Preparation, characterisation and modification of carbon‐based monolithic rods for chromatographic applications

Abstract

A range of porous carbon-based monolithic (PCM) rods with flow-through pore sizes of 1, 2, 5 and 10 mum, were produced using a silica particle template method. The rods were characterised using SEM and energy-dispersive X-ray spectroscopy, BET surface area and porous structure analysis, dilatometry and thermal gravimetry. SEM evaluation of the carbon monolithic structures revealed an interconnected rigid bimodal porous structure and energy-dispersive X-ray spectroscopy analysis verified the quantitative removal of the embedded silica beads. The specific surface areas of the 1, 2, 5 and 10 mum rods were 178, 154, 84 and 125 m(2)/g after pyrolysis and silica removal, respectively. Shrinkage of the monolithic rods during pyrolysis is proportional to the particle size of the silica used and ranged from 9 to 12%. Mercury porosimetry showed a narrow distribution of pore sizes, with an average of approximately 700 nm for the 1 mum carbon monolith. The suitability of bare and surface oxidised PCM rods for the use as a stationary phase for reversed and normal phase LC was explored. The additional modification of PCM rods with gold micro-particles followed by 6-mercaptohexanoic acid was performed and ion-exchange properties were evaluated.

Fabrication and Characterization of Nanotemplated Carbon Monolithic Material

“…10,17 More recently, macro/mesoporous carbon monoliths with a graphitic framework have also been prepared via copolymerization of resorcinol and formaldehyde, with the inclusion of a polyamine (tetraethylenepentamine). 18 The polymers were also be doped with different metallic salts of Fe, Ni, or Co prior to carbonization, forming encapsulated metallic nanoparticles during the carbonization step.…”

Hierarchical porous graphitic carbon monoliths with detonation nanodiamonds: synthesis, characterisation and adsorptive properties

“…Compared to carbon powders, continuous porous carbon monoliths offer a high degree of permeability, ease of handling, lower hydraulic resistance, and improved electrolyte diffusion, all of which are advantageous for applications in separation processes, such as chromatography or filtration [7,12]. These attributes arise from the high degree of porosity and the hierarchical interconnected porous network within carbon monolithic materials.…”

“…Porous carbon materials provide the advantage of chemical stability, which eliminates swelling in most organic solvents. Furthermore, they have high hydrolytic stability across a wide pH range (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), unlike silica, which has a relatively narrow pH stability range (pH 2-8) due to the presence of polar silanol groups. Carbonaceous materials have been identified as an alternative adsorbent material for use in applications such as SPE and liquid chromatography [4,5].…”

“…Carbon monoliths can be prepared in a variety of forms, and the rod-shaped composites reported within this work are suitable for use in such applications, such as SPE for the extraction or pre-concentration of analytes in liquid samples of environmental, biological or pharmaceutical origin. The use of carbon monoliths as alternative sorbents for HPLC has been explored by Guichon and co-workers [8], and later by Eltmimi et al [7] using a method adapted from the one developed by Knox and Gilbert in 1979 for production of porous graphitic carbon-based materials for HPLC [21]; however, separation efficiencies were relatively poor, and this research is still at the exploratory stage of development. The development of new adsorbents whether through fabrication of new compositions, or through surface modifications, is important in furthering separation and extraction technologies.…”

“…The development of new selective and useful adsorbents still remains an important challenge in SPE, chromatography and other adsorption applications where sample enrichment, extraction or pollutant removal is a requirement. Carbon monoliths have emerged relatively recently for SPE and chromatographic applications [7][8][9], after their widespread use in other fields including catalyst supports, electrode materials and energy storage devices [10,11].…”