Synthesis and characterization of novel N-methylimidazolium-functionalized KCC-1: A highly efficient anion exchanger of hexavalent chromium.

A key challenge in adsorption process of toxic organic and inorganic species is the design and development of adsorbent materials bearing an abundance of accessible adsorption sites with high affinity to achieve both fast adsorption kinetics and elevated adsorption capacity for toxic contaminants. Herein, a novel anion-exchange adsorbent based on fibrous silica nanospheres KCC-1 was synthesized by a facile hydrothermal-assisted post-grafting modification of KCC-1 with 1-methyl-3- (triethoxysilylpropyl)imidazolium chloride for the first time. Silica fibers with micro-mesoporous structure display the proper combination of features to serve as a potential scaffold for decorating adsorption sites to create desired ion-exchange adsorbent. The obtained N-methylimidazolium-functionalized KCC-1 (MI-Cl-KCC-1) with fibrous nanosphere morphology showed a high surface area (∼241 m ²  g ^-1 ) and high pore volume (0.81 m ²  g ^-1 ). The adsorption behaviors of toxic hexavalent chromium from aqueous media by the MI-Cl-KCC-1 were systematically studied using the batch method. The adsorption rate was relatively fast, and MI-Cl-KCC-1 possesses a high capacity for the adsorption of Cr(VI). The maximum Cr(VI) adsorption was obtained at pH 3.0-4.0. Different non-linear isotherm equations were tested for choosing an appropriate adorption isotherm behavior, and the adsorption data for MI-Cl-KCC-1 were consistent with the Langmuir model with a maximum adsorption capacity of 428 ± 8 mg g ^-1 .
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