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Adsorption of nitrate from aqueous solution by magnetic amine-crosslinked biopolymer based corn stalk and its chemical regeneration property

Song, Wen, Gao, Baoyu, Xu, Xing, Wang, Fang, Xue, Nan, Sun, Shenglei, Song, Wuchang, Jia, Ruibao
Journal of hazardous materials 2016 v.304 pp. 280-290
Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, adsorbents, adsorption, aqueous solutions, biopolymers, corn stover, effluents, electrostatic interactions, endothermy, ion exchange, kinetics, magnetism, models, nitrates, pH, phosphates, scanning electron microscopy, sorption isotherms, sulfates, thermodynamics, thermogravimetry, transmission electron microscopy
A novel adsorbent of magnetic amine-crosslinked biopolymer based corn stalk (MAB-CS) was synthesized and used for nitrate removal from aqueous solution. The characters and adsorption mechanisms of this bio-adsorbent were determined by using VSM, TGA, XRD, SEM, TEM, FT-IR and XPS, respectively. The results revealed that the saturated magnetization of MAB-CS reached 6.25emu/g. Meanwhile, the studies of various factors indicated that this novel magnetic bio-adsorbent performed well over a considerable wide pH range of 6.0∼9.0, and the presence of PO4³⁻ and SO4²⁻ would markedly decrease the nitrate removal efficiency. Furthermore, the nitrate adsorption by MAB-CS perfectly fitted the Langmuir isotherm model (R²=0.997–0.999) and pseudo second order kinetic model (R²=0.953–0.995). The calculated nitrate adsorption capacity of MAB-CS was 102.04mg/g at 318K by Langmuir model, and thermodynamic study showed that nitrate adsorption is an spontaneous endothermic process. The regeneration experiments indicated its merit of regeneration and stability with the recovery efficient of 118∼147%. By integrating the experimental results, it was found that the removal of nitrate was mainly via electrostatic attraction and ion exchange. And this novel bio-adsorbent prepared in this work could achieve effective removal of nitrate and rapid separation from effluents simultaneously.