Application of response surface methodology on efficiency of fig leaf activated carbon for removal of methylene blue dye

Fig leaves that have fallen off the tree are a common agricultural waste in Iraq. In this study, a very common used dye methylene blue (MB), was tested to be removed using a low-adsorbent "fig leaves activated carbon, FGAC" from its solution. Scanner electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the adsorbent. The effects of quantity of activated carbon, the concentration of methylene blue, the pH of solution, and the length of agitation were investigated using response surface methodology software. The studied variables included the amount of activated carbon (0.02-0.1 g), methylene blue dye concentration levels (20-100 mg/L), sample solution (25-100 mL), pH solution (4-11), carbonization temperature (150 °C-550 °C), and contact time (20-60 min). The Analysis of Variance was investigated to test the model's efficacy. The greatest MB removal efficiency was achieved by combining the effects of activated carbon quantity and solution pH, activated carbon amount, agitation time, pH solution, and agitation duration. Several contemporaneous interactions produced less striking outcomes. To achieve 99.5% high removal efficiency for MB under ideal conditions, the ideal activated carbon amount, methylene blue concentration, contact time, pH solution, sample volume, and carbonization temperature were 0.1 g, 75 mg/L, 60 min, pH 7, 25 mL, and 350 °C, respectively. The equilibrium adsorption isotherms were also examined. The Langmuir and Freundlich adsorption models were used to examine the experimental data. The greatest quantity of MB that could adsorb on the FGAC surface was 65 mg/g, as predicted by the Langmuir model.