Batch removal of aqueous nitrate ions using an effective nano-biocomposite

The intent of this research is the investigation of the nitrate reduction from aqueous solution using biomass (pine cone (PC) and PC activated carbon (PCAC)) - supported zero valent iron nanoparticles (PC-Fe-0 and PCAC-Fe-0). The synthesis of these nano-bio-composites was based on the reduction of ferrous iron with borohydride, in which PC and PCAC acted as porous-based support materials. The structure of the adsorbents was characterized by SEM, XRD, FTIR and BET analysis. The SEM images revealed that nZVI immobilized on PC-Fe-0 and PCAC-Fe-0 were spherical and uniformly dispersed on the surface of the stabilizers. Batch experiments indicated that the nitrate removal efficiency decreased with the increase in the initial nitrate concentration and initial pH, but increased with the increase in the sorbent dosage and temperature. The maximum adsorption capacities of PC-Fe-0 and PCAC-Fe-0 for nitrate were 18.16 and 22.30 (mg/g), respectively. The nitrogen mass balance calculations revealed that zero valent iron nanoparticles in both PC-Fe-0 and PCAC-Fe-0 beads could generally reduce nitrate into ammonium, and nitrite usually was occurred as intermediate. Subsequently, PCAC-Fe-0 absorbs completely un-wanted ammonium, while PC-Fe-0 releases little ammonium in the solution.