Elemental mercury removal by the modified bio-char from medicinal residues

Shen, Bo; Li, Guoliang; Wang, Fumei; Wang, Yinyin; He, Chuan; Zhang, Min; Singh, Surjit

doi:10.1016/j.cej.2015.03.006

Cited by 128 publications

(41 citation statements)

References 41 publications

(66 reference statements)

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“…19 Chemical modications of biochars are widely applied, mainly using the reagents citric acid, 20 KOH, 20 KMnO 4 , 21 and ZnCl 2 (ref. 22) to impregnate the raw feedstock, which inuence their pyrolytic decomposition. Among these reagents, ZnCl 2 is considered a less expensive and more effective agent for producing modied biochar.…”

Section: -19mentioning

confidence: 99%

Development, modification, and application of low-cost and available biochar derived from corn straw for the removal of vanadium(v) from aqueous solution and real contaminated groundwater

et al. 2018

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In this work, a low-cost and available material for use as a permeable reactive barrier (PRB) to prevent vanadium in groundwater from leaking into river water was developed. Three modified biochars were prepared from available corn straw pretreated with CsCl, Zn(II), and Zr(IV) to enhance ion exchange capacity (IEC) and specific surface area, and were designated as Cs-BC, Zn-BC, and Zr-BC, respectively. These materials were characterized via IEC, N 2 adsorption-desorption, Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses. The Langmuir isotherm model could be applied for the best fit for the adsorption data of Cs-BC and Zr-BC, indicating that vanadium(V) sorption occurred in a monolayer. The vanadium(V) adsorption capacities of Cs-BC, Zn-BC, and Zr-BC were 41.07, 28.46, and 23.84 mg g À1 , respectively, which were 3.22-5.55 times higher than that of commercial activated carbon (AC) (7.40 mg g À1 ), probably because of their higher IECs and specific surface areas after modification. In addition, no heavy metal leaching was found from the modified biochars during the adsorption processes when pH > 2. According to the FTIR and XRD patterns, the adsorption mechanism of Cs-BC and Zr-BC was ion exchange, whereas for Zn-BC, it was mainly surface precipitation and electrostatic attraction. The adsorption of vanadium(V) onto the modified biochars was independent of pH in the range of 4.0 to 8.0. Furthermore, the removal efficiency of the vanadium(V) in real contaminated groundwater from the catchment of the Chaobei River by Zn-BC reached 100% at a dose of 4 g L À1. Hence, modified biochars are promising PRB filling materials for removing vanadium(V) from contaminated groundwater.

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Section: -19mentioning

confidence: 99%

Development, modification, and application of low-cost and available biochar derived from corn straw for the removal of vanadium(v) from aqueous solution and real contaminated groundwater

et al. 2018

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“…Microwave/steam activation and NH 4 Cl impregnation were used to modify various chars to investigate the effect of physical and chemical modification on the active constituents of char. NH 4 Cl was selected as the impregnation reagent since it has been demonstrated to be the optimal modification reagent among NH 4 Cl, HCl and ZnCl 2 in our previous study [16]. The purpose of this paper is to investigate the influence of inherent active constituents in raw materials and chars for the mercury removal and to further optimize the modification method of char.…”

Section: Introductionmentioning

confidence: 99%

Role of inherent active constituents on mercury adsorption capacity of chars from four solid wastes

Wang

Tang

et al. 2017

Chemical Engineering Journal

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Many raw materials have active constituents for mercury removal, such as the elements oxygen (O), sulfur (S) and chloride (Cl), but these constituents are frequently neglected during the preparation process of mercury adsorbents. This study investigated the effect of various inherent active constituents of four solid wastes (waste tire, cotton straw, Chinese medicinal residue and municipal solid waste) on the mercury removal performance of their derived chars. Modification methods (chemical impregnation and physical activation) were used to clarify modification influence on inherent active constituents and mercury removal performance of chars. Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), temperature programmed decomposition technic (TPDT) and elemental mercury adsorption testing were used to measure and evaluate various chars. The results indicated that only waste tire generated mercury chemisorption sites (sulfide) during pyrolysis process. Sulfide could oxidize Hg 0 into HgS on char T6 derived from tire waste whereas sulfate could not on char derived from Chinese medicinal residue. The evaporation of element Cl during pyrolysis process led to the low adsorption capacity of municipal waste

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“…Li et al showed that biochars modified with ammonium halides exhibited higher Hg 0 removal efficiency than that with potassium halides. Different adsorption properties are related to amino groups, which may form chemical adsorption sites . Therefore, NH 4 Br was selected as the modifier to study the adsorption performance of the sorbent in O 2 /CO 2 atmosphere, and compared with that in O 2 /N 2 atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…Different adsorption properties are related to amino groups, which may form chemical adsorption sites. 24,25 Therefore, NH 4 Br was selected as the modifier to study the adsorption performance of the sorbent in O 2 / CO 2 atmosphere, and compared with that in O 2 /N 2 atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Effect of flue gas components on Hg⁰ oxidation and adsorption by modified walnut shell coke in O₂/CO₂ atmosphere

Zhang

Duan

Wang

et al. 2020

Asia-Pacific J Chem Eng

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Walnut shell was pyrolyzed and then impregnated with NH4Br to make sorbent for Hg0 removal. The effect of flue gas components on Hg0 removal performance was studied in O2/CO2 atmosphere, and the results were compared with those in O2/N2 atmosphere. The mercury valence distribution during adsorption was obtained. NH4Br‐modified walnut shell coke promoted Hg0 removal, the Br‐containing chemisorption site was a crucial factor. Although addition of CO2 did not introduce new oxygen‐containing functional groups or change the mercury species, Hg0 removal efficiency increased significantly. This may be because CO2 can increase the active sites on the carbon surface. In O2/N2 atmosphere, O2 promoted formation of active center on the sorbent surface, which made Hg0 more easily adsorbed and then reacted with Br‐functional group to form more HgBr2. In O2/CO2 atmosphere, O2 promoted formation of some reactive carbon–oxygen complexes which acted as catalyst to facilitate Hg0 oxidation and formation of HgO. NO improved removal of Hg0, because the C─O functional group on the sorbent surface could catalyze the conversion of NO to NO2 in the adsorbed state and then formed Hg2(NO3)2. SO2 consumed oxygen on the sorbent surface and inhibited the Hg0 removal.

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Elemental mercury removal by the modified bio-char from medicinal residues

Cited by 128 publications

References 41 publications

Development, modification, and application of low-cost and available biochar derived from corn straw for the removal of vanadium(v) from aqueous solution and real contaminated groundwater

Development, modification, and application of low-cost and available biochar derived from corn straw for the removal of vanadium(v) from aqueous solution and real contaminated groundwater

Role of inherent active constituents on mercury adsorption capacity of chars from four solid wastes

Effect of flue gas components on Hg⁰ oxidation and adsorption by modified walnut shell coke in O₂/CO₂ atmosphere

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Elemental mercury removal by the modified bio-char from medicinal residues

Cited by 128 publications

References 41 publications

Development, modification, and application of low-cost and available biochar derived from corn straw for the removal of vanadium(v) from aqueous solution and real contaminated groundwater

Development, modification, and application of low-cost and available biochar derived from corn straw for the removal of vanadium(v) from aqueous solution and real contaminated groundwater

Role of inherent active constituents on mercury adsorption capacity of chars from four solid wastes

Effect of flue gas components on Hg0 oxidation and adsorption by modified walnut shell coke in O2/CO2 atmosphere

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Effect of flue gas components on Hg⁰ oxidation and adsorption by modified walnut shell coke in O₂/CO₂ atmosphere