The Characterizations Of The Modified Biochar And Its Adsorption Capacity For Chromium(Ⅵ)

Biochar is a carbon-rich material produced from the argricultural biomass, which is pyrolysis under the limit or no oxygen condition. It is a potential widused and cost-effective adsorbent for water heavy metal pollutants. The modification method was taken to increase the properties and enhance the adsorption ability of biochar. In this paper, sugarcane bagasse and Zinc nitrate hexahydrate are used to produce a modified biochar nanocomposites to adsorb Cr(VI) ions from the solution.A new synthesis method was developed to produce Zinc-biochar nanocomposites from sugarcane bagasse. The modified biochar maintained 1.2 to 2.0 times higher removal efficiency than that of pristine biochar. FTIR, XPS, BET and SEM were used to analysis the physical and chemical properties of the composite adsorbent.Batch sorption experiments were carried out to investigate the adsorption behavior of Cr(VI) by Zinc-biochar. Experimental data were better fitted by pseudo-second-order kinetics equation and Freundlich isotherms model. Thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic. The maximum adsorption of the modified biochar was observed at pH 2.0 with the sorption capacity of 102.66 mg g–1.In this investigation, the common salt, NaCl, was chosen to study the effect of background ionic strength on Cr(VI) removal. the presence of NaCl scarcely influenced Cr(VI) removal at low concentrations(0.001 and 0.005 mol L–1). However, it obviously reduced the removal capacity of Cr(VI) at higher concentrations(0.1 and 0.5 mol L–1). The adsorbed Zinc-biochar could be effectively regenerated by 0.5 mol L–1 NaOH solutions and the adsorption ability decreased from 84.16 to 59.75 mg g–1 in the sixth cycles.In conclusion, the porous Zinc-biochar nanocomposites, with excellent Cr(VI) adsorption ability and physical and chemical properties,It is a great potential cost-effective adsorbent for water heavy metal pollutant.