N. Ahalya¹, M.N. Chandraprabha¹, R.D. Kanamadi², T.V. Ramachandra^3,*

¹Department of Biotechnology, M.S. Ramaiah Institute of Technology,Bangalore.
²Department of Zoology, Karnatak University, Dharwad, Karnataka.
³ Centre for Ecological Sciences, Indian Institute of Science, Bangalore
^*Corresponding author: T.V. Ramachandra, cestvr@ces.iisc.ernet.in
Web: http://wgbis.ces.iisc.ernet.in/energy

Research Methodology

Biomass and dye solution preparation:

The coffee husk (CH) were collected from dehulling unit and were washed extensively in running tap water to remove dirt and other particulate matter. This was later subjected to colour removal through washing and boiling in distilled water repeatedly. Subsequently the husks were oven dried at 105°C for 24 hours, stored in a desiccator and used for biosorption studies in the original piece size. Fast green has been used as dye in the present study. Stock solutions were prepared by dissolving accurately weighed samples of dye in distilled water to give a concentration of 1000 mg/L and diluting when necessary. Initial pH was adjusted by adding dilute solutions of HCl or NaOH.

Batch adsorption experiments:

Batch adsorption studies were conducted in a routine manner. 250 ml flasks containing 100 ml of the dye solution was contacted with the predetermined amount of the coffee husk at equilibrium time. The flasks were agitated at a 120 rpm constant shaking rate to ensure that equilibrium is achieved. The dye solution was separated from the biosorbent using Whatmann No.1 filter paper. Adsorption uptake values were determined as the difference between the initial dye concentration and the one in the supernatant. All the experiments were carried out in duplicates and the average values were used for further calculations.

Analysis of the dyes:

The concentration of the unadsorbed fast green in the sorption medium was measured colorimetrically using a spectrophotometer. The absorbance of the colour was read at 620 nm.