Gases formed from furan binding agents.

Phosphoric acid concentration affects dentinal MMPs activity

An experimental study of the effect of stepwise dosing of sulfuric acid in the process of decomposition of apatite with sulfuric acid has been performed. The process of decomposition of apatite in the apatite-H3PO4-H2SO4-H2O system was carried out with stepwise dosing of sulfuric acid. At the beginning of the process, the calculated amount of phosphoric acid and half of the stoichiometric amount of sulfuric acid required for the decomposition of the loaded amount of apatite was loaded into the batch reactor. It was experimentally shown that the pH of the reaction mixture at the beginning of the process increases to a pH value of 6.13, at the same time there is a decrease in the concentration of sulfuric acid and the formation of phosphoric acid, this is due to the decomposition of apatite in the reaction mixture. Already in the seventh minute, the concentration of sulfuric acid is zero, and the concentration of phosphoric acid has the first peak value, after which it begins to decrease. Thus, at the beginning of the process, the formation of phosphoric acid occurs due to the decomposition of apatite with sulfuric acid. Since sulfuric acid was added at the beginning of the process with a deficiency (0.5 mol) of sulfuric acid is not enough to decompose the charged apatite, a decrease in the concentration of phosphoric acid and the formation of monocalcium phosphate are observed after the peak. This is due to the consumption of phosphoric acid on the decomposition of the remaining apatite with the formation of monocalcium phosphate. At the 140th minute, the remaining stoichiometric amount of sulfuric acid was added to the reactor (0.5 mol), a sharp drop in pH to 5.48 and a simultaneous increase in the concentration of phosphoric acid were observed. Consequently, sulfuric acid is consumed for the decomposition of monocalcium phosphate. Thus, it was shown that with an insufficient amount of sulfuric acid, the resulting phosphoric acid is spent on the decomposition of apatite with the formation of monocalcium phosphate. Adding sulfuric acid makes it possible to extract production phosphoric acid from monocalcium phosphate.

Furfurylation with a low concentration of furfuryl alcohol (FA) promotes the improvement of the properties and the effectiveness of FA on cell–wall action without darkening the furfurylated wood to the point that it affects its applications. In this paper, the effects of furfurylation on the hygroscopicity and water uptake dimensional stability of poplar (Populus sp.) and Chinese fir (Cunninghamia lanceolata) were analyzed. Meanwhile, the distribution of FA resin, the relationship between wood and water, the change in pore size distribution, and the weight percentage gain and cell wall bulking coefficient of wood were also investigated. The results were as follows: (1) A low concentration of FA could better enter the cell walls of the Chinese fir than the poplar, as FA resin was almost cured in the secondary walls, cell corners, and compound middle lamellae when a 10% concentration of FA was applied to the Chinese fir and poplar. When the FA concentration was increased to 30%, there were no significant increases in the amount of FA entering the cell walls and the amounts of FA cured in the cell lumen of the poplar were greater than those of the Chinese fir. Meanwhile, the modification of cell walls was more suitable in poplar than in Chinese fir. (2) The pointed ends of the pit chambers and the pit apertures (800–1000 nm) in the poplar and the small pores of the pit membranes and the pit apertures (1–6 μm) in the Chinese fir were partially deposited by the FA resin, which formed new pores in the size ranges of 80–600 nm and 15–100 nm, respectively. The porosity of the poplar was greater than that of the Chinese fir, and the bulk density of the poplar was less than that of the Chinese fir before and after modification. (3) Furfurylation with a low concentration of FA was able to better reduce the equilibrium moisture content, improve the anti-swelling efficiency, and enhance the dimensional stability of the poplar wood compared to the Chinese fir. Furfurylation effectively reduced water uptake due to the hydrophobic property of the FA resin. The water uptake of the Chinese fir increased by 17%–19% in second cyclic water soaking when treated with FA with various concentrations, which indicated the loss and leaching of FA resin during the test. Low-field NMR was used to demonstrate that the furfurylation not only reduced the amount of water but also affected the combination state of bound and free water with wood. Thus, furfurylation at a low concentration is a feasible method by which to extend applications of furfurylated wood.

<p>Phosphoric acid and papain enzyme able to hydrolyzing collagen from Tilapia into gelatin . The<br />purpose of this research was to determine the best concentration of phosphoric acid and papain enzyme<br />and to determine the physicochemical characteristic gelatin to from Tilapia fish bone which processed<br />with phosphoric acid and papain enzyme. The first research phase was making bone gelatin tilapia using<br />phosphoric acid at concentration of 4%, 5% and 6%, and the papain enzyme 0.5%, 1% and 1.5%. The<br />second phase was characterize the physicochemical gelatin from the best concentration of phosphoric acid<br />concentration (6%) and papain enzyme (1.5%), all treatment done with three repetitions. Analysis of the<br />data using ANOVA with completely randomized (CRD) design If there was difference between treatment<br />then continued with Honestly Significant Difference Test (HSDT). The results of the first research phase<br />found the best concentration were 6% of phosphoric acid and 1.5% papain enzyme, its shows by the value<br />gel strength 325,95 and 373,32 g.bloom. The second research phase shows that the the best results obtained<br />in this study was gelatin from 1.5% papain enzyme as hydrolysis agent, the physicochemical characteristic<br />were: 376.21 g.bloom gel strength; viscosity of 7.57 cP; yield 6.30%; protein content of 86.46%; water content<br />of 7.12%; and the pH value of 5.11.<br />Keywords : gelatin, hydrolysis, papain enzyme, phosphoric acid, tilapia bones</p>

One of the problems the aircraft industry faces is equipment that has decreased performance in the period before planning. The solution to this condition is that a material that has hard properties and is corrosion-resistant is needed. Aluminium is a metal that is applied as equipment in the industry because it has the characteristics of being light, strong, corrosion resistant and easy to shape, but has properties that are easy to deform, have low hardness and wear resistance. Anodizing process has the characteristics to improve the surface properties of aluminium metal in physical and mechanical properties. The anodizing process of aluminium metal using sulfuric acid solution produces a thicker oxide layer than in other solutions, such as phosphoric acid solution. This research studied the effect of phosphoric acid concentration on process efficiency, oxide layer thickness, and the hardness of the anodized oxide layer in 16% sulfuric acid solution. Phosphoric acid solution concentration varied from 0; 0.5; 1;2;4; and 8% in 16% sulfuric acid solution at 5 Volts voltage or 1.12 A/dm2 current density with 25 minutes processing time. The results showed that the anodizing process in 16% sulfuric acid solution had the lowest efficiency of 19.3% after adding variations in the concentration of phosphoric acid. These conditions reached the optimum in 16% sulfuric acid solution with the addition of 1% phosphoric acid; 26.6 mg oxide mass; 50.33% efficiency; 90.48 mg/dm2 oxide layer thickness and 86.57 HV metal surface hardness

Chemical activation of pine sawdust using aqueous solutions of phosphoric and boric acid was studied. Thermogravimetric analyses of the impregnated lignocellulosic precursor as well as their reactivities are presented. The role of the activating agents in the thermal decomposition of the precursor and their effects on the development of porosity in activated carbons is discussed. The use of boric acid as activating agent and a final heat treatment temperature (HTT) of 600 °C produced some porosity and activated carbons with a surface area of 600 m2 g−1. With a HTT of 450 °C, molecular sieve‐like materials were produced. In contrast, phosphoric acid activation produced activated carbons with high surface areas. The amount of phosphoric acid retained in the precursor was, as expected, a function of the initial concentration as well as the impregnation time and temperature. The fact that the activated carbon porosity increases with the phosphoric acid content per gram of precursor was confirmed. The use of 6 M phosphoric acid solution and HTT of 450 °C produced the activated carbon with the highest surface area, about 1600 m2 g−1. The high degree of microporosity which developed in phosphoric acid‐activated carbons is related to the low reactivity during the thermal treatment of chemical activation. The presence of up to 10% oxygen during HTT with phosphoric acid activation caused only small textural changes. Copyright © 2003 Society of Chemical Industry

This work involves the study of the operational performance of phosphoric acid based electrochemical hydrogen pumps with a polybenzimidazole (PBI) electrolytic membrane. During characterization of the device, the power consumption was found to be highly sensitive to the water vapor pressure in the supply gas stream which affects the phosphoric acid concentration. The power requirement was 30 times higher when the supply gas stream was not humidified than when the supply gas stream was humidified to a dew point of 60°C. The increase in power consumption was caused by a decrease in platinum catalyst activity due to the adsorption of a species on the platinum catalyst when the phosphoric acid concentration exceeded 72.4 wt% P2O5 (100 wt% H3PO4). The increase in power consumption can be prevented by humidifying the supply gas stream.

Corrosion behavior and passive film properties of nickel-based alloy in phosphoric acid

A new reductimetric reagent: iron II in a strong phosphoric acid medium—III : Titration of vanadium IV or vanadium V with iron II at room temperature: determination of chromium VI and vanadium V in the same solution

The electrochemical and corrosion behavior of Pb and Pb-In alloys in both phosphoric and sulfuric acid solutions containing various concentrations of phosphoric acid (0.05 to 0.20 M) at different temperatures was studied. Tafel plot and electrochemical impedance spectroscopy (EIS) techniques were used to obtain the experimental data, and the corrosion products formed on the surface were characterized by scanning electron microscopy (SEM). The results of both Tafel plot extrapolation and impedance measurements showed the same trend. Minor indium (0.5 %) alloying with lead significantly reduced corrosion rate in pure phosphoric acid solution. However, opposite behavior arises in the case of alloys containing indium more than 0.5 %, that is, the corrosion is higher than that of lead and alloy I. The corrosion current density decreases in both Pb and alloy I (0.5 %) in 4 M sulfuric acid with increasing the concentration of phosphoric acid up to 0.1 M, and then starts to increase relatively with increasing the additive concentration up to 0.2 M (but still lower than that in pure H2SO4). This exhibits that the higher concentration (0.2 M) of H3PO4 is less inhibitive of alloy I corrosion in H2SO4 solution. However, addition of phosphoric acid in various concentrations to sulfuric acid has little influence to inhibit the corrosion of alloys containing higher indium content (1 to 15 %). SEM photographs showed that the presence of indium as a minor alloying element retards the formation of PbSO4, but the formation of β-PbO2 enhances.

Development and characterization of novel activated carbons based on reed canary grass

Two major problems facing agriculture at present are soil pollution and the disposal of solid wastes generated during plant growth. The method of preparing biochar from solid wastes produced by plants is a means of maximizing the use of resources to combat the problem of soil pollution. In this study, we did not choose straw in the traditional sense but the waste branches from grape pruning, which has higher lignin cellulose, as the raw material. The biochar derived from grape branches pyrolyzed at 300˚C for two hours was utilized as a raw material to prepare modified biochar with varying concentrations of phosphoric acid. The adsorption performance and mechanism of Cd2 were explored through experiments involving different concentrations, addition amounts, reaction times, kinetic analyses, and isothermal adsorption tests. The findings indicated that the optimal adsorption of Cd2 occurred with a 20% phosphoric acid concentration, achieving the highest adsorption rate of 84.62%. At a dosage of 10 g/L, the maximum adsorption capacity reached 7.02 mg/g. The adsorption kinetics and isothermal adsorption of Cd2 on biochar modified with 0.2% phosphoric acid (0.2 PB) closely followed the pseudo-first-order kinetics model (R2 > 0.98) and the Freundlich model (R2 > 0.97), respectively. This suggests that the adsorption process involves both physical and chemical mechanisms. SEM and FTIR analyses revealed that phosphoric acid modification primarily increased the biochar’s specific surface area and enhanced certain original functional groups. The adsorption process predominantly involved rapid ion diffusion and chemical adsorption, as confirmed by kinetic analysis and isothermal adsorption model analysis. In summary, the adsorption efficiency of 0.2 PB significantly improved, showing potential and feasibility for heavy metal remediation in soil. This supports the environmentally friendly concept of “treating waste with waste”.

Uranium is recovered from wet phosphoric acid by a DEHPA/TOPO mixture. It was found that stripping is the most crucial step in this process. Several studies were undertaken to understand this process in greater depth. This study investigates the main operating variables, mainly concentration of phosphoric acid, temperature and concentration of iron on stripping, by the method of factorial design. A mathematical model was developed to represent the data. Another experiment was undertaken to find out the effect of fluoride ion on stripping. The results agree well with those of earlier investigations, namely that it is beneficial to increase the concentration of phosphoric acid and the temperature. The increase in fluoride ion concentration leads to an enhancement of the stripping distribution ratio.

To avoid undesired polymerization and maximize the selectivity of alkyl levulinate from the acid-catalyzed conversion of biomass-derived furfuryl alcohol, the effects of catalyst and reaction parameters on the formations of humin and alkyl levulinate were investigated. The results show that Amberlyst 15, of moderate acidic strength, was more favorable for the selective conversion of furfuryl alcohol to alkyl levulinate, and heteropolyacids of strong acidic strength tended to promote furfuryl alcohol polymerization. Compared with water as a reaction medium, alcohol significantly lowered humin formation and enhanced the yield of the resulting products. The formations of humin and alkyl levulinate were both favored at high catalyst loadings and reaction temperatures. An augmentation in initial furfuryl alcohol concentration caused an increase in humin formation and a decrease in alkyl levulinate yield. A high alkyl levulinate yield of up to 94% (100% furfuryl alcohol conversion) was achieved at 110 °C for 4 h with 5 g/L Amberlyst 15 catalyst and an initial furfuryl alcohol concentration of 0.1 mol/L. At this point, about 5% furfuryl alcohol was polymerized to form the humin, and its polymerization occurred mainly during the initial reaction stage.

To avoid undesired polymerization and maximize the selectivity of alkyl levulinate from the acid-catalyzed conversion of biomass-derived furfuryl alcohol, the effects of catalyst and reaction parameters on the formations of humin and alkyl levulinate were investigated. The results show that Amberlyst 15, of moderate acidic strength, was more favorable for the selective conversion of furfuryl alcohol to alkyl levulinate, and heteropolyacids of strong acidic strength tended to promote furfuryl alcohol polymerization. Compared with water as a reaction medium, alcohol significantly lowered humin formation and enhanced the yield of the resulting products. The formations of humin and alkyl levulinate were both favored at high catalyst loadings and reaction temperatures. An augmentation in initial furfuryl alcohol concentration caused an increase in humin formation and a decrease in alkyl levulinate yield. A high alkyl levulinate yield of up to 94% (100% furfuryl alcohol conversion) was achieved at 110 °C for 4 h with 5 g/L Amberlyst 15 catalyst and an initial furfuryl alcohol concentration of 0.1 mol/L. At this point, about 5% furfuryl alcohol was polymerized to form the humin, and its polymerization occurred mainly during the initial reaction stage.