In-Situ Production of Cellulose Nanocrystal-Alginate Hydrogel Beads and Dye Removal in Fixed Bed Adsorption Column

Abstract

In this study, adsorption modeling of a model organic dye, methylene blue (MB), onto cellulose nanocrystal-alginate (CNC-ALG) hydrogel beads in a fixed bed column until full breakthrough was performed. A method for the in-situ production and loading of CNC-ALG hydrogel beads in a fixed bed column adsorption process was proposed for the first time. Fixed bed column adsorption experiments using MB and 0.5 wt % ALG and 2 wt % CNC beads were conducted using various initial dye concentrations, influent flow rates and adsorbent mass. The results were evaluated using a mathematical model with axial dispersion, film and pore diffusion to predict the fluid and particle phase continuity, and good agreement with the experimental data was observed. Experiments conducted using the spent hydrogel beads in a fixed bed column suggested that these adsorbents could be regenerated to 81% of its original adsorption capacity upon elution with 1 M hydrochloric acid:ethanol (1:1 v:v), and a subsequent adsorption cycle indicated that these adsorbents could achieve 96% of the renewed adsorption capacity. Furthermore, both batch and fixed bed column adsorption experiments displayed the maximum adsorption capacities of 401.8 and 410.5 mg MB/g adsorbent, respectively, and these similar values signify the reproducibility of the adsorption capacity of the adsorbents when operated under batch and continuous modes.

High-Efficiency Photocatalytic Reactors Fabricated via Rapid DLP 3D Printing: Enhanced Dye Photodegradation with Optimized TiO2 Loading and Structural Design

“…Unprocessed discharge can severely harm the ecosystem . Common treatment technologies include adsorption, biocatalytic degradation, oxidation, chemical/electrocoagulation, and photodegradation, , with the latter being a green technology without secondary pollution gaining attention . In the process of photocatalytic oxidation for dye photodegradation, a common photocatalyst like TiO 2 , when irradiated with light energy exceeding its band gap energy (e.g., 3.2 eV for TiO 2 ), generates conduction band electrons (e CB – ) and valence band holes (h VB + ).…”