Study On Preparation And Adsorbing Performance Of Activated Carbon Based On Sheep Bone

In this paper, the component of sheep bone was confirmed by the component analysis, elemental analysis and thermal analysis. Further, new activated carbon materials were prepared by the activation of sheep bone using zinc chloride (ZnCl₂) and carbon dioxide (CO₂) as activators. Structure and component of the active carbon were characterized by BET analysis, energy spectrum analysis (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques. Moreover, the static and dynamic adsorption properties of the prepared activated carbon to heavy metals were also investigated in detail.Through the orthogonal experiment, single factor experiment and response surface method, the effects of varying bone granularity, dipping time, concentration of the activator, charring time, charring temperature, activation time, activation temperature and CO₂ flow weight on the property (yield, iodine adsorption value, methylene blue adsorption value and specific surface area) of activated carbon prepared by the activation of sheep bone using ZnCl₂ and CO₂ as the activators were studies and optimized. The ZnCl₂ activated carbon was studies by the static adsorption experiments of heavy metal Pb(II) in waste water. Meanwhile, the effects of adsorption time, activated carbon dosage, pH value, temperature and initial concentration on Pb(II) adsorption capacity and removal efficiency were explored. The CO₂ activated carbon was studies by the dynamic adsorption experiments of heavy metals Pb(II), Cr(VI),Cd(II) and Hg(II) in waste water. Also, the effects of solution flow rate, heavy metal ion concentration, pH value, activated carbon dosage on adsorption capacity of heavy metal and removal efficiency were investigated. The adsorption mechanism of heavy metals was analysized. Additionally, maximum adsorption capacity of the activated carbon, the choice of the desorption agent and its concentration, and repeated use number, were studied. The optimum preparation conditions for the activated carbon using ZnCl₂ were concluded from the experiments as follows: The concentration of zinc chloride, charring temperature, charring time and dipping time were 0.05 g/100 L, 350℃, 10 min and 36 h, respectively. Under the above conditions, the iodine absorption amount was 407.35mg/g, the specific surface area of activated carbon was 59m²/g evaluated by BET method; Response surface methodology (RSM) was used to optimize the activated carbon using CO₂ as activating agent. The optimum preparation conditions were as follows: activation temperature 487℃, activation time 9.8 min, flow of CO₂ 100 mL/min. As a result, the iodine absorption amount was 408.56 mg/g, the specific surface area of activated carbon was 55.29 (m²/g) by BET method; The orthogonal experiment was used to optimize the activated carbon using CO₂ as activating agent. The optimum preparation conditions were as follows: charring temperature, charring time, activation temperature, activation time and flow of CO₂ were 400℃, 40 min, 550℃, 10 min, 80 mL/min, respectively. As a result, the iodine absorption amount was 438.15 mg/g, the specific surface area of the activated carbon was 128.80 m2/g evaluated by BET method; The optimum static adsorption for Pb(II) conditions of ZnCl₂ activated carbon were as follows: the initial Pb(II) concentration 80 mg/L, activated carbon dosage 0.10 g, adsorption time 6 h and temperature 45℃. As a result, the best absorption amount was 4.99 mg/g.The dynamic adsorption for Pb (II), Cr (VI), Cd (II), Hg (II) conditions of CO₂ activated carbon prepared by sheep bones: the optimal concentrations40mg/L,8mg/L,1.5mg/Land0.4μg/L. The pH values of adsorption solution: pH=7-8 for Pb(II) and Cd(II), Cr(VI) be acidic and pH=5-6 for Hg(II). The activated carbon dosage:0.7g,0.7g,0.7g,0.1g. As a result, the maximum adsorption capacity for Pb(II) is 10 mg/g. The desorption agent is HNO₃, and its concentration is 0.3 mol/L. The repeated use number is under six times. The two adsorption isotherm curves are similar to that for Type II, suggesting multi-molecular layer adsorption.In summary, a new method for perparing the activated carbon by chemical and physical activation strategies was put forward.In this Process had many advantages,such as reducing environmental pollution, imrpoving additional values, broading raw materials for the activated carbon, supplying new pathway for the utilization of solid wastes. Additionally, when this as-obtained product is used in the disposal of heavy metal-including waste water, it will be of great significance to control environmental pollution, utilize wastes and develop recycling economy for nonferrous industry.