虾壳生物质炭对水体中Cr6+的吸附

    Adsorption Characteristic and Mechanism of Cr6+ by Shrimp Shell-Derived Biochar

    • 摘要: 以废弃虾壳为原料制备生物质炭,并用于吸附模拟废水中的Cr6+,考察溶液pH值、Cr6+初始浓度、生物质炭用量和温度对虾壳生物质炭吸附Cr6+的影响,并对Cr6+在虾壳生物质炭表面的吸附机理进行了探究。结果表明,溶液pH值、Cr6+初始浓度和生物质炭用量对虾壳生物质炭吸附Cr6+的平衡吸附量有明显影响。当溶液pH=3.0,生物质炭用量为0.2 g·L-1,初始ρ(Cr6+)为15 mg·L-1时,虾壳生物质炭对Cr6+的平衡吸附量可达73.83 mg·g-1。虾壳生物质炭对Cr6+的吸附过程符合准二级动力学模型,同时也符合Langmuir和Freundlich等温吸附模型,通过Langmuir等温吸附模型计算得出25℃时Cr6+的最大吸附量为111.0 mg·g-1。Cr6+通过静电引力和配位作用吸附于生物质炭表面,且部分被还原为Cr3+

       

      Abstract: The adsorption properties of Cr6+ from simulated chrome solution by biochar, which was prepared with shrimp shell, was investigated. The effect of pH, Cr6+ concentration, biochar dosage and temperature on the adsorption capacity was systematically examined. Furthermore, the biochar and the concentration of the dissolved chromium in the solution were analyzed to elucidate the adsorption mechanism involved in the process. The experimental results indicated that the equilibrium adsorption capacity of the shrimp shell-derived biochar to Cr6+ was dramatically affected by pH and the dosage of biochar, as well as the initial concentration of Cr6+.The equilibrated adsorption capacity of Cr6+ could reach 73.83 mg·g-1 under the conditions of the biochar dosage of 0.2 g·L-1, Cr6+ concentration of 15 mg·L-1 and pH 3.0. The shrimp shell-derived biochar adsorption process on Cr6+ could be described by the pseudo-second order kinetics model. While the equilibrium data fitted well with the Langmuir isotherm and Freundlich isotherm.The Langmuir maximum adsorption amounts were detected to be 111.0 mg·g-1. Cr6+ adsorbed on the biochar via the electrostatic power and coordination was partially reduced to Cr3+.

       

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