Assessment of the conventional molybdenum-blue and magnesium-induced coprecipitation procedures in phosphorus measurement in various aquatic environments

Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were applied for the measurement of dissolved inorganic phosphorus （DIP） and total dissolved phosphorus （TDP） in more than 840 water samples collected between 2003 and 2005, including seawater （the Huanghai Sea, the East China Sea, and the northern South China Sea）, water from rivers and estuaries （the Changjiang, the Huanghe, and the major rivers emptying into the Jiaozhou Bay）, groundwater （in the drainage basin surrounding the Jiaozhou Bay）, rain-water, and aquaculture water samples. The MAGIC method allows the investigation of phosphorus distributions and cycling for systems in which DIP is below the detection limits of conventional methods. Comparison between the two methods demonstrated that the concentrations obtained with both methods were significantly correlated. The differences of DIP and TDP concentrations measured with the two methods were higher when the concentrations of DIP and TDP were lower, implying the lower reproducibility at low concentrations. The concentration differences increase with the increase in the proportion of DOP in TDP, which indicates that the discrepancy of DIP concentrations measured with the two methods increases when the DOP concentration is high. The discrepancies indicated that the composition of P compounds differs depending on sample sources and water type; it would be useful to infer the presence of different phosphorus compound pools from differences between the two methods. This study indicates the potential presence of a pool of alkaline-labile compounds for samples from rainwater and rivers and estuaries surrounding the Jiaozhou Bay; the potential presence of acid-labile compounds that were adsorbed by Mg（OH）2 for samples from the Changjiang Estuary, Huanghai Sea, East China Sea, and groundwater; the potential presence of a substantial pool of acid-labile compounds that were not adsorbed by Mg（OH）2 for samples from the Huanghe Estuary, aquaculture water, the East China Sea algal bloom water, and the northern South China Sea.

Thermodynamics and kinetics of adsorption of molybdenum blue with D301 ion exchange resin

The adsorption behavior of D301 for molybdenum blue was investigated.The thermodynamics parameters in adsorption process were calculated and the adsorption kinetics was studied.The experimental results show that the adsorption characteristic of D301 for molybdenum blue fits well with the Freundlich adsorption isotherm equation.In the adsorption process of D301 for molybdenum blue,both the enthalpy change ΔH and entropy change ΔS are positive,while the free energy change ΔG is negative when temperatures are in the range of 303-333 K.It is indicated that the adsorption is a spontaneous and endothermic process,and the elevated temperatures benefit to the adsorption.Kinetic studies show that the kinetic data are well described by double driving-force model,and the adsorption rate of molybdenum blue on D301 is controlled by the intraparticle diffusion during the adsorption process.The total kinetic equation is determined.

Recovery of molybdenum，phosphorus and arsenic from leaching solution ofmolybdenum residues by solvent extraction with primary amine and tributylphosphate

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Create Rich Oxygen Defects of Unique Tubular Hierarchical Molybdenum Dioxide to Modulate Electron Transfer Rate for Superior High-Energy Metal-Ion Hybrid Capacitor

Metal-ion capacitors could merit advantages from both batteries and capacitors,but they need to overcome the severe restrictions from their sluggish reaction kinetics of the battery type electrode and low specific capacitance of capacitor type electrode for both high energy and power density.Herein,we use the Kirkendall effect for the first time to synthesize unique tubular hierarchical molybdenum dioxide with encapsulated nitrogen-doped carbon sheets while in situ realizing phosphorus-doping to create rich oxygen vacancies(P-MoO_(2-x)@NP-C)as a sodium-ion electrode.Experimental and theoretical analysis confirm that the P-doping introduced oxygen defects can partially convert the high-bond-energy Mo–O to low-bond-energy Mo–P,resulting in a low oxidation state of molybdenum for enhanced surface reactivity and rapid reaction kinetics.The as-prepared P-MoO_(2-x)@NP-C as an ion-battery electrode is further used to pair active N-doped carbon nanosheet(N-C-A)electrode for Na-ion hybrid capacitor,delivering excellent performance with an energy density of 140.3 Wh kg^(−1),a power density of 188.5 W kg^(−1)and long stable life in non-aqueous solution,which ranks the best among all reported MoO x-based hybrid capacitors.P-MoO_(2-x)@NP-C is also used to fabricate a zinc-ion hybrid capacitor,also accomplishing a remarkable energy density of 43.8 Wh kg^(−1),a power density of 93.9 W kg^(−1),and a long stable life@2A g^(−1)of 32000 cycles in aqueous solutions,solidly verifying its universal significance.This work not only demonstrates an innovative approach to synthesize high-performance metal ion hybrid capacitor materials but also reveals certain scientific insights into electron transfer enhancement mechanisms.

Dimensional regulation in gigantic molybdenum blue wheels featuring{(W)Mo_(5)}motifs for enhanced proton conductivity

Dimensional regulation in polyoxometalates is an effective strategy during the design and synthesis of polyoxometalates-based high proton conductors,but it is not available to date.Herein,the precise regulation of dimensionality has been realized in an unprecedented gigantic molybdenum blue wheel family featuring pentagonal{(W)Mo5}motifs through optimizing the molar ratio of Mo/W,including[Gd_(2)Mo_(124)W_(14)O_(422)(H_(2)O)62]38-(0D-{Mo_(124)W_(14)},1),[Mo_(126)W_(14)O441(H_(2)O)51]^(70-)(1D-{Mo_(126)W_(14)}n,2),and[Mo_(124)W_(14)O_(430)(H_(2)O)50]60-(2D-{Mo_(124)W_(14)}n,3).Such important{(W)Mo5}structural motif brings new reactivity into gigantic Mo blue wheels.There are different numbers and sites of{Mo2}defects in each wheel-shaped monomer in 1-3,which leads to the monomers of 2 and 3 to form 1D and 2D architectures via Mo-O-Mo covalent bonds driven by{Mo2}-mediated H_(2)O ligands substitution process,respectively,thus achieving the controllable dimensional regulation.As expected,the proton conductivity of 3 is 10 times higher than that of 1 and 1.7 times higher than that of 2.The continuous proton hopping sites in 2D network are responsible for the enhanced proton conductivity with lower activation energy.This study highlights that this dimensional regulation approach remains great potential in preparing polyoxometalates-based high proton conductive materials.

硅钼蓝法测定海水中的活性硅酸盐含量测量不确定度评估

依据HY/T 147.1-2013《海洋监测技术规程第1部分:海水》测定海水中的活性硅酸盐。分析不确定度的来源、计算不确定度分量、合成标准不确定度(u)和扩展不确定度(U)。结果表明,海水活性硅酸盐含量测量不确定度主要来源于标准溶液和拟合标准曲线带来的不确定度。通过对不确定度进行评估,有利于提高检测结果的可靠性。

硅钼蓝法测定石灰岩中高含量二氧化硅

石灰岩中高含量(>4%)二氧化硅的一般检测方法是重量法和容量法,二者虽然满足高含量二氧化硅的测定,但其步骤极其繁琐,检测成本、人工成本较高,且检测周期较长,不适用于大批量矿石样品的化验分析。而用于测定低含量(≤4%)二氧化硅的硅钼蓝分光光度法则完全避免了重量法和容量法的缺点,不仅大幅缩短了检测周期,而且其检测灵敏度及准确度也相较于前者更好。因此,本文探究建立了利用硅钼蓝分光光度法检测石灰岩中高含量二氧化硅的方法。实验结果表明,硅钼蓝法不仅可以用于测定石灰岩中含量范围0.05%~60.00%的二氧化硅,而且其相较于重量法和容量法检测周期大幅缩短,节约了试剂和人工成本,且方法灵敏度及准确度也符合分析检测要求。

碱熔-钼蓝光度法测定萤石中二氧化硅含量

目的通过碱熔-钼蓝光度法对萤石中二氧化硅含量展开测定。方法样品经氢氧化钾熔融,以水浸取,用硫酸酸化,然后在弱酸性溶液中,硅酸与钼酸铵生成可溶性的黄色硅钼杂多酸,提高酸度,用还原剂将硅钼黄还原成硅钼蓝,在波长700 nm处测量吸光度,测得二氧化硅含量。大量氟干扰,加入铝盐消除。结果采用碱熔-钼蓝光度法进行萤石中二氧化硅含量测定,二氧化硅具备良好的校准曲线线性,线性回归方程为Y=0.34733ρ+0.00228,相关系数R=0.9999;方法精密度在1.5%以内,用国家标准物质进行准确度测量,相对标准偏差<2%。结论经研究发现,采用本方法对萤石样品中二氧化硅含量测定,精密度和准确度良好,满足相关标准要求。

Differences in Modified Morgan Phosphorus Levels Determined by Colorimetric and Inductively Coupled Plasma Methods

Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P –1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.

Extraction of Tungsten and Molybdenum by Various Organic Compounds as Extractants

Seventy organic compounds including various organophosphorus esters, amines and oxygen-based ligands were investigated as extractants. The experiment results show that amines are excellent extractants for W and Mo. Their sequence of extraction ability for W is as follows: quarternary amine > tertiary amine > secondary amine > primary amine. Acidic organophosphorus extractants do not extract W, but can extract Mo with high extraction ability from the acidic solution. These extractants could provide a potential process for separating W from Mo.

钼蓝分光光度法测定污水中总磷的研究

对钼锑抗分光光度法和氯化亚锡分光光度法测定污水中总磷的结果进行了对比,探讨了氯离子浓度对两种测定方法的影响,验证了新的抗坏血酸溶液配制方法。结果表明,钼锑抗分光光度法和氯化亚锡分光光度法测定污水中总磷没有显著差异(P>0.05),但氯化亚锡分光光度法易受氯离子的干扰,钼锑抗分光光度法能更好地满足检测工作的需要。抗坏血酸溶液中加入适量的EDTA和冰乙酸,放置60 d时吸光值仅下降1.61%,说明使用该方法配制的抗坏血酸溶液至少可稳定保存60 d;使用保存了60 d的抗坏血酸溶液测定污水样品,测定结果的准确度、精密度、重复性等均满足生产需要。

不同因素对柠檬酸浸提-硅钼蓝比色法测试土壤有效硅的影响及优化措施

准确测定土壤中有效硅含量可以了解土壤硅素肥力状况,有助于指导施肥、改善土壤质量。同时土壤中有效硅含量作为第三次全国土壤普查必测的一项参数,有利于全面摸清土壤硅的含量水平。通过改变浸提方式、浸提剂浓度以及显色方式等参数对柠檬酸浸提-硅钼蓝比色法测试土壤有效硅进行考察,对测试过程中的影响因素进行分析,并进行针对性的优化,最后对改进后的测试条件进行方法学研究。结果表明,浸提时间不足、浸提剂浓度偏低以及显色时温度不稳定均会导致所测的有效硅含量偏低。采用连续振荡2 h的方式浸提、增加浸提剂浓度为0.050 mol/L、显色过程全程于35℃水浴中操作等措施可以较好地减少误差,获得更准确的结果。改进后的方法线性良好,相关系数r为0.999 6,检出限为1.0 mg/kg,精密度RSD(n=6)最大为2%,准确度相对误差最大为-4.7%。测定结果可靠,可以为第三次全国土壤普查内业检测提供参考和借鉴。

生物有机肥中解磷菌和固氮菌的筛选与鉴定

从生物有机肥中筛选出高效的解磷菌和自生固氮菌后,通过形态学观察、生理生化特征分析和16S rRNA序列测定等方法进行菌种鉴定,并用磷钼蓝比色法和凯氏定氮法测量解磷量和固氮量,对所筛选的菌种特性进行初步研究。实验表明,筛选出的解磷菌为芽孢杆菌(P1、P3)和根瘤菌(P2),自生固氮菌为根瘤菌(N1)和芽孢杆菌(N2)。其中测得菌株P1的解磷能力为93.53 mg/L、菌株P2的解磷能力为23.25 mg/L、菌株P3的解磷能力为126.46 mg/L,测得菌株N1固氮能力为28.33 mg/L、菌株N2固氮能力为32.39 mg/L。结果表明菌株P3和菌株N2可作为优势菌种进一步优化,为微生物菌肥扩大生产提供更好的实验依据。

葫芦科作物叶片硅含量测定方法的优化

为优化葫芦科作物硅含量的测定方法,给园艺植物硅肥应用与硅营养研究提供技术支持,以‘津优1号’黄瓜、‘蜜本’南瓜和‘早佳8424’西瓜3种葫芦科作物为研究材料,分析硅提取与含量测定过程中不同的研磨温度、研磨时间、浸提时间、硅钼黄显色反应水浴时间、硅钼蓝还原反应时间、显色液吸光度测定波长等对作物叶片硅含量测定结果的影响。结果表明:在植物样品硅提取过程中,研磨仪低温(液氮,-196℃)研磨硅含量测定值高于室温研磨。在样品研磨时间与浸提时间方面,正交试验与全因子试验结果均显示,50 Hz低温研磨30 s、浸提10 min组合测定效果最佳。在硅显色测定方面,硅钼黄显色反应水浴3 min后测定值趋于稳定,硅钼蓝还原反应2 min后测定结果趋于稳定,硅钼蓝显色反应液在波长810 nm附近出现最大吸收峰。针对葫芦科作物叶片硅含量的最优测定流程为植物样品采用研磨仪50 Hz液氮研磨30 s,常温浸提10 min,50℃水浴3 min进行硅钼黄显色反应,硅钼蓝还原反应2 min,810 nm处测定吸光度,该方法回收率为93%~108%。

砷钼蓝分光光度法和氢化物发生—原子荧光光谱法测定煤中砷含量的比较分析

对砷钼蓝分光光度法和氢化物发生—原子荧光光谱法测定煤中砷的含量进行了比较分析,2种方法分别在砷含量0~50μg/g、0~40μg/g范围内符合朗伯—比耳定律,线性相关性良好;分别用2种方法对砷含量在0~40μg/g范围内的10个样品各进行2次重复测定,利用t检验和F检验法分别对2种方法的正确度(偏倚试验)和精密度进行了评估,得出氢化物发生—原子荧光光谱法与砷钼蓝分光光度法相比没有实质性偏倚的存在,2种方法的精密度均在规定范围内。

四氧化三锰中微量磷的快速测定研究

用盐酸和硫酸对样品进行前处理,在硫酸介质中,用抗坏血酸为还原剂,以乙醇为稳定剂,当磷与钼酸铵、硝酸铋出现蓝色络合物的显色反应后能快速测定四氧化三锰产品中磷的含量。研究结果表明,磷量在0~10μg/50 mL范围内线性良好,遵守比耳定律,加标回收率达98.7%~104.9%,相对标准偏差是1.64%~4.04%。此方法操作简单、快速稳定,结果准确可靠,能够满足测定要求。

MoO_(3)催化材料的制备及性能研究

文章通过水热法制备α-MoO_(3)催化材料,利用扫描电镜(SEM)对样品进行表征,观察不同水热温度对α-MoO_(3)的形貌产生的影响,研究不同水热温度制备的α-MoO_(3)对甲基蓝的光催化降解性能。结果表明,不同水热温度下样品形貌不同,光催化降解能力也不同,随着温度的升高,它的结构会变得更加的清晰,光催化能力会变的越来越好。在180℃时,它的结构最为清晰,光催化降解能力最好;180℃以后随着温度的升高,它的光催化能力逐渐降低,通过实验可以得到α-MoO_(3)具有光催化性能,其中在180℃性能最高。

分光光度法测定乳粉中磷的不确定度评定

采用钼蓝分光光度法进行乳粉中磷含量的测定,并对乳粉中磷含量进行不确定度评定。根据GB 5009.87—2016标准分析了乳粉中磷含量的关键测试步骤是样品称量、标准溶液配制、重复性实验、仪器测定,为此进行不确定度评定。结果表明,乳粉中磷含量测定结果为(180.63±1.66)mg/100 g,k=2。影响乳粉中磷含量测定的主要因素是磷质量浓度。

蔗汁中蔗糖含量的分光光度法测定

建立了测定蔗糖的分光光度法 ,在酸性介质中 ,蔗糖还原磷钼黄生成磷钼蓝 ,对该反应进行了详细的研究 ,确定了最佳反应条件 ;结果表明 ,所生成的磷钼蓝最大吸收波长在820nm ,蔗糖溶液在0.57～22.56mg/L服从比尔定律 ,表观摩尔吸光系数为1.17×104 L/(mol·cm) ,定量下限为0.57mg/L;该法灵敏度高、选择性好 ,用于甘蔗汁样品的测定 ,结果令人满意 ;

钼硅酸化学吸收同时去除气流中的SO_2和NO_x

对钼硅酸溶液脱除废气中的ＳＯ２和ＮＯ２及其吸收机理进行了研究．实验结果表明，钼硅酸能十分有效地吸收ＳＯ２并使杂多酸还原为杂多兰；而杂多兰则能还原ＮＯｘ为Ｎ２，从而达到同时去除ＳＯ２和ＮＯｘ的目的．