acid red 73 dye is a colorant dyes is using in many dyeing processes and may causes many
harmful effects to aquatic life with lasting effects. So, it must be removed from aquatic
environment, one of the most useful methods is the using of plants biomass in its removal.
Therefore, both of raw andacid activated (with HCl) Calotropis procera fruits (CPF) was used
for the adsorption of Acid red 73 (AR73) dye from an aqueous solution.Various parameters
(including dye concentration,contact time, dose, temperature, and pH) were optimized to obtain
the maximum adsorption capacity.Surface morphology and surface functional groups of both
raw and modified CPF samples were investigated by scanning electron microscope (SEM) and
fourier transformation infrared (FTIR). Among the adsorbents, HCl-CPF had more adsorption
capacity (65%) than CPF (22.4%) at an initial concentration of 20 mg/L and at 30°C.The
thermodynamic parameters, such as the changes in enthalpy (ΔH°), entropy (ΔS°), and Gibbs
free energy (ΔG°), showed that the adsorption is exothermic, random and nonspontaneous at
high temperatures.