Modified Clinoptilolite for the Removal of Rhodamine B Dye from Wastewater

Abstract

This study reveals the modification of the surface area of natural zeolite Clinoptilolite (CLN) by implementing the ion exchange method. The ammonium chloride cation exchange method was adopted and was followed by calcination at 450 °C for 5 h. This procedure helps to increase the surface area of CLN and also enhances its adsorption efficiency. The modifications of the CLN were confirmed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis. The efficiency and adsorption capacity of the modified CLN were determined by the adsorption of a Rhodamine B (Rh B) dye from an aqueous medium. The comparative analysis of the adsorption efficiency of raw CLN and the modified CLN revealed an enhanced adsorption of Rh B by the modified CLN at pH = 10. For desorption, different solvents were used. The results showed good desorption in ethanol and methanol, and poor desorption in acidic (HCl) and basic (NaOH) solutions. The kinetic study of the adsorption of Rh B by the modified CLN helped us to conclude that the adsorption follows a pseudo-second-order kinetics. For the surface study and to understand the mechanism of adsorption, several isotherm models were applied to the adsorption data at equilibrium. The data showed consistency with the Freundlich adsorption isotherm confirming that the process took place at its heterogeneous surface. The experimentally calculated adsorption capacity of the modified CLN was 2.81 mg g−1, showing a comparable value to certain other common adsorbents. Therefore, the modified CLN may also be considered a cost-effective and promising adsorbent for the removal of Rh B dye from wastewater.