The potential use of banana stem adsorbent has been investigated via batch adsorption experiment. A series of batch experiment was carried out to determine the effect of various adsorbent dosage ( 0.2 – 1.4 g) and various contact time ( 15 – 120 minutes). Analysis on adsorption isotherm was done using Langmuir and Freundlich model. In addition to it, the behaviour and mechanism of adsorption was analysed using kinetic model, namely Pseudo-first order and pseudo second order kinetic. The result shows that more than 90% of colour was removed at optimum dosage of 1 g of banana stem adsorbent in 100 mL synthetic dye at optimum contact time of 90 minutes. Analysis of isotherm models showed that the adsorption of colour by banana stem adsorbent was fitted to Freundlich with coefficient of determination, r1 of 0.917. Adsorption kinetics of colour showed that Pseudo-second order fit better (r2 = 0.99) than Pseudo-first order (r2 = 0.94) kinetic model. From the result, it was indicated that the adsorption of colour occurred by multilayer on a heterogeneous surface of the banana stem through the chemical reaction process. As a conclusion, the use of banana stem adsorbent has good potential for colour removal in textile wastewater treatment because of low cost of the media. Thus, it is an alternative to overcome problems related to an excessive of colour in dye wastewater treatment plant.

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In this research, the decolourisation performance of Reactive Red 120 (RR120) in aqueous solution using O3/S2O8 2was evaluated. RR120 was selected due to high solubility in the aquatic environment. Ozonation (O3) experiments were conducted as a control, to compare the treatment performance after addition of sodium persulphate. The aim of this research is to identify the effect of operational parameters of O3/S2O8 2treatment on colour and COD removal. All experiments were carried out under continuous operation in a bubble column reactor. Operational parameters, namely initial dye concentration, S2O8 2dosage, initial pH, and contact time, were manipulated to optimize the performance of O3/S2O8 2-. The effect of parameters on decolourisation performance was identified based on colour and COD removal. The performance of colour and COD removal in the O3 was also compared with O3/S2O8 2treatment processes. The intermediates were characterized based on its spectra evolution via UV-Vis spectrophotometer. The findings showed on increases in S2O8 2dosage that leads to an increase in the decolourisation efficiency. In addition, when the initial concentration increased to 300 mg/L, the decolourisation efficiency decreases as high concentration of azo bond cause the deficiency of the oxidation process. The O3/S2O8 2performance also improved in alkaline pH, in the presence of hydroxyl radical. By comparing these two treatments, O3/S2O8 2obtained better removal efficiency in colour than O3.