Isoniazid-Modified Silica for Hydrophilic Interaction Chromatography and as an Adsorbent for Dye Removal in Wastewater Samples

The new isoniazid-derived material was synthesized with a surface-immobilizable functional group by a reaction between isoniazid and succinyl anhydride and grafted onto silica surfaces. The material was designed so that multiple functional groups could interact with the guest molecules. Initially, the silica surface was modified with 3-amipropyltrimethoxysilane. Succinyl isoniazid (SID) was synthesized and then immobilized to 3-aminopropylsilica by an amide coupling reaction to obtain Sil-SID. The ATR-FTIR and ¹H NMR were used to characterize the SID before immobilization. After grafting, Sil-SID was confirmed by elemental analysis, ATR-FTIR, scanning electron microscopy, and thermogravimetric analysis (TGA). The same material was finally used as a stationary phase in hydrophilic interaction chromatography (HILIC) to separate nucleosides and nucleobases and as an adsorbent for wastewater treatment for the first time. Due to the presence of multiple functional groups and a heteroaromatic ring in the phase, it exhibited excellent separation for polar analytes in HILIC and, at the same time, exceptionally high adsorption capacity and removal efficiencies for an anionic dye in wastewater. The maximum adsorption capacity reached 714.3 mg/g at pH 3. Here, a single material (Sil-SID) was used as a stationary phase and an adsorbent with excellent performance in both cases. This work is a good example of material development and its multiple applications. It will also reduce the design and production costs of novel materials for various applications. A single material can serve two or more purposes.