In this study, banana fibers extracted from banana leaves, stem, and stalk were used to remove acid green dye from aqueous solution. Three initial concentrations (750, 1000, and 1500 ppm) were chosen to determine the kinetic characteristics of the banana fiber sorbents at 25 ∘ C, agitation speed of 200 rpm, and total contact time of 3 hours. The pseudo-first-order, pseudo-second-order, and Dunwald-Wagner kinetic models were applied to the experimental kinetic data. For isotherm study, the batch experiments were performed at 25 ∘ C, initial pH 2, agitation speed of 200 rpm, and initial concentrations between 100 and 2000 ppm. The experimental data was fitted to the Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms. The equilibrium was achieved in less than 90 minutes. The removal of the acid green dye was found to be following closely the pseudo-second-order kinetic model. For equilibrium study, the Freundlich isotherm was found to fit well with adsorption of acid green dye on the banana leaves, stem, and stalk sorbents. The calculated mean free energy of 4-11 J/mol indicated that the sorption process was mostly physical in nature. Experimental results also showed the adsorption performance is greatly affected by the initial solution pH.

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The aims of this study were to characterize carrot residues and to determine the removal of Cr(VI) in water depending on the temperature and the dosage of carrot residues. To identify the functional group present in carrot residue, Fourier-Transform Infrared (FTIR) was used to characterize it. The functional group that responsible for the metal binding is hydroxyl (-OH) group. The adsorption of Cr(VI) was conducted by using batch experiment. The effect of temperature and dosage were studied in batch experiment, in which temperatures were varied from 25ºC to 55ºC and the dosages were varied from 0.5 mg/L to 2 mg/L. Preliminary study was done to determine the time equilibrium for adsorption. The equilibrium contact time was 30 min with 12.66% removal efficiency. Meanwhile, the highest dosage for removal efficiency of metal that used was 2 mg/L with 13.09%. The optimum temperature was 25ºC with 12.66% removal efficiency. This study has indicated that the carrot residues is less likely a good adsorbent for removal of Cr(VI).

The growing concerns on the environment in recent years have influenced the usage of renewable sources as alternative materials to create a platform for the development of new technology with possible economic potential. Adsorbents derived from agricultural wastes have hidden economic values which could be benefited by transforming the agricultural wastes into valuable and useful products. Numerous agricultural wastes such as skins/peels, cores, pits, leaves, brunches, and pericarp are being produced in plantation and processing industries. The agricultural