褐煤腐植酸对钾的吸附特性研究

Characteristics of adsorption of K^+ on humic acid extracted from brown coal

为给褐煤的有效利用和腐植酸缓效肥的研制提供理论依据,本试验采用吸附等温线的试验方法,探讨了K+平衡溶液浓度、平衡时间、pH值及固液比对褐煤腐植酸钾吸附的影响。结果表明:介质pH值升高有利于腐植酸样品对钾的吸附,且能加快吸附反应的速度;当pH<4.4时,Kd 1>Kd 2,此时以物理吸附为主。当7.12<pH<12.95时,Kd 1<Kd 2,化学交换占主导地位。其等温吸附曲线符合L angm u ir吸附形式,动力学吸附用E lov ich方程描速最佳。经硝酸处理后的褐煤腐植酸样品对钾的吸附能力有了一定程度的提高。适宜的固液比能提高2种样品对钾的单位吸附量,分别在固液比为0.06和0.04时达最大,其单位吸附量分别为0.079 g/g和0.094 g/g。

The purpose of this research is to offer basic data for the utilization of brown coal and the production of humic acid slow-release fertilizers. The effects of K^＋ concentration, equilibrium time, ratio of solid to liquid and pH value on adsorption characteristics of the K^＋ humic acid extracted from brown coal and its absorptive regularity were studied by isothermal adsorption methods. Results show that pH value increase of medium was of great advantage of K^＋ adsorption and could improve the velocity of adsorption reaction. Under the condition of pH〈 4.4, physical adsorption was dominant. However, under the cohdition of 7.12〈pH〈12.95, chemical exchange was dominant. The distribution coefficient and adsorption capacity of the experimental humic acid treated by nitric was significantly higher than that of the brown coal without being treated. The adsorption of K^＋ on humic acid could be well described by Langmuir equation and its kinetics adsorption fitted Elovich equations best. The adsorption capacity of the experimental humic acid treated by nitric was higher than that of the brown coal without treated. Suitable ratio of solid to liquid could increase the unit adsorption, when the ratios were 0.06 and 0.04, the unit adsorptions can reach maximum being 0. 079 g/g and 0. 094 g/g, respectively.