Adsorption of Zn (II) from Aqueous Solution Using Chitin Extracted from Carapace Crab Shells

Zinc is one of the most important metals often found in effluents discharged from industries. It is important for the phyonsiological functions of living tissues and regulates many biochemical processes. However, excessive zinc can cause eminent health problems. The aim of this study was to investigate zinc removal from aqueous solutions using chitin extracted from carapace crab shells.

To study the removal of zinc, chitin extracted from carapace crab shells was used as biosorbent in a batch system. Also the influence of pH, initial metal concentration, amount of adsorbent and contact time on adsorption process was investigated.

The results of this research showed that the absorption capacity of zinc closely depends on the pH of solution, because zinc absorption concentration (mg/g) increased with the increase of pH. The maximum biosorption capacity of Zn2 onto chitin (181.181 mg/g) was obtained at biomass dosage of 4g/L and contact time of 180 min. The result showed that removal efficiency of zinc was decreased by increase of initial zinc concentration. The results of equilibrium studies revealed that zinc absorption process on the extracted chitin was desirable and followed the Freundlich isotherm model and pseudo second kinetic model. Moreover, fourier transform infrared spectroscopy (FTIR) results demonstrated that functional groups such as amine (-NH2 (and hydroxyl (-OH) had the largest effect on zinc adsorption.

According to the obtained results, the chitin extracted from crab shells appears to be a suitable adsorbent for the removal of zinc from aqueous solutions