scholarly journals Effects of Buffering Properties and Undissociated Acid Concentration on Dissolution of Dental Enamel in Relation to pH and Acid Type

2013 ◽  
Vol 47 (6) ◽  
pp. 601-611 ◽  
Author(s):  
R.P. Shellis ◽  
M.E. Barbour ◽  
A. Jesani ◽  
A. Lussi
Keyword(s):  
Acid Concentration ◽  
Dental Enamel ◽  
Acid Type ◽  
Undissociated Acid

scholarly journals Ammonia recovery from human urine as liquid fertilizers in hollow fiber membrane contactor: Effects of permeate chemistry

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Mekdimu Mezemir Damtie ◽  
Federico Volpin ◽  
Minwei Yao ◽  
Leonard Demegilio Tijing ◽  
Ruth Habte Hailemariam ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Phosphoric Acid ◽  
Acid Concentration ◽  
Hollow Fiber ◽  
Human Urine ◽  
Hollow Fiber Membrane ◽  
Membrane Contactor ◽  
Fiber Membrane ◽  
Acid Type

The production of the existing nitrogen fertilizer is costly and less environmental-friendly. Various green technologies are currently emerging toward providing alternative options. In this study, a liquid/liquid hydrophobic hollow-fiber membrane contactor was employed at ambient temperature and natural urine pH ~ 9.7 to recover ammonium fertilizers from human urine. Results showed that permeate side chemistry was one of the major factors affecting the ammonia mass transfer. The study on the ammonia capturing performance of diluted sulfuric acid, phosphoric acid, nitric acid, and DI water confirmed that acid type, acid concentration, and permeate side operating pH were the most important parameters affecting the ammonia capturing tendency. Sulfuric acid was slightly better in capturing more ammonia than other acid types. The study also identified increasing acid concentration didn’t necessarily increase ammonia mining tendency because there was always one optimum concentration value at which maximum ammonia extraction was possible. The best permeate side operating pH to extract ammonia for fertilizer purposes was selected based on the dissociation equilibrium of different types of acids. Accordingly, the analysis showed that the membrane process has to be operated at pH > 3 for sulfuric acid, between 3.5 to 11.5 for phosphoric acid, and above 0.5 for nitric acid so as to produce their respective high-quality liquid ammonium sulfate, ammonium monophosphate/diphosphate, and ammonium nitrate fertilizer. Therefore, permeate side acid concentration, pH, and acid type has to always be critically optimized before starting the ammonia mining experiment.

Dietary Protein Level and Dietary Interaction Affect Quinolinic Acid Concentration in Rats

2007 ◽  
Vol 77 (2) ◽  
pp. 142-148 ◽  
Author(s):  
Egashira ◽  
Sato ◽  
Saito ◽  
Sanada
Keyword(s):  
Fatty Acid ◽  
Acid Concentration ◽  
Quinolinic Acid ◽  
Dietary Protein ◽  
Protein Levels ◽  
Acid Diet ◽  
Acid Type ◽  
Dietary Interaction ◽  
Linoleic Acid Diet ◽  
Fatty Acid Type

During tryptophan-niacin conversion, hepatic α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) [EC4.1.1.45] plays a key role in regulating NAD biosynthesis. ACMSD activity is greatly affected by many factors such as nutritional status and disease. The tryptophan catabolite quinolinic acid has been reported to be associated with the pathogenesis of various disorders and is a potential endogenous toxin. However the effects of dietary protein levels or dietary interaction between protein levels and fatty acid type to this process have not been investigated and are still unknown. In this study, we examined whether dietary protein level, fatty acid type, namely saturated fatty acid and polyunsaturated fatty acid, and their interaction affect serum quinolinic acid concentration in rats. Male Sprague-Dawley rats (4-weeks old) were fed with 20% casein + 10% stearic acid diet (20C10S), 20% casein + 10% linoleic acid diet (20C10L), 40% casein + 10%stearic acid diet (40C10S), or 40% casein + 10% linoleic acid diet (40C10L) for 8 days, and serum quinolinic acid concentration and ACMSD activity were determined. Serum quinolinic acid concentration was significantly increased in the 40C10L group compared with other three groups. There was also the negative correlation between the sum of liver and kidney ACMSD activities, and serum quinolinic acid concentration per tryptophan intake (r = 0.8209, p < 0.01). Increased serum QA concentrations are probably due to a decreased ACMSD activity.

Acid Equilibrium Development in Mushrooms, Pearl Onions and Cherry Peppers

1985 ◽  
Vol 48 (7) ◽  
pp. 590-594 ◽  
Author(s):  
WILLIAM H. STROUP ◽  
ROGER W. DICKERSON ◽  
MELVIN R. JOHNSTON
Keyword(s):  
Acetic Acid ◽  
Citric Acid ◽  
Acid Concentration ◽  
Clostridium Botulinum ◽  
Ph Measurements ◽  
Acid Type ◽  
Time Required

Mushrooms, pearl onions, and cherry peppers were packed with either citric acid or acetic acid to determine the time required for the pH inside the particulates to decrease to 4.8 or less. The blanched products were packed into home canning jars, covered with acidified brine, and pasteurized in steam at 100°C. After storage at 25°C, pH measurements were taken on samples of drained brine, individual particulates, and a puree of all particulates. With acetic acid, equilibrium pH was achieved in approximately 1, 15, and 30 d for mushrooms, onions, and peppers, respectively. Longer times would be required to achieve equilibrium pH for each product with citric acid. The time required for the pH inside the particulates to decrease to 4.8 or less was a function of acid type, initial acid concentration, and the product being acidified. With sufficient acidulant to achieve an equilibrium pH of 4.6 or less, the time required for particulates of mushrooms, onions, or peppers to decrease to pH 4.8 or less was 7 d or less in all instances. Since studies (inoculated packs) of similar products have shown that a minimum of about 10 d is required for Clostridium botulinum growth at a pH of 5.0, the rate of acidification for these products was sufficient to prevent growth of C. botulinum.

Effect of Acid Type on Kinetics and Mechanism of Dental Enamel Demineralization

1987 ◽  
Vol 66 (9) ◽  
pp. 1425-1430 ◽  
Author(s):  
M.V. Patel ◽  
J.L. Fox ◽  
W.I. Higuchi
Keyword(s):  
Physical Model ◽  
Dental Enamel ◽  
Dissolution Kinetics ◽  
Rotating Disk ◽  
Bulk Solution ◽  
Dissolution Rates ◽  
Diffusion Layer Thickness ◽  
Weak Organic Acid ◽  
Acid Type ◽  
Viable Approach

The influence of acid type (pKa effects) of weak organic acid buffers on dissolution kinetics of dental enamel was critically examined for rigorous testing of the behavioral validity of the physical model of Patel et al. (1987). Quantitative evaluation of this model indicated that monitoring initial dissolution rates was a viable approach to critical testing of the model. Initial dissolution rates were determined in 0.1 mol/L acetate (pKa = 4.77), benzoate (pKa = 4.20), and salicylate (pKa = 2.98) buffers (pH = 4.50, μ = 0.50), with ground bovine enamel blocks of known surface area mounted in a rotating disk apparatus. The Levich theory was used to study dependence of dissolution rates on stirring rates in these buffers. The experimental data were analyzed by the physical model which includes pKa effects, complexation of the buffer anion with the other ions, surface kinetics, simultaneous diffusion and equilibrium of all species in enamel pores, diffusion layer thickness, and bulk solution composition. The KIAp [ a10Ca2 + a6 PO34-a2OH-] governing the dissolution reaction and the surface resistance factor were deduced from the model. Dissolution kinetics was also followed in these buffers in the presence of calcium or phosphate common ions. In effect, by conducting both the stirring rate studies and common ion experiments, we derived the driving force function independently by these two techniques. The results obtained in this study were consistent with the model, indicating that pKa effects on the dissolution of dental enamel can be accountedfor quantitatively by the model, and it was found that weak acids do not influence either the apparent solubility or the surface reaction process of bovine dental enamel.

scholarly journals Optimization of the Obtaining of Cellulose Nanocrystals from Agave tequilana Weber Var. Azul Bagasse by Acid Hydrolysis

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 520
Author(s):  
Manuel Alberto Gallardo-Sánchez ◽  
Tania Diaz-Vidal ◽  
Alejandra Berenice Navarro-Hermosillo ◽  
Edgar Benjamin Figueroa-Ochoa ◽  
Rogelio Ramirez Casillas ◽  
...  
Keyword(s):  
Acid Concentration ◽  
Cellulose Nanocrystals ◽  
Photoelectron Spectroscopy ◽  
Agave Tequilana ◽  
Hydrolysis Time ◽  
X Ray ◽  
Force Microscopy ◽  
Acid Type ◽  
Size And Morphology ◽  
Total Sulfate

A multilevel factorial design of 23 with 12 experiments was developed for the preparation of cellulose nanocrystals (CNC) from Agave tequilana Weber var. Azul bagasse, an agro-industrial waste from tequila production. The studied parameters were acid type (H2SO4 and HCl), acid concentration (60 and 65 wt% for H2SO4, 2 and 8N for HCl) temperature (40 and 60 °C for H2SO4, 50 and 90 °C for HCl), and hydrolysis time (40, 55 and 70 min for H2SO4; and 30, 115 and 200 min for HCl). The obtained CNC were physical and chemically characterized using dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XDR) techniques. The maximum CNC yield was 90 and 96% for HCL and H2SO4, respectively, and the crystallinity values ranged from 88–91%. The size and morphology of A. tequilana CNC strongly depends on the acid type and hydrolysis time. The shortest CNC obtained with H2SO4 (65 wt%, 40 °C, and 70 min) had a length of 137 ± 68 nm, width 33 ± 7 nm, and height 9.1 nm, whereas the shortest CNC obtained with HCl (2 N, 50 °C and 30 min) had a length of 216 ± 73 nm, width 69 ± 17 nm, and height 8.9 nm. In general, the obtained CNC had an ellipsoidal shape, whereas CNC prepared from H2SO4 were shorter and thinner than those obtained with HCl. The total sulfate group content of CNC obtained with H2SO4 increased with time, temperature, and acid concentration, exhibiting an exponential behavior of CSG=aebt.

scholarly journals Optimization of the Obtaining of Cellulose Nanocrystals from Agave Tequilana Weber Var. Azul Bagasse by Acid Hydrolysis

2021 ◽  
Author(s):  
Manuel Alberto Gallardo-Sánchez ◽  
Tania Diaz-Vidal ◽  
Alejandra Berenice Navarro-Hermosillo ◽  
Edgar Benjamín Figueroa Ochoa ◽  
Rogelio Ramirez Casillas ◽  
...  
Keyword(s):  
Acid Concentration ◽  
Cellulose Nanocrystals ◽  
Photoelectron Spectroscopy ◽  
Agave Tequilana ◽  
Hydrolysis Time ◽  
X Ray ◽  
Force Microscopy ◽  
Acid Type ◽  
Size And Morphology ◽  
Total Sulfate

A multilevel factorial design of 23 with 12 experiments was developed for the preparation of cellulose nanocrystals (CNC) from Agave tequilana Weber var. Azul bagasse. The studied parameters were acid type (H2SO4 and HCl), acid concentration (60 and 65 wt% for H2SO4, 2 and 8N for HCl) temperature (40 and 60&deg;C for H2SO4, 50 and 90&deg;C for HCl), and hydrolysis time (40, 55 and 70 min for H2SO4, 30, 115 and 200 min for HCl). The obtained CNC were physical and chemically characterized using dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XDR) techniques. The size and morphology of A. tequilana CNC strongly depend on the acid type and hydrolysis parameters. The shortest CNC were obtained with H2SO4 (65 wt%, 40 &deg;C, and 70 min) had a length of 137 &plusmn; 68 nm, width 33 &plusmn; 7 nm, and height 9.1 nm, whereas the shortest CNC obtained with HCl (2 N, 50 &deg;C and 30 min) had a length of 216 &plusmn; 73 nm, width 69 &plusmn; 17 nm, and height 8.9 nm. CNC prepared from H2SO4 resulted shorter and thinner than those obtained with HCl. The total sulfate groups content in CNC obtained with H2SO4 increase with time agree to CSG=aebt, and increases with temperature and acid concentration.

Demineralization of Enugu coal: effect of acid type and acid concentration

2018 ◽  
Vol 6 (4) ◽  
pp. 573-604
Author(s):  
Sylvanus Ezenwa Okoro ◽  
Christian Oluchukwu Asadu ◽  
Ikechukwu Maxwell Onoh
Keyword(s):  
Acid Concentration ◽  
Acid Type

XRF and nitrogen adsorption studies of acid-activated palygorskite

Clay Minerals ◽  
2010 ◽  
Vol 45 (2) ◽  
pp. 145-156 ◽  
Author(s):  
Junping Zhang ◽  
Qin Wang ◽  
Hao Chen ◽  
Aiqin Wang
Keyword(s):  
Chemical Composition ◽  
Surface Area ◽  
Acid Concentration ◽  
Pore Volume ◽  
Great Influence ◽  
Nitrogen Adsorption ◽  
Acid Activation ◽  
Mesopore Volume ◽  
Acid Type ◽  
Adsorption Desorption

AbstractThe effects of acid activation on the chemical composition, surface area and pore structure of palygorskite from Xuyi (Jiangsu, P.R. China) were investigated systematically using X-ray fluorescence (XRF) and BET techniques. The palygorskite samples were activated with HCl, H2SO4 and H3PO4 of various concentrations at 80ºC for 4 h. The influences of acid concentration and acid type on the chemical composition, adsorption-desorption isotherms at 77 K, pore-size distribution, surface area and pore volume were studied in detail. The contents of most components of palygorskite decrease with increasing acid concentration except for Si and Ti. HCl shows a greater activation activity and its effect on the dissolution of components of palygorskite is greater than that of H2SO4 and H3PO4. It was found that 3 mol l–1 H3PO4 is a more efficient activator for increasing the number of micropores in palygorskite, whereas 12 mol l–1 HCl is more suitable for use in enhancing the number of meso- and macropores. The acid concentration and acid type have a great influence on the surface area and pore volume. HCl is the most effective at enhancing the external surface area and mesopore volume of palygorskite, whereas, H3PO4 is more suitable for use in improving the micropore surface and volume.

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