Thermogravimetric Analysis Methods Research Articles

Conversion characteristics of lignite and petroleum coke in chemical looping combustion coupled with an annular carbon stripper

Chemical looping combustion (CLC) of solid fuels was studied in a 30 kW dual fluidized-bed system coupled with an annular carbon stripper for char separation by using a kaolin-promoted manganese ore oxygen carrier. Two solid fuels, a lignite and a petroleum coke, were tested in the CLC unit. The CLC unit was operated continuously for more than 160 h. The effects of the fuel size and residence time in the fuel reactor on the carbon capture efficiency and oxygen demand were investigated. The char separation efficiency of the annular carbon stripper reached 90%, and a maximum carbon capture efficiency of 97% was achieved for the 106–212 μm lignite. The carbon capture efficiency was affected by the fuel particle size and residence time. When >212 μm lignite particles were used, there was a ~ 12% oxygen demand. The carbon capture efficiency in the experiment with petroleum coke was only 45% due to the slow gasification rate. A model was applied to analyze the influence of key factors on the carbon capture efficiency. The redox kinetics of the tested oxygen carrier were studied by a micro-fluidized bed thermogravimetric analysis method.

Controlled Release of Novel Volatile Corrosion Inhibitor (VCI) Nanoparticles Incorporated in Low Density Polyethylene (LDPE) Films for Steel Coverings: Correlation of Experimental Results with Molecular Dynamics Simulation

The compositions of 10 different VCI compounds were optimized. Low density polyethylene (LDPE), ECA-5 copolymer (poly(ethylene-co-methyl acrylate) as an ethylene based coupling agent) and the prepared VCI compound, so called BFA-200, were processed in a twin screw extruder followed by a film casting method to make films. The 80/20 LDPE/ECA-5 composition was determined as the optimized VCI unfilled blend having the maximum mechanical properties for the film processing; the BFA-200 VCI nanoparticles (5, 10 and 15%) were added to this composition. Measurement of the controlled release of the VCI within the LDPE/ECA-5/BFA-200 80/20/15 sample was carried out using thermo-gravimetric analysis (TGA). The TGA method was also used for determination of the VCI content after periods of 3, 6 and 12 months in polyethylene bags stored at ambient conditions. There was a significant difference in the release of VCI agent for the blends as compared to that of VCI incorporated in only LDPE. The preservative quality of the blend films was tested on steel plates using the TL8135-002 standard. There were acceptable degrees of corrosion with all of the virgin blends containing BFA-200, especially 10% upward. However, there was a different behavior after each time period, in good accordance with the release tests. Moreover, a molecular dynamics (MD) simulation was performed to determine the diffusion of the VCI molecules within pure LDPE and the LDPE/ECA-5 blends. There was a decrease in the simulated diffusion of the VCI material through the blends with addition of the ECA-5 content which fitted well to the experimental data.

Quantification of Total Organic Carbon in Ashes from Smoldering Combustion of Sewage Sludge via a Thermal Treatment-TGA Method.

Self-sustaining smoldering combustion is a promising technology for treating sewage sludge from wastewater treatment plants because of its low energy inputs. Proper use or disposal of the resulting ashes requires thorough characterization of their properties, including the content of total organic carbon (TOC). Here, we develop a two-step method for quantifying TOC in the raw ashes from sewage sludge smoldering combustion. The first step is to thermally treat the raw ashes at 500 °C in N2 for 1 h, followed by ultimate analysis of both the raw ashes and the thermally treated ashes. This enables the quantification of carbon released during thermal treatment. The second step is nonisothermal thermogravimetric analysis (TGA) of the thermally treated ashes, in which the samples are heated to 900 °C at 10 °C/min in air. The weight losses at 310–500 °C are confirmed to be caused by organic carbon oxidation, allowing us to determine the contents of carbon retained in the thermally treated ashes. The sums of these two portions of carbon represent the contents of TOC in the raw ashes, which are ∼0.85–6.52 wt % (dry basis), depending on their locations and particle sizes. The two-step (thermal treatment–TGA) method is validated via a method that includes acid washing of the thermally treated ashes, ultimate analysis of the acid-washed ashes, and TOC analysis of the leachates. The two-step method is simple and accurate and, importantly, provides thorough information on the thermal behavior of the raw and thermally treated ashes.

Preparation and properties of modified aluminum diethylphosphinate flame retardant for low‐density polyethylene

AbstractTo improve the flame retardancy of low‐density polyethylene (LDPE) and mechanical properties of LDPE composites, phenol‐formaldehyde aluminum diethylphosphinate microcapsules (PF@ADP) was prepared by in‐situ polymerization with phenol‐formaldehyde (PF) resin as the wall material and halogen‐free flame‐retardant aluminum diethylphosphinate (ADP) as the core material. The effects of PF@ADP on flame retardancy and mechanical properties of LDPE were investigated by methods of combustion experiments, mechanical analysis, thermogravimetric analysis (TGA), and smoke density analysis. The results indicated that, compared with ADP/LDPE composites, the flame retardancy and mechanical properties of PF@ADP/LDPE were obviously improved. With the addition of 20 wt% PF@ADP (PF:ADP = 3:7), the limit oxygen index (LOI) of LDPE composites increased to 30.7% and UL‐94 reached V‐1 grade. The tensile strength and elongation at break reached 12.5 MPa and 431.2%, which was 20.2% and 23.1% higher than that of ADP/LDPE with the same addition. The addition of PF@ADP was beneficial to the smoke suppression of LDPE.

Heterogeneous reaction kinetics of a perovskite oxygen carrier for chemical looping combustion coupled with oxygen uncoupling

• A new perovskite oxide, CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ , was developed as oxygen carrier. • Micro-fluidized bed thermogravimetric analysis (MFB-TGA) was used for kinetic study. • Oxygen uncoupling kinetics was accurately measured by MFB-TGA. • Full oxidation can be achieved within 5 s. The determination of more exact heterogeneous kinetics of oxygen carriers is a crucial task for modelling, used to predict performance and design of demonstrating pilot units. Thermogravimetric analysis (TGA) is the most widely used method to measure the kinetics. However, the mass and heat transfer limitations observed inside the TGA specially for oxygen uncoupling effect will lead to underestimation of the kinetics. Micro-fluidized bed thermogravimetric analysis method (MFB-TGA) solve this challenge to measure the fast heterogeneous kinetics precisely, based on real-time mass measurement of oxygen carrier in a fluidizing state with similar mass and heat transfer characteristics as in a CLC reactor. In this study the oxygen uncoupling kinetics and redox reactions kinetics of a newly developed perovskite oxygen carrier material (CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ ) is established using a MFB-TGA method. The oxygen uncoupling kinetics measured by MFB-TGA is ~4 times faster than that measured by regular TGA. The oxidization reaction of CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ occurs only in the initial stage controlled by chemical reaction, and the time required for full oxidation is ~5 s, while the reduction kinetics consists of a fast reaction stage and a slow reaction stage, controlled by chemical reaction and diffusion through the product layer, respectively. Both the oxygen uncoupling kinetic parameters and redox kinetic parameters are obtained by analyzing the MFB-TGA data based on the simplified K-L model for the fluidized bed. The morphology characterizations of the fresh and tested CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ particles were investigated by SEM-EDS. The comparison of heterogeneous reaction kinetics with the mainstream OCMs were done.

A Highly Active Catalyst 2,4,6‐Tris (di‐4‐chlorobenzamido)‐1,3,5‐triazine Palladium (II) Chloride for the Green Synthesis of Substituted Dihydrobenzo[b]thiophene in Ionic Liquid

AbstractThe palladium‐metallodendrimer (Pd‐MD) 2,4,6‐tris (di‐4‐chlorobenzamido)‐1,3,5‐triazine palladium (II) chloride was synthesized by the reaction of substituted triazine, substituted benzoyl chloride, and (Ph3P)2PdCl2 in DMF at 100 °C. This Pd‐MD was characterized by FTIR, 1H NMR, 13C NMR, Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray (EDX), mass spectrometry, X‐ray photoelectron spectroscopy (XPS), elemental analysis, Thermogravimetric analysis (TGA), and Differential scanning calorimetry (DSC) methods. This catalyst was successfully applied for the green synthesis of different substituted alkyl 2,3‐dihydrobenzo[b]thiophene‐2‐carboxylates in ionic liquid tetra‐n‐butylammonium bromide (TBAB) solution at 120 °C for 2.5 hours with a good to an excellent percentage of yields (75 % to 96 %). Importantly, this homogeneous catalytic system was easily recoverable and reusable at least five times without a significant loss of activity.

Castor oil based eco-friendly lubricating oil additives

The application of vegetable oil based additive for lubricating oil has attracted considerable interest due to their biocompatibility and multifunctional performances compared to conventional additives. In the present work, we have synthesized homopolymer of castor oil and copolymer of castor oil with styrene by thermal method without any solvent at different percentage composition by using BZP (benzoyl peroxide) as initiator. Characterization of the additives was completed by spectral technique (FT-IR and NMR spectroscopy). The molecular weight of the prepared additives was determined by gel permeation chromatography method (GPC method). Thermo gravimetric analysis (TGA) method was used to study the thermal stability of the prepared polymers. Standard ASTM methods were used to investigate the performance of all the prepared polymers in SN150 mineral oil as viscosity index improver (VII), pour point depressant (PPD) and antiwear. Biodegradability of all the polymers was determined disk diffusion method. From the experimental results, it was found that copolymers are more effective as VII, PPD and antiwear than homopolymer. Moreover, average molecular weight, thermal stability and performances as VII and antiwear increase with increasing the percentage of styrene in copolymers.

Comparative thermal research on tetraazapentalene-derived heat-resistant energetic structures

Organic inner salt structures are ideal backbones for heat-resistant energetic materials and systematic studies towards the thermal properties of energetic organic inner salt structures are crucial to their applications. Herein, we report a comparative thermal research of two energetic organic inner salts with different tetraazapentalene backbones. Detailed thermal decomposition behaviors and kinetics were investigated through differential scanning calorimetry and thermogravimetric analysis (DSC-TG) methods, showing that the thermal stability of the inner salts is higher than most of the traditional heat-resistant energetic materials. Further studies towards the thermal decomposition mechanism were carried out through condensed-phase thermolysis/Fourier-transform infrared (in-situ FTIR) spectroscopy and the combination of differential scanning calorimetry-thermogravimetry-mass spectrometry-Fourier-transform infrared spectroscopy (DSC-TG-MS-FTIR) techniques. The experiment and calculation results prove that the arrangement of the inner salt backbones has great influence on the thermal decompositions of the corresponding energetic materials. The weak N4-N5 bond in “y-” pattern tetraazapentalene backbone lead to early decomposition process and the “z-” pattern tetraazapentalene backbone exhibits more concentrated decomposition behaviors.

Castor Oil and Acrylate based Copolymers as Greener Additives for Lubricating Oil

In this work, the authors synthesized three different acrylates by esterification reaction of acrylic acid with long chain alcohols (octyl alcohol, decyl alcohol and dodecyl alcohol). Homopolymer of castor oil (CO) and three copolymers of castor oil with acrylates were synthesized by free radical polymerization using azobisisobutyronitrile (AIBN) as initiator. FT-IR and NMR spectral technique were used to characterize the synthesized polymers. The average molecular weight was determined by gel permeation chromatography (GPC). Thermo gravimetric analysis (TGA) method was used study the thermal behaviour of the polymers at high temperature. Performances of the polymers as additives in lubricating oil were carefully assessed in terms of viscosity index, and pour point. The experimental results showed that the prepared copolymers are better additives than homopolymer. Disc diffusion method was applied to carry out biodegradability test of all the prepared polymers.

A New Approach to Analyze the Initiated Thermal Destruction of Polycarbonate

It is established by the method of dynamic thermogravimetric analysis that bismuth dimethyldithiocarbamate (DMDTC), which protects a number of polymers from heat and light, accelerates the thermal destruction of polycarbonate (PC) based on bisphenol A and is, in this case, an initiator of the thermal destruction. The kinetics of the multistage process of the initiated thermal destruction of PC is modeled by the method of nonlinear regression analysis. The peculiarity of the proposed approach lies in estimating the parameters of the Arrhenius equation for each of the stages together for all temperature programs. It is shown that such an analysis allows us to avoid the limitations characteristic of the Kissinger (Kiss) and Kissinger–Akahira–Sunose (KAS) methods, which are traditionally used to determine the activation energies of thermal destruction of polymers.

Effect of Preliminary Firing on Oxidation of Mo–Mo3Si Alloyed with Sc or Nd

The main tasks of studying molybdenum silicides for use at elevated temperature include development of materials with a melting point Tme ≥ 2000°C, possibly with a low brittle-ductile transition temperature and resistance to high temperature oxidation. The possibility is considered of increasing corrosion resistance of a model alloy consisting of molybdenum solid solution and Mo3Si. The effect of Sc or Nd alloying additives, as well as preliminary high-temperature annealing. i.e., pre-oxidation in order to create a protective oxide layer on the alloy surface of a model alloy, is evaluated. Non-isothermal oxidation of alloys is performed using combined thermogravimetric and differential thermal analysis methods. The phase composition of the scale formed is determined by an X-ray diffraction method. As a result of these studies it is established that preliminary oxidation firing of Mo–Mo3Si–REE (about 3 at.%) alloys at 1100°C for 5–10 min provides conditions for forming a layer of SiO2 and REE molybdates Sc2(MoO4)3 and Nd2Si2O7 at the alloy surface. Oxidation in a dynamic regime for treated alloys in the range 500–850°C proceeds much more slowly than for the initial samples. This can be explained by the difficult access of oxygen to the reaction zone through a protective layer of non-volatile oxides. In addition, preliminary oxidation of Mo–Mo3Si alloyed with Sc or Nd during subsequent oxidation leads to an increase in the transition temperature for the process from the stage of oxide formation to intense MoO3 sublimation.

Trastuzumab Modified Barium Ferrite Magnetic Nanoparticles Labeled with Radium-223: A New Potential Radiobioconjugate for Alpha Radioimmunotherapy.

Barium ferrite nanoparticles (BaFeNPs) were investigated as vehicles for 223Ra radionuclide in targeted α-therapy. BaFe nanoparticles were labeled using a hydrothermal Ba2+ cations replacement by 223Ra with yield reaching 61.3 ± 1.8%. Radiolabeled nanoparticles were functionalized with 3-phosphonopropionic acid (CEPA) linker followed by covalent conjugation to trastuzumab (Herceptin®). Thermogravimetric analysis and radiometric method with the use of [131I]-labeled trastuzumab revealed that on average 19–21 molecules of trastuzumab are attached to the surface of one BaFe–CEPA nanoparticle. The hydrodynamic diameter of BaFe–CEPA–trastuzumab conjugate is 99.9 ± 3.0 nm in water and increases to 218.3 ± 3.7 nm in PBS buffer, and the zeta potential varies from +27.2 ± 0.7 mV in water to −8.8 ± 0.7 in PBS buffer. The [223Ra]BaFe–CEPA–trastuzumab radiobioconjugate almost quantitatively retained 223Ra (>98%) and about 96% of 211Bi and 94% of 211Pb over 30 days. The obtained radiobioconjugate exhibited high affinity, cell internalization and cytotoxicity towards the human ovarian adenocarcinoma SKOV-3 cells overexpressing HER2 receptor. Confocal studies indicated that [223Ra]BaFe–CEPA–trastuzumab was located in peri-nuclear space. High cytotoxicity of the [223Ra]BaFe–CEPA–trastuzumab bioconjugate was confirmed by radiotoxicity studies on SKOV-3 cell monolayers and 3D-spheroids. In addition, the magnetic properties of the radiobioconjugate should allow for its use in guide drug delivery driven by magnetic field gradient.

Study of operating properties of aanticorrosion packing papers

Metal products are subjected to atmospheric corrosion during transportation and storing. An important way to prevent this negative phenomenon is application of special packing materials, in particular materials, containing volatile inhibitors of corrosion, which protect metal against various corrosion agents. To protect metal effectively it is necessary to provide a definite level of operating characteristics of packing materials. The purpose of the work was the study of operating properties of inhibited crepe, inhibited and laminated polyethylene film, inhibited crepe and reinforced by polypropylene web papers, manufactured by OJSC “PP TechnoKhim”, Magnitogorsk, used for packing of metals. Structural and dimensional, sorption, deformation and strength characteristics, of the studied anticorrosion papers are presented, the characteristics being calculated based on the results of measurements. To determine their physical-mechanical and anticorrosion properties, standard methods and methodologies were used. To evaluate impact of moisture and transportation conditions, indices of water adsorption and wear of the studied papers were determined. Inhibitor content in these materials was determined by thermogravimetric analysis method. Their protective ability was studied on samples of low carbon steel strip. For accelerated corrosion tests the strip samples were degreased by alcohol, dried in air and packed in the studied anticorrosion papers, after that they were exposed under increased temperatures and moisture conditions. It was determined, that among the materials under the study, the inhibited crepe paper, reinforced by polypropylene web, hhas the best complex of physical-mechanical and anticorrosion properties. It provides a higher level of prevention corrosion of metal l and surpasses other materials in a number of deformation and strength characteristics. Recommendations were proposed to improve qquality of produced anticorrosion papers.

A TGA Investigation to Co‐Pyrolysis Characteristics of Shenhua Direct Coal Liquefaction Residue and Huolinhe Lignite and the CO2 Gasification Behavior of the Derived Char

AbstractCo‐pyrolysis of direct coal liquefaction residue (DCLR) and low rank coals was regarded as reliable and efficient method to process DCLR. The treatment of the derived co‐pyrolysis char is important for the comprehensive utilization of DCLR. In this study, the non‐isothermal co‐pyrolysis of Shenhua DCLR and Huolinhe lignite, and the isothermal CO2 gasification of the co‐pyrolysis char were performed by the thermogravimetric analysis method. The interactive effect of co‐pyrolysis and the CO2 gasification behavior of the derived char were explored by comparing the experimental and calculated thermogravimetric/derivative thermogravimetric (TG/DTG) curves and reactivity – conversion (R ‐ x) curves, respectively. The results show that the devolatilization pattern at 200–600 °C was modified and part of volatiles were released in advance. As the experimental co‐pyrolysis Tmax was lower by 7–13 °C than the calculated value, while it was almost equal to the Tmax of lignite pyrolysis. We tentatively concluded that lignite devolatilization could promote the evaporation of molten components of DCLR. Moreover, DCLR and lignite could polymerize or condensation with each other at 650–900 °C. The lignite char within co‐pyrolysis char could support the char skeleton and hold a high porosity. Therefore, the CO2 gasification reactivity of co‐pyroysis char was promoted and the experimental reactivity exceeded the calculated value over the conversion range of 12–90 %.

Six transition metal–organic materials with the ditopic 4,4′-diaminodiphenylmethane ligand: Synthesis, structure characterization and luminescent properties

Six coordination compounds based on 4,4′-diaminodiphenylmethane (dadpm) and different salts (acetates, nitrates and perchlorates) of four (Ni, Co, Zn, Cd) transition metals have been prepared and characterized by IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction methods. The crystalline solids include four monomers: [Co(dadpm)2(CH3COO)2(H2O)2] (1), [Cd(dadpm)2(CH3COO)2(H2O)2] (2), [Zn(dadpm)4(H2O)2](NO3)2(H2O)2 (3), [Ni(dadpm)3(dmf)(H2O)2](ClO4)2(dadpm)(H2O) (4), and two one-dimensional coordination polymers: {[Cd(dadpm)2(H2O)(ClO4)](ClO4)}n (5) and {[Cd(dadpm)4](ClO4)2}n (6). The transition metals used in this study accommodate two, three, four and six dadpm ligands in the coordination cores. The luminescence properties for six coordination compounds are reported.

Features of Structure and Properties of pнeмa-gr-pvp Block Copolymers, Obtained in the Presence of Fe2.

This paper presents the research results of the copolymer structure and properties of 2-hydroxyethylmethacrylate (HEMA) with polyvinylpyrrolidone (PVP) and their hydrogels, obtained by block polymerization in the presence of iron sulfate (II). By the methods of chemical analysis, IR spectroscopy, Thermogravimetric (TG) and Differential Thermal Analysis (DTA), the course of grafted copolymerization of HEMA on PVP with the formation of a cross-linked copolymer was confirmed. The results received by scanning electron microscopy showed that due to the copolymerization of HEMA with PVP, macroporous hydrogels with a pore size of 10–30 μm were obtained. The peculiarities of the structure formation of the obtained copolymers depending on the initial composition formulation were established and their structural parameters were investigated: PVP grafting efficiency, PVP content in copolymer, molecular weight of internodal fragment of polymer network, crosslinking degree, and crosslinking density. The interrelation of sorption–diffusion, physical–mechanical and thermophysical properties along with the structure of the obtained materials was proved. It was shown that with the increasing PVP content in the original composition, the efficiency of its grafting and crosslinking density of the polymer network decreased, but the surface hardness, heat resistance, sorption capacity of copolymers in the dry state, as well as ion permeability and elasticity in the swollen state increased, while their tensile strength deteriorated. It is proved that by changing the original composition formulation it is possible to change the structure and hence the properties of the copolymers in the desired direction.

Investigation of effectiveness of pine cone biochar activated with KOH for methyl orange adsorption and CO2 capture

In this study, pyrolysis of pine cone, a lignocellulosic biomass, was carried out in a fixed bed reactor. The biochar product obtained was activated by using chemical activation method. KOH was used as the activating agent with the impregnation ratio was ¼. Activated pine cone biochars were characterized by using analysis techniques such as SEM, BET, and FT-IR. The usage potential of the activated biochar product with a surface area of 1714.5 m2/g has been investigated in two different application areas. As the first application area, the CO2 holding capacity of activated biochar was measured by using the thermogravimetric analysis method. The CO2 adsorption capacity of the activated biochar was determined as 160 mg/g (3.64 mmol/g) at 25 °C. As a second application area, the effectiveness of activated biochar product in the removal of dyestuff (methyl orange) from aqueous solutions was investigated. The methyl orange adsorption capacity of the activated biochar in optimum conditions (pH 2, temperature of 25 °C, initial concentration of 100 mg/L, adsorbent amount 0.8 g/L) was calculated as 109.5 mg/g. Isotherm modeling and kinetic investigations showed that Freundlich and pseudo-second-order models describe the adsorption equilibrium and kinetic behavior well. As a result, this type of biomass could be successfully evaluated in removing both methyl orange dye, which is a potential pollution risk for aquatic environment, and CO2 that is responsible for climate change and greenhouse effect in the atmosphere.

Combination effect of limestone filler and slag on hydration reactions in ternary cements

An overview of the effect of mineral additives on hydration reactions in ternary cement systems is of high importance for concrete design and durability. In this paper, the combination effect of limestone filler and slag on hydration reactions in ternary cements was investigated. Tests were carried out on cement pastes with various replacement levels of cement by limestone filler and slag (15, 25 and 45%) and two w/b ratios (0.35 and 0.48). The hydration reactions of ternary cement pastes were evaluated by measuring their degree of reaction at 7, 28 and 90 days. The degree of reaction was followed by thermogravimetric analysis (TGA) method. The results showed that the reaction degree was dependent on the replacement level and w/b ratio. The hydration heat and the compressive strength were further examined to verify the results obtained. Both hydration heat and compressive strength were found to be proportional to the reaction degree.

Application and limitations of thermogravimetric analysis to delineate the hot melt extrusion chemical stability processing window.

Thermogravimetric analysis (TGA) is frequently used to define the threshold of acceptable processing temperatures for hot melt extrusion. Herein, evaluation of chemical stability of amorphous drug and polymer systems was assessed by a critical evaluation of TGA nonisothermal and isothermal methods. Nonisothermal analysis of three crystalline APIs of high glass-forming ability (posaconazole, indomethacin, and bicalutamide), as well as six common polymers, identified a degradation onset temperature that ranged from 52 to 170°C, depending on heating rate and degradation detection method employed. In particular, the tangent method significantly overestimated the onset of acceptable levels of degradation, while weight loss threshold criteria were more suitable. Isothermal analysis provided a more direct indication of chemical stability, however neat amorphous materials are likely to recrystallize. By forming an amorphous solid dispersion, the polymer can stabilize the amorphous drug against recrystallization, enabling isothermal analysis of chemical degradation. However, TGA mass loss of volatiles should be considered only as an approximate indicator of degradation, as actual potency loss is likely to be significantly higher; this was confirmed by high performance liquid chromatographic analysis of samples. TGA methods should be selected to generate highly sensitive outcomes, and caution should be applied when extrapolating suitability of processing conditions.

A design for detecting phosphate ions in aqueous solution by luminescent Tb-coordination polymer

Phosphate usually plays an important role not only in biological processes but also in environmental pollution, and therefore there is an urgent need for a simple, quick and efficient method to detect phosphate ions. For this design, a new terbium coordination polymer (Tb-CP) has been prepared under hydro-solvothermal conditions using 3,3′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpboda) in the existence of Tb(NO3)3‧6H2O. It was studied by infrared spectroscopy (IR), single crystal X-ray diffraction, thermogravimetric analysis (TGA), and fluorescence method. Structurally, the Tb-CP gives a 2D network based on binuclear Tb(III) units. Optically, the Tb-CP is prepared as a colloidal nanoparticle suspension for detecting phosphate in water solution. Namely, the suspensions show intense green emissions gradually disappear with the addition of PO43− ions, indicating that the Tb-CP can rapidly, sensitively and reversibly detect phosphate ions in aqueous solutions. This can be applied in pollutant monitoring with a limit of detection down to 4.53 × 10−8 M (0.0096 ppm). Furthermore, a convenient method is successfully set to observe PO43− ions in applications.