Phosphating Modification with Metal Ions of Carbon Steel Surface to Improve the Influence of Anticorrosion Properties

The purpose of this research is to investigate the influence of the phosphatizing process with Ni2+, Ce3+, and Ti2+ ions on the properties of the coating to obtain better corrosion protection of the metal. Steel corrosion occurs through physicochemical interaction between the metal and its surrounding environment. This leads to a change in the metal’s physical, mechanical, and optical properties that can cause damage to the functionality of the metal, which in turn may result in accidents or other malfunctions. Carbon steel grade has limited resistance to corrosion, depending on the carbon content and alloying element, the microstructure, and the surrounding environment of the material. This paper present tests that have been carried out on some of the physicochemical properties of protective epoxy and polyurethane coating on carbon steel grade. Coatings represent one of the methods available to protect metal surfaces from corrosion. Coating properties such as thickness, hardness, and adhesion were investigated. The same properties were tested by exposing the sample plates to corrosive conditions of the humid chamber and seawater. Their anticorrosion properties were explored by electrochemical impedance spectroscopy (EIS) techniques under immersion in 3.5 wt.% NaCl solutions as a corrosive medium. Part of the samples prior to application of the coatingwere modified with a phosphate solution containing metal ions: Ni2+, Ce3+, and Ti2+ to further investigate the effects of phosphatization on the properties of the coating. After exposure of the plates to the salt and moist chamber conditions, no traces of corrosion products, cracking or peeling of the coating were found on the surfaces. The adhesion properties were tested by the pull-off adhesion test. It was found that metal/polymer adhesion was satisfied according to EN ISO 4624:2016 and had the same value for all samples. However, a detailed EIS analysis showed a higher resistance of phosphate samples with Ce3+ ions than samples that were phosphated with Ni2+ and Ti2+ ions and those that did not have a sparingly soluble phosphate salt layer.

Restoring Tumour Selectivity of the Bioreductive Prodrug PR-104 by Developing an Analogue Resistant to Aerobic Metabolism by Human Aldo-Keto Reductase 1C3

PR-104 is a phosphate ester pre-prodrug that is converted in vivo to its cognate alcohol, PR-104A, a latent alkylator which forms potent cytotoxins upon bioreduction. Hypoxia selectivity results from one-electron nitro reduction of PR-104A, in which cytochrome P450 oxidoreductase (POR) plays an important role. However, PR-104A also undergoes ‘off-target’ two-electron reduction by human aldo-keto reductase 1C3 (AKR1C3), resulting in activation in oxygenated tissues. AKR1C3 expression in human myeloid progenitor cells probably accounts for the dose-limiting myelotoxicity of PR-104 documented in clinical trials, resulting in human PR-104A plasma exposure levels 3.4- to 9.6-fold lower than can be achieved in murine models. Structure-based design to eliminate AKR1C3 activation thus represents a strategy for restoring the therapeutic window of this class of agent in humans. Here, we identified SN29176, a PR-104A analogue resistant to human AKR1C3 activation. SN29176 retains hypoxia selectivity in vitro with aerobic/hypoxic IC50 ratios of 9 to 145, remains a substrate for POR and triggers γH2AX induction and cell cycle arrest in a comparable manner to PR-104A. SN35141, the soluble phosphate pre-prodrug of SN29176, exhibited superior hypoxic tumour log cell kill (>4.0) to PR-104 (2.5–3.7) in vivo at doses predicted to be achievable in humans. Orthologues of human AKR1C3 from mouse, rat and dog were incapable of reducing PR-104A, thus identifying an underlying cause for the discrepancy in PR-104 tolerance in pre-clinical models versus humans. In contrast, the macaque AKR1C3 gene orthologue was able to metabolise PR-104A, indicating that this species may be suitable for evaluating the toxicokinetics of PR-104 analogues for clinical development. We confirmed that SN29176 was not a substrate for AKR1C3 orthologues across all four pre-clinical species, demonstrating that this prodrug analogue class is suitable for further development. Based on these findings, a prodrug candidate was subsequently identified for clinical trials.

Assessment of High Salinity Wastewater Treatment with Dewatered Alum Sludge-Aerobic Membrane Reactor

The discharge of wastewater containing both high salinity and high organic content without prior treatment is detrimental to aquatic life and water hygiene. In order to integrate the advantages of membrane treatment and biological treatment, and exert the phosphorus removal efficiency of dewatered alum sludge, in this study, an aerobic membrane reactor based on dehydrated alum sludge was used to treat mustard tuber wastewater with salinity of 6.8-7.3 % under the conditions of 30 °C, 20 kPa trans-membrane pressure (TMP) and chemical oxygen demand (COD) of 3300-3900 mg/L. Three replicate reactors were applied to assess the operational performance under different organic loading rate (OLR). The results showed that all reactors were effective in removing COD, ammonia nitrogen (NH4 +-N) and soluble phosphate (SP) under the conditions of 30 °C and 20 kPa of TMP. Meanwhile, the effluent concentration of COD, NH4 +-N and SP all increased while OLR was changed from 1.0 to 3.0 kg COD/m3/day, and the effluent COD and NH4 +-N concentration except for SP could reach the B-level of Chinese “Wastewater quality standards for discharge to municipal sewers” when OLR was less than 3.0 kg COD/m3/day. This indicates that dewatered alum sludge-based aerobic membrane reactor is a promising bio-measure for treating high salinity wastewater.

Influence of flow rate on the transport of nTiO2 and phosphate and its modeling

We studied Zeta potentials of nanoparticles titanium dioxides （nTiO2） in different concentration of NaNO3 and phosphate (P) solutions. In addition, the effect of flow rate on the transport of nTiO2 in P was investigated at pH＝6.5. Experimental results show that the Zeta potential of nTiO2 is compressed with the increasing ion concentration (IC) of NaNO3 at pH＝6.5. The negative charge increases with the augment of P. Therefore, the high P and low NaNO3 induce the stabilization of nTiO2 aggregates. The transport experiments suggest that the rapid flow rate is favorable for the transportability of nTiO2 and soluble phosphate. The breakthrough transport curves (BTCs) of nTiO2 in sand columns can be fitted well with two-site kinetic attachment model. The modeling results suggest that the values of first-order attachment rate coefficients (k2) and detachment rate coefficients (k2d) on site 2 and first-order attachment rate coefficients (k1) on site 1 are responsible to the attaching efficiency of nTiO2 on sands and their transportability.

Corrosion Inhibition Mechanism of Steel Reinforcements in Mortar Using Soluble Phosphates: A Critical Review

The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (Na2PO3F) (MFP), disodium hydrogen phosphate (Na2HPO4) (DHP) and trisodium phosphate (Na3PO4) (TSP), embedded in mortar. Phosphate corrosion inhibitors have been deployed in two different ways, as migrating corrosion inhibitors (MCI), or as admixed corrosion inhibitors (ACI). The chemical stability of phosphate corrosion inhibitors depends on the pH of the solution, H2PO4− ions being stable in the pH range of 3–6, the HPO42− in the pH range of 8–12, while the PO43− ions are stable above pH 12. The formation of iron phosphate compounds is a thermodynamically favored spontaneous reaction. Phosphate ions promote ferrous phosphate precipitation due to the higher solubility of ferric phosphate, thus producing a protective barrier layer that hinders corrosion. Therefore, the MFP as well as the DHP and TSP compounds are considered anodic corrosion inhibitors. Both types of application (MCI and ACI) of phosphate corrosion inhibitors found MFP to present the higher inhibition efficiency in the following order MFP > DHP > TSP.

A Low Cost of Burning Raw Material For PO43−-P And F− Solidification/Stabilization In Phosphogypsum

Phosphogypsum (PG) contains a lot of soluble phosphate (PO4 3−-P) and fluorine ion (F−), which seriously has hindered the sustainable development of phosphorous chemical industry. In this study, a new burning raw material (BRM) was used for the stabilize of PO43−-P and F− in PG. The characteristics of PG and BRM, stabilize mechanism of PO43−-P and F−, leaching test and economic evaluation were investigated. The effect of PG and BRM weight ratio, solid to liquid ratio, reaction time and reaction temperature on the concentrations of PO43−-P and F− were studied. The results showed that the concentration of F− in PG leaching solution was 8.65 mg/L and the removal efficiency of PO43−-P was 99.78 %, as well as the pH of PG leaching solution was 8.12, when the weight ratio of PG and BRM was 100:2, and the solid to liquid ratio was 4:1, reacting for 24 h at the temperature of 30 ℃. PO43−-P and F− were mostly solidified as Ca5(PO4)3F, CaPO3(OH), Ca5(PO4)3(OH), Ca2P2O7·2H2O, CaSO4PO3(OH)·4H2O, CaF2, and CaFPO3·2H2O. Leaching test results indicated that the concentrations of PO4 3−-P, F− and heavy metals were less than the integrated wastewater discharge standard (GB8978-1996). Economic evaluation revealed that the cost of PG treatment was $ 0.88/ton. This study provides a new low cost and harmless treatment method for PG.

Characterization of Pseudomonas bacteria of Piper tuberculatum regarding the production of potentially bio-stimulating compounds for plant growth

ABSTRACT Despite advances in the identification and characterization of endophytic bacteria in various plant species worldwide, little is known about such microorganisms in plants from the Amazon region. Previous studies reported that Piper tuberculatum endophytic Pseudomonas (isolates Pt12 and Pt13, identified as Pseudomonas putida and Pseudomonas sp., respectively) were able to inhibit the in vitro growth of Fusarium solani f. sp. piperis, which causes root rot in black pepper (Piper nigrum), and that Pt13 promoted the growth of P. nigrum. Therefore, the aim here was to characterize these bacteria regarding their ability to produce plant growth-promoting substances [siderophores, indol acetic acid (IAA) and soluble phosphate]. Chrome azurol S assays were performed for the detection of siderophores. For qualitative and quantitative assays of IAA production and phosphate solubilization, Salkowski´s reagent and NBRIP medium with molybdenum blue reagent, respectively, were used. Results revealed that Pt12 and Pt13 were able to synthesize IAA, mainly under a high concentration of L-tryptophan, indicating that they are IAA-producing bacteria, probably through a tryptophan-dependent biosynthesis pathway. The presence of P. nigrum extract positively influenced the IAA production by Pt12 and Pt13, with highest values of 125 and 90 µg mL-1, respectively. In addition, Pt12 was positive for the production of siderophores and produced 56.56 µg mL-1 of soluble phosphate. In contrast, Pt13 showed no ability to produce siderophores or to solubilize phosphate. Besides their potential in controlling plant diseases, Pt12 and Pt13 have potential as biofertilizers, favoring sustainable agriculture.