Endocrine Disruptors-(estrone and β-estradiol) removal from water by Nutshell activated carbon: Kinetic, Isotherms and Thermodynamic studies

Abstract

A large number of substances in the environment designated as endocrine-disrupting chemicals (EDCs) are amongst the most intoxicating compounds found in environmental waters. The removal of two EDCs: estrone (E1) and β-estradiol (E2) by activated carbon was examined in an agitated non-flow batch adsorption studies. The macadamia nutshell activated carbon (MAC) was characterized by TGA, FTIR, and SEM. Properties such as contact time, adsorbent dosage, pH, initial steroids concentration, and temperature were examined. Mathematical models like pseudo-first-order and pseudo-second-order kinetics, thermodynamic, the Freundlich, and Langmuir isotherms model were used to describe the steroids adsorption phenomenon. From the Langmuir isotherm, maximum adsorption capacity was found to be 22.0 mg/g. Thermodynamic factors: ∆G° values of –1.223 to –1.308 kJ/mol, ∆H° = –11.72 kJ/mol, and ∆S° = 37.34 J/mol k of steroids adsorbed onto MAC indicate that the adsorption was spontaneous, proceeded favourably at lower temperature and exothermic in nature, demonstrating that physisorption mechanism predominates. The distinctive data and adsorption intensity disclosed that MAC could be engaged as a substitute for effective adsorbents for the removal of endocrine disruptors-steroids from water.

Keywords

• Endocrine Disruptors
• Water
• Adsorption, Activated Carbon
• Estrone
• β-Estradiol
• Thermodynamic