Microwave-assisted synthesis of carbon nanotubes for the removal of toxic cationic dyes from textile wastewater

Toxic cationic dyes are used in different textile industries. When the colour interacts with the sunlight, it causes incomplete photosynthesis, inhibiting aquatic organisms’ growth and disrupting gas permeability in the water system. In this work, carbon nanotubes (CNTs) were prepared to employ acetylene and hydrogen as precursor gases in a microwave-assisted reactor. The obtained CNTs were tested for their ability to remove the crystal violet (CV) dye. However, the effect of removal parameters, such as pH of ion solution, initial concentration, and contact time, was optimized on the adsorption process through response surface methodology. It was found that the optimized removal of CV dye was 81% at an optimum pH value of 7.0 with 10 mg/L of an initial concentration and a contact time of 25 min. Complete dye extraction can be achieved by increasing the CNT dosage.Moreover, by using both the Langmuir model and Freundlich model of adsorption, the equilibrium data obtained from experiments were analyzed. The study also revealed that the adsorption at room temperature, having a high adsorption capability of 2.615 mg/g for CV, was best defined using the Langmuir model. For the reaction order, the adsorption rates represented the pseudo-first-order kinetic model.