Rhodamine 6g Removal from Aqueous Solution with Coconut Shell-Derived Nanomagnetic Adsorbent Composite (Cs-Nmac): Isotherm and Kinetic Studies

Abstract

Untreated effluents from the textile industry containing colorant dyes are harmful to the environment, aquatic organisms, and human health. Among these effluents, Rhodamine 6G is known as a corrosive and irritant dye. A coconut shell-derived nanomagnetic adsorbent composite (CS-NMAC) was developed to remove Rhodamine 6G from aqueous solution. Physical and adsorption properties of CS-NMAC were characterized via Brunauer–Emmett–Teller (BET) surface area analysis (SBET: 1092.17 m2/g; total pore volume: 0.6715 cm3/g), X-ray diffraction (Fe3O4 [θ=35.522], Fe2O3 [θ=35.720] and FeO [θ=41.724]) and Fourier transform infrared spectroscopy (Fe–O, C–H, asymmetric C=C=C, CN and O–H). CS-NMAC was found to be electropositive within a broad pH range of 3–10) owing to the presence of nanoscale iron oxides on the surface of the coconut shell-derived adsorbent that enhanced the chemical and electrochemical outputs. Isotherm study revealed that the adsorption process of Rhodamine 6G followed a multilayer type of adsorption onto a heterogeneous surface. Freundlich model fitted better (R2 = 0.981) than the other models (Langmuir, Temkin and BET). The maximum adsorption capacity was 32.02 mg/g. Rhodamine 6G removal by CS-NMAC obeyed the pseudo-second-order reaction (R2 = 0.9995) as opposed to other kinetic models. CS-NMAC has the potential to become an effective treatment for dye pollution.