Removal of Copper (II) Ions from the Effluent by Carbon Nanotubes Modified with Tetrahydrofuran

In this study, a carbon nanotube modified with tetrahydrofuran was first synthesized. After preparing the adsorbent, discontinuous adsorption experiments of copper metal were performed on the adsorbent. Atomic absorption spectrometry was used to measure the concentration of copper metal. In this paper also, the effect of contact time, adsorbent amount, pH, initial metal concentration and temperature were investigated. The experiments were performed at concentrations of 2 ppm to 35 ppm and at temperatures of 303 to 343 Kelvin. The results showed that the highest removal efficiency was obtained at pH about 5. Equilibrium contact time for 6 ppm concentration was obtained in 30 minutes and the optimal adsorbent is 0.2 g. After optimizing these variables, the maximum absorption value was 96.33%. Kinetic studies of copper removal by synthesized adsorbent were performed. The results obtained for discontinuous experiments follow the quasi-quadratic kinetic model with (R2 = 0.9931). Also, equilibrium studies of adsorption show that the adsorption process is better consistent with the Tamkin isotherm (R2 = 0.9683). In thermodynamic analysis, it is observed that the adsorption process is an endothermic process due to the positive enthalpy changes 3287.32 ( j/molok)and the positive sign of Gibbs free energy at temperature 303 oK with value (1715.53 j) shows, the process is non-spontaneous. It is also a sign of positive and equal entropy changes (5.187 J * -K), which indicates an increase in entropy during the adsorption process in the system. Therefore, the absorption process is associated with an increase in irregularities.