凹凸棒石缓释钾肥的制备及缓释效果研究

以凹凸棒石为缓释载体,研究凹凸棒石缓释钾肥的制备条件,并以其吸附时间、K+初始浓度与吸附量的关系,确定K+吸附量最大时的K+初始浓度缓释效果。用pH=5的HCl溶液和(Ca2++Mg2+)浓度为1.6mmol/L,3.2mmol/L,6.4mmol/L,12.8mmol/L,19.2mmol/L,25.6mmol/L的混合溶液对凹凸棒石缓释肥进行解吸。结果表明:凹凸棒石对K+的吸附量在30min内达到平衡,单位质量凹凸棒石对K+的最大吸附量为13.97×10-3;pH=5的HCl溶液对K+的解吸率最小,随解吸溶液中(Ca2++Mg2+)浓度增加,解吸率增大,凹凸棒石对K+的解吸过程符合Elovich方程,解吸速率远小于吸附速率;以pH=5的HCl溶液对凹凸棒石缓释钾肥进行动态解吸和静态解吸实验,动态解吸得出的解吸率较静态解吸的解吸率低,解吸液为450ml时,动态解吸和静态解吸的解吸率分别为35.5%和50.3%,前者能更真实地反应凹凸棒石缓释钾肥的缓释效果;该凹凸棒石是钾肥良好的缓释载体。

STUDY ON PREPARATION AND SLOW-RELEASING EFFECT OF ATTAPULGITE ON SLOW-RELEASE POTASH FERTILIZER

Attapulgite is used as slow-release carrier to study preparation conditions and slow-releasing effect of attapulgite on slow-release potash fertilizer.The relationship between adsorption time,K+ initial concentration and the adsorption quantity were discussesed.Desorb K+ from attapulgite slow release fertilizers is desorbed by HCl solution(pH=5) and(Ca2++Mg2+) with concentration of 1.6 mmol/L,3.2 mmol/L,6.4 mmol/L,12.8 mmol/L,19.2 mmol/L and 25.6 mmol/L respectively.The results showed that the adsorption reached equilibrium after half an hour and the maximum adsorption capacity of attapulgite is 13.97×10-3.When pH=5,the amount of desorption of HCl to K+ reaches its minimum.Desorption rate increases as the concentration of(Ca2++Mg2+) increases.The desorption process of K+ on attapulgite consistent with the elovich equation,and the desorption rate is much smaller than adsorption rate.By using pH 5 HCl solution as desorption solution,the dynamic desorption and static desorption experiments were made.The desorption rate of the dynamic desorption was low than that of static desorption.When desorption solution volume was 450 ml,the dynamic and static desorption rates were 35.5% and 50.3% respectively.The former reflect more realistically the release effect of attapulgite slow-release potash fertilizer.The attapulgite is a good slow-release fertilizer carrier.