Extended isotherm and kinetics of binary system dye removal using carbon nanotube from wastewater

This paper investigates the ability of multi-walled carbon nanotube (CNT) to adsorb three cationic dyes from colored wastewater in single and binary systems. Basic Blue 41 (BB41), Basic Red 18 (BR18), and Basic Violet 16 (BV16) were used as model dyes. The surface characteristic of CNT was studied using Fourier transform infrared. The effect of operational parameters (CNT dosage, dye concentration, pH, and salt) on dye removal was investigated. The adsorption isotherm and kinetic were studied. The isotherm data in single and binary systems followed Langmuir isotherm. The maximum adsorption capacity (Q0) of BB41, BR18, and BV16 in single dye systems were 123.457, 80.012, and 64.935 mg/g, respectively. In adsorption from binary dye solutions, the isotherm of each individual dye followed extended Langmuir isotherm model. The paper also measured the kinetic adsorption of the dyes on CNT in single and binary dye systems at different dye concentrations. The adsorption follows a pseudo-second-order kinetic model at all the concentrations and values on the rate constants (k2) in binary systems at optimum dye concentration (25 mg/L) have been calculated as 0.612, 0.548, and 0.517 g/mg min, respectively. Results showed CNT was an effective adsorbent to remove cationic dyes from single and binary systems.