Abstract: “Rhamnolipid biosurfactant is not only environmentally friendly but also effective in adsorbing on metal oxide surface. However, the hydrophilic property of rhamnolipid tends to decrease its solid-liquid adsorption capacity. Rhamnolipid surfactant can be modified to enhance its hydrophobicity by adding some linker molecules to the solution. Therefore, effects of linker molecules to the adsorption capacity of rhamnolipid biosurfactant on aluminum oxide surface were evaluated. Results showed that the longer carbon chain in linker molecules (1-butanol, 1-octanol and 1-dodecanol) and the higher rhamnolipid adsorption capacity were observed. Surfactant mixed with 1-butanol (4-Carbon atom) showed the lowest rhamnolipid adsorption capacity of 0.10 mmol per gram while the 8-Carbon atom of octanol yielded the highest amount of 0.30 mmol per gram. This result can be attributed to the coiling effect of the linker molecules (1-dodecanol), which hinders the interaction between the head group and the”

Keywords: Adsorption, Rhamnolipid, Linker molecule