Umudike Journal of Engineering and Technology

Present study was conducted to investigate the removal of total dissolved solid (TDS) from paint wastewater (PW) by using phosphoric acid modified mucuna shell (MSA). Characterization of MSA is done by us FTIR, SEM and XRD. Batch experiment was carried out to determine effect of parameters such as pH, biosorbent dose, contact time and temperature. Adsorption capacity of the experimental results was fitted into two isotherm model; Langmuir and Freundlich, but the Freundlich isotherm model was found to have higher correlation coefficient, implying MSA had heterogeneous surface. The adsorption kinetic has been described by pseudo-first-order and pseudo-second-order model. It was observed that the rate of TDS adsorption follow pseudo second-order model. Free energy of adsorption (ΔG^o), enthalpy (ΔH^o) and entropy (ΔS^o) changes are calculated to know the nature of adsorption. The calculated value of ΔG^o at 303K-323K indicates that the adsorption process is spontaneous. From the calculation, values of ΔH^o and ΔS^o shows positive sign, which indicates that the adsorption process is endothermic in nature and the positive, ΔS^o suggested increased randomness at the solid/interface.