Fourier Transform Infrared Spectroscopic Study of Sodium Phosphate Solids and Solutions

Solids and solutions of sodium phosphates with various chain lengths have been studied by using the techniques of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and attenuated total reflection-Fourier transform infrared (ATR-ETIR) spectroscopy, respectively. A systematic study of the infrared spectra of the solid sodium phosphates has been conducted on the basis of the information available it? the literatures to establish the assignments of the infrared vibrations of the different groups in the phosphate molecules. The infrared spectra of the solutions of sodium phosphates have been analyzed according to the infrared study on the relevant solids, in conjunction with the study of the phosphate species distribution in solution on the basis of the acid-base reaction equilibria. The results obtained have revealed the correlations between the infrared absorption spectra and the structure of the different P-O groups in different kinds of phosphates and are useful in the analysis of phosphate solids and solutions widely used in the various operations of mineral processing.

In Situ FTIR Spectroscopic Study of Electrochemical Adsorption of Phosphate Ions on Gold

Infrared reflection-absorption spectra for primary, secondary and tertiary orthophosphate anions on a gold electrode in aqueous solution were studied by in situ FTIR spectroscopy. The spectra show that H2PO4- , HPO ions do not interact with the electrode surface as strong as PO do. According to the surface selection rule, we deduce the modes of adsorption of these anions on the electrode from these spectra. The experiment also confirms the affection to adsorption of ion on the electrode due to ion-migration into thin-layer cavity.

Raman Spectroscopy Analysis of Wollastonite/Tricalcium Phosphate Glass-Ceramics after Implantation in Critical Bone Defect in Rats

In this work wollastonite/tricalcium phosphate (W/TCP) glass-ceramics with three W/TCP weight ratios (20/80;60/40 and 80/20) were implanted in rat calvaria and the modifications taking place during implantation were studied by Raman spectroscopy. The experimental glass-ceramics were composed of different contents of βW, αW, βTCP, αTCP, and glassy phases. Materials were implanted for 7-, 15-, 45- and 120-day periods after which the implanted materials were recovered and analyzed by FT-Raman spectroscopy. The results suggested that the αW phase reabsorbs fast during implantation in the glass-ceramics 60/40 and 80/20, whereas βTCP and αTCP glass-ceramic are gradually attenuated and replaced by biological apatite-like bands. In the glass-ceramic 20/80, the bands related to the βTCP phase remained unvaried in all analyzed periods. New bands associated with the deposition of collagenous material appeared during implantation for all 60/40 and 80/20 glass-ceramics experimental groups, but important differences in intensities between both groups. The spectra corresponding to implants of 60/40 glass-ceramic at the 120-day period were very similar to those of the control group (normal cortical bone), with regards to Raman shifts and intensities, as well as in the FWHM value of the 962 cm-1 apatite band (ν1 PO4 in hydroxyapatite), evidencing that apatite deposited at the implant site has the same crystallinity than biological apatite in normal bone mineral. The glass-ceramic 20/80 behaved just as an osteoconductive filling material, while glass-ceramics 60/40 and 80/20 were able to induce deposition of organic matrix mineralized new tissue. The 60/40 glass-ceramic showed the best performance and the most similar Raman spectrum to normal cortical bone.

Solid-state impedance spectroscopy studies of dielectric properties and relaxation processes in Na_(2)O–V_(2)O_(5)–Nb_(2)O_(5)–P_(2)O_(5) glass

Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary mixed glass former(MGF)system 35Na_(2)O–10V_(2)O_(5)–(55-x)P_(2)O_(5)–xNb_(2)O_(5)(x=0–40,mol%).The dielectric parameters,including the dielectric strength and dielectric loss,are determined from the frequency and temperature-dependent complex permittivity data,revealing a significant dependence on the Nb2O5 content.The transition from a predominantly phosphate glass network(x<10,region I)to a mixed niobate–phosphate glass net-work(10≤x≤20,region II)leads to an increase in the dielectric parameters,which correlates with the observed trend in the direct-cur-rent(DC)conductivity.In the predominantly niobate network(x≥25,region III),the highly polarizable nature of Nb5+ions leads to a fur-ther increase in the dielectric permittivity and dielectric strength.This is particularly evident in Nb-40 glass-ceramic,which contains Na_(13)Nb_(35)O_(94) crystalline phase with a tungsten bronze structure and exhibits the highest dielectric permittivity of 61.81 and the lowest loss factor of 0.032 at 303 K and 10 kHz.The relaxation studies,analyzed through modulus formalism and complex impedance data,show that DC conductivity and relaxation processes are governed by the same mechanism,attributed to ionic conductivity.In contrast to glasses with a single peak in frequency dependence of imaginary part of electrical modulus,M″(ω),Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation times.The high-frequency peak indicates bulk ionic conductivity,while the additional low-fre-quency peak is associated with the grain boundary effect,confirmed by the electrical equivalent circuit(EEC)modelling.The scaling characteristics of permittivity and conductivity spectra,along with the electrical modulus,validate time-temperature superposition and demonstrate a strong correlation with composition and modification of the glass structure upon Nb_(2)O_(5) incorporation.

Investigation of Hexavalent Chromium Reduction in Strong Saline and Acidic Nitro-Phosphate Solutions

Phosphorus fertilizers from less pure sedimentary sources become increasingly important, due to depletion of phosphorus from igneous rock of high quality. Consequently, robust methods with potential to remove various types of hazardous elements are required. Among such impurities, hexavalent chromium (Cr(VI)) is very likely to become a future challenge. Different industrial ways to treat phosphate rock are currently being practised, and we have here studied how chromium behaves when using the nitro-phosphate process. The reduction mechanism of Cr (VI) in nitric acid and phosphoric acid solutions was investigated by measuring redox potential and UV-VIS spectra. The results show that Cr (VI) is not stable in strong nitric acid solutions. Reduction of Cr (VI) species decreased with decreasing temperature, NO2 concentration, ionic strength and absence of light. These findings support the proposed reduction reaction:The reduction rate was observed proportional to the nitric acid decomposition: .

Synthesis and Diffuse Reflectance Spectrum of Open－framework Cobalt Phosphate DAF－2 From Alcoholic System

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Phosphating process of AZ31 magnesium alloy and corrosion resistance of coatings

Zinc phosphate films were formed on AZ31 magnesium alloy by immersing into a phosphatation bath to enhance the corrosion resistance of AZ31. Different films were prepared by changing the processing parameters such as immersing time and temperature. The corrosion protection of the coatings was studied by electrochemical measurements such as electrochemical impedance spectroscopy, potentiodynamic polarization curves, and the structure of the films were studied by metalloscopy and X-ray diffraction (XRD). The results show that, the film formed at 80 ℃, 10 min has the highest corrosion resistance. The XRD patterns show that the film consists of hopeite (Zn3(PO4)2·xH2O).

Study of Sodium-Chromium-Iron-Phosphate Glass by XRD, IR, Chemical Durability and SEM

Chromium iron phosphate glass was investigated for use as waste form because of its improved chemical durability. The introduction of chromium in sodium-iron-phosphate glass is used to compare its effect with iron in inhibition of corrosion. The sodium-chromium-iron phosphate glass of composition 10Na2O-30Fe2O3-5Cr2O3-55P2O5 (mol%) was produced by melting batches of (99, 98% pure) Cr2O3, Fe2O3, Na2CO3, and (NH4)2HPO4 at 1080°C for one hour and pouring the liquid into steel mold. The sample was annealed at 680°C for 48 h. We have performed the measurement of X-Ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), Infra-Red spectroscopy (IR), and the chemical durability. The IR of the glass studied, contains two dominant bands, which were characteristic of pyrophosphate groups, (P-O) stretching mode of P-O non bridging oxygen at 1055 cm-1 and sym stretching mode of bridging oxygen at444 cm-1 respectively. There is also a band at603 cm-1 attributed to isolated tetrahedral units (PO4)3-. The chemical durability of the glass was investigated by measuring the weight loss in distilled water at 90°C for 22 days.

Elaboration and Structural Investigation of Iron (III) Phosphate Glasses

The regular melting-quenching method allowed isolating very large vitreous domains within the ternary system Li2O-P2O5-Fe2O3 at 1100. The vitrification and crystallization effects are discussed in terms of phosphorus pentaoxide concentration (mol%). In the course of the present study, we analyzed chemical durability along the glass domain and many sample glasses were isolated. We noticed that our compounds demonstrated very high chemical resistance to attack, even with very highly concentrated mineral acid solutions. This behavior can be assigned to the presence of poorly crystalline phases in these glasses, which tended to increase as the Fe2O3 content increased. This property is a prerequisite for many interesting industrial applications. XRD, IR spectroscopy and SEM micrographs allowed an efficient investigation of the structural changes versus composition within ternary diagrams. The results were found to be consistent with the regular structural changes of phosphate glasses.

Transformation of Coordinate Forms of Phosphate Ad－sorbed on Goethite Snrfaces Under Conditions of Vary－ing pH

X-ray photoelectron spectroscopy (XPS) and automatic titrimeter were nsed to study the relation be-tween pH and the transformation of the coordinate forms of P on goethite surfaces. The results showed thatfor a given P concentration, increasing the pH of suspension could cause a fast transformation of monodentatecomplexes of phosphate ions on goethite surfaces to binuclear ones. When lowering the PH, additional adsorp-tion of P occurred and the binuclear complexes reverted slowly to the monodentate ones. The dissociationand association of protons of the sorbed P caused by PH changes was considered to be a major reason lewtingto the transformation of the coordinate forms of P on the surfaces. The stability of binuclear surface complexof P was greater than that of monodentate complex. The possible reactions on the interface of goethite andsolutions with pH changes, and the reasons causing the different stabilities of the two coordinate P complexesare discussed in the paper.

Inflnence of PH on Chemical Forms of Phosphate Ad－sorbed on Goethite Snrfaces

Chemical forms of the phosphate adsorbed on goethite surfaces and characteristics of the coordinategroups which exchange with P on goethite surfaces in solutions with different pll values were investigated.Results showed that the chemical forms of P on goethite surfaces changed from the dominance of monodentatecorrdination to that of bidentate one with increasing pH of the solution. By influencing types of phosphateions in solutions, pH affected the chemical forms of P on goethite surfaces. The amount of OH￣- displacedby phosphate on goethite surfaces was the most at pH 7.0, the second at pH 9.0, and the least at pH 4.5.

Quantification of Inositol Hexa-Kis Phosphate in Environmental Samples

Phosphorous (P) is a major contributor to eutrophication of surface waters, yet a complete understanding of the P cycle remains elusive. Inositol hexa-kis phosphate (IHP) is the primary form of organic (PO) in the environment and has been implicated as an important sink in aquatic and terrestrial samples. IHP readily forms complexes in the environment due to the 12 acidic sites on the molecule. Quantification of IHP in environmental samples has typically relied on harsh extraction methods that limit understanding of IHP interactions with potential soil and aquatic complexation partners. The ability to quantify IHP in-situ at the pH of existing soils provides direct access to the role of IHP in the P cycle. Since it is itself a buffer, adjusting the pH correspondingly alters charged species of IHP present in soil. Density Functional Theory (DFT) calculations support the charged species assignments made based pKas associated with the IHP molecule. Raman spectroscopy was used to generate pH dependent spectra of inorganic (PI) and IHP as well as (PO) from IHP and (PI) in soil samples. Electro-spray ionization mass spectroscopy (ESI-MS) was used to quantify IHP-Iron complexes in two soil samples using a neutral aqueous extraction.

X射线荧光光谱法快速测定饲料级磷酸氢钙、磷酸二氢钙中总磷、总钙

在饲料级磷酸氢钙、磷酸二氢钙的总磷、总钙含量检验中,使用熔融制样,X荧光仪分析,X射线荧光光谱仪具有分析速度快、准确性好、精密度高的优点。以无水四硼酸锂、偏硼酸锂混合熔剂Li_(2)B_(4)O_(7)(67%)+LiBO_(2)(33%)作为熔剂,以NH 4I为脱模剂,选择合适的熔融条件,制成均匀、透明、无杂质的玻璃状样品。选取内部标准样品建立校准曲线,并在同一实验条件下,进行多组数据验证,准确度和精密度满足要求,适合于日常检测。

利用ICP-OES测定磷酸铁锂中复杂金属杂质的方法实践

随着锂离子电池产业的蓬勃发展,废旧锂离子电池及锂离子电池生产过程中的报废体量剧增,锂离子电池相关的回收产业发展迅猛,其中磷酸铁锂电池的市场最大。无论哪种回收路径,回料中的金属杂质成分都比较复杂,而金属杂质的准确测定,对锂离子电池回收产业至关重要。文中通过高温热解法对样品进行前处理,建立了一种用ICP-OES测量复杂基体中多种金属元素的分析方法。将高温热解得到的磷酸铁锂回料进行高温下的酸消解,然后在ICP-OES中对不同的观测位进行比较。将得到的数据进行测量系统分析,通过计算精度/容差(%P/T)评估最佳的检验能力组合。经过对比,发现270℃的高温消解更利于金属异物的充分溶出,Al(径向)、Na(径向)、Ni(径向)、Mn(径向)、Cr(轴向)、Zn(径向)的ICP-OES观测方位组合能更准确、稳定地分析复杂基体的金属杂质元素组分。该分析方法简单、高效、计算量小,便于快速评估检验能力。在利用ICP-OES进行复杂基体的金属异物分析方面,此方法具有很好的借鉴意义。

铝合金三价铬化学氧化用无磷脱脂剂的制备及性能

[目的]针对某厂家在铝合金三价铬化学氧化过程中所用脱脂剂含磷的问题,研制一款无磷脱脂剂。[方法]采用响应面法对多种常见的表面活性剂、金属螯合剂和助剂进行筛选及用量优化,同时研究了脱脂剂的使用浓度、温度和时间对其清洗效果及腐蚀性的影响。[结果]在脱脂温度60℃、脱脂时间10 min的条件下,由8.4 g/L OP-10、12.4 g/L葡萄糖酸钠、0.44 g/L钼酸钠、15.0 g/L四硼酸钠、5.4 g/L二乙二醇单丁醚和1.6 g/L硅酸钠组成的脱脂剂的净洗力达到99.85%,对2024铝合金的腐蚀速率为0.15 g/(m^(2)·h)。[结论]与某市售脱脂剂相比,自制脱脂剂的净洗力略高,腐蚀性明显降低。

电感耦合等离子体原子发射光谱法测定饲料级磷酸二氢钙中铬的含量

提出了电感耦合等离子体原子发射光谱法(ICP-OES)测定饲料级磷酸二氢钙中铬的含量。样品中加入盐酸(1+1)溶液20 mL,定容、过滤后,直接采用ICP-OES法进行测定。结果表明:ICP-OES法可以稳定测定饲料级磷酸二氢钙中铬的含量,通过对仪器参数优化,测定耗时不超过40 min;方法的回收率为99.2%~102.0%,测定结果的相对偏差不超过10%,符合国家标准《饲料中铬的测定》(GB/T 13088—2006)的要求。

ZK60镁合金磷酸盐及锡酸盐化学转化膜

为了提高ZK60镁合金的耐腐蚀性能,利用磷酸盐溶液或锡酸盐溶液,考察了在ZK60镁合金上形成磷酸盐或锡酸盐化学转换膜的工艺条件及膜层的耐蚀性能。通过改变处理时间和温度,可以得到性能不同的转换膜。通过电化学阻抗谱技术和极化曲线技术研究转化膜的耐腐蚀性能,利用扫描电镜研究其微观结构。结果表明:在磷酸盐溶液中,当处理温度为50℃时,磷化30min后试样的电荷转移电阻(Rct)为224.03Ω·cm2;当温度为80℃,反应时间为45min时,所得转换膜的Rct为377.67Ω·cm2,阻值最大,耐腐蚀性能最好;对于锡酸盐化学转化膜,90℃下,处理60min的膜层耐蚀性能最好,其Rct为388.32Ω·cm2,与磷酸盐化学转化膜相比,两种膜的保护性能相差不大。

Incorporation of Reactive Corrosion Inhibitor in Waterborne Acrylic Polyurethane Coatings and Evaluation of its Corrosion Performance

Hydroxyl-epoxy phosphate （HEP） as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite （HEP-APU） coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.

交流阻抗谱研究钙磷陶瓷电沉积层的结构

用交流阻抗技术研究了不同电沉积时间的钙磷陶瓷沉积层 ,结果表明 ,沉积时间不同的陶瓷沉积层的交流阻抗谱存在显著的差别。采用双层结构物理模型 ,对不同沉积时间陶瓷沉积层的交流阻抗谱进行计算机拟合 ,得到的等效电路各元件拟合值显示 :电极表面钙磷陶瓷为内密外疏型梯度沉积层。在陶瓷电沉积过程中 ,钙磷晶粒同时沉积于距电极表面不同距离的部位 ,沉积层厚度增加的同时内层密度也在逐渐增加 。

MF_2(M=Mg,Ca,Zn,Sr,Ba)对掺Yb^(3+)磷酸盐玻璃性质的影响

熔制了60P_2O_5·6Al_2O_3·(33-x)BaO·xBaF_2·1Yb_2O_3(x=0,3,6,9)和60P_2O_5·6Al_2O_3·27BaO·6MF_2·1Yb_2O_3(M=Mg、Ca、Sr、Zn、Ba)(分子分数)玻璃,测试了其折射率、密度、转变温度、析晶温度、熔点温度、红外光谱和紫外吸收光谱,讨论了二价氟化物MF_2(M=Mg、Ca、Sr、Zn、Ba)对磷酸盐玻璃热稳定性及内部结构的影响,测试了Yb^(3+)离子的吸收光谱、荧光光谱、荧光寿命,计算了光谱参数,讨论了MF_2对Yb^(3+)磷酸盐玻璃光谱性质的影响,结果表明二价金属氟化物是作为网络外体进入到磷酸盐玻璃结构中,并没有改变磷酸盐玻璃内部的[PO_4]链状结构,二价金属氟化物还有助于提高Yb^(3+)离子的受激发射截面,和自发辐射几率,荧光半高宽。