scholarly journals Mechanism of the process of decomposition of apatitis with phosphoric acid

2019 ◽  
Vol 81 (1) ◽  
pp. 294-297
Author(s):  
R. F. Sabirov ◽  
A. F. Makhotkin ◽  
Yu. N. Sakharov ◽  
I. A. Makhotkin ◽  
I. Yu. Sakharov
Keyword(s):  
Phosphoric Acid ◽  
Ph Value ◽  
Batch Reactor ◽  
Experimental Studies ◽  
Hydrogen Ions ◽  
Experimental Conditions ◽  
Monocalcium Phosphate ◽  
Ph Values ◽  
Whole Process ◽  
Proportional Increase

Experimental studies of the kinetics and mechanism of the process, decomposition of apatite by phosphoric acid, in the Apatite-H3PO4-H2O system without the addition of sulfuric acid have been performed. The study of the decomposition process of Kovdorsky apatite with certain particle sizes was carried out in a batch reactor with a volume of 1 dm3 with stirring of the reaction mixture, and an initial concentration of phosphoric acid of 17% by weight, at a temperature of 78–82 °C. Observation of the process was carried out by determining the concentration of phosphoric acid and the concentration of monocalcium phosphate. The acidity of the reaction mixture was determined by the pH meter readings (pH-105 MA with a glass combined-ESC-10603 electrode). It was shown that during the whole process a constant smooth increase in the pH value of the reaction mixture to pH 6 occurs. Comparison of the pH values of the reaction mixture during the actual at the time of determining the concentration of phosphoric acid and pH of phosphoric acid of the corresponding concentration in the aqueous solution shows that the pH value of the reaction mixture is significantly affected by the presence of monocalcium phosphate gel. During the process, during the first thirty minutes, the concentration of phosphoric acid decreases from 17 to 10% by weight, the corresponding quantitative formation of monocalcium phosphate gel and a proportional increase in the pH of the reaction mixture. Then, as the concentration of phosphoric acid decreases, the process slows down and does not proceed to the end under the experimental conditions. The dependence of the concentration of hydrogen ions in the reaction mixture on the time of the process of decomposition of apatite in phosphoric acid, which is presented in logarithmic coordinates, shows that the mechanism of formation of hydrogen ions during the whole process does not change. Thus, it is shown that the process of decomposition of apatite by phosphoric acid in the Apatite-H3PO4-H2O system proceeds with the formation of an intermediate product - monocalcium phosphate gel. When this occurs, a corresponding significant change in the pH values of the reaction mixture occurs. During the whole process there is a constant decrease in the concentration of phosphoric acid.

scholarly journals Change of acidity of the environment in the process of decomposition of apatitis sulfuric acid

2019 ◽  
Vol 81 (1) ◽  
pp. 325-328
Author(s):  
R. F. Sabirov ◽  
A. F. Makhotkin ◽  
Yu. N. Sakharov
Keyword(s):  
Sulfuric Acid ◽  
Phosphoric Acid ◽  
Ph Value ◽  
Raw Materials ◽  
Batch Reactor ◽  
Glass Electrode ◽  
Monocalcium Phosphate ◽  
Rapid Decomposition ◽  
Ph Values ◽  
Phosphoric Acids

An experimental study of the decomposition process of Kovdorsky apatite with certain particle sizes, in a 1 dm3 batch reactor with stirring of the reaction mixture, initial phosphoric acid concentration 17% by weight, in the system: Apatite-H3PO4 – H2SO4-H2O. Sulfuric acid was introduced in stoichiometric amount at the beginning of the process. The process was carried out at a ratio L:S 2.5:1, at a temperature of 78– 82 °C. The process was monitored by the method of joint determination of sulfuric and phosphoric acids by titrimetric analysis of the composition of the reaction mixture in the presence of methyl orange, and then phenolphthalein. Determined the concentration of phosphoric acid, the concentration of excess or deficiency of sulfuric acid and the concentration of monocalcium phosphate gel were determined. The acidity of the reaction mixture was recorded according to the indications of a Ph-meter (pH-105 MA with a combined glass electrode – ESK-10603). In the system: Apatite-H3PO4-H2SO4-H2O, when analyzing the obtained experimental values of these parameters, it was shown that during the process the pH of the reaction mixture rises to pH 6.3 for about 30 minutes, and then decreases to pH 4.5–5. Comparison of the dependence of pH values on the concentration of sulfuric acid in an aqueous solution of phosphoric acid and the pH values of the reaction mixture with the corresponding concentrations of sulfuric and phosphoric acids shows that the pH value of the reaction mixture is determined by the presence in the mixture between weft product - monocalcium phosphate gel. The process of decomposition of apatite in the system Apatite-H3PO4-H2SO4-H2O proceeds in several stages. At the beginning, a rapid decomposition of phosphate raw materials with phosphoric acid and a corresponding change in the pH of the reaction mixture, associated with the accumulation of monocalcium phosphate in solution, takes place. Then there is a slow decomposition of monocalcium phosphate with sulfuric acid and a corresponding decrease in pH to 4.5–5. The pH value at the end of the process is determined by the physicochemical properties of phosphoric acid present in the reaction mixture. At all stages of the process there is a constant increase in the concentration of phosphoric acid associated with the decomposition of monocalcium phosphate gel.

scholarly journals Study of the effect of stepped dosing of sulfuric acid in the process of decomposition of apatitis

2019 ◽  
Vol 58 (4) ◽  
pp. 123-126
Author(s):  
Rauf F. Sabirov ◽  
◽  
Alexey F. Makhotkin ◽  
Yury N. Sakharov ◽  
Igor A. Makhotkin ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Phosphoric Acid ◽  
Ph Value ◽  
Batch Reactor ◽  
Simultaneous Increase ◽  
Sharp Drop ◽  
Monocalcium Phosphate ◽  
Stoichiometric Amount ◽  
Insufficient Amount ◽  
Calculated Amount

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.

scholarly journals OPTIMIZATION OF STAGES OF PRE-SPAWNING AND SPAWNING PERIODS OF TILAPIA IN COMMERCIAL GROWING

2021 ◽  
Vol 2021 (3) ◽  
pp. 120-126
Author(s):  
Ekaterina Vasil'eva ◽  
Irina Melnik
Keyword(s):  
Vital Capacity ◽  
Ph Value ◽  
Necessary Condition ◽  
Commercial Fish ◽  
Feeding Level ◽  
Ph Values ◽  
Whole Process ◽  
Production Pattern ◽  
Spawning Periods ◽  
Minimal Prime

The article describes the process of commercial fish production in modern aquaculture, which requires high technologies and significant input. Optimization of technological processes while breeding fish is a necessary condition for the development of the industry. It is difficult and virtually impossible to develop a universal production pattern, this is why it is reasonable to split the whole process into several optimization tasks corresponding to each of the stages of the technological cycle. It is proposed to regulate such indicators as the level of feeding, pH value, age of producers as control actions at the stages of pre-spawning and spawning periods. The possibility to use the mentioned parameters for stage optimization, as well as for selecting the best values for each of the factors was assessed. The optimization target is to define the optimal amount of viable eggs, which would correspond to the minimal prime cost. It has been demonstrated that the optimal feeding level for the producers equals to 4 – 4.5 per cent of the fish body weight. The increase in the feeding level influences the fertility of producers insufficiently, inflating the costs. It has been found out that 12 – 24 months old producers have the best reproduction indices. The preferred quality and the vital capacity of spawn received from the producers within this group have also been registered. Another factor which may be used in order to control the process is the pH of water in pools. Regardless of the fact that tilapia producers are relatively undemanding to the habitat conditions and resistant to pH values, it is possible to single out the optimal range of this factor. It corresponds to pH values between 6 and 7.5. This is when the best rates of eggs fertilization and survival are observed.

Influence of Ionic Strength and pH-value on the Silicon Dioxide Polishing Behaviour of Slurries Based on Pure Silica Suspensions

2010 ◽  
Vol 1249 ◽  
Author(s):  
Ulrich Kuenzelmann ◽  
Kathrin Estel ◽  
Johann W Bartha ◽  
Erwin-Peter Meyer ◽  
Herbert Barthel
Keyword(s):  
Ionic Strength ◽  
Fumed Silica ◽  
Ph Value ◽  
Acidic Ph ◽  
Experimental Conditions ◽  
Ph Values ◽  
Pure Silica ◽  
Silica Sols ◽  
Ph Range ◽  
Silica Suspensions

AbstractIn this study, the effect of the addition of electrolytes in a given ionic strength to various high-purity silica suspensions was investigated by measurement of the removal rates (RR's) in CMP processes on oxide layers under the same experimental conditions. As so-called slurries the following suspensions were used: i) silica sols produced by the Stöber process, ii) conventional silica sols based on alkali silicate as well as iii) suspensions of fumed silica, with the same SiO2 concentration in each suspension. Ionic strength of the added electrolyte was adjusted to e.g. 0.065 mol/l, with the electrolytes being HCl, NH4Cl, KOH, or binary mixtures of these substances.These investigations revealed significant differences of the polishing behaviour between the different types of silica dispersions as slurries. While for the Stöber sols investigated, the RR's are highest in the acidic range and almost negligible in the alkaline pH range, fumed silica suspensions show an entirely different behaviour: RR is very low for acidic pH-values, and increases with the alkalinity of the slurry. In contrast to these observations, the RR's of slurries based on conventional silica sols are highest around the neutral point, and show a decrease for both more alkaline and acidic pH-values. In comparison to the other two types of material, these suspensions have a high amount of electrolyte background, originating from their manufacturing process.A model is developed to explain these results in a comprehensive manner. It involves effects of the electrolyte type and the ionic strengths as well as influences of the particle size.

Separation of metals and phosphorus from incinerated sewage sludge ash

2013 ◽  
Vol 67 (11) ◽  
pp. 2488-2493 ◽  
Author(s):  
A. Ito ◽  
K. Yamada ◽  
N. Ishikawa ◽  
T. Umita
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Ethylenediaminetetraacetic Acid ◽  
Ph Value ◽  
Batch Reactor ◽  
The Other ◽  
Ferric Ion ◽  
Sewage Sludge Ash ◽  
Ph Values ◽  
Sludge Ash

Microbial acidification of incinerated sewage sludge ash and dissolution of metals from the acidified ash were investigated using a semi-batch reactor at different solid retention times (SRTs). The average pH values ranged from 0.91 to 1.2 at SRTs longer than 10 days, whereas the reduction of SRT to 4 days resulted in an increase in the pH value to about 2. The dissolution efficiencies of Al, As, Cd, Cu and Mn were greater than 60% at a SRT of 4 days. Moreover, the effect of pH on precipitation of metals and P (dissolution of 80%) in the filtrate removed from the acidified sewage ash suspension, and the separation of phosphorus and the other metals in the filtrate using ethylenediaminetetraacetic acid (EDTA) or ferric ion, were examined. Although neutralisation of the filtrate to a pH of 5 simultaneously precipitated 100% of Al and 80% of P recovered from the acidified sewage ash, the addition of EDTA decreased their precipitation to 70 and 50%, respectively, at the same pH value, which would promote precipitation of P as calcium phosphate. Furthermore, neutralising to a pH of 2.5 after the addition of ferric ion precipitated P separately from Al and heavy metals.

The experimental study of Cr6+ contaminated water remediation by zero-valent nano-Fe

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542044 ◽  
Author(s):  
X. N. Sun ◽  
A. P. Liu ◽  
Q. F. Chen ◽  
X. Wang
Keyword(s):  
Experimental Study ◽  
Ph Value ◽  
Reaction Times ◽  
Water Remediation ◽  
Contaminated Water ◽  
Soil Leaching ◽  
Removal Rates ◽  
Experimental Conditions ◽  
Ph Values ◽  
Soil And Water

In recent years, researchers have developed a number of new types of zero-valent nano-Fe remediation materials applied in the remediation of contaminated soil and water, which has attracted wide attentions. This paper selected soil leaching wastewater severely contaminated by chromium as target of the study and chose zero-valent nano-Fe, [Formula: see text] and [Formula: see text] for comparison experiments to study the effects on removing [Formula: see text] under experimental conditions of different pH values, dosages and reaction times. As is shown in the experiments, zero-valent nano-Fe has the highest removal rates for [Formula: see text], while the reaction of [Formula: see text] is the slowest under the same conditions. However, both removal rates are prone to be stable after 10 min. Dosages do not make a distinct difference and the pH value has the least effect on the repair of zero-valent nano-Fe.

Molecularly Imprinted Sensor for Ascorbic Acid Based on Gold Nanoparticles and Multiwalled Carbon Nanotubes

2020 ◽  
Vol 16 (7) ◽  
pp. 905-913
Author(s):  
Youyuan Peng ◽  
Qingshan Miao
Keyword(s):  
Carbon Nanotubes ◽  
Gold Nanoparticles ◽  
Ascorbic Acid ◽  
Multiwalled Carbon Nanotubes ◽  
Ph Value ◽  
Biological Fluids ◽  
Water Soluble ◽  
Multiwalled Carbon ◽  
Experimental Conditions ◽  
Molecularly Imprinted

Background: L-Ascorbic acid (AA) is a kind of water soluble vitamin, which is mainly present in fruits, vegetables and biological fluids. As a low cost antioxidant and effective scavenger of free radicals, AA may help to prevent diseases such as cancer and Parkinson’s disease. Owing to its role in the biological metabolism, AA has also been utilized for the therapy of mental illness, common cold and for improving the immunity. Therefore, it is very necessary and urgent to develop a simple, rapid and selective strategy for the detection of AA in various samples. Methods: The molecularly imprinted poly(o-phenylenediamine) (PoPD) film was prepared for the analysis of L-ascorbic acid (AA) on gold nanoparticles (AuNPs) - multiwalled carbon nanotubes (MWCNTs) modified glass carbon electrode (GCE) by electropolymerization of o-phenylenediamine (oPD) and AA. Experimental parameters including pH value of running buffer and scan rates were optimized. Scanning electron microscope (SEM), fourier-transform infrared (FTIR) spectra, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized for the characterization of the imprinted polymer film. Results: Under the selected experimental conditions, the DPV peak currents of AA exhibit two distinct linear responses ranging from 0.01 to 2 μmol L-1 and 2 to 100 μmol L-1 towards the concentrations of AA, and the detection limit was 2 nmol L-1 (S/N=3). Conclusion: The proposed electrochemical sensor possesses excellent selectivity for AA, along with good reproducibility and stability. The results obtained from the analysis of AA in real samples demonstrated the applicability of the proposed sensor to practical analysis.

Donnan Equilibria in Polymeric Micellar Systems with Weak Polyelectrolyte Shells: The Lowering of the pH Value

1997 ◽  
Vol 62 (11) ◽  
pp. 1730-1736 ◽  
Author(s):  
Petr Munk ◽  
Zdeněk Tuzar ◽  
Karel Procházka
Keyword(s):  
Ionic Strength ◽  
Block Copolymer ◽  
Ph Value ◽  
Electrolyte Solutions ◽  
Hydrogen Ions ◽  
Micellar Systems ◽  
Weak Electrolytes ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Polyelectrolyte Solutions

When two electrolyte solutions are separated and only some of the ions can cross the boundary, the concentrations of these ions are different on both sides of the boundary. This is the well-known Donnan effect. When weak electrolytes are involved, the imbalance includes also hydrogen ions: there is a difference of pH across the boundary and the dissociation of nondiffusible weak electrolytes is suppressed. The effect is very pronounced when the concentration of the weak electrolyte is high and ionic strength is low. The significance of this phenomenon is discussed for polyelectrolyte solutions, and particularly for block copolymer micelles with weak polyelectrolyte shells. The effect is quite dramatic in the latter case.

scholarly journals Zeolite NaP1 Functionalization for the Sorption of Metal Complexes with Biodegradable N-(1,2-dicarboxyethyl)-D,L-aspartic Acid

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2518
Author(s):  
Dorota Kołodyńska ◽  
Yongming Ju ◽  
Małgorzata Franus ◽  
Wojciech Franus
Keyword(s):  
Experimental Data ◽  
Aspartic Acid ◽  
Ph Value ◽  
Complexing Agents ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Modified Zeolite ◽  
X Ray ◽  
Slow Release Fertilizers ◽  
Pseudo Second Order

The possibility of application of chitosan-modified zeolite as sorbent for Cu(II), Zn(II), Mn(II), and Fe(III) ions and their mixtures in the presence of N-(1,2-dicarboxyethyl)-D,L-aspartic acid, IDHA) under different experimental conditions were investigated. Chitosan-modified zeolite belongs to the group of biodegradable complexing agents used in fertilizer production. NaP1CS as a carrier forms a barrier to the spontaneous release of the fertilizer into soil. The obtained materials were characterized by Fourier transform infrared spectroscopy (FTIR); surface area determination (ASAP); scanning electron microscopy (SEM-EDS); X-ray fluorescence (XRF); X-ray diffraction (XRD); and carbon, hydrogen, and nitrogen (CHN), as well as thermogravimetric (TGA) methods. The concentrations of Cu(II), Zn(II), Mn(II), and Fe(III) complexes with IDHA varied from 5–20 mg/dm3 for Cu(II), 10–40 mg/dm3 for Fe(III), 20–80 mg/dm3 for Mn(II), and 10–40 mg/dm3 for Zn(II), respectively; pH value (3–6), time (1–120 min), and temperature (293–333 K) on the sorption efficiency were tested. The Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin adsorption models were applied to describe experimental data. The pH 5 proved to be appropriate for adsorption. The pseudo-second order and Langmuir models were consistent with the experimental data. The thermodynamic parameters indicate that adsorption is spontaneous and endothermic. The highest desorption percentage was achieved using the HCl solution, therefore, proving that method can be used to design slow-release fertilizers.

scholarly journals Study on Chromaticity Removal from Mineral Processing Wastewater with Salicylic Hydroxamic Acid by Granular Activated Carbon Catalyzed Ozonation

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 359
Author(s):  
Liping Zhang ◽  
Shengnian Wu ◽  
Nan Zhang ◽  
Ruihan Yao ◽  
Eryong Wu
Keyword(s):  
Activated Carbon ◽  
Reaction Time ◽  
Hydroxamic Acid ◽  
Ph Value ◽  
Oxygen Demand ◽  
Granular Activated Carbon ◽  
Mineral Processing ◽  
Ultraviolet Absorption Spectrum ◽  
Experimental Conditions ◽  
Removal Ratio

Salicylic hydroxamic acid is a novel flotation reagent used in mineral processing. However, it impacts the flotation wastewater leaving behind high chromaticity which limits its reuse and affects discharge for mining enterprises. This study researched ozonation catalyzed by the granular activated carbon (GAC) method to treat the chromaticity of the simulated mineral processing wastewater with salicylic hydroxamic acid. The effects of pH value, ozone (O3) concentration, GAC dosage, and reaction time on chromaticity and chemical oxygen demand (CODCr) removal were discussed. The results of individual ozonation experiments showed that the chromaticity removal ratio reached 79% and the effluent chromaticity exceeded the requirement of reuse and discharge when the optimal experimental conditions were pH value 3, ozone concentration 6 mg/L, and reaction time 40 min. The orthogonal experimental results of catalytic ozonation with GAC on chromaticity removal explained that the chromaticity removal ratio could reach 96.36% and the chromaticity of effluent was only 20 when the optimal level of experimental parameters was pH value 2.87, O3 concentration 6 mg/L, GAC dosage 0.06 g/L, reaction time 60 min respectively. The degradation pathway of salicylic hydroxamic acid by ozonation was also considered based on an analysis with ultraviolet absorption spectrum and high-performance liquid chromatography (HPLC).

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