还原条件下水铁矿对钙磷形态的影响

发布时间：2018-04-02 01:08

本文选题：水铁矿　切入点：钙磷　出处：《华中农业大学》2015年硕士论文

【摘要】：铁磷和钙磷是沉积物中两种重要的磷形态,对维持磷在水—沉积物界面的正常循环、调节水体的生产能力具有重要作用。水铁矿是一种无定形氢氧化铁,相比其它结晶态氧化铁,比表面积更大,对磷固持能力更强。本实验模拟沉积物环境条件下,从水铁矿与无机磷、钙反应着手,研究厌氧条件下,水铁矿被还原后,沉积物磷的形态迁移转化过程。主要结果如下:(1)在还原过程中不添加磷酸二氢钾溶液。在化学还原中,水溶性磷增加,饱和吸附钙磷的水铁矿表面直接转化成磷灰石,未饱和吸附钙磷的水铁矿表面生成Fe Fe2(PO4)2(OH)2,Ca3(PO4)2·2H2O,Monetite(三斜磷钙石)等形态的产物。吸附钙磷较多的水铁矿和吸附钙磷较少的水铁矿,在微生物还原中,水溶性钙含量先增加后降低,磷的有效性降低产物以蓝铁矿为主,伴随着弱结晶态的磷酸钙盐生成。(2)在还原过程中逐渐加入磷酸二氢钾溶液。吸附Ca/P为1的水铁矿表面逐渐生成结晶度较低的磷灰石,吸附Ca/P为1.67的水铁矿表面,先生成以透钙磷石为主的产物,后转化为羟基磷灰石。而在纯钙和磷溶液反应的体系中,生成无定形态的磷酸三钙和透钙磷石等混合物,后转化为结晶度较高的羟基磷灰石。(3)KCl浓度越高,钙的解吸量越大,在两种Ca/P吸附值的水铁矿表面磷的解吸量大小与KCl浓度高低无关。饱和吸附钙磷的水铁矿钙解吸,0.1mol/L KCl解吸40h时,钙解吸量达166.3mg/g(水溶性钙mg/总钙g),钙磷解吸量(物质的量)之比约为0.55;解吸后的矿物主要以羟基磷灰石为主。未饱和吸附钙磷的水铁矿钙解吸,0.1mol/L KCl解吸40h时,钙解吸量达892.8mg/g(水溶性钙mg/总钙g),解吸量是饱和吸附钙磷的水铁矿的5.4倍,钙磷解吸量(物质的量)之比约为2.7;解吸后矿物主要衍射峰变低或消失。(4)有钙离子存在,抗坏血酸还原吸附钙磷的水铁矿,生成以磷钙铁羟基水合物、斜钙磷铁矿、三斜磷钙铁矿为主的结晶度较低的矿物,不生成蓝铁矿,再氧化后三斜磷钙铁矿的峰强减弱,抑制了钙铁磷化合物往稳定形态转化。
[Abstract]:Iron phosphorus and calcium phosphorus are two important forms of phosphorus in sediments, which play an important role in maintaining the normal circulation of phosphorus in the interface between water and sediment and regulating the production capacity of water body. Compared with other crystalline ferric oxide, the specific surface area of ferric oxide is larger and the fixation ability of phosphorus is stronger than that of other crystalline ferric oxide. The main results are as follows: no potassium dihydrogen phosphate solution was added to the reduction process. In chemical reduction, water soluble phosphorus increased, and the surface of water ore saturated with calcium and phosphorus was transformed directly into apatite. On the surface of water ore with unsaturated adsorption of calcium and phosphorus, Fe Fe _ 2o _ 4O _ 4H _ (2) O _ (2) O ~ (2 +) Ca _ (3) O _ (4) O _ (2) H _ (2) H _ (2) O _ (3) O _ (2) O _ (2) H _ (3) O _ (2) O _ (2) O _ (2) O _ (2) O _ (2) H _ (2) O _ (2) O _ (2) O _ (2). The degradation of phosphorus availability was dominated by bluestone, accompanied by the weak crystalline calcium phosphate formation. The potassium dihydrogen phosphate solution was added gradually during the reduction process. The surface of water ore with Ca/P = 1 gradually formed apatite with low crystallinity. On the surface of water ore adsorbed with Ca/P of 1.67, the product was formed as the main product of permeable calcium phosphate, and then converted into hydroxyapatite. In the reaction system of pure calcium and phosphorus solution, the amorphous mixture of tricalcium phosphate and permeable calcium phosphate was formed. The higher the KCl concentration of hydroxyapatite with higher crystallinity, the greater the desorption of calcium. The amount of phosphorus desorbed on the surface of two kinds of Ca/P adsorbed water is independent of the concentration of KCl. The desorption of calcium on the surface of water ore saturated with calcium and phosphorus is 0.1 mol / L KCl for 40 h. The amount of calcium desorbed was 166.3 mg / g (total Ca ~ (2 +) 路g ~ (-1) of water-soluble calcium mg/, the ratio of Ca ~ (2 +) ~ (P) desorption (mass) was about 0.55. The desorbed minerals were mainly hydroxyapatite. The desorption of calcium from unsaturated sorbed calcium and phosphorus was 0.1 mol / L KCl for 40 h. Calcium ions were present in the desorption capacity of 892.8 mg / g (water soluble calcium mg/ total calcium gn, the desorption amount was 5.4 times as much as the saturated sorption of calcium and phosphorus, and the ratio of calcium to phosphorus desorption was about 2.7; the main diffraction peak of the minerals after desorption decreased or disappeared. Ascorbic acid reduced the sorption of calcium and phosphorus to ferric hydroxyl hydrate, clinophosphorite, triorthophosphorite, and did not form blue iron ore. After reoxidation, the peak strength of tricophosphate calcium iron ore decreased. The transformation of calcium, iron and phosphorus compounds into stable form was inhibited.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P579;X52

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