Carboxylated cellulose-based aerogel with cellular pores prepared by stir freezing for cationic dye adsorption

Abstract

A TEMPO-oxidized cellulose (TOC)/nanofiber cellulose (NFC) biomass aerogel was prepared through freeze-drying (FD) for cationic dye adsorption. The stir freezing method was utilized to build cellular pores so as to improve the mechanical property of aerogel. The dielectric-assisted microwave (MW) heating was adopted to increase the FD rate. The results showed that the proposed method could simultaneously intensify the mass and heat transfer of FD, reducing more than 36% of drying time. The TOC/NFC aerogel exhibited a high mechanical property with 91.36 kPa of compressive stress at 80% strain. The maximum adsorption capabilities of aerogel prepared by stir freezing for methylene blue (MB) and malachite green (MG) dyes were 248.27 and 227.30 mg·g–1, respectively. The prepared aerogel showed high selective adsorption of cationic dyes in binary dye solutions. Moreover, the prepared aerogel exhibited a satisfactory recycling performance in 20 cycles of adsorption/desorption experiments. This work provides a new freezing and FD strategy to prepare TOC/NFC aerogels with promising applications in industrial printing and dyeing wastewater treatment.