Metal Oxide and Carbon Monoliths

Metal oxides are inert materials that exhibit higher stability under strongly acidic, basic, or oxidizing solutions then conventional silica materials. They are even stable at elevated temperatures. All these advantageous properties attract scientific attention on metal oxide materials as new supports for enhanced HPLC application. 

Randon et al. reported on an alternative approach for the preparation of zirconia monoliths [96]. The sol-gel process is initiated by hydrolysis of an ethanolic zirconium alkoxide solution, on addition 

Taguchi et al. [97] and Liang et al. [98,99] reported on the preparation of monolithic carbon columns, which exhibit a hierarchical, fully interconnected porosity. Silica particles (10 pm) have been suspended in an aqueous solution, containing ethanol, FeClj, resorcinol, and formaldehyde. After polymerization, the solid rod was dried, cured, and carbonized by raising temperature to 800°C and finally up to 1250°C. Finally, concentrated FIF was used to remove silica and iron chloride. Even if carbon have been shown to possess a high specihc surface area (up to lllSmVg), their chromatographic efficiency is moderate (FIETP of 72 pm). 

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