Controllable Synthesis, Chemical Modification And Adsorption Properties Of Ordered Mesoporous Carbon

In order to improve the adsorption and separation properties of ordered mesoporous carbon (OMC), we dedicated to tailoring pore size and amino-functionalization of OMC in this article. The effect of1.3.5-trimethylbenzene (TMB) on the pore size tailoring in the soft-templating synthesis of OMC was systematically studied. A series of OMC materials with tailorable pore size was successfully synthesized by using TMB as a pore expander. The resultant samples were denoted as OMC-X (X refers to the addition ratio of TMB). Meanwhile, a new research was carried out on synthesis of amino-functionalized ordered mesoporous carbon (AF-OMC). AF-OMC was prepared by grafting (3-Aminopropyl) trimethoxysilane onto the channels of oxidized OMC. On this basis, OMC-X materials were used to explore the enrichment efficacy towards peptides E7and AM1. AF-OMC was used as adsorbent for Cr (VI) removal from aqueous solution to evaluate its adsorption properties. After adsorption of Cr (VI), the sample was denoted as Cr-AF-OMC. The obtained samples were characterized by XRD, TEM, N2adsorption-desorption, FTIR and XPS. Following conclusions can be concluded.1. All OMC-X materials maintained highly ordered two-dimensional hexagonal mesostructure. By increasing the addition ratio of TMB from0to1.05, the pore size of OMC was increased from4.4to5.4nm. However, excessive TMB addition had no influence on further pore size expansion in this synthetic system. OMC-0with a smaller pore size of4.4nm had a high enrichment performance towards E7peptide with a MW of1121Da, while OMC-1.05with a relatively larger pore size of5.4nm exhibited a higher enriching efficiency for AMI peptide with a larger MW of2474Da. Our results indicated that OMC-X materials with tailorable pore size should have a good application prospect in separating and enriching macro molecular substances.2. AF-OMC and Cr-AF-OMC materials retained highly ordered two-dimensional hexagonal mesostructure. Compared with the parent OMC, there was a remarkable decrease in surface area, pore volume and pore size of AF-OMC and Cr-AF-OMC. Combined with the analysis of FTIR and XPS, it was confirmed that the mesochannels were essentially grafted with abundant amino groups and loaded with Cr (VI). Batch adsorption data fitted pseudo-second-order kinetic model and Langmuir isotherm model very well, and the Cr (VI) adsorption capacity on AF-OMC could reach168.4mg/g at45℃. The thermodynamic analysis indicated that the Cr (VI) adsorption with AF-OMC was a spontaneous endothermic chemisorption process. An adsorption-reduction mechanism was proposed:Cr (Ⅵ) was partially reduced to Cr (Ⅲ) and chelated with amino groups. With such highly efficient adsorption characteristics, AF-OMC would become a very promising Cr (Ⅵ) adsorbent compared with other carbon materials.