摘要
研究了铵浓度、处理时间及介质pH对2种褐煤腐殖酸吸附铵的影响及其规律。结果表明,褐煤腐殖酸对铵的吸附等温式可用Freundlich等温曲线描述,其动力学吸附方程用Elovich方程描述最佳。在pH<7.04时,介质pH的升高有利于铵的吸附。当pH<4.03时,主要以物理吸附为主;当4.03<pH<7.04时,化学交换占主导地位。经硝酸处理褐煤样品的分配系数Kd和吸附量Q明显大于未处理样品的Kd和Q。适宜的固液比例能提高2种样品铵的吸附量,在固液比例分别为0.04和0.03时达最大,单位吸附量分别为34.9和72.2mg/g。
Low N use efficiency and high environmental risk of chemical N fertilizer are worldwide concern, which may be overcome by using new slow-release fertilizers. Purpose of this research was offering basic data for the production of humic acid slow-release fertilizers. The effects of NH4^＋ concentration, equilibrium time and pH value on the NH4^＋ adsorption of humic acid extracted from Shanxi brown coal and its absorptive regularity were studied by ion-exchange equilibrium method in this paper. The characteristics of isothermal adsorption and kinetics adsorption on humic acid was discussed too. Results showed that with the increase of NH4^＋ concentration, adsorption capacity of NH4^＋ increased. The adsorption of NH4^＋ on humic acid could be well described by Freundlich equation and its kinetics adsorption fit Elovich equations best. Under the condition of pH lower than 7.04, pH increase of medium was of great advantage of NH4^＋ adsorption and could improve the velocity of adsorption reaction. Under the condition of pH lower than 4.03, physical adsorption was the dominant. However, under the condition of 4.03 〈 pH 〈 7.04, chemical exchange was dominant. The distribution coefficient and adsorption capacity of the experimental humic acid treated by nitric acid was significant higher than that of the brown coal without treated by nitric acid. The adsorption capacity could be increased by 58.03 % at the optimal condition. On the whole, chemical exchanged played a more important role on NH4^＋ absorpiton. Adsorption capacity rose markedly in the beginning of the adsorption process, however, it slowed down later. While suitable ratio of solid to liquid could increase unit adsorption until the ratio increased to some extent, then the unit adsorption would decrease. As to sample one and sample two, when the ratio was 0.04 and 0.03, the unit adsorption reach maximum being 34.9 ,72.2 mg/g, respectively.
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2005年第4期514-518,共5页
Journal of Plant Nutrition and Fertilizers
基金
山东省2003年科学技术发展计划攻关项目(031030102)
山东省教育厅自然科学基金(J03I02)资助。
关键词
褐煤
腐殖酸
吸附
铵
humic acid
adsorption
NH4^＋
brown coal
