum adsorption (qm) for cesium in the MAA-PAC-PB LBL group that showed high PB content was 40.03 mg/g, and the adsorption isotherm was more suitable for the Langmuir model than the Freundlich model. The LBL group showed a high removal efficiency of 99.81% and a high DF value (525.88) for radioactive cesium (120 Bq/g). These results demonstrate the potential efficiency of the MAA-PAC-PB LBL group for the decontamination of radioactive cesium-contaminated water systems. Furthermore, it was verified that the LBL group of MAA-PAC-PB could be used as an adsorbent without an additional design of the existing water treatment facility. This can an economical decontamination method for removing radioactive cesium.

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