Mechanism of Cr(VI) removal by magnetic greigite/biochar composites

Wang, Xuedong; Xu, Jin; Liu, Jia; Li, Jun; Xia, Fang; Wang, Cuicui; Dahlgren, Randy A.; Liu, Wei

doi:10.1016/j.scitotenv.2019.134414

Cited by 126 publications

(56 citation statements)

References 63 publications

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“…In addition, the surface area decreased from 25.56 m 2 /g in CMB to 5.44 m 2 /g in M-CMB, which could be attributed to the synthesis of magnetic biochar, causing many micropores were covered by the ash of M-CMB. Similar phenomenon was obtained in the previous work of some researchers reporting the reduction in the surface area after magnetization, because the Fe-containing particles reduced the surface area by filling micropores [6,10,27].…”

Section: Biochar Propertiessupporting

confidence: 89%

“…Among these precipitates, such as CdCO 3 , Cd 3 (PO 4 ) 2 , CdSiO 3 , Cd(OH) 2 and CdS, were probably due to high concentrations of CO 3 2− , PO 4 3− , S and Si content in the original biochars ( Figure 1 and Table 1), which were also observed in the previous studies on the heavy metal adsorption by the biochars [1,49,50]. In particular, the precipitates of CdFe 2 O 4 were detected on the surface of M-CMB after adsorption, which could be attributed to the presence of Fe 3 O 4 particles, generating adsorption sites for metal ions [6,10]. Generally, the intensities of XRD peak were strong in both biochars, suggesting the precipitation played an important role in total adsorption.…”

Section: Metal Precipitationsupporting

confidence: 81%

“…While Son et al [6] developed an engineered magnetic biochar by pyrolyzing waste marine macro-alga, and found that the adsorption efficiency of heavy metal was partially reduced by magnetic biochar. These investigations and other studies [7][8][9][10] showed that the adsorption capacity of heavy metal by magnetic biochar, might be higher or lower than to that of nonmagnetic biochar. Therefore, it is necessary to evaluate the effect of magnetism loading on biochar in terms of the cationic heavy metal adsorption capacity, before a decision for the potential use of magnetic biochar as an industrial adsorbent is made.…”

Section: Introductionsupporting

confidence: 52%

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Adsorption Behavior and Relative Distribution of Cd2+ Adsorption Mechanisms by the Magnetic and Nonmagnetic Biochars Derived from Chicken Manure

Huang

Zhang

et al. 2020

IJERPH

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The present study investigated the adsorption of Cd2+ by nonmagnetic and magnetic biochars (CMB and M-CMB) derived from chicken manure, respectively. The adsorption characteristics were investigated as a function of initial pH, contact time, initial Cd2+ concentration and magnetic separation. Adsorption process of both biochars were better described by Pseudo-second-order kinetic equation and Freundlich isotherm model, which were spontaneous and endothermic in nature. It was found that maximum capacities were 60.69 and 41.07 mg/g obtained at the initial Cd2+ concentration of 180 mg/L for CMB and M-CMB, and the turbidity of adsorption-treated solution was reduced from 244.3 to 11.3 NTU after magnetic separation of 0.5 min. These indicated that M-CMB had lower adsorption capacity of Cd2+ than CMB, though it was successfully separated from the treated solutions. Furthermore, both biochars before and after adsorption were analyzed by SEM-EDS, XRD and FTIR. Adsorption mechanisms mainly included precipitation, ion-exchange, complexation and Cπ-coordination, in which precipitation and ion-exchange dominated the adsorption process by CMB, while in M-CMB, precipitation was always predominant mechanism, followed by ion-exchange. The two other mechanisms of complexation and Cπ-coordination were trivial in both biochars, jointly contributing 7.21% for CMB and 5.05% for M-CMB to total adsorption. The findings deepen our understanding of the mechanisms governing the adsorption process, which are also important for future practical applications in the removal of heavy metals from wastewater by the biochars.

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Section: Biochar Propertiessupporting

confidence: 89%

Section: Metal Precipitationsupporting

confidence: 81%

Section: Introductionsupporting

confidence: 52%

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Adsorption Behavior and Relative Distribution of Cd2+ Adsorption Mechanisms by the Magnetic and Nonmagnetic Biochars Derived from Chicken Manure

Huang

Zhang

et al. 2020

IJERPH

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“…The Cr(VI) ions were first adsorbed on MGBs surface and subsequently reduced to Cr(III). The enhancement of Cr(VI) removal was attributed to efficient surface Fe(III)/Fe(II) cycling via electron transfer with persistent free radicals of biochar, and the Cr(VI) removal efficiency was strongly dependent on the amount of Fe 3 S 4 loaded on MGBs (Wang et al 2020a). The biochar-supported nanoscale iron sulfide (FeS) composites combined carboxymethyl cellulose (CMC) (CMC-FeS@biochar) with the mass ratio of FeS:CMC:Biochar = 1:1:1 exhibited Cr(VI) sorption capacity of 130.5 mg/g at pH 5.5 comparing to FeS (38.6 mg/g) and biochar (25.4 mg/g).…”

Section: Sorption Of Heavy Metal Ions and Radionuclidesmentioning

confidence: 99%

Efficient elimination of organic and inorganic pollutants by biochar and biochar-based materials

Jin

et al. 2020

Biochar

313

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Biochar have received multidisciplinary attention because of their extraordinary physicochemical properties. In this review, the application of biochar and biochar-based materials for the efficient elimination of organic and inorganic pollutants are summarized. The sorption of organic chemicals and heavy metal ions/radionuclides, degradation/transformation of organic pollutants, and sorption-reduction-solidification of high-valent metal ions are described in detail. The interaction mechanism at molecular level from advanced spectroscopic techniques and theoretical calculations is discussed. Finally, the challenges in the application of biochar and biochar-supported materials in the immobilization of heavy metal ions and photocatalytic degradation of persistent organic pollutants in soils or wastewater are pointed out. This review is helpful for the graduate students to understand the recent works about biochar and biochar-supported materials in environmental pollutants management.

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“…However, these suffer from the shortcomings such as tendencies for oxidation and aggregation, limited adsorption capacity, low selectivity, and high cost [ 7 ]. Thus, the further development of highly efficient, abundant, and magnetically separable adsorbent materials has attracted much attention [ 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Study on the Adsorption of CuFe2O4-Loaded Corncob Biochar for Pb(II)

Zhao

Cai

et al. 2020

Molecules

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A series of the magnetic CuFe2O4-loaded corncob biochar (CuFe2O4@CCBC) materials was obtained by combining the two-step impregnation of the corncob biochar with the pyrolysis of oxalate. CuFe2O4@CCBC and the pristine corncob biochar (CCBC) were characterized using XRD, SEM, VSM, BET, as well as pHZPC measurements. The results revealed that CuFe2O4 had a face-centered cubic crystalline phase and was homogeneously coated on the surface of CCBC. The as-prepared CuFe2O4@CCBC(5%) demonstrated a specific surface area of 74.98 m2·g−1, saturation magnetization of 5.75 emu·g−1 and pHZPC of 7.0. The adsorption dynamics and thermodynamic behavior of Pb(II) on CuFe2O4@CCBC and CCBC were investigated. The findings indicated that the pseudo-second kinetic and Langmuir equations suitably fitted the Pb(II) adsorption by CuFe2O4@CCBC or CCBC. At 30 °C and pH = 5.0, CuFe2O4@CCBC(5%) displayed an excellent performance in terms of the process rate and adsorption capacity towards Pb(II), for which the theoretical rate constant (k2) and maximum adsorption capacity (qm) were 7.68 × 10−3 g·mg−1··min−1 and 132.10 mg·g−1 separately, which were obviously higher than those of CCBC (4.38 × 10−3 g·mg−1·min−1 and 15.66 mg·g−1). The thermodynamic analyses exhibited that the adsorption reaction of the materials was endothermic and entropy-driven. The XPS and FTIR results revealed that the removal mechanism could be mainly attributed to the replacement of Pb2+ for H+ in Fe/Cu–OH and –COOH to form the inner surface complexes. Overall, the magnetic CuFe2O4-loaded biochar presents a high potential for use as an eco-friendly adsorbent to eliminate the heavy metals from the wastewater streams.

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Mechanism of Cr(VI) removal by magnetic greigite/biochar composites

Cited by 126 publications

References 63 publications

Adsorption Behavior and Relative Distribution of Cd2+ Adsorption Mechanisms by the Magnetic and Nonmagnetic Biochars Derived from Chicken Manure

Adsorption Behavior and Relative Distribution of Cd2+ Adsorption Mechanisms by the Magnetic and Nonmagnetic Biochars Derived from Chicken Manure

Efficient elimination of organic and inorganic pollutants by biochar and biochar-based materials

Study on the Adsorption of CuFe2O4-Loaded Corncob Biochar for Pb(II)

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