Trapping synthetic dye molecules using modified lemon grass adsorbent

Abstract

Physicochemical method was used to prepare lemongrass leaf activated carbon (LLAC) for removal of Remazol brilliant violet 5 R (RBV5R) dye from aqueous solutions. The surface area, mesopore surface area, total pore volume and average pore diameter of the LLAC are 836.04 m2/g, 598.6 04 m2/g, 0.472 04 cm3/g and 3.62 nm, respectively. The surface functional groups of LLAC before adsorption showed the existence of C–H, O–H, C-O, C = O, C = C, CH3, N–O and C–N; they are significantly altered after adsorption. The equilibrium data were fitted into Freundlich, Langmuir, Dubinin Radushkevich, Temkin, Koble Corrigan, Vieth Sladek, Radke Prausnitz and Brouers Sotolongo isotherm models. The Koble Corrigan and Freundlich models gave the best fit judging from the correlation coefficient (R2). The monolayer adsorption capacities (qm) obtained for Langmuir and Koble Corrigan isotherm models are 125 and 342.9 mg/g respectively. Kinetic data were fitted using pseudo-first order, pseudo-second order, intraparticle diffusion, Elovich, Boyd and Avrami models respectively. Thermodynamic parameters (ΔS0, ΔH0and ΔG0) were estimated. The mean adsorption energy Ea was 2.811 kJ/mol signifying that the adsorption is physically controlled. This study revealed that lemongrass leaf is effective in removing RBV5R dye from aqueous systems.