Résumé
The aim of this work was to study the adsorption of methylene blue (MB) on local agricultural waste in the batch process. The adsorbent, washed rice husk (WRH) was subjected to some physical and chemical analyses such as EDX/SEM, FT-IR, XRD and XRF. The adsorbent showed an amorphous structure and dominated by silica in its composition. The influence of adsorption parameters such as contact time, adsorbent dose and initial concentration was studied. The mass of washed rice husk (WRH) varied at 1 to 6 g, the initial concentrations MB (50-250 mg/L) and the contact time (10-90 min). The MB removal percentage reached 86% with a WRH amount of 4.5 g and an optimal time of 30 min. Langmuir and Freundlich isotherm models were used to process the adsorption data. Q max , the maximum adsorption capacity of MB from Langmuir’ model was 13.23 mg.g -1 . The values of the R L constant varying between 0-1 for the initial concentrations studied proved that the adsorption is favorable. The value of the parameter n being less than 1obeys the condition of heterogeneity. Pseudo-first order and pseudo-second order models were used to study the kinetic adsorption process. The kinetic parameters calculated from each model showed that the adsorption of MB on the WRH could be describe by the pseudo-second order.