Plant extract mediated synthesis of Fe3O4-chitosan composite for the removal of lead ions from aqueous solution

Abstract

Divalent lead ion contamination in drinking water pose adverse health effect, hence its removal using minute amount of chemical (Fe3O4) with the use of natural biopolymer (Chitosan) and green plant extracts Ricinus communis (Castor plant) for the synthesis of nanocomposites was determine in the present study. The phyto-magnetic nanomaterial was synthesized via co-precipitation method and characterized using Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform-Infrared spectrometer (FTIR) and X-ray diffractometer (XRD) techniques. The application of the green synthesized (RC-Fe3O4-Chitosan) nanocomposites was determined in the adsorption of Pb(II) from aqueous solution. The experimental parameters such as contact time, pH range, adsorbent dosage, and effect of temperature were evaluated. The results showed that the maximum adsorption capacity of the divalent lead ions occurred at pH = 7.0, temperature = 323 K, contact time = 60 min and adsorbent dose = 0.3 g/L. The adsorption equilibrium was best fitted to the Freundlich isotherm. The maximum capacity determined from Freundlich isotherm was 50.72 mg/g at 323 K. Adsorption kinetics of Pb(II) was best described with pseudo-second-order kinetic model. Thermodynamics studies reveal that with an increase of solution temperature (303 K, 313 K and 323 K) the adsorption efficiency increases correspondingly to −4.35, −6.12, and −7.91 kJ/mol respectively, suggesting endothermic nature of the adsorption process. The reusability of the green synthesized adsorbent (RC-Fe3O4-chitosan) depicts seven successful sequential cycles. Therefore, the synthesized green magnetite chitosan composites can be used as a reliable and sustainable material for efficient removal of Pb(II)species from aqueous solution.