Conversion of Untanned Proteinaceous Solid Wastes from Tanneries into Aerogel and Its Application in Batch and Continuous Fixed-Bed Adsorption of Acid Red 97

Abstract

Gelatin-based aerogel (G-Aerogel) from untanned proteinaceous solid wastes was applied as an adsorbent in batch and fixed-bed column systems to remove acid red 97 (AR97) from water. Adsorption was evaluated as a function of pH, adsorbent mass, contact time, temperature, and initial dye concentration. Maximum removal of AR97 was achieved at pH 3 after about 4 h. The pseudo-second-order equation provided the best adsorption kinetic model. The adsorption of AR97 onto G-Aerogel was best described with the Langmuir model, and the maximum adsorption capacity was about 196 mg·g−1. A thermodynamic study showed an exothermic and spontaneous adsorption process. It was also demonstrated that G-Aerogel can be reused several times. The column study showed that breakthrough and saturation times decreased with increasing initial AR97 concentration. Thomas and Yoon-Nelson kinetic models were applied to the experimental data to predict the breakthrough curves and determine the characteristic parameters of column adsorption.