Pillar[5]arene-Based Crosslinked Polymer Gel Films for Organic Dyes Adsorption

Abstract

Two types of gel films—denoted as PVA–AA–WP[5] (HF-1) and PVA–WP[5] (HF-2)—were fabricated using an amphiphilic carboxylated pillararene (WP[5]), poly(vinyl alcohol) (PVA), and adipic acid (AA) as the primary building blocks. The characterization results indicate that polyvinyl alcohol (PVA) forms gel films through chemical crosslinking with acrylic acid (AA) and WP[5], and both resulting gel films exhibit an amorphous structure. Both gel films exhibited effective adsorption capabilities toward Rhodamine B (RhB) and Basic Red 46 (BR46). Notably, the PVA–pillararene composite gel film (HF-2) demonstrated superior adsorption performance. The adsorption of RhB by HF-2 remained relatively stable across a wide acidic pH range (pH 1–6), achieving a maximum adsorption capacity of 448.5 mg/g. In contrast, the adsorption of BR46 was more sensitive to solution acidity, with a maximum uptake of 192.8 mg/g observed under optimal conditions. The dye-loaded gel films were regenerated by soaking in ethanol, and after five adsorption–desorption cycles, HF-2 retained a high RhB removal efficiency of 96.2 %.