Almond Shell-Derived, Biochar-Supported, Nano-Zero-Valent Iron Composite for Aqueous Hexavalent Chromium Removal: Performance and Mechanisms

Nano-zero-valent iron biochar derived from almond shell (nZVI-ASBC) was used for hexavalent chromium (CR) removal. Experiments showed that pH was the main factor (p < 0.01) that affected the experimental results. At a dosage of 10 mg·L−1 and pH of 2–6, in the first 60 min, nZVI-ASBC exhibited a removal efficiency of 99.8%, which was approximately 20% higher than the removal yield at pH 7–11. Fourier transform infrared spectroscopy results indicated N-H was the main functional group that influenced the chemisorption process. The pseudo second-order dynamics and Langmuir isotherm models proved to be the most suitable. Thermodynamic studies showed that the reaction was exothermic and spontaneous at low temperatures (T < 317 K). Various interaction mechanisms, including adsorption and reduction, were adopted for the removal of Cr(VI) using the nZVI-ASBC composite. The findings showed that the BC-modified nZVI prepared with almond shell exerts a good effect and could be used for the removal of Cr(VI).

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Modified Spruce Sawdust for Sorption of Hexavalent Chromium in Batch Systems and Fixed-Bed Columns

Molecules ◽

10.3390/molecules25215156 ◽

2020 ◽

Vol 25 (21) ◽

pp. 5156

Author(s):

Dororthea Politi ◽

Dimitrios Sidiras

Keyword(s):

Sulfuric Acid ◽

Adsorption Capacity ◽

Hexavalent Chromium ◽

Diethylene Glycol ◽

Fixed Bed ◽

Second Order ◽

Isotherm Models ◽

Order Kinetic ◽

Order Kinetic Model ◽

Pseudo Second Order

This study investigated the potential use of spruce sawdust that was pretreated with diethylene glycol and sulfuric acid for the removal of hexavalent chromium from wastewater. The sawdust pretreatment process was conducted at different temperatures and times. The adsorbent was characterized by quantitative saccharification, scanning electron microscopy, and Brunauer–Emmet–Teller surface area analysis. Adsorption capacity was studied for both batch and column processes. The experimental adsorption isotherms were simulated using seven isotherm models, including Freundlich and Langmuir models. By using the Langmuir isotherm model, the maximal Cr(VI) adsorption capacity of organosolv-pretreated spruce sawdust (qm) was 318.3 mg g−1. Furthermore, the kinetic data were fitted to Lagergren, pseudo-second-order, and intraparticle diffusion models, revealing that the adsorption of Cr(VI) onto spruce sawdust pretreated with diethylene glycol and sulfuric acid is best represented by the pseudo-second-order kinetic model. Three kinetic models, namely, the Bohart–Adams model, Thomas model, and modified dose–response (MDR) model, were used to fit the experimental data obtained from the column experiments and to resolve the characteristic parameters. The Thomas adsorption column capacity of the sawdust was increased from 2.44 to 31.1 mg g−1 upon pretreatment, thus, demonstrating that organosolv treatment enhances the adsorption capability of the material.

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Assessment of Polyphenol Coated Nano Zero Valent Iron for Hexavalent Chromium Removal from Contaminated Waters

Bulletin of Environmental Contamination and Toxicology ◽

10.1007/s00128-014-1442-z ◽

2014 ◽

Vol 94 (3) ◽

pp. 302-307 ◽

Cited By ~ 32

Author(s):

C. Mystrioti ◽

D. Sparis ◽

N. Papasiopi ◽

A. Xenidis ◽

D. Dermatas ◽

...

Keyword(s):

Hexavalent Chromium ◽

Zero Valent Iron ◽

Chromium Removal ◽

Nano Zero Valent Iron ◽

Contaminated Waters

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

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.18447 ◽

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.

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Mechanism of Oxytetracycline Removal by Coconut Shell Biochar Loaded with Nano-Zero-Valent Iron

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph182413107 ◽

2021 ◽

Vol 18 (24) ◽

pp. 13107

Author(s):

Qi Li ◽

Siyu Zhao ◽

Yuhang Wang

Keyword(s):

Single Molecule ◽

Zero Valent Iron ◽

Ion Concentration ◽

Coconut Shell ◽

Batch Adsorption ◽

Isothermal Adsorption ◽

Pseudo Second Order ◽

Nano Zero Valent Iron ◽

Addition Amount ◽

Coconut Shell Biochar

In this paper, coconut shell biochar (BC), pickling biochar (HBC), and nano-zero-valent iron-loaded biochar (nZVI-HBC) were prepared; these were used to remove oxytetracycline (OTC), and the removal mechanism and degradation product were analyzed. These biochars were characterized using SEM, XRD, FTIR, and XPS. The effects of biochar addition amount, pH, ion type, and ion concentration on OTC adsorption were studied by a batch adsorption experiment. Under the optimal conditions, the equilibrium adsorption capacity of nZVI-HBC to OTC was 196.70 mg·g−1. The adsorption process can be described by Langmuir isothermal adsorption equations, conforming to the pseudo-second-order dynamics model, indicating that adsorption is dominated by single-molecule chemical adsorption, and a spontaneous process of increasing heat absorption entropy. Mass spectrometry showed that the OTC removal process of nZVI-HBC included not only adsorption but also degradation. These results provide a practical and potentially valuable material for the removal of OTC.

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Preparation of highly dispersive and antioxidative nano zero-valent iron for the removal of hexavalent chromium

Chemosphere ◽

10.1016/j.chemosphere.2020.127733 ◽

2021 ◽

Vol 262 ◽

pp. 127733 ◽

Cited By ~ 1

Author(s):

Jinhua Wu ◽

Mingjia Yan ◽

Sihao Lv ◽

Weizhao Yin ◽

Huaitian Bu ◽

...

Keyword(s):

Hexavalent Chromium ◽

Zero Valent Iron ◽

Nano Zero Valent Iron

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High dispersions of nano zero valent iron supported on biochar by one-step carbothermal synthesis and its application in chromate removal

RSC Advances ◽

10.1039/c9ra00304e ◽

2019 ◽

Vol 9 (22) ◽

pp. 12428-12435 ◽

Cited By ~ 9

Author(s):

Shifeng Li ◽

Tingting You ◽

Yang Guo ◽

Shuhua Yao ◽

Shuyan Zang ◽

...

Keyword(s):

Aqueous Solution ◽

Hexavalent Chromium ◽

Zero Valent Iron ◽

Synthesis And Characterization ◽

Carbothermal Synthesis ◽

Nanoscale Zero Valent Iron ◽

Nano Zero Valent Iron ◽

One Step

A one-step carbothermal synthesis and characterization of biochar-supported nanoscale zero-valent iron (nZVI/BC) was performed for the removal of hexavalent chromium (Cr(vi)) from aqueous solution.

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