(in mg/g) was calculated using the following relationships:
percentage removal = 100
Ci − Cf
Ci
amount adsorbed, Q =
Ci − Cf
m
where Ci and Cf are the initial and final concentrations (in mg/l) of
metal ion, respectively and m is the mass of mangosteen shells (in
mg/l). Blanks containing no metal ions were used for each series
of experiments as controls. The average values of duplicate runs
were obtained and analyzed. Error in data: ±1–3% for percentage
removal and ±0.005–0.01 mg/g for amount adsorbed.
2.4. Fourier transform infrared spectroscopy analysis
For the IR studies, 5% (w/w) of ground and dried of mangosteen
shells before and after dyes extraction were pressed to form KBr
disc. The FTIR spectra were recorded in the range of 4000–450cm−1
spectral range using a Bio-Rad FTS 60 instrument. A total of 128
scans were averaged for each sample with a resolution of 2 cm−1.