Chitosan/Ag-hydroxyapatite nanocomposite beads as a potential adsorbent for the efficient removal of toxic aquatic pollutants

Abstract In the present study, the potential of synthesized chitosan/Ag-substituted hydroxyapatite nanocomposite beads to remove basic dye, heavy metal and microbes from aqueous solutions was investigated. Beads were prepared in different ratios via embedding of Ag-hydroxyapatite (Ag-HA) into chitosan (CS) solution. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) in order to get an insight of the functional groups and morphology. Batch adsorption studies were conducted with copper ions (Cu (II)) and rhodamine B (RhB) dye by changing several parameters such as Ag-HA to Cs ratio, contact time, solution pH and initial concentration of pollutants. The antibacterial efficiency of beads was tested under dynamic contact conditions against commonly found bacteria in water, Escherichia coli . The adsorption isotherm data were best fitted with Langmuir model. The maximum Langmuir adsorption capabilities for Cu (II) ions and rhodamine B were found to be 40.11 mg/g and 127.61 mg/g, respectively. The adsorption process could be best described by pseudo-second-order kinetic model for both rhodamine B and Cu(II). The percentage removal efficiency of Cu (II) and rhodamine B from tap water and untreated river water ranged from 86.7 to 94.4% along with 99.99% of decontamination of microbial load.