Acidic pH Values Research Articles

PH induced incongruent-dissolution impacts Al-ferrihydrite transformations and As mobilization.

This study investigated the role of Al and As fate during the transformation process of ferrihydrite influenced by different pH values under oxic conditions. The results indicate that the Al doping greatly enhanced the transformation of ferrihydrite (Fh) to Al-substituted goethite at all acidic or alkaline pH values under oxic conditions by promoting the incongruent dissolution and reprecipitation reactions of Al-substituted ferrihydrite (AlFh). Under acidic conditions, the preferential dissolution of structural Fe (4.73 mg/L) from AlFh occurs, whereas under alkaline conditions, the preferential dissolution of structural Al (1.25 mg/L) takes place. In contrast, under neutral conditions, the low solubility of Fh and AlFh induces the significant particle assembly, with Fe/Al minerals primarily transforming into goethite through oriented aggregation. As predominantly remains in an adsorbed state at all pH values during the transformation of Fh and AlFh, with the highest proportion of adsorbed As (86.9-96.7%) observed under neutral conditions. During the aging process, the adsorbed As gradually transforms into non-extractable As, and the changes in As speciation within Fe/Al minerals are closely coupled with the transformation of AlFh and Fh. Under alkaline and acidic conditions, the proportion of non-extractable As in the transformation products of Fh and AlFh increases by 14.02-19.72% and 12.27-16.28%, respectively, while under neutral conditions, it increases only by 12-13.02%. Therefore, regulating soil pH can partially modify As speciation and mitigate its environmental impact by altering the mineral transformation process. The results of this study facilitate better understanding of the role of Al substitution in the transformation of Fh and the cycling of As in the environment.

Relative Saccharification of Sawdust Materials at Different Incubation pH-values

The uncontrolled production of waste is a daily phenomenon that is experienced by most global communities, and the situation worsens due to the lack of effective waste management procedures. Solid waste such as sawdust is primarily produced by the forestry industry and although it is utilized by certain countries as briquettes to make fire or as an absorbent to clean fluid spillage as well as a component of ceilings, most of the sawdust along the Lagos Lagoon in Nigeria is left unattended as waste, contributing to environmental pollution. Cellulose, composed of glucose units is a structural component of sawdust and when saccharified the resulting glucose can be fermented into renewable substances such as bio-ethanol. The cellulose degradation process can be performed with a cellulase enzyme such as available in the fungus Aspergillus niger and during the current investigation, this enzyme system was used to bio-convert the cellulose component of sawdust from ten different trees along the Lagoon into glucose. To increase the cellulase action all sawdust materials were delignified before cellulase action with the main aim of determining the optimum pH value for maximum degradation of the various sawdust materials. The pH-related saccharification profile of each type of sawdust was constructed as well as the relative percentage of saccharification and it was concluded that all the materials were optimum degraded at acidic pH-values which varied between pH 5.0 and pH 6.0 that are like optimum pH-values reported for the other types of cellulose materials.

Emergence of ADM-mediated bioconjugate to enhance longevity and catalytic efficiency of urease.

Emergence of ADM-mediated bioconjugate to enhance longevity and catalytic efficiency of urease.

EFFECTS OF Eucalyptus PLANTATIONS ON THE PHYSICAL AND CHEMICAL PROPERTIES OF SOIL IN FLOODPLAINS OF THE EASTERN REGION OF PARAGUAY

The floodplains of the eastern region of Paraguay have soils with a shallow water table that causes flooding in months of heavy rainfall (August to December). The soils, predominantly Ultisols with gleyic properties, display high contents of soil organic matter (SOM) and an acidic pH. These environments are being transformed into Eucalyptus camaldulensis Dehnh. plantations, primarily for energy purposes. The aim of this study was to evaluate the chemical and physical properties of soils in eucalyptus plantations established on the native lowland grasslands. For this purpose, three chronosequences were selected, consisting of native grasslands and eucalyptus plantations aged between 2 and 8 years. In each system, the chemical and physical properties were determined at depth increments (0–5, 5–10, 10–20, and 20–40 cm). Each soil sample in the plots included six repetitions for both chemical and physical analyses. In the first years of eucalyptus planting, soil organic carbon (SOC) decreased by 50 % due to the intensive tillage carried out in the first years to establish the eucalyptus plantations. SOC concentrations recovered over time, although they did not reach the levels observed in the native grasslands. Soils with eucalyptus plantations displayed a higher bulk density (up to 1.35 g cm-3), greater acidity (pH value of 4), and a decrease in phosphorous (P) and exchangeable bases (up to 30 %) in comparison with natural grasslands. It is concluded that, in order to prevent the degradation of the chemical and physical properties of the soil in natural grasslands, it is necessary to plan practices that include land-use changes with native forest species and reconsider the practice of transforming these natural systems.

PHYSICOCHEMICAL PROPERTIES OF THE LEAF AND FLOWER EXTRACT OF CITRONELLA PLANT (CYMBOPOGON NARDUS), PIGNUT (HYPTIS SUAVEOLENS), AFRICAN BASIL (OCIMUM GRATISSIMUM), AND FORMULATED MOSQUITO COILS

This research aims to identify the physical and chemical characteristics of the leaf and flower extracts from Citronella plant (Cymbopogon nardus), Pignut (Hyptis suaveolens), and African basil (Ocimum gratissimum), as well as mosquito coils formulated with different plant concentrations. We evaluated nine mosquito coil formulations with varying amounts of Cymbopogon Nardus, Ocimum gratissimum, and Hyptis suaveolens (10g, 15g, and 20g, respectively), along with extracts from the three plant samples. The leaves and flowers of these plants were collected, dried, and ground into fine powder. The mosquito coil samples were prepared by crushing the coils. We then tested the finely powdered plant samples and the crushed mosquito coil samples for various physicochemical parameters, including appearance, color, pH, density, specific gravity, ash content, moisture content, acid value, and primary, secondary, and tertiary alcohols. The results showed that the pH of Ocimum gratissimum plant sample was highly acidic (pH=3), while Cymbopogon nardus was slightly acidic (pH=6), and Hyptis suaveolens was neutral (pH=7). The formulated mosquito coils had slightly acidic pH values ranging between 5 and 6. The plant samples of Ocimum gratissimum appeared brownish-green, Hyptis suaveolens appeared dark green, and Cymbopogon nardus appeared green. The formulated coils had colors of dark brown, black, and grey for Ocimum gratissimum, Hyptis suaveolens, and Cymbopogon nardus, respectively. Cymbopogon nardus and Hyptis suaveolens showed similar values for ash content and acid value. These properties are consistent with those reported in other studies and are known to contribute to the repellent and medicinal properties of these plants.

Novel Collector of a Dodecylpyridinium Chloride Ionic Liquid in the Reverse Flotation Separation of Muscovite from Apatite.

Reverse flotation separation of muscovite from apatite using a dodecylpyridinium chloride (DPDC) ionic liquid as the collector was studied in this work. The microflotation results depicted that DPDC had a strong collecting for muscovite but had a slight collecting for apatite when using phosphoric acid as a depressant for apatite in a weakly acidic pH value pulp, artificial mixture mineral flotation showed that reverse flotation separation of muscovite from apatite can be effectively achieved in the reagent scheme of phosphoric acid/DPDC, and DPDC had a better separation performance in the muscovite/apatite system than DDA. The adsorption measurements indicated that the adsorption amount of DPDC on the apatite surface was less than that of DPDC on the muscovite surface, and the zeta potential results confirmed that a strong interaction occurred between DPDC and the muscovite surface, while an extremely weak interaction occurred between DPDC and the apatite surface in the presence of phosphoric acid at pH ∼ 5.5. XPS analysis indicated that a hydrogen bond occurred between DPDC and the muscovite surface. Thus, it was inferred that DPDC could be used as an appreciation collector for the reverse flotation of muscovite from apatite.

The Influence of pH on Long-Range Electron Transfer and Proton-Coupled Electron Transfer in Ruthenium-Modified Azurin.

Long-range electron transfer (ET) is an essential component of all biological systems. Reactions of metalloproteins are important in this context. Recent work on protein "charge ladders" has revealed how the redox state of embedded metal ions can influence the ionization of amino acid residues at protein surface sites. Inspired by these observations, we carried out a variable pH investigation of intramolecular ET reactions in a ruthenium-modified protein system built on azurin from Pseudomonas aeruginosa. We also generate a Pourbaix diagram that describes the variable pH redox behavior of a Ru model complex, Ru(2,2'-bipyridyl)2(imidazole)2(PF6)2. The intramolecular ET rate constants for the oxidation of azurin-Cu+ by flash-quench-generated Ru3+ oxidants do not follow the predictions of the semi-classical ET rate expression with fixed values of reorganization energy (λ) and electronic coupling (HDA). Based on the pH dependence of the Ru3+/2+ redox couple, we propose a model where pure ET is operative at acidic pH values (≤ 7) and the mechanism changes to proton-coupled electron transfer at pH ≥ 7.5. The implications of this mechanistic proposal are discussed in the context of biological redox reactions and with respect to other examples of intramolecular ET reactions in the literature.

Pequi Pulp (Caryocar brasiliense) Oil-Loaded Emulsions as Cosmetic Products for Topical Use.

The pequi (Caryocar brasiliense) is a typical fruit from the Brazilian Cerrado. From it, pequi pulp oil is extracted, a valuable product for cosmetic applications due to its high levels of unsaturated fatty acids and carotenoids. Carotenoids are antioxidant compounds that are easily oxidized. To improve pulp stability, emulsification techniques with carboxymethylcellulose at 1% (w/w) were used to encapsulate the pequi pulp oil at 1, 3, 5% (w/w), and 8% (w/w) of polysorbate 80® using a high-rotation mechanical stirrer. The pequi pulp oil was first characterized by FTIR and GC-MS. The results indicated the presence of chemical groups characteristic of the oil itself and the presence of a large proportion of fatty acids, which are essential for the maintenance of cutaneous hydration and the barrier, also acting in the tissue repair process. All emulsions presented stable over 120 days with slightly acidic pH values and were compatible with human skin. The droplet diameter was less than 330 nm, and the polydispersity index was around 0.3, indicating systems with low polydispersity. The Zeta potential (ζ) exhibited negative values sufficient to stabilize the emulsified systems. All emulsions behaved as non-Newtonian fluids, presenting pseudo-plastic and thixotropic properties that are considered important for topical applications.

Formation of Amyloid-Like Conformational States of β-Structured Membrane Proteins on the Example of the OmpF Porin from the <i>Yersinia pseudotuberculosis</i> Outer Membrane

The work presents the results of an in vitro and in silico study of the formation of amyloid-like structures under harsh denaturing conditions by the nonspecific OmpF porin of Yersinia pseudotuberculosis (YpOmpF), a membrane protein with a β-barrel conformation. It has been shown that in order to obtain amyloid-like porin aggregates, preliminary destabilization of its structure in a buffer solution with an acidic pH value at elevated temperature, followed by long-term incubation at room temperature is necessary. After heating at 95 °C in a solution with pH 4.5, significant conformational rearrangements are observed in the porin molecule at the level of the tertiary and secondary structure of the protein, which are accompanied by an increase in the content of the total β-structure and a sharp decrease in the value of the characteristic viscosity of the protein solution. Subsequent long-term exposure of the resulting unstable intermediate YpOmpF at room temperature leads to the formation of porin aggregates of various shapes and sizes that bind thioflavin T, a specific fluorescent dye for the detection of amyloid-like protein structures. Compared to the initial protein, early intermediates of the amyloidogenic porin pathway, oligomers, have been shown to have increased toxicity to Neuro-2aCCL-131™ mouse neuroblastoma cells. The results of computer modeling and analysis of changes in intrinsic fluorescence during protein aggregation suggest that during the formation of amyloid-like aggregates, changes in the structure of YpOmpF affect not only areas with an internally disordered structure corresponding to the external loops of the porin, but also the main framework of the molecule, which has a rigid spatial structure inherent to β-barrel.

Edible Coating Based on Alginate Nanoparticles Containing Menthol and Zataria multiflora Essential Oil: Effect on the Shelf Life of Chicken Thigh in the Refrigerator.

Chicken thigh is a popular and widely consumed meat product. However, its high moisture content and susceptibility to microbial spoilage limit its shelf life. To address this issue, we investigated the efficacy of an edible coating based on alginate nanoparticles (AlgNPs) containing menthol, Zataria multiflora essential oil (EO), or their combination for extending the shelf life of chicken thigh. The nanoparticles were prepared through ionic gelation methods; their particle size was obtained as 87-205 nm with PDI values of < 0.3 and SPAN values of < 1. The AlgNPs containing both menthol and the EO showed the most potent antimicrobial activity (the lowest counts of pseudomonas, aerobic mesophilic, and yeast-mold), during cold storage. This coating treatment showed also the highest antioxidant activities, with the lowest thiobarbituric acid reactive substances (TBARS), pH and total volatile basic nitrogen (TVBN) values. Moreover, this coating significantly (p < 0.05) showed the highest sensory quality of chicken thighs, as evidenced by the higher sensory scores for texture, odor, color, and overall acceptability. Therefore, the edible coating based on AlgNPs containing menthol and Z. multiflora EO is an effective and promising approach for extending the shelf life of chicken thighs.

Influence of Fermentation Time on Total Lactic Acid Bacteria, pH Value, Water Activity, and Organoleptic Properties of Mutton Jerky

Influence of Fermentation Time on Total Lactic Acid Bacteria, pH Value, Water Activity, and Organoleptic Properties of Mutton Jerky

Challenges of Providing Safe Drinking Water in African Rural Communities: A Case Study on the Oio Region, Guinea-Bissau

Access to safe drinking water is a fundamental human right, yet it remains a global challenge affecting nearly 2 billion people, particularly in Africa in regions such as Guinea-Bissau. This study investigated the microbiological and physicochemical quality of drinking water in four rural areas of the Oio region of Guinea-Bissau—Cangha N’Tchugal, Cajaque, Infaidi and Insanha—over a one-year period (October 2022–September 2023) to assess water safety and seasonal variations. During this period, eight water samples were collected and analysed from each site, split evenly between the dry and wet seasons. The results showed widespread faecal coliform contamination, with concentrations escalating during the wet season (2 to 39 CFU/100 mL), posing a health risk. Physicochemical analysis showed consistently acidic pH values (from 4.93 to 6.58) and seasonal variations in phosphate and iron concentrations, with a marked decrease in iron concentrations during the wet season. These results indicated that the water from the four sampling points was unfit for human consumption. In light of these findings, there is an urgent need for the regular monitoring of water sources used for drinking and for improved access to resources and basic sanitation in the future.

The Protein Engineering of Zearalenone Hydrolase Results in a Shift in the pH Optimum of the Relative Activity of the Enzyme.

An acidic shift in the pH profile of Clonostachys rosea zearalenone hydrolase (ZHD), the most effective and well-studied zearalenone-specific lactone hydrolase, is required to extend the range of applications for the enzyme as a decontamination agent in the feed and food production industries. Amino acid substitutions were engineered in the active center of the enzyme to decrease the pKa values of the catalytic residues E126 and H242. The T216K substitution provided a shift in the pH optimum by one unit to the acidic region, accompanied by a notable expansion in the pH profile under acidic conditions. The engineered enzyme demonstrated enhanced activity within the pH range of 3-5 and improved the activity within the pH ranging from 6 to 10. The D31N and D31A substitutions also resulted in a two-unit shift in the pH optimum towards acidic conditions, although this was accompanied by a significant reduction in the enzyme activity. The D31S substitution resulted in a shift in the pH profile towards the alkaline region. The alterations in the enzyme properties observed following the T216K substitution were consistent with the conditions required for the ZHD application as decontamination enzymes at acidic pH values (from 3.0 to 6.0).

Shelf Life Estimation of Probiotic Peanut Chocolate Jam By Accelerated Shelf Life Testing (ASLT) Method

Probiotics are beneficial bacteria found in probiotic products that can maintain the balance of microflora in the gut. Peanut chocolate jam has the potential to be developed into a probiotic food product. However, the shelf life of this product has not been determined so it is necessary to determine the shelf life using the Accelerated Shelf Life Testing method. This method uses the Arrhenius approach. Determination of shelf life through the calculation of total lactic acid bacteria, aw value, pH value, and total acid during storage. The storage of probiotic peanut chocolate jam used three temperature treatments: 4 ℃, 30 ℃, and 37 ℃. Observations of samples stored at 4 ℃ were made every 5 days until day 25, while samples at 30 ℃ and 37 ℃ were made every 3 days until day 15. The data were analyzed using Microsoft Excel 2016 through the presentation of data in the form of a scatter diagram accompanied by a trendline and then described descriptively. The shelf life of probiotic peanut chocolate jam based on best before stored at 4 ℃, 30 ℃, and 37 ℃ were 49.52 days; 10.98 days; and 7.64 days, respectively. The jam can still be consumed up to 255.29 days; 86.73; and 66.89 days but no longer has the benefits of the probiotics.

Bioenergy Production from Sorghum Distillers Grains via Dark Fermentation.

Sorghum distillers grains (SDGs) produced from a sorghum liquor company were used for generating biohydrogen via dark fermentation at pH 4.5-6.5 and 55 °C with a batch test, and the biohydrogen electricity generation potential was evaluated. The experimental results show that pH markedly affects hydrogen concentration, hydrogen production rate (HPR) and hydrogen yield (HY), in that high acidic pH values result in high values. The HPR and HY ranged from 0.76 to 3.2 L/L-d and 21.4 to 62.3 mL/g chemical oxygen demand, respectively. These hydrogen production values were used to evaluate bioelectricity generation using a newly developed gas/liquid-fuel engine. The results show a new and prospective biomass source for biohydrogen production, bioelectricity generation and simultaneously solving the problem of treating SDGs when producing kaoliang liquor. Applications of the experimental results are also discussed.

New Styryl 1,3,4-Oxadiazol-Based Fluorometric "Turn on" pH Sensor.

A new 1,3,4-oxadiazole derivative (MeO-SODA) was synthesized, fully characterized by means of IR, NMR and HRMS data and and additionally, its ability to detect extremely acidic pH values ​​was examined. Firstly, the characteristic behavior of MeO-SODA was examined in ten different solvents, revealing that it underwent non-radiative transitions as the hydrogen bonding capacity of solvent increased. Secondly, the absorption and fluorescence measurements for MeO-SODA were conducted across various pH levels (pH 2, 4, 6, 7, 9, 10, 12), with fluorescence emission observed exclusively at pH 2. We propose that this new probe could serve as a highly selective sensor at extremely acidic pH levels. Additionally, experiments with lemon juice demonstrated that this new 1,3,4-oxadiazole derivative could be suitable for practical applications. Furthermore, the results of this study are expected to provide insights into synthesizing new probes capable of detecting at a single pH value, setting them apart from the typical pH studies found in the literature.

Determination of antioxidant activity in milk extracts with phosphomolibdate method

Antioxidants are mainly non-nutrient compounds in both human and animal feed, but have the antioxidant capacity in vitro to provide an artificial power index in preventing the destruction of cells and tissue potential by inhibiting nutrient oxidation. Milk contains lipophilic and hydrophilic antioxidants, which play a key role in maintaining. The efficiency of extraction for determining the antioxidant activity of milk corresponds to the method used for plant extraction. For this purpose, the phosphor molybdenum method based on the reduction of Mo (VI) in Mo (B) in samples of milk. Extracts obtained with methanol and ethanol, Soxlet method. Green complexes formed at acidic pH value, measurements of spectrophotometer (UV), λ = 695 nm. The values of milk samples are compared with respect to the calibration curve of gallic acid range (0.00 to 14.00 μg / ml, y = 0.0344 + 0.0519, R2 = 0.9709). The results of milk extract was concentration/ c = 3, 80; 2.35; 3.78; 4.85 / (μg / ml). The highest value of antioxidant activity in packs milk, which has 3.2% fat, also affects the fat and the presence of vitamin E, which found in fat droplets and has a synergistic effect with vitamin C. It concluded that the highest value of the total antioxidant activity in milk obtained from the first sample due to the use of several types of feed – alfalfa, two types of concentrated and straw, which proves the dependence of antioxidant activity on the impact of nutrients, that is, of their type and quantities.

Study of the Acidic, Basic, and Thermal Degradation Kinetics of Three Antihypertensive Drugs-Individually and in Combination.

The importance of fixed-dose combinations (FDCs) for the treatment of hypertension is well established. However, from a stability perspective, FDCs present a challenge since the degradation of one active pharmaceutical ingredient (API) can be affected by the presence of another API. The aim of this study was to compare the degradation behaviors and evaluate the degradation kinetics of three antihypertensive drugs, perindopril tert-butylamine (PER), amlodipine besylate (AML), and indapamide (IND). The degradation processes were studied using the previously developed reverse phase high-performance liquid chromatographic (RP-HPLC) method after exposing each drug individually, as well as the combinations of two/three drugs, to different stress factors, such as light, oxidation, acidic, basic, or neutral pH values at different temperatures. The results show that PER is most unstable under basic conditions and that AML displays a negative, while IND displays a positive effect, on PER stability when combined. AML is most affected by basic conditions and oxidation, and its stability is affected by both drugs positively; IND undergoes extreme photolysis, which is positively affected by AML but negatively by PER. Great care must be taken when formulating FDCs with these three drugs, as well as solutions or oral suspensions adjusted for geriatric or pediatric populations, since the stability of all three drugs is greatly affected by pH conditions, as well as light or oxidation factors and their interactions.

Geochemical study of heavy metals in samples from dumpsites at Onitsha, Anambra Basin, Southeastern Nigeria

Core (0-60cm) samples were collected from selected dumpsites at Onitsha and control site at Awka, Nigeria. Physiochemical parameters (particle size distribution, cation exchange capacity (CEC), pH, Organic Matter (OM in %)) and heavy metals (Lead (Pb), Copper (Cu), Zinc (Zn), Chromium (Cr), Nickel (Ni), Aluminium (Al), Cobalt (Co), Molybdenium (Mo), Cadmium (Cd), Manganese (Mn) and Silicon (Si)) were analyzed using standard methods. The result of the physiochemical analysis shows that the samples were generally sandy with acidic pH values (4.89-6.24); OM ranged from 5.693-27.71%; CEC ranged from 0.072-0.62(Cmol/kg). Comparatively, DS 5 (Obosi) has the highest levels of these heavy metals followed by DS 2 (Woliwo). The order is Bida &lt; Okpoko &lt;Obosi 1 &lt; Woliwo &lt; Obosi 2. The levels of these heavy metals were above the control values. They were equally above national and international guidelines. Enrichment Factor (EF) values varied between no enrichment to extremely severe enrichment. Pollution load index (PLI) indicated that all the sampled sites were polluted while the ecological risk of heavy metals varied between low contamination to high contamination. The prevailing indiscriminate disposal of wastes occasioned by nonexistence of appropriate disposal facilities is the direct cause of the situation. Proactive measures and regular environmental monitoring must be taken to minimize further deterioration as the contaminants pose serious deleterious effects on human and soil organisms.

Decolorization of Acid Red 337 dye with hydroxyl and sulfate radical based advanced oxidation processes using different iron Catalyst: An experimental and statistical Investigation

Decolorization of Acid Red 337 dye with hydroxyl and sulfate radical based advanced oxidation processes using different iron Catalyst: An experimental and statistical Investigation