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首页> 外文期刊>International journal of soil science >Effect of Si/Al ratio of allophane on competitive adsorption of phosphate and oxalate.
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Effect of Si/Al ratio of allophane on competitive adsorption of phosphate and oxalate.

机译：铝硅铝石的硅铝比对磷酸盐和草酸盐竞争性吸附的影响。

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摘要

Allophane is a soil clay constituent with high adsorption capacity for cationic and anionic solutes and the adsorption characteristics depend on its Si/Al molar ratio. Adsorption experiments of phosphate and oxalate on two natural allophane samples obtained from Japan with low (0.67; KyP) and high (0.99; KnP) Si/Al ratios were conducted at initial adsorbate concentration of up to 0.6 mM and at pH of 5.0 to 7.0. In both single and binary (equimolar phosphate and oxalate) adsorbates systems, KnP had less capacity for adsorption of both phosphate and oxalate than KyP had, because in the structure of KnP, accessory Si is already adsorbed onto aluminol groups to which phosphate and oxalate will be adsorbed. For KyP with lower Si/Al ratio and higher adsorption capacity, the efficiency of phosphate to depress the adsorption of coexisting oxalate, EOX<-P, was always greater than the reverse efficiency, EP<-OX, at a same condition; the ratio of oxalate/phosphate adsorbed in the binary system was less than unity and the ratio decreased with increasing pH and initial adsorbate concentration. These indicated higher selectivity of KyP for phosphate than for oxalate and the selectivity increased with increasing the competition between phosphate and oxalate toward KyP. KnP with higher Si/Al ratio showed higher selectivity for phosphate than KyP did, but the ratio of oxalate/phosphate adsorbed was almost constant when pH and initial adsorbate concentration were raised. This means that even under the lowest pH and the lowest adsorbate concentration examined (pH 5.0, 80 micro M), the competition between phosphate and oxalate toward KnP was already severe and further increase in the phosphate selectivity was not caused.
机译：Allophane是一种土壤粘土成分，对阳离子和阴离子溶质具有高吸附能力，其吸附特性取决于其Si / Al摩尔比。在初始吸附物浓度最高为0.6 mM且pH值为5.0至7.0的条件下，进行了两种从日本获得的低（0.67; KyP）和高（0.99; KnP）Si / Al比的天然脲烷样品中磷酸盐和草酸盐的吸附实验。 。在单一和二元（等摩尔磷酸盐和草酸盐）吸附剂体系中，KnP吸附磷酸盐和草酸盐的能力都比KyP少，因为在KnP的结构中，辅助Si已被吸附到铝酸盐基团上，磷酸盐和草酸盐将吸附到硅铝上被吸附。对于具有较低Si / Al比和较高吸附能力的KyP，磷酸盐抑制共存草酸盐E OX <-P 的吸附效率始终大于逆向效率E P <-OX ，在相同条件下;二元体系中草酸盐/磷酸盐的吸附比小于1，并且随着pH值的增加和初始吸附物浓度的增加而降低。这些表明KyP对磷酸盐的选择性高于草酸盐，并且选择性随着磷酸盐和草酸盐之间对KyP竞争的增加而增加。 Si / Al比值较高的KnP对磷酸盐的选择性高于KyP，但是当提高pH和初始吸附物浓度时，草酸盐/磷酸盐的吸附率几乎恒定。这意味着即使在最低的pH值和最低的被吸附物浓度（pH 5.0，80 micro M）下，磷酸盐和草酸盐之间对KnP的竞争也很激烈，并且不会导致磷酸盐选择性的进一步提高。

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