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Magnetic Porous Carbonaceous Material Produced from Tea Waste for Efficient Removal of As(V), Cr(VI), Humic Acid, and Dyes
journal contribution
posted on 2017-03-22, 00:00 authored by Tao Wen, Jian Wang, Shujun Yu, Zhongshan Chen, Tasawar Hayat, Xiangke WangMagnetic
porous carbonaceous (MPC) materials derived from tea waste were synthesized
by an integrated biosorption–pyrolysis process and were applied
as adsorbents for wastewater cleanup. On the basis of various characterizations,
we demonstrated that the formation mechanism of γ-Fe2O3 anchored on the porous carbonaceous material surface
consisted of the adsorption of iron ions and then the γ-Fe2O3 nucleation and growth through pyrolysis at alternative
peak temperatures (300–500 °C). The sample pyrolyzed at
300 °C (MPC-300) showed good capacities for As(V) (38.03 mg g–1) and Cr(VI) (21.23 mg g–1) adsorption,
outperforming that of commercial bulk Fe2O3 and
many other materials. Moreover, the large available positive charge
density can facilitate the effective adsorption of anionic dye (MO)
and humic acid (HA) on the γ-Fe2O3 surface
while the adsorption performance is sluggish for cationic dyes (MB
and RhB). Relatively, the adsorption isotherms could significantly
conform to the Langmuir model, and the pseudo-second-order dynamic
equation was the optimal model to describe the kinetics for the adsorption
of As(V), Cr(VI), humic acid, and dye pollutants on MPC-300. Kinetic
studies show that MPC-300 can efficiently remove these pollutants
in aqueous solution within 3 h. The presence of HA reduced Cr(VI)
and As(V) adsorption on MPC-300 at pH < 6.0. The XPS and FTIR analysis
further demonstrated that ion exchange between surface hydroxyl groups
and Cr(VI)/As(V) dominated the adsorption while the adsorption mechanism
of MO and HA was attributed to electrostatic attraction on protonated–OH
on the γ-Fe2O3 surface. The results suggested
that the MPC material was a potential material to remove heavy metal
ions, HA, and organic contaminants simultaneously with remarkable
adsorption capacity, fast uptake rate, and easy magnetic separation.
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γ- Fe 2 O 3 surfaceadsorption performancetea wasteadsorption mechanismmetal ionsXPSdye pollutantsMPC materialiron ionsion exchangeCrMBTea WasteMOuptake rateadsorption isothermssurface hydroxyl groupscharge density3 hcarbonaceous material surfaceEfficient RemovalMagnetic Porous Carbonaceous Material Producedwastewater cleanupsample pyrolyzedformation mechanismHAadsorption capacityhumic acidbulk Fe 2 O 3MPC -300. Kinetic studies showFTIR analysiscationic dyesγ- Fe 2 O 3Langmuir modelγ- Fe 2 O 3 nucleation
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