The presence of carcinogenic dye like rhodamine B (Rh-B) in textile
wastewater affects the quality of water to consumers. The adsorption of Rh-B on used
black tea leaves (UBTL) was studied in batch process to investigate its removal
efficiency. The effects of contact time, concentration, temperature, pH etc. on adsorption
have been investigated. The UV-visible spectrophotometer was used for analysis of Rh-B
at constant pH. The adsorption isotherms were constructed for different temperatures
using acidic solution of pH 2.0. Freundlich, Langmuir and Dubinin–Raduskevich (D-R)
equations were used to analyze the equilibrium adsorption data. The experimental data
follows Freundlich equation more precisely compare with the Langmuir one. The
maximum amount adsorbed calculated from Langmuir equation is 72.5 mg/g at 30
o
C
which is increased with increasing temperature. Separation factor and thermodynamic
parameters revealed that the process is favorable, spontaneous and endothermic nature.
Possible mechanism of the process was elucidated from the effect of solution pH on
amount adsorbed. The endothermic nature of the adsorption might be due to the
fragmentation of Rh-B molecules during the adsorption process.
