Poly[β-(1→4)-2-amino-2-deoxy-D-glucopyranose] based zero valent nickel nanocomposite for efficient reduction of nitrate in water

Chemical reduction of nitrate using metal nanoparticles has received increasing interest due to over-dependence on groundwater and consequence health hazard of the nitrate ion.One major drawback of this technique is the agglomeration of nanoparticles leading to the formation of large flocs.A low cost biopolymeric material,poly [β-(1→4)-2-amino-2-deoxy-D-glucopyranose](β-PADG) obtained from deacetylated chitin was used as stabilizer to synthesize zero valent nickel(ZVNi) nanoparticles.The β-PADG-ZVNi nanocomposite was characterized using infra red(IR),UV-Vis spectrophotometric techniques and Scanning Electron Microscope(SEM).The morphology of the composite showed that β-PADG stabilized-ZVNi nanoparticles were present as discrete particles.The mean particle size was estimated to be(7.76 ± 2.98) nm and surface area of 87.10 m 2 /g.The stabilized-ZVNi nanoparticles exhibited markedly greater reactivity for reduction of nitrate in water with 100% conversion within 2 hr contact owing to less agglomeration.Varying the β-PADG-to-ZVNi ratio and the ZVNi-to-nitrate molar ratio generally led to a faster nitrate reduction.About 3.4-fold difference in the specific reaction rate constant suggests that the application of the β-PADG-stabilizer not only increased the specific surface area of the resultant nanoparticles,but also greatly enhanced the surface reactivity of the nanoparticles per unit area.