Physical entrapment of chitosan in fixed-down-flow column bed enhances triclosan removal from water.

Triclosan (TCS) is an emergent pollutant with wide-ranging deleterious effects on aquatic organisms and humans. There is a growing concern about the development of low-cost and efficient treatment systems for the removal of TCS from water. This report describes the performance of a prototype of a continuous flow, fixed bed column device with physically entrapped industrial by-product chitosan. The effects of initial TCS concentration, adsorbent dose in the column matrix, and flow rate were investigated with regard to removal efficiency (%), adsorption capacity and breakthrough time. To understand the thermodynamic properties of the adsorption process, three kinetic models - Thomas, Yoon-Nelson and Adams-Bohart - were applied to the experimental data for the prediction of characteristic parameters of the adsorption process. The Yoon-Nelson model showed the best agreement between the experimental and calculated values. The column showed a near saturation state (Ct/C0 = 0.92; C0 and Ct are the concentration of TCS before and after treatment.) at 90 mg L-1 TCS concentration after 60 minutes. In view of non-availability of a treatment process for the emergent pollutant TCS, the data of the present investigation will facilitate the development of novel prototypes of column bed reactors for the removal of TCS.

Chemical Modification and Performance Evaluation of an Agro-Waste for Column Mode Removal of Textile Dyes.

The performance of a newly designed column bed device packed with chemically modified agro-waste (sugarcane bagasse) is evaluated for efficient removal of two textile dyes, Optilan yellow and Lanasyn brown and textile industry dye effluent. The parameters used for performance evaluation are removal efficiency (R%), adsorption capacity (q), and breakthrough (C e/C 0). The column exhibits >90% removal of both the dyes and >80% removal of textile industry dye effluent. The experimental data are fitted to three models, viz., Thomas, Adams-Bohart, and Yoon-Nelson for understanding the kinetic behavior of adsorption. The results reveal that the Yoon-Nelson model is the best-fitted model for both the dyes with R 2 values 0.995 and 0.905 for Optilan yellow and Lanasyn brown, respectively. However, Thomas and Yoon-Nelson fit the best for textile industry effluent. Overall, this investigation provides baseline information about the column mode removal of textile dyes using the agro-waste material as an adsorbent. The Fourier transform infrared spectroscopy spectra show the characteristic vibrational mode of C-H stretching of hydroxyl group around 2800-3000 cm-1. The change in the vibrational pattern is evident after alginic acid treatment, indicating delignification of the bagasse after treatment.