Facile fabrication of lignocellulose-chitosan composite aerogel using ZnBr₂·4H₂O for dye adsorbent

The development of low-cost and high-performance water purification adsorbents has attracted increasingly attentions. In this work, corn stalk pith (CSP) and chitosan rich in amino groups were treated with ZnBr₂·4H₂O to prepare lignocellulosic aerogels (LAs) and lignocellulose-chitosan composite aerogels (LCAs) for wastewater treatment. The effects of the ZnBr₂·4H₂O treatment time and the addition of chitosan on the structure and adsorption performance of the aerogels were evaluated. The results showed that the lignocellulosic aerogel LA₁₅ had a three-dimensional porous structure and the optimal adsorption capacity of which reached 489.4 mg/g for Congo red. After the addition of chitosan, the adsorption performance and the adsorption behavior of LCA₁₀ for Congo red were evaluated in detail. The maximum adsorption capacity of the prepared LCA₁₀ for Congo red was up to 641.5 mg/g, which was 31 % higher than that of LA₁₅. Adsorption kinetics suggested that the adsorption of Congo red on LCA₁₀ followed the pseudo-second-order kinetic and the Langmuir isotherm model, indicating that the adsorption was dominated by chemical adsorption and the adsorption of Congo red was mainly occurred on the surfaces of LCA₁₀. This study provides a simple method for preparing high-performance dye adsorbents under mild conditions.