Development and treatment procedure of arsenic-contaminated water using a new and green chitosan sorbent: kinetic, isotherm, thermodynamic and dynamic studies

摘要

Arsenic is classified as one of the most toxic elements for humans by the World Health Organization (WHO). With the tightening drinking water regulation to 10 μg L?1 by the WHO, it is necessary to find efficient sorbent materials for arsenic. In this work, the removal of arsenic(V) from water is achieved with an insoluble chitosan sorbent in the protonated form obtained by a simple heating process. Kinetic studies show a very fast sorption (less than 10 min). The Langmuir isotherm model is best describing experimental data with a capacity of 42 mg g?1 at pH 8. The sorption process is based on anion exchange (chemisorption) determined from the Dubinin-Radushkevich model. The sorption efficiency of the chitosan sorbent is 97% at low concentrations (e.g. 100 μg L?1). Thermodynamic analysis reveals that the sorption process is exothermic and is controlled by enthalpic factors. Breakthrough curves (BTC) were acquired in real-time by instrumental chromatography and was better described by the Thomas model. BTC from column sorption and desorption with a salt solution suggest that this sorbent is relevant for large scale applications. With this new renewable product, it will be possible to treat arsenic contaminated water at low cost and with little waste (concentration factor of 1500).