significantly affected by the pH, the initial dye concentration,
and the material to liquor ratio (MLR). It was found that dye
uptake increased with decreasing pH. Also, the dye uptake increased
at higher initial concentrations of the lac dye and was
influenced by the material to liquor ratio (MLR). Batch isotherm
studies showed that the adsorption of lac dye on cotton
was described by the Langmuir and Freundlich isotherms. The
enthalpy (DHo) for the adsorption of lac dye on cotton at pH
3.0 was found to be 4.88 kJ indicating that the process is
an exothermic one. The small negative value of DHo suggested
the adsorption to be a physical one.