Effect Of pH Variation Research Articles

Effects of pH variations caused by redox reactions and pH buffering capacity on Cd(II) speciation in paddy soils during submerging/draining alternation

Incubation experiments were conducted to investigate the influencing factors of pH variation in different paddy soils during submerging/draining alternation and the relationship between pH buffering capacity (pHBC) and Cd speciation in ten paddy soils developed from different parent materials (including 8 acid paddy soils and 2 alkaline paddy soils). The soil pHBC and the changes in soil pH, Eh, Fe2+, Mn2+, SO42- and Cd speciation were determined. The results showed that there was a significant positive correlation between cation exchange capacity (CEC) and pHBC of these paddy soils, indicating that soil CEC is a key factor affecting the pHBC of paddy soils. The contribution of Fe(III) oxide reduction to H+ consumption is far greater than the reduction of Mn(IV)/Mn(III) oxides and SO42- during the submerging. For example, the contribution of the reduction of manganese oxides, SO42- and iron oxides to H+ consumption in the paddy soils from Anthrosol at 15 d submerging was 1.2%, 11.6% and 87.2%, respectively. This confirms that the reduction of Fe(III) oxides plays a leading role in increasing soil pH. Importantly, we noticed that during submerging, soil pH was increased and resulted in the content of available Cd in soils being reduced. This was due to the transformation of Cd to less active forms. Also, there was a significant positive correlation between the change rate of available Cd, the percentage of acid extractable Cd and pH variation. This suggests that the variation in soil pH was responsible for the transformation of Cd speciation. In addition, the change rate of available Cd and the percentage of acid extractable Cd concentration were significantly negatively correlated with soil pHBC. The soil with higher pHBC experienced less pH change, and thus the change rate of available Cd and the percentage of acid extractable Cd concentration were less for the soil. The results of this study can provide a basis for the remediation of Cd-contaminated acidic paddy soils.

Analisis Pengaruh Variasi PH Larutan Acid Zinc Pada Sel Volta Dua Kompartemen dengan Elektrode Cu(Ag)-Zn

The research was conducted to analyze the effect of variations in pH of acid zinc solution in two compartment voltaic cells with Cu(Ag)-Zn electrodes on the value of electrical characteristics and the resulting corrosion rate. The Cu(Ag)-Zn pair is used to generate voltage and current in the cell with seawater electrolyte and zinc acid solution. The two compartments are lined with salt bridge made from mixture of Al2O3 (aluminum oxide), NaCl (seawater) 1 mole concentration dissolved in “tiga roda” white cement. The voltaic cell consisted of 5 cells arranged in series circuit, for each cell at the cathode (Cu(Ag)) containing ± 250 ml seawater and at the anode (Zn) containing ± 200 ml cid zinc solution which was varied with a pH of 4.5 and 6. The voltaic cell was measured with multitester every 1 hour for 3 days. Based on the research that has been done, it can be concluded that by using an acid zinc electrolyte solution which has a lower pH value, it will increase the value of the electrical characteristics and increase the corrosion rate produced by voltaic cell.

Synthesis and characterization of ZnO nanorods-Zn2SiO4 nanoparticles-PMMA nanocomposites for UV-C protection

Nowadays, UV-C is used in a variety of applications, such as disinfection and sterilization of air, surface, and liquids. In particular, its application against the pandemic COVID-19 virus is of great interest. On the other hand, it must be remarked that UV-C is harmful to the eyes, face, head, ears, and skin of engaged employees or personnel but studies on the UV-C range are rare. To the best of our knowledge, studies on zinc silicate as UV-absorber are very rare. In this research, flexible and transparent ZnO nanorods-Zn2SiO4 nanoparticles-PMMA nanocomposite thin films were made for protecting against UV-C radiation. To find the most suitable morphology, the effect of pH variation on the morphology and structural properties of the prepared ZnO–Zn2SiO4 composites were studied. Here we show that the most regular morphology of composites consisting of ZnO nanorods decorated with Zn2SiO4 nanoparticles was obtained at pH 12.5. The UV–vis spectra show that ZnO–Zn2SiO4-PMMA nanocomposite thin films prepared at pH 12.5 exhibit optical transparency in the visible-wavelength region and a prominent UV-C absorbing capability.

Production of Single Cell Protein from Banana Peel Waste in Batch Fermentation Using Saccharomyces Cerevisiae

Through engineering the fermentation process, it is hoped that new data can be obtained that will explain the ability of Saccharomyces cerevisiae to maximize the production of single-cell protein (SCP). SCP microorganisms have a high protein content, making them suitable for use as a human protein source as well as food additives in the cattle and fishing industries. The goal of this experiment is to see if the microbe Saccharomyces cerevisiae can generate SCP from banana peel waste. Some of the process variables used in this study include the variation in nutrition, fermentation time, and the effect of pH variations on SCP production. Where the variation in pH used is 3; 3.5; 4; 4.5; 5; and 5.5. As for the nutrients used, namely (NH4)2SO4 and KH2PO4 with a variety of nutrients, namely 0; 0.3; 0.6; 0.9; and 1.2 grams. Then the fermentation time was varied to 1,2,3,4 days. This study also analyzed the growth of microorganism cells using wet weight and dry weight with variations in pH and nutrition. The variation in nutrition is the same as the variation in the previous analysis of protein content, and the fermentation time is 1,2,3,4,5,6, and 7. In the analysis of protein content with Kjeldahl protein, the obtained optimal pH is 4.5 and the optimal protein content is 0.6 grams. As for the fermentation time, the optimal protein content is obtained on the 4th day. For the growth of microorganisms, the optimal pH is obtained at a pH value of 4.5 with optimal nutrition of 0.6 grams, and the optimal fermentation time is obtained on the 7th day.

Molecular dynamics simulation study of doxorubicin adsorption on functionalized carbon nanotubes with folic acid and tryptophan

In this work, molecular dynamics (MD) simulation is used to study the adsorption of the anticancer drug, doxorubicin (DOX), on the wall or surface of pristine and functionalized carbon nanotubes (FCNTs) in an aqueous solution. Initially, the CNTs were functionalized by tryptophan (Trp) and folic acid (FA), and then the DOX molecules were added to the system. The simulation results showed that the drug molecules can intensely interact with the FCNTs at physiological pH. Furthermore, it was found that as a result of functionalization, the solubility of FCNTs in an aqueous solution increases significantly. The effect of pH variation on drug release from both pristine and FCNTs was also investigated. The obtained results indicated that in acidic environments due to protonation of functional groups (Trp) and as a result of repulsive interaction between the DOX molecule and functional groups, the release of DOX molecules from FCNT’s surface is facilitated. The drug release is also strongly dependent on the pH and protonated state of DOX and FCNT.

Synthesis of the platinum particle with the pH variation for the particle size control

Platinum is a precious metal widely used in the jewelry industry due to its property and intrinsic value. The different particle sizes of platinum can be applied in various applications, especially for jewelry production. In the present article, submicron, and nano-sized platinum particle sizes were synthesized through simple chemical reduction methods and the effect of pH variation was revealed. The scanning electron microscope (SEM) images showed that the pH variations give rise to significant changes of the obtained particle size. The size of platinum particle was decreased from submicron to nanoscale while the pH was increased. The UV-Vis spectra indicated the maximum absorption at 220 nm confirming the spherical shape of the platinum particle. The FT-IR spectroscopy was used to analyze the residuals from the synthesis. The result showed that there is no indication of residual in the synthesized particle. Additionally, this synthesis can provide stability in terms of size and shape, as well as high production yield.

Effect of pH variation and annealing on covalently assembled nanodiamond films

This work examines the effect of using low-ionic strength zwitterionic buffer and post-deposition thermal annealing on the microstructure and thermal conductivity of continuous nanocrystalline diamond films that are deposited via the directed covalent assembly of detonation nanodiamonds. Variation of the zwitterionic buffer pH was found to tune the surface coverage, film thickness, thermal conductivity, and film morphology as quantified by apparent porosity and pore size distribution. The sequential annealing of these films up to 400 °C, showed the anticipated severance of amide bonds holding the nanodiamonds together, followed by the detrimental aggregation of the nanodiamonds to segregated islands, losing film continuity and increasing apparent porosity. The change in thermal conductivity with annealing was subjective to buffer pH, suggesting that the morphology changes associated with annealing may have a complex relationship with thermal conductivity. The thermal conductivity data were further analyzed using a phonon hopping model to quantify the degree of phonon movement across boundaries. Overall, the results demonstrate a way to achieving porous, low-cost nanocrystalline diamond thin films with tunable film morphology and thermal conductivity.

Effect of pH Variation on Synthesis and Photocatalytic Activity of Bi2Fe4O9

The Pechini synthesis method, presents chemical homogeneity as its main advantage, enabling the desired phase to be obtained. This synthesis usually occurs at pH 7. In this study, Bi2Fe4O9 was synthesized using the Pechini method at different pHs (pH= 3, 5, 7, 8, 10 and 12) to verify if the pH conditions can influence in its photocatalytic activity. The materials obtained at different conditions were characterized by using X rays diffraction (XRD), UV/Vis diffuse reflectance and scanning electron microscopy by field emission (MEV/FEG).It was possible to synthesize the material under conditions already mentioned, but it was not observed significant differences in the chemical structure of the obtained materials from the characterization techniques. However, they presented a small variation in the band gap values, morphological aspects and photocatalytic activities. All the materials proved to be a good semiconductor, maintaining high degradation rates. The photocatalyst synthesized at pH 3 (BFO - 1) presented a degradation rate of approximately 95% for the group chromophore and 93% for the aromatic group of the structure of the tartrazine yellow dye, proving to be a promising photocatalyst for industrial applications. This result is particularly important because BFO – 1 showed higher catalyst activity since the chromophore of the aromatic group was degraded. The highlights of this study is the synthesis of Bi2Fe4O9 performed at pH=3, since it reduces the quantity of reagents comparing to the conventional Pechini method and presented high photocatalytic activity. DOI: http://dx.doi.org/10.17807/orbital.v13i2.1486

Effect of pH variation on the activity of green algae (Chlorella Vulgaris) and bacteria (Bacillus subtilis) in remediation of toxic dye (Congo red)

The present study used two species of microorganism, algae (Chlorella Vulgaris) and bacteria (Bacillus subtilis), in the removal of toxic industrial dye(Congo red) and deal with the effect of pH variation on the activity of these organisms to remediation and reduces of dye in vitro. Algae (C.vulgaris) also bacteria(B.subtilis) isolated from habitats and cultured under controlled laboratory conditions and using different concentration of dye (50, 150 and 250 mg/l) used in different pH (4, 7 and 9) during different period times (3, 7, 9, 11 and 13 days) to algae and 7 days to bacteria to testing the ability of bioremediation. The results showed that the best pH for removal by Chlorella Vulgaris was (7) for a period of (13 days) at concentration (150)mg/l and with the complete removal (75%) and Bacillus subtilis best pH(7) complete removal(98%) at concentration (50)mg/l. The efficiency of the Chlorella Vulgaris and Bacillus subtilis in the removal of pollutants increased with the high value of many environmental factors such as pH.

Non-enzymatic electrochemical sensor to detect γ-aminobutyric acid with ligand-based on graphene oxide modified gold electrode

Abstract In this study, the simple and sensitive enzymeless electrochemical gamma-aminobutyric acid (GABA) neurotransmitter sensor was developed based on the graphene oxide modified Au electrode with the ligand. A mixture of ortho-phthalaldehyde (OPA) and an alkylthiol reagent is used as a ligand to interact with GABA, which became an electrochemical active compound. The sensor consisted of a graphene oxide modified Au electrode. The effect of pH variation on the electrochemical signal of GABA was investigated; a good electrochemical response was observed in neutral- and slightly alkaline- medium, i.e. the value of the pH for the physiological-like media. The proposed sensor detected the wide range concentration of GABA from 250 nmol L−1 to 100 μmol L−1 with a detection limit of 98 nmol L−1. And the sensor could detect a mixture of GABA and Glutamate, and GABA in complex solutions including human serum and urine, which indicated the capability of the sensor to detect GABA in complicated matrixes. The proposed sensor system can be applied to detect neurotransmitters in the brain and be used in the field of diagnosis and treatment of neurological disorders.

Solid state electron density aspects of mordenite with experimentally evaluated nitrate and phosphate sorption

Mordenite is one of the famous members of zeolites having diverse applications in material sciences. Due to the potentiality to act as molecular sieve or channel, the current report deals with the synthesis and characterization of this mineral at the experimental-density functional theory (DFT) convergence. The main analytical methods that were used to characterize the selected zeolite were Fourier Transform Infrared (FTIR) spectroscopy, Ultra-violet Visible spectroscopy and X-ray diffraction technique. Each set of the experimental results was compared with the respective theoretical data. Density functional theory (DFT) level of theory involving Stuttgart-Dresden (SDD) basis set along with WB97XD as functional was the formalism applied in the computational evaluation. Computational investigation supported thermodynamics, KH2PO4 versus NH4NO3 sorption studies and surface modification effects on sorption are the main applied aspects of this work. Using 3D-modelling some other significant factors like electron density mapping, electrostatic potential determination, sieve or channel dimensions of the zeolite, global reactive descriptors, etc, were also computed. Experimental verification of effects of variation in pH, temperature and surface modifications were done in connection with the applied interest. The study reveals a good agreement between DFT speculations and the experimental observations, and hence approves the reliability of the computational formalism employed in this work.

Effect of pH variation and oxygen presence on the cathodic recovery of copper in the microbial fuel cell with bioenergy generation and wastewater treatment

Effect of pH variation and oxygen presence on the cathodic recovery of copper in the microbial fuel cell with bioenergy generation and wastewater treatment

Effect of pH variation and oxygen presence on the cathodic recovery of copper in the microbial fuel cell with bioenergy generation and wastewater treatment

Effect of pH variation and oxygen presence on the cathodic recovery of copper in the microbial fuel cell with bioenergy generation and wastewater treatment

Crossing the Nernst Limit (59 mV/pH) of Sensitivity Through Tunneling Transistor-Based Biosensor

In this work, an underlap structure of tunneling field-effect transistor (TFET) containing electrolyte/watery solution is examined to enhance the Nernst limit (59 mV/pH) of sensitivity. After incorporating the electrolyte medium in TFET, effect of pH variation on device characteristics such as drain current vs front gate voltage, voltage sensitivity, and current sensitivity are investigated. The interface charge density at the oxide-silicon interface of TFET is obtained as a function of electrolyte pH from physics-based modelling. Voltage sensitivity value ~180 mV/pH that is greater than three times of Nernst limit of 59 mV/pH and current sensitivity value that is more than one decade per pH are observed for TFET based sensor. In order to validate the results, models used in TFET are well-calibrated with experimental data and the result of TFET are compared with inversion mode (IM) device. Results show that TFET gives superior performance than IM device; hence an underlap TFET can be a promising alternative for the next generation biosensor.

Effect of pH variation and crosslinker absence on the gelling mechanism of high acyl gellan: Morphological, thermal and mechanical approaches

This article describes the preparation of superabsorbent hydrogels made of high acyl gellan without the addition of a crosslinker . Variations of the pH of the medium and different gellan solution concentrations were evaluated. The samples produced were investigated regarding their morphology by scanning electron microscopy, thermal resistance by thermogravimetry, and compressive strength by mechanical testing. Rheological tests were also performed and the swelling decree of the hydrogels was calculated. The results showed that the morphology of the samples could be modified by varying the preparation conditions, ranging from a foliaceous structure to a brittle structure, containing voids with different sizes.The hydrogels prepared with acidic pH presented less compressive strength than those prepared with basic pH. Although all the samples had swelling degree greater than 1000 %, the highest values were obtained with the samples prepared at pH 4, regardless of the concentration of the gellan solution.

Cleaning fungal stains on paper with hydrogels: The effect of pH control

Fungal stains affect documents and artworks on paper all over the world, diminishing their chemical stability and compromising their readability. The present paper studies the suitability of agarose and gellan gum hydrogels to remove fungal stains from paper, using paper impregnated with alizarin as a model system to simulate the most common colorant molecules produced by fungi - polyketide quinones. The effect of pH variation on the efficacy of the gels was evaluated by UV spectrometry. The results show that the cleaning efficacy of the gels greatly depends on the gel matrix, the colorant molecules, and the pH balance of the process.

Behavior of Listeria monocytogenes in the presence or not of intentionally-added lactic acid bacteria during ripening of artisanal Minas semi-hard cheese

The fate of Listeria monocytogenes during ripening of artisanal Minas semi-hard cheese, as influenced by cheese intrinsic properties and by autochthonous (naturally present) or intentionally-added anti-listerial lactic acid bacteria (LAB) was modeled. Selected LAB strains with anti-listerial capacity were added or not to raw or pasteurized milk to prepare 4 cheese treatments. Counts of LAB and L. monocytogenes, pH, temperature and water activity were determined throughout cheese ripening (22 days, 22±1ᵒC). Different approaches were adopted to model the effect of LAB on L. monocytogenes: an independent approach using the Huang primary model to describe LAB growth and the linear decay model to describe pathogen inactivation; the Huang-Cardinal [pH] model using the effect of pH variation in a dynamic tertiary approach; and the Jameson-effect with Nmax tot model which simultaneously describes L. monocytogenes and LAB fate. L. monocytogenes inactivation occurred in both treatments with added LAB and inactivation was faster in raw milk cheese (−0.0260 h−1) vs. pasteurized milk cheese (−0.0182 h−1), as estimated by the linear decay model. Better goodness-of-fit was achieved for the cheeses without added LAB when the Huang primary model was used. A faster and great pH decline was detected for cheeses with added LAB, and the Huang-Cardinal [pH] model predicted higher pathogen growth rate in cheese produced with raw milk, but greater L. monocytogenes final concentration in pasteurized milk cheese. The Jameson-effect model with Nmax tot predicted that LAB suppressed pathogen growth in all treatments, except in the treatment with pasteurized milk and no LAB addition. The Huang-Cardinal [pH] model was more accurate in modeling L. monocytogenes kinetics as a function of pH changes than was the Jameson-effect model with Nmax tot as a function of LAB inhibitory effect based on the goodness-of-fit measures. The Jameson-effect model may however be a better competition model since it can more easily represent L. monocytogenes growth and death. This study presents crucial kinetic data on L. monocytogenes behavior in the presence of competing microbiota in Minas semi-hard cheese under dynamic conditions.

Does soil anion storage capacity affect plant response to Olsen P status?

ABSTRACT In New Zealand horticulture there is a widely-held opinion that target soil test P (Olsen P) values increase with soil anion storage capacity (ASC) – an idea that arose in the 1986 Fertiliser Recommendations of Wood et al. with little supporting evidence. We report a direct test of whether ASC influences plant response to soil Olsen P. This was carried out with three soils of different ASC values (14%, 75% and 92%) under glasshouse conditions where supply of other nutrients was not limiting. For each soil we generated samples with 10 different Olsen P values. These were then used to grow spring onion (Allium fistolosum L.) in 0.25-L containers kept moist with P-free nutrient solution. The Olsen P values ranged from 3 to 51 μg g−1. Plant growth varied strongly with soil Olsen P, but regression slopes for plant mass on Olsen P showed no differences associated with ASC. A further analysis filtered out possible effects of variations in pH and the mass of soil in each pot. Again this indicated no influence of ASC on plant responsiveness to Olsen P. Our results suggest caution in using the 1986 recommendations for determining application rates of P fertiliser for vegetables.

Synthesis of Hidroxyapatite Using Microwave Irradiation and Sintering with Variation pH and Time

Hydroxyapatite (HAp) with the formula of chemical compound Ca10(PO4)6(OH)2 is a bone replacement material used in alternative bone graft technology. This study aims to analyze the effect of variations in pH and time on Hydroxyapatite synthesis using microwave irradiation and sintering. The results show variations in pH and time affect crystal size, degree of crystallinity and morphological forms. XRD characterization showed that the samples irradiated by microwaves with time variations produced a crystal size of around 15 until 21 nm. The addition of the sintering process results in three times the crystal size be compared to the microwave process. XRD characterization also shows that variations in pH give rise to a secondary phase in the form of chlorapatite. FTIR characterization shows that the sintering process removes carbonate groups and SEM-EDX characterization of pH 11 samples which are only irradiated by microwaves produces a particle size of about 63.43 nm with a Ca / P ratio of 1.59 and the addition of the sintering process produces a particle size of around 180.62 nm with a Ca / P ratio of 1.48. The use of high temperatures affects the growth of crystals in the synthesis of Hydroxyapatite.

The Effect of pH Variation on Fluor-Hydroxyapatite Nano Crystal Synthesis with Microwave Irradiation Method

Fluoride-substituted hydroxyapatite (FHA) can be used for biomaterial applications because it has biocompatible properties. FHA is formed by replacing flour ion (F−) with hydroxyl ion (OH−) from hydroxyapatite. This work aims to see the influence of changes in the form of acidity (pH) at the FHA synthesis process using microwave irradiation method. FHA nano-powder was synthesized using a titration of calcium hydroxide solution with diammonium hydrogen phosphate and ammonium fluoride, which will vary the level of fluoride at FHA by 0.9 and 1.3. Subsequently, HCl 1 M or NaOH 1 M to give a variation of pH value. X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy analysis techniques were utilized to evaluate the characteristic of synthesized FHA nano-powder. The XRD and FTIR results showed that the powder with pH under control conditions had several additional formed phases such as chlorapatite and carbonate. The value of crystallinity had the distinction of each powder in each pH, but only pH control had crystallinity values, such as tooth enamel. Using the Scherrer formula, the average crystallite size was found around 21-80 nm. SEM and EDX characterization results showed the Ca/P ratio formed was 1.34. The results showed that the addition of acid resulted in the formation of a new phase which dominated and revamped some crystal parameters. Therefore, the synthesis in these conditions is not recommended.