几种天然多孔矿物对钾肥的吸附及缓释效果

以KCl为钾源、斜发沸石、膨润土和凹凸棒石粘土3种天然多孔矿物为缓释载体,进行矿物对钾肥的吸附性能和缓释效果研究。探讨了吸附时间、K+初始浓度与吸附量的关系,确定出K+吸附量最大时的K+初始浓度。用pH=5的HCl溶液和(Ca2++Mg2+)浓度为1.6、3.2、6.4、12.8、19.2、25.6 mmol/L的混合溶液对各矿物缓释肥进行解吸。结果表明:各矿物对K+的吸附在30 min内达到平衡。斜发沸石、膨润土和凹凸棒石粘土对K+的饱和吸附量分别为44.53 mg/g、21.38 mg/g和13.97 mg/g。斜发沸石和膨润土对K+的吸附曲线符合Langmuir吸附等温式,凹凸棒石粘土对K+的吸附曲线总体符合Freundlich等温式。pH=5的HCl溶液对K+的解吸量最小,随解吸溶液中(Ca2++Mg2+)浓度增加,解吸量增大,解吸速率远小于吸附速率。斜发沸石的固钾能力最强,凹凸棒石粘土次之,膨润土相对最弱。

Adsorption of Potash by Several Natural Porous Minerals and Slow-Releasing Effect of Potash Fertilizer

This paper presented an experimental study related to slow-release potash fertilizer,in which KCl as a potash source,natural porous minerals,i.e.clinoptilotite,bentonite and attapulgite clay,as slow-release carriers,focusing on adsorption and desorption properties of these porous minerals.Relationship between adsorption capacity and adsorption time and initial concentration of K+ in the solution was investigated for clinoptilotite,bentonite,and attapulgite clay,respectively,giving results of their maximum K+ adsorption capacities.Also desorption of K+ from the minerals was studied with the conditionas HCl solution(pH 5) containing different concentrations of Ca2+ and Mg2+.It was found adsorption curve of attapulgite clay fit the Freundlich equation in general,and potash fixation capacity of clinoptilotite ranked first,followed by attapulgite and then bentonite.