NH_4Cl-NH_3·H_2O-H_2O系仲钨酸铵溶解度研究

采用测试和回归方程求极限的方法 ,研究了NH4Cl掺入下 ,5(NH4)2O·12WO3·5H2O的平衡溶解度。结果表明 ,当NH4Cl浓度为1mol/L、2mol/L、3mol/L时APT的溶解度分别为NH3·H2O -H2O系的1/2、1/3、1/4。NH4Cl浓度<1.5mol范围内 ,其对APT溶解度的影响较为明显。NH4Cl浓度>1.5mol/L后影响减弱。NH4Cl掺入下APT溶解度受温度的影响变小     

NH_3·H_2O—H_2O系仲钨酸铵溶解度研究

采用测试和回归方程求极限的方法 ,得出温度87～95℃ ,终点NH32mol/L的条件下 ,5(NH4)2O·12WO3·5H2O的平衡溶解度。5(NH4)2O·12WO3·5H2O的溶解度与温度(t)的线性关系为 :y= -588.08+7.28t,其与终点NH3 浓度(mol/L)的线性关系为 :y=36.76+18.86x。中国离子交换法所产5(NH4)2O·12WO3·5H2O溶解度较低 ,其可能原因是晶体中的Si含量较低 ,而NH4Cl含量较高 ,以及由于结晶过程NH4Cl的大量存在 ,水的活度较低 ,致使结晶产物中存在少量溶解度较低的5(NH4)2O·12WO3·7H2O     

SO2-3、NH3?H2O、Cu2＋对高硫金精矿石硫合剂浸出的影响

采用石硫合剂提金法对高硫金精矿进行浸出试验,考察了SO 2-3、NH3? H2 O、Cu 2＋浓度对浸出过程的影响。其结果表明：在磨矿细度-400目80％,液固比6∶1,SO 2-3浓度0．1 mol/L, NH3? H2 O浓度1．6 mol/L,Cu 2＋浓度0．04 mol/L,Na2 CO3浓度0．1 mol/L,搅拌速度500 r/min,浸出温度40℃,浸出时间8 h的条件下,金的浸出率达到88％左右;浸出过程中加入SO 2-3,保证S 2-x和S2 O 2-3的稳定性,并减少因S单质、CuS和Cu2 S的沉积而阻碍浸金传质过程的影响;NH3? H2 O不仅调节浸出pH值,而且与Cu 2＋形成[Cu（NH3）4]2＋,促进金的浸出。     

NH3·H2O—H2O系仲钨酸铵溶解度研究

采用测试和回归方程求极限的方法，得出温度87～95℃，终点NH32mol/L的条件下，5(NH4)2O     

SO3^2-、NH3·H2O、Cu2＋对高硫金精矿石硫合剂浸出的影响

采用石硫合剂提金法对高硫金精矿进行浸出试验,考察了SO3^2-、NH3·H2O、Cu2＋浓度对浸出过程的影响。其结果表明：在磨矿细度-400目80％,液固比6：1,SO;一浓度0．1mol／L．NH3·H20浓度1．6mol／L,Cu^2＋浓度0．04mol／L,Na2C03浓度0．1mol／L,搅拌速度500r／min,浸出温度40℃,浸出时间8h的条件下,金的浸出率达到88％左右;浸出过程中加入SO3^2-,保证Sx^2-和S2O3^2-的稳定性,并减少因S单质、CuS和Cu2S的沉积而阻碍浸金传质过程的影响;NH3·H2O不仅调节浸出pH值,而且与Cu^2＋形成[Cu（NH3）4]^2＋,促进金的浸出。     

NH3-NH4HCO3-H2O体系浸出钢铁厂含锌烟灰

研究了在NH3-NH4CO3-H2O体系下,以钢铁厂含锌烟灰为原料,影响锌浸出的因素.实验表明:影响锌浸出率的主要因素为氨浓度和浸出时间;较优的工艺条件是总氨浓度9.0 mol/L、浸出温度40℃、浸出液初始pH值11.0～11.5、搅拌速度400r/min、液固比4:1、浸出时间1 h.     

NH_3-NH_4Cl-H_2O体系氧化锌矿柱浸试验研究

采用NH3-NH4Cl-H2O体系柱浸方法浸出氧化锌矿。结果表明,在矿石粒度为0.1～10mm、双柱串联操作、第一柱中填料2 629g、第二柱填料1 314g、总氨浓度7.5mol/L、NH4Cl/NH3=2∶1、浸出液循环喷淋30d条件下,锌浸出率达到92.19%,浸出液中锌离子浓度达到54.38g/L。与瓶浸结果相比,柱浸工艺锌浸出率提高约4个百分点,浸出液中Zn2+浓度提高约11g/L。     

LaCl3·7H2O晶体的热分解

采用 TG- DTG方法 ,得到 L a Cl3 · n H2 O晶体在空气中热分解过程及相应分解反应的活化能 ,即在84～ 112℃时 ,L a Cl3 · 7H2 O失去 4个结晶水 ,分解反应的活化能为 133.2 k J/ mol,在 12 3.2～ 137.9℃时 ,L a Cl3 ·3H2 O失去 2个结晶水 ,分解反应的活化能为 15 3.9k J/ mol,在 16 2 .5～ 177.4℃时 ,L a Cl3 · H2 O失去 1个结晶水 ,分解反应的活化能为 45 4.6 k J/ m ol,在 397.7～ 46 4.5℃时 ,L a Cl3 气相水解为 L a OCl,活化能为 6 6 k J/ m ol。在温度低于90 0℃ (最高测试温度 )时 ,L a OCl能稳定存在。     

示波极谱法测定氨浸法炼锌的Zn- NH3- NH4Cl-H2O体系浸出液和净化液中铅

建立了氨浸法炼锌的Zn NH3 NH4Cl H2O浸取体系溶液中铅的测定方法。研究发现示波极谱法测铅时在底液中加入氯化铵能增加方法灵敏度,检测下限可由微量级降低至痕量级。经优化实验,确定了底液的最佳组分为0.6 mol/L盐酸,2 mol/L氯化铵,8×10-5 g/L明胶,7.9×10-7 mol/L抗坏血酸。方法检出限为1.0×10-5 g/L,线性范围为3.48×10-5～0.64 g/L。对样品平行测定6次,RSD为3.3%,测定结果与ICP AES的结果相吻合。该方法可应用于氨浸法炼锌的Zn-NH3-NH4Cl-H2O体系浸出液和净化液中低含量、微量、痕量不同含量范围铅的测定。     

用NH3-(NH4)2CO3-H2O体系从高炉瓦斯灰中浸出锌试验研究

研究了以NH_3-(NH_4)_2CO_3-H_2O体系从高炉瓦斯灰中浸出锌,考察了温度、总氨浓度、液固体积质量比、[NH_3]/[NH~+_4]、搅拌速度和浸出时间对锌浸出率的影响。结果表明:在25℃、总氨浓度5 mol/L、液固体积质量比4 mL/g、[NH_3]/[NH~+_4]=1/1、搅拌速度300 r/min、浸出时间30 min条件下,锌浸出率达76.71%,浸出效果较好。     

Promotion effect of H2 pretreatment on CeO2 catalyst for NH3-SCR reaction

In this study, the promotion effect of H₂ pretreatment on the SCR performance of CeO₂ catalyst was investigated based on the characterization results of XRD, H₂-TPR, Raman and in situ DRIFT techniques. Lower crystallinity, higher reducibility and surface acidity can be found on CeO₂-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO₂ catalyst with H₂ can facilitate the adsorption of NH₃ and NO_x species, while the adsorbed NO_x is basically inactive in the NH₃-SCR reaction. Moreover, the reaction mechanism of the NH₃-SCR reaction over CeO₂ catalyst is not changed by H₂ pretreatment, which is mainly under the control of Eley-Rideal (E-R) mechanism. The enhanced SCR performance of CeO₂-H catalyst is mainly due to the promoted NH₃ adsorption and the subsequent facilitation of SCR reaction through E-R pathway.     

铁粉-H_2O_2对PdCl_3SC(NH_2)_2~-的还原

以含PdCl_3SC(NH_2)_2~-溶液为原料,采用Fe-H_2O_2还原法回收溶液中的钯,研究了还原过程的机理,考察了pH、还原时间、H_2O_2用量和铁粉用量对还原率的影响。结果表明,铁粉被氧化后的Fe~(2+)可催化H_2O_2而产生氧化能力极强的·OH自由基,该自由基对复杂的PdCl_3SC(NH_2)_2~-结构具有很强的破坏力,使稳定的PdCl_3SC(NH_2)_2~-以PdCl _4~(2-)形态分离出来,提高了铁对钯的还原性能。在溶液体积20mL,25℃,pH=2,H_2O_2用量0.10mL/mL,反应时间60min和铁粉用量0.50mg/mL的条件下,钯的平均还原率可达99.25%。     

Synthesis and Structural Determination of Eight Coordinate NH_4[Yb(Ⅲ)(Cydta)(H_2O)_2]·5H_2O

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NH_4Cl-NH_3·H_2O-H_2O系仲钨酸铵结晶成核级数研究

在不同初始浓度下,采用“最大成核速率法”和“成核期积分平均速率法”研究了仲钨酸铵(APT)结晶的成核级数。测出的APT结晶成核级数分别为1.88和2.15。     

Water and solute activities in the aqueous H2SO4 -(NH4)2SO4 solutions

The activities of water in H₂SO₄-(NH₄)₂SO₄-H₂O solutions, the concentrations of which ranged from 0.1 to 4.0 mol kg_-1 H₂SO₄ and 0.1 to 5.0 mol kg_-1 (NH₄)₂SO₄, were determined by an isopiestic method at 298 K. The experimentally determined water activities showed considerable deviation from the Zdanovskii rule. The activities of water were not in agreement with those calculated from the Robinson-Bower equation, even though the formation of sulfato-complexes of NH₄(I) and the dissociation of sulfuric acid were taken into consideration. The behavior of H₂SO₄-(NH4)₂SO₄ solu-tions is quite different from other systems. Water activities of aqueous solutions of H₂SO₄-Li₂SO₄ and H₂SO₄-Na₂SO₄ can be calculated from the Robinson-Bower equation with satisfactory accuracy. The interesting behavior of (NH₄)₂SO₄ can be attributed to the water structure-breaking property of NH₄ ⁺ ions. An additivity equation for estimating the water activity of aqueous H₂SO₄ solutions con-taining (NH₄)₂SO₄ was proposed by considering the contributing effects of solutes on the structure of water. The proposed equation satisfactorily described the solution system under investigation. The mean activity coefficients of H₂SO₄ and (NH₄)₂SO₄ in the solution system, H₂SO₄-(NH₄)₂SO₄-H₂O, at 298 K, were calculated by the McKay-Perring method using the water activities experimentally determined. It is believed that the calculated values for concentrated solutions of more than one sol-ute are sufficiently accurate since the mean activity coefficients of H₂SO₄ agree with the values measured by the emf method.