LAUSR

Heavy metals are considered as the hazardous pollutants of water sources around the world. The objective of this study is to investigate the kinetics, thermodynamics, and the isotherms of arsenic heavy metal ion removal process from the aqueous solution using Chlorella vulgaris micro algae. The effects of various parameters such as temperature, initial arsenic concentration, contact time, and the adsorbent dosage were studied on the overall adsorption efficiency. Based on the results of the experiments, the optimum values of temperature, arsenic ion initial concentration, contact time, and adsorbent dosage were 323.15 K, 25 ppm, 210 min, and 6 g/L, respectively. In order to study the adsorption kinetics behavior, pseudo-first order and pseudo-second order kinetic models were used. The results showed that the pseudo-second order model was better to describe arsenic ions adsorption kinetics. The maximum adsorption efficiency was estimated 13 mg/g. The RL, n, and B1 and values of Langmuir, Freundlich, and Temkin models were equal to 0.645, 1.296, and 4.68 respectively, which approve that as a physical process, arsenic ion adsorption was desirable. Based on evaluated thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy, it can be said that the current adsorption process was spontaneous.