Preparation of graphene oxide/4A molecular sieve composite and evaluation of adsorption performance for Rhodamine B

Abstract

Dye pollutants in various water resources have brought about severe damages to individuals’ health. To attenuate the adverse effects on human beings, we design a novel composite based on graphene oxide and molecular sieve 4A (GO/4A) towards efficient removal of Rhodamine B (RB) in aqueous solutions. The adsorption properties were tested via adjusting experimental conditions, and the adsorption capacity of GO/4A-3 for RB reached as high as 62.81 mg·g−1 when pH equaled 3. Compared with acid-modified 4A molecular sieve, the removal performance of RB was improved by 291%, attributed to the electrostatic interaction between GO and RB dye molecules. The successful combination of GO and 4A molecular sieve also effectively improved the poor separation performance of GO itself. Adsorption isotherm and kinetic studies demonstrated that the adsorption of RB on GO/4A-3 composite followed the Langmuir isotherm (R2 = 0.996) and pseudo-second-order kinetic model (R2 = 1). The thermodynamics of adsorption showed that the RB was spontaneously, endothermically, and entropy-increasing adsorbed onto 4A molecular sieve and GO/4A composites. This study provided a facile and efficient way to process the difficult-to-decompose dye wastewater.