The efficiency of zeolite Y and surfactant-modified zeolite Y for removal of 2,4-dichlorophenoxyacetic acid and 1,1′-dimethyl-4,4′-bipyridinium ion

Abstract

The capacity of zeolite Y with a large Si/Al mole ratio and modified-zeolite Y, for removal of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat ion; PQ2+) from aqueous solution was investigated. The surfaces of HY/NaY zeolites were modified using hexadecyltrimethylammonium (HDTMA) chloride and sodium dodecyl sulfated (SDS), and their physical characteristics were determined by X-ray diffractometry (XRD), FTIR, CHN/S analyzer, WD-XRF, TG-DTG, N2-adsorption-desorption isotherm, and NH3-TPD to confirm successful modification. Arrangement of surfactant in the admicelles was key for enhancing adsorption capacity of the zeolite. In the adsorption study, the concentration of surfactant and the pH were monitored and optimized. It was found that the adsorption capacity of PQ2+ increased with increasing SDS concentration. Conversely, high HDTMA density resulted in decreased adsorption capacity. For 2,4-D adsorption, adsorbents are more effective at greater HDTMA and SDS concentrations. The greatest adsorption values for 2,4-D and PQ2+ occurred at pH 3 and pH 11, respectively. Additionally, the water content of SDS-modified zeolite played an important role in the removal of pesticide. The equilibrium adsorption data can be fitted well using the Langmuir isotherm model and the adsorption kinetics follows a pseudo-second order model.