Stock solutions of Cu(II) and Cr(VI) containing 1.000 g/L and
0.500 g/L respectively were prepared by dissolving proper amounts
of analytical grade copper sulfate or potassium dichromate in dis-
tilled water.
Cotton gauzes coated with chitosan at three different percent-
ages (10, 20 and 30%) were dried in oven at 50 ◦C for 4 h and
conditioned in standard atmosphere at 20 ◦C and 65% R.H. for 24 h.
The adsorption tests were carried out in batch by shaking, in sealed
test tubes, 0.100 g of adsorbent material in 10 mL of the metal
solution (estimated volume ratio: 6 mL of swollen chitosan-coated
gauze to 100 mL of solution) by varying concentration, pH value,
temperature and contact time.
The effects of these variables on the adsorption capacity of
gauze coated and uncoated with chitosan were studied. After the
adsorption, the adsorbent was settled and the metal ion residual
concentration in the supernatant was analyzed by an Inductively
Coupled Plasma – Optical Emission Spectrometer (ICP-OES, Optima
7000 DV PerkinElmer) for Cu(II) and total Cr determination, while
Cr(VI) was determined by 1,5-diphenylcarbazide method using UV-
Visible Spectrometer (Lambda 35 PerkinElmer).
The adsorption tests were repeated three times and the results
reported were averaged.
The adsorption capacity was evaluated using Eq. (2):
qt = (C0 − Ct)V
m (2)
where qt (mg/g) is the adsorption capacity of the adsorbent at a
given time t; C0 and Ct (mg/L) are the initial metal concentration
andattime t, respectively;V(L)is the volume ofthemetal solutions;
and m (g) is the mass of the adsorbent.