Investigation of Potential of Activated Carbon by Activation of Rubia cordifolia with Phosphoric Acid in Removal of Cr (VI) from Aqueous Solution

The aim of present study is about the elimination of hexavalent Cr ion from solution with the help of activated carbon from chemical activation of Rubia cordifolia with H₃PO_4. It is a medicinal plant commonly known as “Manjistha” a low cost and locally available raw material. Raw material was dried and crushed into powder and it was then treated with H₃PO₄ and undergo pyrolysis in Muffled Furnace at 750 °C for 1 h. Characterization of prepared activated carbon was done by using analytical techniques such as FTIR, XRD, SEM–EDX, BET-analysis, Raman analysis. The present work was performed in Batch experiments and Effect of contact time, pH, adsorbent dose, initial concentration of metal ion and temperature were observed. Then, multiple adsorption isotherm models and kinetic models were used to examine the obtained equilibrium adsorption data. Maximum adsorption capacity of AC was found to be 11.7 mg/g and adsorption of Cr (VI) on AC was highly pH dependent and optimum pH found was 2 for this study. Thermodynamic study shows that the adsorption of Cr (VI) was spontaneous, feasible and endothermic reaction. Pseudo second order and Langmuir isotherm model were the best fit for the present study.