3种农用腐植酸的钾离子吸附及解吸特性

Adsorption and desorption properties of three types of agricultural humic acids for K^+

研究了在湖南烟草专用肥中普遍使用的A、B、C 3种农用腐植酸对钾的饱和吸附、解吸及pH对其吸附和解吸钾离子的影响。结果表明:C腐植酸属于钾饱和腐植酸钾盐型,较A、B腐植酸具有更强的解吸活性,阳离子交换量达375.74 cmol/kg,解吸反应进行到60 min时趋于最大解吸量(71.00 mg/g);A、B腐植酸对钾离子的吸附趋势基本相似,A腐植酸在反应到60 min时达到吸附饱和,单位吸附量为10.2 mg/g,B腐植酸在反应到20 min时达吸附饱和,单位吸附量为7.72 mg/g;3种腐植酸对介质的pH变化都有较强的缓冲能力,在其有效的缓冲范围内,随着pH值的升高,A、B腐植酸对钾的吸附量有所降低,而C腐植酸对钾离子的解吸量则在pH3~5时增大,其后趋于稳定。

The experiment studied： The saturated adsorption and desorption of the 3 types（A,B,C） of agricultural humic acids for K＋,and the effects of pH on the adsorption and desorption.Results showed that： Compared with A and B,potassium-saturated humic acid C exhibited stronger adsorption and desorption activities of its cation exchange capacity（CEC） 375.74 cmol/kg,the maximum desorption 71.00 mg/g.Besides,in the first 60 min of desorption reaction the capacity of desorption was very close to the maximum;the properties of humic acid A,B were similar in their K＋ adsorption capacity.The adsorption saturation was reached in the first 60 min for humic acid A,and the adsorption quantity per unit was 10.2 mg/g.The adsorption saturation was reached in the first 20 min for humic acid B,and the adsorption quantity per unit was 7.72 mg/g.However,the adsorptive rate of K＋ for humic acid B was faster than A,and B could reach saturated adsorption in a shorter period of time.All of the 3 types of humic acid had a strong buffering capacity to adapt to the changes in the medium pH.With the rise of pH value,the adsorptive quantity for K＋ of humic acid A and B decreased within the effective buffering range,but the desorption of K＋ for humic acid C appeared to reach a plateau after an ascent in pH range of 3-5.