Removal of CR by CCDA from aqueous solutions
The CR removal study was carried out by CCDA and the extracted cellulose as reference, using 0.025 g of adsorbent in 25.0 mL of dye solution (25 ppm, pH 7.0) at 37 °C. After specific time intervals (10–120 min), solution aliquots were withdrawn and the concentration of the remaining dye was determined at 498 nm with a Photolab 6600 UV–vis spectrophotometer to evaluate the performance of CCDA and equilibrium adsorption time for further adsorption experiments. The effect of the temperature (25–65 °C), pH (2.0–9.0), and initial dye concentration (5–100 ppm) on the adsorption capacity was studied at the optimized time. The maximum removal capacity (MRC) of the CCDA was determined by the repeated treatments of the same sample against 25 ppm of CR at the optimized conditions obtained for the maximum dye uptake. Regeneration of the adsorbent was affected by stripping-off the adsorbed dye with 0.5 N HCl. Reusability studies were carried out with the regenerated adsorbent. The adsorption results were evaluated with the following expressions: