Adsorption of mercury (II) ions on kaolinite from aqueous solutions: Isothermal, kinetic, and thermodynamic studies

Abstract

Due to industrial activity, heavy metal contamination is present in water, air, and soil around the world. Due to this circumstance, serious environmental issues arise. Natural kaolin (NK) clay underwent batch processing to remove Hg2+. Scanner electron microscopy (SEM), energy dispersion spectroscopy (EDS), x‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) were used to analyze the morphological and chemical characteristics of kaolin. Investigations were done into how adsorption is impacted by contact duration, adsorbent dosage, temperature, and solution pH. Kaolin's BET surface area was found to be 8.085 m2/g, while its pore volume was found to be 0.0537 cm3/g. The best working conditions were found to be pH 6.81 and an equilibrium period of 90 min. It was discovered that the Langmuir isotherm model was the most suitable one. At 298, 308, and 318 K, respectively, the adsorption capacities of NK were calculated to be 10.964, 10.515, and 10.101 mg/g. The pseudo‐second‐order kinetic model agreed with this. It was revealed that NK had a maximum desorption efficiency of 91.36%. Through this process, the potential of NK as an eco‐friendly adsorbent for heavy metal removal was shown.