Removal of chromium (Cr6+) from aqueous solutions using adsorption onto pistachio shell

Among the environmental pollutants which have involved many parts of the world, one can observe the pollution caused by heavy metals such as hexavalent chromium (Cr6+) , the presence of which in water causes many problems such as dysfunction of the skin, kidneys and liver as well as cancer. Thus, its removal from aqueous environments seems necessary. The present study has been conducted to investigate the efficiency of hard pistachio shell as a natural and inexpensive adsorbent for the removal of Cr6+ from aqueous solutions.

The study was performed experimentally and on a laboratory scale, and it was attempted to investigate the effect of effective parameters such as reaction time, solution pH, adsorbent amount (hard pistachio shell) and Cr6+ concentration on removal efficiency. Kinetic studies and adsorption isotherms were also investigated.

The results showed that the maximum removal of Cr6+ was 98.2% under optimal conditions including reaction time of 60 minutes, pH of 9, adsorbent amount of 2 g/L and Cr6+ concentration of 10 mg/L. Kinetic studies showed greater agreement with second order kinetics (R2= 0.9929). Also, the Cr6+ adsorption process followed Langmuir adsorption isotherm (R2= 0.9965).

According to the obtained results, it can be concluded that hard pistachio shell can be used as a cheap and suitable and also environmentally friendly adsorbent to remove Cr6+ from aquatic solutions.