Removal mechanisms of Cr(VI) and Cr(III) by biochar supported nanosized zero-valent iron: Synergy of adsorption, reduction and transformation

Qiu, Yue; Zhang, Qian; Gao, Bin; Li, Meng; Fan, Zhenhong; Sang, Wenjiao; Hao, Huiru; Wei, Xiaonan

doi:10.1016/j.envpol.2020.115018

Cited by 177 publications

(70 citation statements)

References 75 publications

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“…Usually, the number of active sites increases with the increase of adsorbent doses that yields higher surface area resulting in access to the metal ions to get interacted with the active sites of the adsorbent [23]. Similar results were obtained by Qiu, et al in their research work on Cr(III) removal using sludge-derived biochar with supported nanosized zero-valent iron [24]. However, the sorption capacity reduces with an augmentation of the adsorbent amount.…”

Section: +supporting

confidence: 67%

Synthesis and Characterization of Graphene Oxide for the Adsorption of Cr(III) from Chrome-Tanning Effluent

Nurnabi¹

2021

PSBJ

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Chromium released with tannery effluent causes severe water pollution which is a great concern to the environment and public health. The removal of chromium from tannery effluent before discharging to the surface water is a crying need for protecting environment and human health. This research work highlights the adsorption potential of graphene oxide (GO) for chromium(III) from hazardous chrome-tanning effluents. The research framework includes preparation and characterization of GO employing Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD) analysis, Zeta potential charge (ZPC), and Fourier Transform Infrared Spectroscopy (FTIR). Explanation of the adsorption mechanism, kinetics, and feasibility were also documented. The influence of different operational variables pH, adsorbent dosage, Cr(III) ion concentration, contact time and temperature on adsorption were evaluated by batch experiments. The results demonstrated that the highest chromium removal (98.77 %) was ascertained while treating chrome-tanning effluents (174 mg/L) with 0.6 g/L GO for 20 minutes at pH 4. The adsorption equilibrium followed both Langmuir and Freundlich isotherms with maximum adsorption capacity (qm) of 366.3 mg/g. The adsorption kinetics was nicely interpreted with a pseudo-second-order reaction model and thermodynamically it was spontaneous at lower temperature and exothermic in nature. The metal ions loaded adsorbent was also regenerated and reused for further adsorption of Cr(III) ions from chrome-tanning effluents.

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Section: +supporting

confidence: 67%

Synthesis and Characterization of Graphene Oxide for the Adsorption of Cr(III) from Chrome-Tanning Effluent

Nurnabi¹

2021

PSBJ

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“… 5 , 17 , 18 , 27 One was to modify feedstock with FeCl 3 ·6H 2 O before pyrolysis denoted as x BC-Fe@B, 44 and the other was to modify biochar with zerovalent iron (ZVI) after pyrolysis followed by a drying process, denoted as xBC-Fe@A. 43 Both modified biochars were pyrolyzed and sieved as described above. For the sample names, the letters A and B were referred as post-modification and pre-modification methods, respectively, and letter x was referred as the modifier ratio.…”

Section: Methodsmentioning

confidence: 99%

Influence of Synthesis Methods on the High-Efficiency Removal of Cr(VI) from Aqueous Solution by Fe-Modified Magnetic Biochars

Jian

Feng

et al. 2020

ACS Omega

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Fe-modified biochars have been widely used in removal of Cr(VI) from water due to the resulting modified surface functional groups and magnetization property. However, few studies have synthetically investigated modification methods and synthesis parameters on the improvement of the removal efficiency of Cr(VI) by Fe-modified biochars. Herein, 10 types of corn straw-based magnetic biochars were produced using pre-modification and post-modification methods with various modifier ratios, and the highest heating temperature (HHT). Cr(VI) removal results suggest that the removal efficiency of pre-modified biochars ranged from 50.7 to 98.6%, which was much higher than that of post-modified (6.6–21.6%) and unmodified biochars (0.4–7.6%). The effect of synthesis methods on Cr(VI) adsorption was in the following order: Fe-modification method > modifier ratio > HHT. The adsorption kinetics and isotherm results of three types of pre-modified biochars were well fitted with the pseudo-second-order model (R 2 > 0.99) and the Langmuir adsorption model (R 2 > 0.99), respectively, indicating the surface homogeneity of the pre-modified biochars and unilayer chemisorptions of Cr(VI). Characterization results show that iron oxides or zerovalent iron particles were successfully deposited onto the surface of biochars and magnetism was introduced. A good Pearson correlation (r = −0.9694) between the removal efficiency and pH value in modified biochar suggests that the lower pH value may offer more positive charges and promote electrostatic attraction. Therefore, the dominant mechanism for enhanced Cr(VI) adsorption on pre-modified biochar was electrostatic attraction, resulting from its distinguished acidity nature. Our findings provide new insights into the high-efficiency removal of Cr(VI) onto Fe-modified magnetic biochars and will benefit future design of more efficient magnetic biochars.

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“…40 . However, the reduced removal capacity in higher dosage could be due to inter-particle aggregation, overlapping of adsorption sites, and consequently, less active surface area 15,41 .…”

Section: Effects Of Sn/fe Mass Ratiomentioning

confidence: 99%

“…The reason behind the improvement of removal efficiency is that a higher dosage of composite would provide larger surface area and more available active adsorption sites and more galvanic couples, which could enhance available electrons for Cr(VI) reduction 40 . However, the reduced removal capacity in higher dosage could be due to inter-particle aggregation, overlapping of adsorption sites, and consequently, less active surface area 15,41 .…”

Section: Effects Of Talc-nzvi/sn Dosagementioning

confidence: 99%

Preparation and Characterization of Nano-galvanic Bimetallic Fe/Sn Nanoparticles Deposited on Talc and its Enhanced Performance in Cr(VI) Removal

Bayat

Nasernejad

Falamaki

2021

Preprint

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In this study, talc-supported nano-galvanic nZVI/Sn bimetallic particles was successfully synthesized and utilized for Cr(VI) remediation. Talc-nZVI/Sn nanoparticles were characterized by SEM, EDS, FTIR, XRD, zeta potential, and BET analysis. The findings verified the uniform dispersion of nZVI/Sn nanoparticles on talc surface. The formation of numerous nano-galvanic cells between nZVI core and Sn shell enhanced the potential of bimetallic particles in Cr(VI) mitigation. Batch experiments were carried out to investigate optimum conditions and total Cr(VI) removal was achieved in 20 minutes using Sn/Fe mass ratio of 6/1, the adsorbent dosage of 2 g/L, initial Cr(VI) concentration of 80 mg/L, at the acidic environment (pH=5) and temperature of 303 K. Besides, co-existing of metallic cations turned out to facilitate the electron transfer from the nano-galvanic couple of NZVI/Sn and suggested the revolution of bimetallic particles to trimetallic composites. The aging study of the nanocomposite confirmed its constant high activity during 60 days. The removal reaction was well described by the pseudo-second-order kinetic and the Langmuir isotherm models. Overall, due to the synergistic galvanic cell effect of nZVI/Sn nanoparticles and full coverage of active sites by Sn layer, Talc-nZVI/6Sn was utilized as a promising nanocomposite for fast and highly efficient Cr(VI) elimination.

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Removal mechanisms of Cr(VI) and Cr(III) by biochar supported nanosized zero-valent iron: Synergy of adsorption, reduction and transformation

Cited by 177 publications

References 75 publications

Synthesis and Characterization of Graphene Oxide for the Adsorption of Cr(III) from Chrome-Tanning Effluent

Synthesis and Characterization of Graphene Oxide for the Adsorption of Cr(III) from Chrome-Tanning Effluent

Influence of Synthesis Methods on the High-Efficiency Removal of Cr(VI) from Aqueous Solution by Fe-Modified Magnetic Biochars

Preparation and Characterization of Nano-galvanic Bimetallic Fe/Sn Nanoparticles Deposited on Talc and its Enhanced Performance in Cr(VI) Removal

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