Application of Aptenia cordifolia powder as a biosorbent for methylene blue retention from an aqueous medium: Isotherm, kinetic, and thermodynamic investigations

In this study, Aptenia cordifolia powder was utilized as a biosorbent material to effectively treat a synthetic aqueous solution polluted with methylene blue. The characterization of Aptenia cordifolia was conducted according to several analyses, including Fourier transforms infrared, scanning electron microscopy, the point of zero charge and energy dispersive X-ray. The retention process was investigated considering several factors including biosorbent mass, contact time, initial solution pH, temperature, and the initial concentration of methylene blue. The results obtained indicate that the optimal dose of adsorbent was 2 g.L−1. The equilibrium time was approximately 120 min, and the biosorption capacity of the biosorbent increases with an increase in pH. The pseudo-second-order model describes adequately the retention of methylene blue using Aptenia cordifolia. The Langmuir model proved to be more applicable in the analysis of the isotherm data, indicating a maximum retention amount of 51.82 mg.g−1. Moreover, the removal of methylene blue was thermodynamically endothermic, spontaneous, and favorable. These findings demonstrate the potential of Aptenia cordifolia biomass as an effective biosorbent for the treatment of dyes contaminated effluents.