硝酸处理对褐煤中可提取性腐殖酸含量及其吸附特性的影响

采用硝酸氧化及一次平衡法,研究了硝酸处理对褐煤中的可提取性腐殖酸含量、CEC（阳离子交换量）、E₄/E₆及其对各种养分离子吸附规律变化的影响。结果表明:一定强度的HNO₃能使褐煤中可提取性腐殖酸含量增加45.8%以上,使其阳离子交换能力提高;随硝酸处理时间的不断延长,褐煤中可提取性腐殖酸含量和CEC均呈先增加后减小的趋势,但CEC达到最大值所需时间相对较长;硝酸处理后的褐煤腐殖酸光学性质也发生了很大的变化。经硝酸处理褐煤腐殖酸样品对铵、钾吸附能力分别可提高58.73%和41.53%,其等温吸附式分别符合Freundlich和Langmuir方程。而对磷的吸附能力降低,一定条件下其吸附量仅为处理前的5.33%,其等温吸附式用Langmuir方程描述最佳。上述结果表明,经硝酸处理后,褐煤腐殖酸更适宜作为缓效肥料基质使用。

Effects of nitric acid treatment on content and adsorption characteristics of extractable humic acid in brown coal

Effects of nitric acid treatment on content, cation exchange capacity, optic nature and adsorptive characteristics of extractable humic acid in Shanxi brown coal were studied with the ion-exchange equilibrium method. Results show that content of extractable humic acid increased by 45.8% by treatment with nitric acid of certain concentration, thus consequently bringing up its cation exchange capacity, But the two changes were not conincident, with the latter lagging behind the former. Besides, optic characteristics of the humid acid in the acid treated brown coal were greatly changed too. Its adsorption capacity of NH₄⁺, and K⁺ was significantly increased by 58.73% and 41.53%, of which the isothermal adsorption equation fitted the Freundlich equation and Langmuir equation, respectively. However, contrarily, the adsorption capacity of P was significantly lowered. Its variation could well be described by the Langmuir equation. The changes in the physic-chemical properties of extractable humic acid in the brown coal make the coal fitter for application as slow-release fertilizer.