Microwave-assisted Chitosan Based Activated Bentonite (CAB) for Cr (VI) Removal from Acid Mine Drainage

Background: Acid Mine Drainage (AMD) causes widespread environmental problems including the contamination of land and water bodies. The low-cost adsorbent synthesis from regional resources can be used for removal of toxic metals such as Cr (VI) from AMD. Objectives: Rapid synthesis of Chitosan based Activated Bentonite (CAB) nanocomposite adsorbent using microwave-assisted method for the removal of Cr (VI) from the acidic environment. Methods: The compositional and surface morphological characterization was conducted using FTIR, XRD, and FEG-SEM-EDS analysis. The Synthesized adsorbents were used to removal of Cr (VI) ion under different experimental conditions including initial concentration (45 to 120 mg L-1), contact time (0 to 180 min), dose (0.25 to 4 g L-1), solution pH (2 to 6). Findings: The optimum removal was 73.14 % at room temperature (27 ℃), pH 2, concentration 90 mg L-1 and 2.0 g L-1­ dose of CAB adsorbent. The field evaluation parameters such as ionic strength under various acids and regeneration ability show the potential applicability of the adsorbent in remediation of AMD. The kinetics models and adsorption isotherm were fitted with pseudo first order model (R2 > 0.86) confirmed 49.62 mg g-1 maximum adsorption capacity by Langmuir isotherm (R2 > 0.93). Novelty : Novel microwave assisted rapid synthesis of CAB nanocomposites adsorbent has the possibility to use for large scale synthesis and elimination of Cr (VI) from the AMD. Keywords: Chitosan, Activated bentonite, Cr (VI) removal, Adsorption isotherm, Kinetics rate models