Phosphate Species Research Articles

Theoretical study on 31P NMR chemical shifts of phosphorus-modified CHA zeolites

Abstract The 31P MAS NMR spectra of phosphorus-modified chabazite (P-CHA) zeolites have been observed during the hydrothermal treatment to probe the structural changes of phosphorus species in zeolites. Characteristic changes of the spectra were observed in the range of −27 ~ −42 ppm, which correlates to the hydrothermal structure changes in P-CHA zeolites. Theoretical calculations on the 31P and 27Al NMR chemical shifts have been systematically performed to disclose the possible phosphorus species of intra- and extra-framework and the structural changes during the hydrothermal treatment. The shift of the 31P resonances toward higher field were identified for condensed phosphates and aluminophosphates. Based on the calculated 31P NMR chemical shifts, the peak with increased intensity at −42 ppm in the initial stage of the hydrothermal treatment is mainly assigned to the formation of siliconoaluminophosphate (SAPO) species in the 6-membered ring of the zeolite framework, while the peak with increased intensity at −29 ppm in the later stage of treatment is ascribed to the accumulation of the extra-framework condensed phosphate or aluminophosphate species after the partial framework decomposition. The dominant peak at −33 ppm in all 31P NMR spectra is assigned to the phosphates in the framework.

Influence of coal fly ash on the early performance enhancement and formation mechanisms of silico-aluminophosphate geopolymer

This study proposes the use of two types of coal fly-ash (CFA) (high- and low-calcium, HCFA and LCFA respectively) as additives in silico-aluminophosphate (SAP) geopolymers for early performance improvement. The chemistry of CFA in phosphate environment was clarified using CFA/orthophosphoric acid suspensions through XRD, SEM and NMR analyses. The results revealed that HCFA could seed the active calcium sources which induced the acid-base or/and hydrolysis reaction between the alkaline calcium species within HCFAs and the acidic phosphate species in the activator. The produced calcium phosphate compounds, e.g., brushite and monetite, hurried up the setting (initial and final setting were 18 and 26 min, respectively) and early strength development (1-d and 3-d strengths increased to 15 and 29 MPa, respectively) of the HCFA-SAP geopolymer relative to CFA-free SAP geopolymer. However, the incorporation of LCFA was found to improve the workability but weakened the setting and strength properties of the LCFA-SAP geopolymers.

Modification of silicophosphate glass composition, structure, and properties via crucible material and melting conditions

AbstractCeramic crucibles are known to corrode in contact with glass melts. Here, we investigate the effect of alumina and fused silica crucibles on the composition, structure, and properties of silicophosphate glasses. Glasses in the system 0.3 Na2O‐0.6 P2O5‐0.1 SiO2 were melted in platinum, alumina, or fused silica crucibles at 900°C or 1200°C for 0.5‐12 hours. Al2O3 and SiO2 were found to leach from the crucibles into the glass melt and alter the glass composition: Al2O3 content increased with melting temperature and time, resulting in up to 10 mol% Al2O3; SiO2 from fused silica crucibles was also introduced into the glass, resulting in a 25% higher SiO2 content compared to the nominal composition. Glass density, transition temperature, thermal expansion, and mechanical properties were strongly affected by these compositional changes. Based on vibrational spectroscopy, this is explained by increasing numbers of P–O–Al or P–O–Si bonds, resulting in a depolymerization of the phosphate network, and ionic cross‐linking by high field strength aluminum or silicon ions. With increasing alumina content, P–O–Si bonds were replaced by P–O–Al bonds. 31P and 27Al MAS NMR spectra revealed that aluminum is present in sixfold coordination exclusively and fully bonded to phosphate species, connecting phosphate groups by P–O–Al–O–P bonds.

Submarine Groundwater Discharge and Stream Baseflow Sustain Pesticide and Nutrient Fluxes in Faga'alu Bay, American Samoa

It is increasingly recognized that groundwater discharge in the form of stream baseflow and submarine groundwater discharge (SGD) plays an important role in contaminant transport. This study seeks to demonstrate the importance of groundwater flow for the distribution and transport of selected pesticides and nutrients in the Faga`alu aquifer on the island of Tutuila in American Samoa. Field measurements, including seepage runs and analysis of stream and groundwater for pesticides and nutrients, were combined with hydrological modeling. Selected analytes were glyphosate (GLY), dichlorodiphenyl-trichloroethane (DDT), imidacloprid, and azoxystrobin for pesticides and chemical species of nitrogen, phosphate, and silicate for nutrients. Hydrological flow and transport models of the aquifer were built to simulate groundwater flow and to provide estimates of GLY and dissolved inorganic nitrogen (DIN) fluxes. Stream baseflow was responsible for 59% and SGD for 41% of groundwater flow to the bay, which totaled 6,550 m3/d in the dry season when surface runoff was negligible. DDT was found in 85% and GLY in 100% of tested samples. SGD and baseflow thus delivered 9 g/d of DDT, 0.9 g/d of GLY, 570 g/d of DIN and 840 g/d of dissolved inorganic phosphorus (DIP) into Faga’alu Bay. While all pesticide levels are below environmental limits, their presence in baseflow and SGD, which discharge continuously year-round, result in sustained fluxes of GLY and DDT to the reef. The presence of DDT in groundwater decades after its last application confirms its long-term environmental persistence.

Energy-saving photo-degradation of three fluoroquinolone antibiotics under VUV/UV irradiation: Kinetics, mechanism, and antibacterial activity reduction

Due to the inefficient treatment by the biotic and UV-disinfection processes in wastewater treatment plants, the broad-spectrum Fluoroquinolone antibiotics (FQs) are frequently detected in water environment around the world. In this work, the photo-degradation of three FQs (norfloxacin-NOR, ciprofloxacin-CIP, levofloxacin-LEV) by VUV/UV irradiation was investigated. The results showed that the degradation of FQs in VUV/UV irradiation system were more effective than that in UV irradiation system by enhanced the defluorination and decarboxylation. FQs could be degraded more efficiently with high temperature and low initial concentration, and the effect of flow rate was small. Initial pH played a key role in degradation of NOR and CIP. Most anions could slightly affect the FQs removal in water, except the carbonate and phosphate species. 1O2 and ·OH played the primary role in FQs degradation in VUV/UV system. Defluorination, decarboxylation, and piperazine ring oxidation were the main degradation pathways for three FQs degradation, but demethylation was a particular degradation pathway of LEV. Antibacterial activities of FQs aqueous sample were reduced in both VUV/UV and UV system, while the removal of antibacterial activities in the VUV/UV process were more efficient than UV process for NOR and LEV. VUV/UV system was more energy-saving for removing FQs. These results suggested that VUV/UV system is potential alternative in replacing or enhancing UV system in wastewater treatment plants for FQs removal in the future.

Recovery of Phosphate Rock Equivalents from Incineration Ash of Chicken Manure by Elution-Precipitation Treatment

In order to obtain calcium phosphates - a phosphate rock equivalent - from the incineration ash of chicken manure, which is obtained from power generation systems that use the manure for fuel, incineration ash was treated with an aqueous solution of nitric acid to elute phosphorus. By using 0.3 M of HNO3, most of the phosphorus could be eluted from 1.0 g of ash within 0.1 h. Compared with the composted chicken manure that was previously examined in our laboratory, the concentration of HNO3 was increased for this session of elution. Using the incineration ash of chicken manure made it possible to remove inorganic species at a lower boiling or sublimation temperature, and organic species by calcination in the power generation system. Compared with composted chicken manure, the concentrations of phosphorus contained in the incineration ash and the nitric acid extract were higher in the incineration ash. XRD analysis showed that the obtained nitric acid extract could be treated with aqueous NH3 to form a precipitation of poorly-crystallized calcium hydroxyapatite (Ca10(PO4)6(OH)2), which is one of main components in phosphate rock. In order to confirm the formation and purity of calcium phosphate species, the precipitation calcination was conducted at 1,078 K for 5 h. XRD revealed that the calcined solid was tricalcium phosphate, and no contamination was evident. These results reveal that a phosphate rock equivalent could be easily obtained from the incineration ash of chicken manure, which means that approximately 14% of the phosphate rock that is currently being imported into Japan could be replaced by this product.

Molecular speciation of phosphorus in phosphogypsum waste by solid-state nuclear magnetic resonance spectroscopy

Phosphogypsum (PG), a waste by-product of the phosphate fertilizer industry as well as a point-source P contaminant, has caused serious environmental problems particularly in estuarine and coastal regions. However, in-depth understanding of P speciation in PG, which is critical for its restoration and management, remains largely unknown. Using solid-state 31P NMR spectroscopy, density functional theory calculations of the NMR parameters and NanoSIMS, we for the first time reported that P in PG ubiquitously exists as phosphate incorporated into gypsum and minor fluorapatite. The occasional presences of mineral phosphate phases mainly associated with Ca and Al were also detected. The molecular environment of the incorporated phosphate is HPO42− substituting for SO42− in the gypsum lattice with the H atom away from the H2O molecules and almost parallel to the a–c plane. A high spatial heterogeneity was observed for the distribution of this phosphate species in PG at the submicron scale. Upon heating, at least 64% of the incorporated phosphate could be converted to the easy-to-recover fluorapatite or amorphous calcium phosphate by thermal treatments at above 750 °C for 2–4 h. This information of P speciation transformation may pave a solid basement for the sustainable recovery of P from PG.

Structure and Stability of High CaO- and P2O5-Containing Silicate and Borosilicate Bioactive Glasses.

The present work elucidates about the structure of bioactive glasses having chemical compositions expressed as (mol %) (50.0 - x)SiO2-xB2O3-9.3Na2O-37CaO-3.7P2O5, where x = 0.0, 12.5, 25, and 37.5, and establishes a correlation between the structure and thermal stability. The structural modifications in the parent boron-free glass (B0) with the gradual substitutions of B2O3 for SiO2 are assessed by Raman and 29Si, 31P, 11B, and 23Na magic angle spinning (MAS)-nuclear magnetic resonance (NMR) spectroscopies. The structural studies reveal the presence of QSi2 and QSi3 structural units in both silicate and borosilicate glasses. However, QSi4(3B) units additionally form upon incorporating B2O3 in B0 glass. B-containing silicate glasses exhibit both three-coordinated boron (BIII) and four-coordinated boron (BIV) units. The 31P MAS-NMR studies reveal that the majority of phosphate species exist as isolated orthophosphate (QP0) units. The incorporation of B2O3 in B0 glass increases the cross-linking between the SiO4 and BO4 structural units. However, incorporation of B2O3 lowers the glass thermal stability (ΔT), as shown by differential scanning calorimetry. Although both silicate and borosilicate glasses exhibit good in vitro apatite-forming ability and cell compatibility, the bactericidal action against Escherichia coli bacteria is more evident in borosilicate glass in comparison to silicate base glass. The controlled release of (BO3)3- ions from boron-modified bioactive glasses improves both the cell proliferation and the antibacterial properties, making them promising for hard tissue engineering applications.

Interfacial Study of Nickel-Modified Pt(111) Surfaces in Phosphate-Containing Solutions: Effect on the Hydrogen Evolution Reaction.

The surface modification of electrodes attracts great interest in electrocatalysis. It has often been observed that deposition of foreign adatoms on the surface of an electrode can originate a significant enhancement in the catalytic activity. For example, it has been reported that nickel deposits on Pt surfaces improve the rate of the hydrogen evolution reaction (HER, Nature Energy 2017, 2, 17031). During the deposition process of such metal adlayers, the pH and the nature of the ions in the electrolyte play an important role. Phosphate species are typically used to prepare buffer solutions in a wide range of pH. Therefore, electrolytes containing phosphate species are used in a large number of applications. However, the effect of phosphate on platinum surface modification with nickel deposits has not been studied yet. In this work, new data about the interaction of phosphate with nickel adatoms deposited on Pt(111) at pH 5 is investigated using cyclic voltammetry and infrared spectroscopy. The results show that, when nickel is in solution, the phosphate ions are adsorbed at lower potentials than in the absence of nickel. In addition, Laser-Induced Temperature Jump Technique demonstrates that nickel facilitates the adsorption of phosphate because of a shift of the potential of zero charge (pzc) toward negative potentials. This increases the magnitude of the positive electric field on the electrode surface, at a given potential E>pzc, facilitating the adsorption of anions. CO displacement technique has been also employed to obtain additional information about co-adsorbed phosphate on nickel adlayers. Finally, the HER has been studied at pH 5 in the presence of nickel, with and without phosphate in the bulk solution.

Tribochemical Mechanisms of Trimethyl and Triethyl Phosphite on Oxidized Iron in Ultrahigh Vacuum

The surface chemistry of model lubricant additives, trimethyl phosphite (TMPi) and triethyl phosphite (TEPi), is studied on oxidized iron in ultrahigh vacuum (UHV) and the results compared with the gas-phase lubrication of TEPi on oxidized iron in a UHV tribometer. Oxide films are grown on a polycrystalline iron substrate and characterized by X-ray photoelectron spectroscopy (XPS) and assigned to the formation of an Fe3O4 film. Measurements of the friction coefficient and contact resistance of the oxide films show that the oxide film remains intact while rubbing in UHV at a normal load of 0.29 N. It is found that phosphite esters adsorb on the oxide by electron donation to the phosphorus atom, with a binding energy that increases in the order tributyl phosphite > TMPi > TEPi, and correlates well with the location of the vacant lowest-occupied molecular orbital (LUMO) energy. The phosphite esters decompose via sequential P‒O bond scission to form adsorbed alkoxy species, which then react on the surface either by hydrogen addition to form the corresponding alcohol, or by hydrogen abstraction to yield an aldehyde. XPS studies of the surface shows that essentially no carbon remains after the TMPi has reacted, while a small amount of carbon is present when TEPi has decomposed. On heating, the phosphite esters convert to phosphate species. Gas-phase lubrication experiments in the presence of 1 × 10−7 Torr of gas-phase TEPi reveal that the friction coefficient is significantly reduced, where the friction reduction is found to increase with increasing reaction temperature. The friction reduction correlates well with the proportion of phosphate product formed in the film and indicates that the formation of phosphate tribofilm is primarily responsible for reducing friction. However, friction is also reduced for a reaction at ~ 300 K, lower than the temperature at which the adsorbed phosphite ester reacts, suggesting that its rate of decomposition could be accelerated by interfacial shear.

Experimental and thermodynamic studies of phosphate behavior during the hydrothermal carbonization of sewage sludge.

Recovered phosphate from sewage sludge is becoming a key product in the fertilizer market. This study investigates the fate of phosphate during the hydrothermal carbonization of digested sewage sludge to support the development of an economic and sustainable solution for dealing with sewage sludge for phosphate recovery. The solid products from the hydrothermal carbonization of digested sewage sludge in a batch reactor (180, 220, and 260 °C; 1, 2, and 4 h; digested sewage sludge-to-water ratios of 0.2 and 0.1 w/w) were analyzed using a sequential chemical extraction procedure to understand and predict the formation of phosphate species and the related extraction behavior of phosphate. The obtained results were compared with the thermochemical equilibrium composition of hydrothermal carbonization products, calculated using the software FactSage 7.2. The majority of phosphate was retained as Al, Ca, and Fe salts in hydrochar. The decomposition of organic phosphates was observed by processing at lower temperatures. Hydrothermal carbonization at temperatures higher than 180 °C resulted in the transformation of the Al-bound phosphate into Ca-bound phosphate. Hydroxyapatite (Ca5(PO4)3(OH)) and Fe7(PO4)6 were calculated as stable phosphate-containing minerals at equilibrium. This study suggests that kinetic constraints inhibit the formation of these minerals in the batch reactor and presents a mechanism of phosphate transformation using the obtained data. The results allow for targeted optimization of phosphate recovery strategy.

Are pharmaceuticals removal and membrane fouling in electromembrane bioreactor affected by current density?

Pharmaceutical active compounds (PhACs) have been detected at significant concentrations in various natural and artificial aquatic environments. In this study, electro membrane bioreactor (eMBR) technology was used to treat simulated municipal wastewater containing widely-used pharmaceuticals namely amoxicillin (AMX), diclofenac (DCF) and carbamazepine (CBZ). The effects of varying current density on the removal of PhACs (AMX, DCF and CBZ) and conventional pollutants (chemical oxygen demand (COD), dissolved organic carbon (DOC), humic substances, ammonia nitrogen (NH4-N), nitrate nitrogen (NO3-N) and orthophosphate (PO4-P) species) were examined. High COD and DOC removal efficiencies (~100%) were obtained in all the experimental runs regardless of applied current density. In contrast, enhanced removal efficiencies for AMX, DCF and CBZ were achieved at high current densities. Membrane fouling rate in eMBR with respect to conventional MBR was reduced by 24, 44 and 45% at current densities of 0.3, 0.5 and 1.15 mA/cm2, respectively. The mechanism for pharmaceutical removal in this study proceeded by: (1) charge neutralization between negatively-charged pharmaceutical compounds and positive electro-generated aluminium coagulants to form larger particles and (2) size exclusion by membrane filtration.

On the kinetics of methanol dehydration to dimethyl ether on Zr-loaded P-containing mesoporous activated carbon catalyst

Selective methanol dehydration to DME has been investigated using activated carbon-based catalysts. An activated carbon was prepared by chemical activation of olive stones, a residue of the agri-food industry, with phosphoric acid followed by Zr loading (5% (w/w)). The activation process produced a considerable amount of chemically stable surface phosphorus complexes. The addition of Zr resulted in the formation of zirconium phosphate surface species, as revealed by XPS. TPD and catalytic reaction results determined that the presence of zirconium phosphate species bonded to the carbon surface were responsible for the high steady-state methanol conversion and DME selectivity achieved by this biomass-derived catalyst. A kinetic study for the selective methanol dehydration to DME was carried out on the Zr-loaded P-containing activated carbon catalyst and the corresponding kinetic and thermodynamic parameters were obtained. The reaction seems to proceed through a modified Langmuir-Hinshelwood mechanism (LH2), in which two methanol molecules are subsequently adsorbed on one active site. The competitive adsorption of water on the active sites was also addressed in the proposed mechanism. The activation energy for the DME production was calculated and a value of 70 kJ mol−1 was obtained.

Methanol Dehydration to Dimethyl Ether on Zr-Loaded P-Containing Mesoporous Activated Carbon Catalysts.

Activated carbons have been prepared by the chemical activation of olive stones with phosphoric acid and loaded with Zr. The addition of Zr to the phosphorus-containing activated carbons resulted in the formation of zirconium phosphate surface groups. Gas phase methanol dehydration has been studied while using the prepared Zr-loaded P-containing activated carbons as catalysts. Carbon catalysts showed high steady-state methanol conversion values, which increased with Zr loading up to a limit that was related to P content. The selectivity towards dimethyl ether was higher than 95% for all Zr loadings. Zirconium phosphate species that were present on catalysts surface were responsible for the catalytic activity.

TIGAR promotes growth, survival and metastasis through oxidation resistance and AKT activation in glioblastoma.

Glioblastoma has a poor prognosis and is one of the most lethal types of cancer in the world. TP53 induced glycolysis regulatory phosphatase (TIGAR) is upregulated in various types of cancer. Therefore, the present study investigated the role of TIGAR in glioblastoma. TIGAR expression was measured in glioma samples and cell lines using immunohistochemistry and western blotting. Reduced nicotinamide adenine dinucleotide phosphate (NADPH), glutathione, malondialdehyde and intracellular reactive oxygen species levels were detected to measure oxidative stress in U-87MG cells following short hairpin RNA (shRNA)-mediated knockdown of TIGAR. Cell viability was determined using an MTT assay for TIGAR-overexpression vector- and TIGAR-shRNA-transfected U-87MG cells. Apoptosis was assessed to evaluate whether TIGAR knockdown sensitized cells to the antitumor effects of temozolomide (TMZ). Migration, invasion and epithelial-mesenchymal transition (EMT) were further assessed using Transwell and western blotting assays. A co-immunoprecipitation assay was used to detect the interaction between TIGAR and protein kinase B (AKT). The results of the present study revealed that TIGAR was positively associated with poor survival and was upregulated in glioblastoma. TIGAR knockdown significantly increased oxidative stress, decreased cell proliferation and exacerbated TMZ-induced apoptosis in U-87MG cells. Additionally, TIGAR knockdown decreased migration, invasion and EMT, and treatment of TIGAR-shRNA-transfected cells with NADPH had no effect on metastasis. In addition, TIGAR promoted AKT activation and bound to AKT. In conclusion, the present study demonstrated that TIGAR may promote glioblastoma growth and progression through oxidation resistance and AKT activation.

Dehydration of isopropanol to propylene over fullerene[C60] containing niobium phosphate catalyst: Study on catalyst recyclability

Synthesis of lower olefins from biomass is an attractive area of research as the petroleum feedstocks are limited day to day. A fullerene [C60] based niobium phosphate acid catalyst has been tested for isopropanol dehydration in gas phase for production of propylene and a thorough study has been undertaken on its recyclability. The physicochemical properties of the catalyst before and after reaction have been studied by several techniques, namely FTIR, FESEM, BET surface area, HRTEM, NH3-TPD, TGA, XRD and O2-TPO. The BET result suggests the trapping of coke within the micropores which retard the catalytic activity. Interestingly, the NH3-TPD profile demonstrates the abrupt increase in acidity of the used catalyst due to the widening of narrow pores while, CP-MAS 31 P NMR spectra show increase in population of hydrogen phosphate species may be caused by the decomposition of surfactant phosphoric acid complex. However, the UV–vis spectra support structural change by the oxidation of fullerene during regeneration leads to decrease in the acidity. The catalytic activity is evaluated in the temperature range 453–573 K, shows consistent performance up to 6th regenerated cycle with low activation energy (30 ± 5 kJ/mol). Furthermore, a detailed discussion of the reaction kinetics and reaction mechanism has also been demonstrated.

Regulation of the Bone Vascular Network is Sexually Dimorphic.

ABSTRACTOsteoblast (OB) lineage cells are an important source of vascular endothelial growth factor (VEGF), which is critical for bone growth and repair. During bone development, pubertal differences in males and females exist, but little is known about whether VEGF signaling contributes to skeletal sexual dimorphism. We have found that in mice, conditional disruption of VEGF in osteocalcin‐expressing cells (OcnVEGFKO) exerts a divergent influence on morphological, cellular, and whole bone properties between sexes. Furthermore, we describe an underlying sexual divergence in VEGF signaling in OB cultures in vitro independent of circulating sex hormones. High‐resolution synchrotron computed tomography and backscattered scanning electron microscopy revealed, in males, extensive unmineralized osteoid encasing enlarged blood vessel canals and osteocyte lacunae in cortical bone after VEGF deletion, which contributed to increased porosity. VEGF was deleted in male and female long bone–derived OBs (OBVEGKO) in vitro and Raman spectroscopic analyses of mineral and matrix repertoires highlighted differences between male and female OBVEGFKO cells, with increased immature phosphate species prevalent in male OBVEGFKO cultures versus wild type (WT). Further sexual dimorphism was observed in bone marrow endothelial cell gene expression in vitro after VEGF deletion and in sclerostin protein expression, which was increased in male OcnVEGFKO bones versus WT. The impact of altered OB matrix composition after VEGF deletion on whole bone geometry was assessed between sexes, although significant differences between OcnVEGFKO and WT were identified only in females. Our results suggest that bone‐derived VEGF regulates matrix mineralization and vascularization distinctly in males and females, which results in divergent physical bone traits.

Study of phosphate species of chernozem and sand soils by heterogeneous isotope exchange with 32P radioactive tracer

Weakly and tightly sorbed phosphate species on chernozem and humus sand are investigated by radioactive tracer method using 32P. The comparison of the heterogeneous isotope exchange of 32P-labeled phosphate of non-radioactively incubated soils and desorption of 32P-labeled phosphate of radioactively incubated soils shows the transformation of weakly sorbed species to tightly sorbed ones. The quantity of weakly sorbed phosphorus and the steady state phosphorus exchange rate between soil and soil solution, transformation half-life of weakly to tightly sorbed phosphate are calculated.

Studies on the adsorption of phosphate using lanthanide functionalized KIT- 6

Abstract The sorption of phosphorus (in the form of phosphate species) was investigated using lanthanide functionalised mesoporous KIT-6. Thirteen lanthanide functionalised KIT-6 materials were prepared and studied (La/KIT-6, Ce/KIT-6, Pr/KIT-6, Nd/KIT-6, Sm/KIT-6, Eu/KIT-6, Gd/KIT-6, Tb/KIT-6, Dy/KIT-6, Ho/KIT-6, Er/KIT-6, Tm/KIT-6, and Yb/KIT-6). The prepared materials were characterised using Small Angle X-Ray Scattering, X-Ray Diffraction, BET surface area analysis, HRTEM and electrostatic Zeta potential. Phosphate sorption tests using the prepared materials showed the La (22.76 mg/g), Pr (22.71 mg/g), Nd (22.45 mg/g), Yb (21.91 mg/g) and Sm (20.57 mg/g) functionalised KIT-6 materials achieved the highest sorption capacities under the conditions used (Temp. 25 °C, P conc. 22.80 mg/L, stirring rate 120 rpm, sorbent concentration 0.1 g/mL, in 6h). The higher capacities obtained with these materials were most likely due to a combination of the relatively higher basicity of these materials combined with their relatively low surface charge. The capacities were also most likely influenced by the differences in solubility between the lanthanide phosphates that could form due to chemisorption. Investigations on the influence of other anions (chloride, sulphate, nitrate, and bicarbonate) on phosphate removal showed that only bicarbonate had a significant negative effect on phosphate sorption for all the materials studied. The main finding from this research was that the surface zeta potential of the materials studied had a strong influence on phosphate adsorption.

Exploitation of a promising flame‐retardant engineering plastics by molten composited polyketone and diethyl zinc phosphinate

Aliphatic polyketone (POK) is a new engineering plastic owning outstanding mechanics, chemical resistance, and gas/liquid barrier properties. However, analogous to other polymers, the nature of combustion severely restricts the widespread application of POK. Herein, the diethyl zinc phosphinate (ZnPi) was compounded with three grades of POKs, which were different among each other in viscosity as low (L), medium (M), and high (H) levels, by melt mixing. It is intriguing to suggest that increasing the viscosity of POK could remarkably improve the dispersion homogeneity of ZnPi, which was beneficial to superior flame retardancy, simultaneously with comprehensive mechanical properties. For the H‐POK matrix, only 10% well‐dispersed ZnPi resulted in a V0 ranking with a good maintenance of its notched impact strength, whereas the load of ZnPi for reaching V0 rank increased to 14% in L‐POKs and M‐POKs and the mechanical performances decreased mildly. By a combination of scanning electron microscopy (SEM), Fourier‐transform infrared (FTIR), thermogravimetric analysis (TGA), and cone calorimetry, it is well revealed that the flame retardancy induced by adding ZnPi could mainly ascribe to the formation of various zinc phosphate species. This work exploits a facile and feasible method for fabrication of antiflame engineering plastics, which will be promising for large‐scale applicability of high‐performance POK materials.