4种农业废弃物对废水中Cd2+和Pb2+的吸附特征

    Adsorption Characteristics of Cd2+ and Pb2+ in Wastewater by 4 Agricultural Wastes

    • 摘要: 为探讨不同农业废弃物对废水中Cd2+和Pb2+吸附特征,研究了花生秆(HG)、葵花盘(KP)、棉花壳(MK)和棉花秆(MG)粉末在不同投加量、溶液pH、吸附时间、溶液初始浓度和离子强度条件下对废水中Cd2+和Pb2+的吸附特征。结果表明,随着废弃物投加量增加,单位质量花生秆、葵花盘和棉花壳对Cd2+和Pb2+的吸附量呈幂函数或对数下降(P < 0.05);随着溶液pH升高,4种废弃物对Cd2+和Pb2+的吸附量均呈先增加后基本保持不变的趋势。4种材料对Cd2+和Pb2+的动力学吸附过程可用准二级动力学模型进行描述。在等温吸附模型中,Freundlich模型更适用于棉花秆对Cd2+和Pb2+的吸附过程,而Langmuir模型更适用于其他3种材料的吸附过程。4种材料对Cd2+的最大吸附量为59.18~93.13 mg·g-1,对Pb2+的最大吸附量为106.43~167.73 mg·g-1。共存离子Na+的存在可显著降低4种材料对Cd2+的吸附量和棉花秆对Pb2+的吸附量(P < 0.05)。

       

      Abstract: In order to discuss the adsorption characteristics of different agricultural wastes on Cd2+ and Pb2+ in wastewater, the powder of peanut straw (HG), sunflower faceplate (KP), cotton husk (MK) and cotton straw (MG) were selected for the study. The studied adsorption characteristics include dosage, solution pH, adsorption time, initial solution concentration and ionic strength. The results show that the adsorption capacities of Cd2+ and Pb2+ by the peanut straw, sunflower faceplate and cotton husk decreased exponentially or logarithmically when the dosage increased from 0.025 g to 0.200 g (P < 0.05). With the increasing pH, the adsorption capacities of Cd2+ and Pb2+increased initially and then remain unchanged. Those of peanut straw and cotton husk are significantly higher than the other two materials (P < 0.05). The sorption kinetics of Cd2+ and Pb2+ on the four materials follows the pseudo-second order model. Isothermal adsorption of Cd2+ and Pb2+ by HG, KP, and MK fitted well with Langmuir equation, while Freundlich equation is more suitable for the MG. The maximum adsorption capacity of the four materials on Cd2+ and Pb2+ was 59.18-93.13 mg·g-1 and 106.43-167.73 mg·g-1, respecrtively. The existence of Na+ can significantly reduce the adsorption capacities on Cd2+ by the four materials and on Pb2+ by cotton straw (P < 0.05).

       

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