Dye adsorption characteristic of ultrasound pre-treated pomelo peel

Pomelo peels were pre-treated with ultrasound at 30, 60 and 90% amplitude to enhance its ability to remove methylene blue from aqueous solution. The adsorption capacity of the peels at different solution pH (2-10), dye concentration (50-250 mg/L), adsorbent dose (0.05-0.25 g) and contact time (0.5-5 h) was investigated and the equilibrium isotherms were studied. Ultrasound pre-treated pomelo peel took shorter time to reach higher saturation limit of adsorption capacity than the non-treated pomelo peel. Pomelo peel treated at 30% ultrasound amplitude had highest adsorption capacity, which increased with solution pH, dye concentration and adsorbent dose, respectively reached maximum increment of 5%, 9.9% and 9.3% compared to the non-treated pomelo peel. The adsorption isotherm data fitted best by the Dubinin-Radushkevich model with the highest correlation coefficient in the range of 0.9424-0.9951, compared to Langmuir, Freundlich and Temkin models.