Enhanced Pb (II) ions removal by using magnetic NiO/Biochar composite

The core objective of this work is to establish the performance and characterization of carbon nanocomposite which is derived from agricultural invasive waste and its application on the removal of Pb(II) ions. Biochar was prepared from Prosopis juliflora wood by commercial thermal activation process and mesoporous NiO/Biochar (PJONC) composite synthesized by novel precipitation approach. The activated carbon and PJONC composite were characterised by x-ray diffraction (XRD), pHpzc, BET surface area (BET), scanning electron microscopy (SEM), FTIR and VSM studies. The efficiency sorption parameters such as; pH study, equilibration time, the dosage of adsorbents, feed concentration and kinetic behaviours were studied. At the optimized conditions, the four different isotherms such as Langmuir, Freundlich, Temkin and Dubinin–Radushkevich studies were carried out for each of the adsorbents. It revealed that multi-layer Freundlich isotherm is more reasonable and the Pb(II) ions removal capacity (q e ) (mg g −1 ) was 28 mg g −1 for activated carbon, 43.0 mg g −1 for nanocomposite. Thermodynamic parameter values (ΔS, ΔH, ΔG) were calculated and it was indicated that this adsorption process depended on the temperature and it was spontaneous and exothermic nature. The PJONC is a soft magnetic material, so it can be used in the environmental remediation field and also this adsorbent can be efficiently separated from treated water by using magnetic field.