电感耦合等离子体发射光谱法测定膨润土中的交换性阳离子钙镁钾钠

对膨润土交换性阳离子和阳离子交换容量的测试是评价膨润土矿的主要指标之一,传统的测定膨润土交换性阳离子通常采用原子吸收光谱法或容量法,操作手续复杂繁琐。本文用氯化铵-乙醇交换液交换出试样中的可交换性阳离子钙、镁、钾、钠,分取蒸至湿盐状,制备成盐酸介质的溶液,电感耦合等离子体发射光谱法测定。通过正交试验确定了最佳实验条件为交换1次,加入25 mL交换液,搅拌30 min,沉淀洗涤2次。分别选择315.887 nm、279.079 nm、766.490 nm、589.592 nm作为钙、镁、钾、钠的分析谱线,绘制的标准曲线中钾、钠的浓度在0～0.6 mmol/L,钙、镁的浓度在0～3.0 mmol/L呈良好的线性关系。方法检出限为0.012～0.048 mmol/100 g。经国家标准物质验证,测定值与标准值吻合,精密度为0.5%～2.5%(RSD,n=11),准确度为-6.1%～10%,加标回收率为97.0%～100.0%。本方法样品处理方法程序简单快速,分析重现性好,克服了传统分析方法测定手续繁琐、时间冗长且成本高等缺点,适用于批量样品的分析。     

电感耦合等离子体发射光谱法测定载金炭中铜铁钙镁

样品经灼烧灰化后,用盐酸、硝酸溶解残渣,在稀王水介质中用电感耦合等离子体发射光谱法测定载金炭中的铜、铁、钙和镁。试验了烘样温度、灼烧坩埚的材质、温度和时间、测定介质及共存元素干扰等因素的影响。结果表明,载金炭的烘样温度宜选择150℃,石英材质的坩埚耐侵蚀性高于瓷坩埚,且空白值低、结果稳定,载金炭中共存元素不干扰铜、铁、钙和镁的测定。该方法用于样品的分析,相对标准偏差(RSD)为0.78%～2.69%,加标回收率为97.1%～104.5%,各元素的测定值与火焰原子吸收光谱法的结果基本一致。方法简便,实用性强。     

N523-TBP-磺化煤油萃取体系从饱和氯化镁卤水中萃取锂的工艺研究

进行了以20%N523-30%TBP-50%磺化煤油萃取体系从青海高镁锂比盐湖卤水中萃取锂的工艺研究。根据相比实验求得萃取平衡等温线,通过阶梯图解法确定萃取理论级数为三级,并完成了三级逆流萃取串级实验。通过对洗涤、反萃、转相工艺进行的研究,确定了全流程八级萃取工艺。经此流程,锂的萃取率达96%,反萃液中杂质含量低,萃取剂经过多次循环无溶损,萃取性能良好,萃取过程分相快,未见三相及乳化现象。     

负温下磷酸镁水泥混凝土的力学性能与抗冻性能

研究了磷酸镁水泥（MPC）混凝土在20℃、-10℃、-15℃、-20℃养护环境下的力学性能和抗冻性能,为MPC混凝土应用于寒区旱区的抢修工程提供科学依据。MPC混凝土力学性能按照国标GB/T 50081-2002进行试验,抗冻性能按照GB/T 50082-2009进行试验。结果表明：20℃养护条件下,MPC混凝土的28 d抗压强度达到65.3 MPa,抗折强度达到6.8 MPa;-10℃养护条件下,28 d抗压强度达到59.7 MPa,抗折强度达到7.2 MPa;300次快速冻融循环后,-10℃养护条件下MPC混凝土质量损失率为3.5%,相对动弹性模量为83.5%,抗冻性能优于20℃养护条件下的MPC混凝土。-10℃养护条件下MPC混凝土力学性能和抗冻性能优异,可用于寒区旱区的抢修工程。     

高纯氧化镁制备原理初探

简要分析了高纯氧化镁合成中的一些工艺原理。     

制备硅钢级氧化镁前驱体的原料水化研究

以青海盐湖水氯镁石为初级原料,采用喷雾热解法制备原料氧化镁,原料氧化镁通过水化制备硅钢级氧化镁前驱体氢氧化镁。原料氧化镁水化实验中对水化剂、水化温度、水化时间、液固比、搅拌速度及陈化时间对水化率、过滤速度和纯度的影响进行系统研究。采用均匀实验设计和DPS数据处理,(依次)通过建模分析、二次多项式模型回归建立数学模型,再通过各因素方差分析和总方差分析,确定了理论最优实验条件,再用理论最优条件作重复实验进行验证,最终确定了原料氧化镁的最佳水化条件。在水化温度60℃,水化时间105 min,液固比4,陈化时间4 h,水化剂1含量4.0%,水化剂2含量3.15%,洗水量4倍,搅拌速度120 r/min时,原料氧化镁的水化率达99.50%以上,得到的硅钢级氧化镁前驱体氢氧化镁纯度高、过滤性能良好。     

一株耐盐性阴沟肠杆菌生长产氢对微量元素的需求

用单因素分析法研究在培养基中缺乏铁、镁、微量元素液、维生素液时对阴沟肠杆菌 XA-2生长的影响。实验发现,铁和镁对该菌的生长影响显著,而缺乏微量元素液、维生素液对该菌的生长影响不明显。缺铁培养时该菌在稳定期的菌浊浓度 OD600nm为1.2586,缺镁培养时菌浊浓度为0.6988,仅为完全培养时菌浊浓度的三分之一,其中,镁对该菌生长的影响更显著。产氢实验表明,各因素对产氢情况的影响显著,依次为：铁>镁>维生素液>微量元素液。当该菌利用缺铁培养基产氢时,其累计产氢量仅为44 mL/L ,铁元素的缺乏严重影响该菌的产氢活动。     

Study of magnesium precipitation based on biocementation

Abstract

Magnesium carbonate has a cementing character like calcium carbonate, and the addition of magnesium ion enables the microbe cementitious material to have the denser microstructure with the lower porosity. The effects of various factors, such as the concentration of Ca²⁺ and Mg²⁺, on the urease activity were studied. Comparison of the productive rates for calcium carbonate and magnesium carbonate were carried out, as well as productive rates for magnesium carbonate with adding different amount of urea to medium. Calcium acetate and magnesium acetate were, respectively, used for sands solidification. Results showed that the increase in urea concentration and magnesium ion enhanced urease activity, while calcium ion significantly impaired urease activity. Sodium chloride and acetate ion had little influence on it. Productive rates for magnesium carbonate were dramatically smaller than its calcium counterpart. However, adding urea to medium allowed for more magnesium precipitation, and the higher the urea concentration, the more the magnesium precipitation. The sand columns with adding urea to medium can have a high strength despite using magnesium acetate. Therefore, the method could solve the problem of insufficient magnesium precipitation. The results will act as a guide for the application of biocementation technology with magnesium carbonate.     

Behaviour of boron,calcium and magnesium in a polluted estuary

Behaviour of industrially added boron in the well mixed Ambika river estuary of South Gujarat, India has been studied along with that of calcium and magnesium. The ratios of Ca : Cl and Mg : Cl at varying chlorinities were always within the normal ranges found in river water at one end and seawater at the other end. B : Cl exceeded the river water end limit at the ebb tide at an upstream station. Percentage addition or removal of boron, calcium and magnesium was calculated using the concept of the theoretical dilution line. The external input raised the boron concentration by 263% in the vicinity of the industrial discharge. A correlation coefficient of ?0·82 between chlorinity and percentage addition or removal of boron supports the theory of boron incorporation in sediments in amounts proportional to salinity. Inverse relationship between percentage addition or removal of boron and suspended solids was observed. Behaviour of calcium and magnesium was in line with the replacement of Ca²⁺ ions occupying the majority of ion-exchange sites in riverine clays by Mg²⁺, Na⁺ and K⁺ during their first encounter with seawater.     

水合碱式硫酸镁晶须材料的水热合成

本文研究了水合碱式硫酸镁MgSO4·5Mg（OH）2·3H2O（以下称MOS）晶须的水热合成。良好的晶须可通过MgSO4·7H2O和Mg（OH）2间的水热反应生成。文中研究了各种合成条件对合成过程和产物品质的影响。当反应体系在温度为130℃～170℃、压力为304.0～810．4kPa的条件下，合成出的晶须具有很高的纯度，产率达90％以上，纤维长可达200μm，纤维直径为0．8～1．2μm。