Behaviour of fixed-bed column for the adsorption of malachite green on surfactant-modified alumina

Prepared surfactant-modified alumina (SMA) was used to remove malachite green (MG) from aqueous media. At a dose of 10 g/L, SMA removed approximately 99% MG (initial concentration 100 mg/L). The adsorption capacity (Qmax) of SMA was 185 mg/g as calculated from Langmuir isotherm. In a fixed-bed column study, using the MG-spiked distilled water, the column design parameters were evaluated by Logit model at a bed depth of 10 cm. The adsorption rate constant (K) and adsorption capacity (No) was obtained as 0.002636 L/(mg h) and 76283.16 mg/L for the minimum bed depth 3.33 cm in the 1st cycle. Acetone was used for desorption of MG from SMA. In batch regeneration study, regenerated SMA could remove only approximately 80% of MG under the same experimental conditions. In column regeneration study, the efficiency of the regenerated bed decreased and the values obtained as, K=0.007931 L/mg h and No=12341.08 mg/L for the minimum bed depth of 6.83 cm. Column study was conducted with the real MG bearing wastewater (MG concentration was 396.54 mg/L) under the same experimental condition. The value of adsorption rate constant (K) and adsorption capacity (No) was obtained as 0.0008786 L/(mg h) and 197939.02 mg/L, respectively for the minimum bed depth 5.92 cm.