Synthesis of Chitosan/Carbon Nanotubes Composite Films as Potential Removal of Anionic and Cationic Dyes in Aqueous...

In response to growing environmental concerns about dye-contaminated wastewater, this study introduces a novel approach to enhance the performance of chitosan-based adsorbents by incorporating carbon nanotubes into film matrices. The chitosan/carbon nanotubes (CN/CNTs) films were prepared via the casting technique using the same amount of chitosan but with varying proportions of CNTs (0.1, 0.3, and 0.5% w w^-1). The resulting films showed uniform thickness, progressive darkening with increasing CNT content, and improved mechanical strength (up to 83.3 MPa) and elongation capacity (up to 29.3%) with higher CNTs concentration. Adsorption studies highlighted the influence of pH on dye removal, with maximum adsorption capacities of 800 mg g^-1 for crystal violet (pH 8, CS/CNT 0.5%) and 660 mg g^-1 for tartrazine yellow (pH 2, CS/CNT 0.1%). The PSO model provided the best fit for the kinetic data in all conditions studied, with k ₂ varying from 0.0003 to 0.00053 g mg^-1 min^-1. For crystal violet, the Henry model best fit the experimental data with k _H values ranging from 4.34 to 5.85 L g^-1. In contrast, the Freundlich model was the most appropriate for yellow tartrazine, showing k _F values between 8.11 and 20.23 (mg g^-1)-(mg L^-1)^-1/n . Desorption tests using NaOH solutions demonstrated reusability, with a performance loss of 12% for crystal violet and 6% for yellow tartrazine after four cycles. These findings underscore the potential of CS/CNTs films as sustainable, high-capacity adsorbents for wastewater treatment applications, advancing the design of biopolymer-based composite materials for environmental remediation.