Abstract:

In this study, the adsorption of methyl violet from an aqueous solution using carbonised water lily (CWL) leaves powder as a low-cost, efficient and eco-friendly adsorbent was investigated using a batch system under controlled conditions. The adsorbent's moisture, organic matter, ash, bulk density, pore volume, and pH were determined. The adsorbents were characterised by scanning electron microscopy (SEM) and Fourier Transform Infrared (FT-IR) techniques which confirm the adsorption of the methyl violet onto the CWL adsorbents. The effect of adsorption parameters such as contact time, dosage, initial concentration, pH and temperature were studied for optimisation. It was confirmed that contact time, dosage, concentration, pH and temperature positively affected the adsorption process. The kinetic data were best described by pseudo-second order under all experimental temperatures. The adsorption isotherms were estimated and established to fit nicely into the D-R model compared to other models generated and tested. Thermodynamic studies of the sorption process indicate that the process was feasible, spontaneous, and exothermic and decrease in the randomness of the adsorption process during the transfer of molecules between the adsorbent and adsorbates with entropy (∆S) of 23.77 J/mol.K. due to negative values of Gibb’s free energy observed. This study confirmed that CWL could be employed as a low-cost, eco-friendly adsorbent for removing toxic dyes such as methyl violet from an aqueous solution.

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