Removal Direct Red 23 by Modified Sugarcane Bagasse as Adsorbent: Kinetics and Mechanism

The modified sugarcane bagasse was used as an adsorbent to remove direct red 23 from solution in the batch adsorption system. The effect of initial concentration of direct red 23 and the speed of agitation were investigated. The kinetics and mechanism of adsorption of direct red 23 were studied. It was found that the point of zero charge of modified sugarcane bagasse was pH 2.0. The trend of increase in the initial concentration of direct red 23 from 200 - 1,000 mg/L and the speed of agitation from 60 - 120 rpm increase the adsorption capacity from 12.0 - 45.8 and 20.5 - 45.8 mg/g, respectively. The pseudo-first order and pseudo-second order were employed to evaluate the kinetics model. It was found that the adsorption behavior was fit with pseudo-second order model rather than pseudo-first order model. The mechanism of the adsorption occurred in 3 steps. The rate limiting step for mechanism of adsorption was film diffusion.