pH Values Research Articles

Oxygen isotope fractionation during amorphous to crystalline calcium carbonate transformation at varying relative humidity and temperature

Crystalline calcium carbonate isotope compositions have been widely used to reconstruct past environments. However, if their isotopic compositions are modified because of crystallization from an amorphous precursor, their reliability as paleo-geochemical proxies can be compromised. This study explored the changes in the oxygen isotope compositions during the transformation of amorphous calcium carbonate (ACC) into crystalline carbonate under different conditions of relative humidity (RH of 33 to 95 %), temperature (T of 5 °C and 20 °C) and in the presence/absence of atmospheric CO2. The data showed that at low RH and T (e.g., RH ≤ 45 % and 5 °C) when a complete ACC-crystalline carbonate transformation did not take place then the original ACC δ18O values (δ18OCaCO3 = −15.9 ± 1.0 ‰, VPDB) were preserved throughout the experimental runtime (up to 144 days). In contrast, in fully crystallized CaCO3 (e.g., at RH ≥ 60 %) the δ18OCaCO3 values increased rapidly over the first few days, followed by a slower and gradual increase. By the end of the experiments (i.e., after 103–144 days) the crystalline δ18OCaCO3 values ranged from −10.4 ‰ to −8.1 ‰ in the presence of atmospheric CO2 and from −12.6 ‰ to −9.5 ‰ in the CO2-free experiments. These changes in oxygen isotope compositions of the CaCO3 reaction products (calcite and/or vaterite) were mainly driven by exchange with H2O from the hydrated ACC i.e. the synthesis fluid. In CO2-present experiments, oxygen isotope fractionation factors between the CaCO3 reaction products and the synthesis fluid (18αc–w) approached or exceeded oxygen isotope equilibrium values. This could be explained by a decrease in the initially high pH of the aqueous fluid released from ACC dissolution during CO2 hydration/hydroxylation, which would have increased the oxygen isotope exchange kinetics between H2O and dissolved inorganic carbon (DIC). In some experiments, the hydration/hydroxylation of 18O-enriched CO2, due to isotopic salt-effects, might have also resulted in 18O-enriched calcium carbonates and calculated fractionation factors that exceeded equilibrium values. In the CO2-free experiments, isotopic equilibrium between the crystalline phase and the synthesis fluid was not reached. This oxygen isotope disequilibrium suggests that without the pH lowering effect of the hydroxylation/hydration of CO2, the CO32− released during ACC/calcite dissolution-reprecipitation may have not isotopically equilibrated with the high pH synthesis fluid due to the long equilibration times required to reach isotope equilibrium at high pH values, leading to the self-buffering of δ18OCaCO3 values. The results suggest that the oxygen isotopic compositions of natural carbonates formed from ACC transformation in air and at low water/solid ratio (e.g., biominerals or carbonates formed in caves) are complex and cannot be used as simple proxies if the reaction kinetics (RH/CO2/T) and H2O sources are not known and quantified.

Performance and microstructure of red-mud-blended concrete under different aqueous environments

The effects of aqueous environments on the performances of red-mud-blended concretes (RMCs) were evaluated by measuring their compressive strength, water absorption, and porosity. The pH value, electrical conductivity, and heavy metal concentrations of the immersion solutions were measured to determine the effects of RMCs on the aqueous solutions. The hydration products and microstructures of RMCs were analyzed to determine the effect mechanisms. The results showed that the addition of red mud to concretes increases the apparent porosity and water absorption and decreases the compressive strength. Acidic environments exhibited the most significant effect on the performances of RMCs. In a neutral environment, C–S–H gel generation and a high Si/Ca ratio resulted in enhanced corrosion resistance for the RMC with 35 % red mud, and its compressive strength decreased by 15.07 % after 28 d of immersion. The pH value and electrical conductivity showed a rapid increase, indicating the leaching of soluble alkalis and a large number of ions during soaking. The electrical conductivity showed a rapid increase with the immersion time within 60 d, indicating the leaching out of a large number of ions. The heavy metal concentration and pH value were within the range specified by Chinese standard (DZ/T 0290–2015), which provides many references for evaluating the interaction between RMCs and the aqueous environment.

Influence of ultraviolet illumination on the corrosion behavior of 7A04 aluminum alloy in salt solutions with different pH values

This paper investigated the influence of ultraviolet (UV) illumination on the corrosion behavior of 7A04 aluminum alloy in 3.5% NaCl solutions with various pH values (pH=5.0, 7.0, and 10.0) using weight loss measurement, electrochemical methods, and surface analysis techniques. The research results indicated that the corrosion products of 7A04 alloy in salt solutions with different pH values all exhibited n-type semiconductor properties and could trigger the photovoltaic effect under UV illumination. Simultaneously, UV illumination reduced the compactness of the corrosion products, inhibited the enrichment of copper compounds (Cu2O), and promoted the generation of hydroxyl radicals in the solution. Therefore, UV illumination significantly accelerated the corrosion process of 7A04 alloy, with the overall acceleration effect ranking as follows: alkaline > neutral > acidic. In addition, the corrosion mechanism of 7A04 alloy in the test solutions with and without UV illumination was also discussed in this paper.

An evaluation of the effectiveness of four chemical additives on the fermentation characteristics, in vitro digestibility and aerobic stability of total mixed ration silage based on soy sauce residue.

The study aimed to compare the impact of four chemical additives on fermentation characteristics, aerobic stability and in vitro digestibility of total mixed ration (TMR) silage based on soy sauce residue. The TMR (35% soy sauce residue + 45% Napier grass + 20% concentrate) was placed into silos (10 L). The experiment followed the completely random design, treated with different chemical additives: (1) distilled water (control); (2) 0.1% potassium sorbate (SP); (3) 0.1% sodium benzoate (SS); (4) 0.5% calcium propionate (SC); (5) 0.5% sodium diacetate (SD). Total of 100 silos (5 treatments × 4 aerobic exposure days × 5 replicates) were ensiled for 60 days. After exposure to the air, the samples were analyzed for the dynamic change of fermentation parameters at 4, 9 and 15 days, and the data was analyzed as repeated measures. The content of butyric acid and ammonia nitrogen was maintained at a low level. The highest (p < 0.05) lactic acid (LA) content and the lowest (p < 0.05) pH value were measured in SP. At the first 4 days of aerobic exposure, TMR silages treated with four chemical additives were more stable relative to the control, as indicated by the low pH value and yeast counts. Furthermore, the highest (p < 0.05) LA content and the lowest (p < 0.05) pH value indicated that SP performed superior aerobic stability compared with other chemical additives. The SP shows higher (p < 0.05) 72 h cumulative gas production (GP72) and in vitro neutral detergent fiber digestibility (IVNDFD) relative to the control. In conclusion, the SP performed superior in improving fermentation characteristics, aerobic stability and in vitro digestibility of TMR silages based on soy sauce residue.

Controllable Synthesis of Magnetic Composite Derived from MIL-88D and Study on Adsorption Properties of Cu2+

In this paper, MIL-88D (Fe) with spindle shape was prepared by the hydrothermal synthesis method, a metal oxide with a new structure was obtained by calcination at different temperatures as a precursor, and a magnetic iron oxide composite was prepared successfully. At the same time, it was used as an adsorption material for the adsorption of heavy metal ions Cu2+. The influence of the initial pH value and adsorption time on the adsorption effect was investigated, the adsorption kinetics and adsorption isotherm were further fitted, and the adsorption mechanism was preliminarily analyzed. The results show that the magnetic iron oxide composites have a good adsorption capacity for Cu2+. The pH value is an important parameter that affects the adsorption effect. The adsorption of Cu2+ by magnetic iron oxide composites reached adsorption equilibrium in 30 min. The adsorption of Cu2+ by magnetic iron oxide composites conforms to the second-order reaction kinetics and Langmuir adsorption isotherm equation, which indicates that the adsorption process mainly occurs through chemisorption and typical single-molecular-layer adsorption.

Effects of pH on coprecipitation of As(III) with biogenic synthesized schwertmannite and jarosite

ABSTRACT Secondary iron minerals play significant roles in the immobilization of As under acidic conditions, such as acid mine drainage. However, previous research works have not clarified the effect of pH on As(III) removal through coprecipitation with secondary minerals. Therefore, in this study, we aimed to investigate the discrepancy in As(III) coprecipitation with biogenic synthesized schwertmannite (Sch) and jarosite (Jar) at different pH values. For this, concentrations of Fe2+, TFe, S O 4 2 − , and As(III) in shake flasks were monitored during an overall incubation period of 83 h at initial pH of 1.5, 2.0, and 2.5. In addition, the physicochemical properties of collected minerals after incubation were identified using scanning electron microscopy, X-ray diffraction, pore size distribution, and Brunauer – Emmett – Teller surface area analyses. Our results showed that almost no mineral synthesis and no As(III) removal were detected in coprecipitated schwertmannite (Co-Sch) system and coprecipitated jarosite (Co-Jar) system at an initial pH of 1.5. The TFe precipitation efficiencies and As(III) removal efficiencies increased considerably and morphologies of Co-Sch and Co-Jar improved significantly when the initial pH value increased from 2.0–2.5. The maximum TFe precipitation efficiency and As(III) removal efficiency reached 30.8% and 89.6%, respectively, for the Co-Sch system, and were 47.5% and 37.4%, respectively, for the Co-Jar system. The overall results show that pH significantly affects the formation of Co-Sch and Co-Jar and the behaviour of As(III) coprecipitation.

Adsorption behavior and solidification mechanism of Pb(II) on synthetic C-S-H gel with low and high Ca/Si ratios in highly alkaline environments

Adsorption behavior is rarely investigated as a heavy metal solidification mechanism in alkali-activated municipal solid waste incineration (MSWI) fly ash compacts. This study simulates the adsorption behavior and solidification mechanism of Pb(II) on synthetic C-S-H gel with low and high Ca/Si ratios in high alkaline internal pore solution environments of alkali-activated MSWI fly ash compacts. The study examines the fraction of Pb(OH)3- in a Pb(II) solution (100 mg/L) at pH 11.8 and 12.4, with percentages of 85.9–90.6 % and 93.4–95.1 %, respectively. pH values are identified as the key parameter affecting the adsorption capacity of C-S-H for Pb(II). The equilibrium adsorption capacities (Qe) values of Pb(OH)3- (pH = 11.8) for C-S-H with Ca/Si ratios 1.20 and 0.60 are approximately 104 mg/g and 110 mg/g. At pH 12.4, the C-S-H gel with a Ca/Si ratio = 1.20 performs better in terms of adsorption. The adsorption of Pb(OH)3- by C-S-H is predominantly a chemisorption process at pH 11.8. Based on the ΔG0 data, the adsorption process is determined to be spontaneous. The 1.16 eV LUMO and HOMO difference for Si2O(OH)6 + Pb(OH)3-, compared with the 3.92 eV difference for Si3O2(OH)8 + Pb(OH)3-, indicates a lower difficulty of electron transition in the reaction between Si2O(OH)6 and Pb(OH)3-. XPS and FTIR results confirm the dehydration and combination of Pb(OH)3- and Si-OH in a silicate tetrahedron (Q1 or Q2) on the C-S-H surface to create Si-O-Pb. Partial Ca(II) in C-S-H gel can be replaced or released during the Pb(II) adsorption process. These findings hold significant theoretical importance for the adsorption and solidification mechanism of Pb(II) in alkali-activated MSWI fly ash specimens.

Enhanced pH-sensitive anthocyanin film based on chitosan quaternary ammonium salt: A promising colorimetric indicator for visual pork freshness monitoring

An intelligent pH response indicator film is an easy-to-use device for the real-time monitoring of meat freshness during transport and storage. Therefore, a novel pH-sensitive anthocyanin indicator film composed of polyvinyl alcohol–blueberry anthocyanin (BA)–2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) called PAH-2.0 with 1.2 mg/mL HACC to monitor meat freshness using HACC as the colorimetric enhancer has been developed. BA and HACC were mixed and immobilized in the polyvinyl alcohol matrix by hydrogen bonds, as confirmed via Fourier-transform infrared spectroscopy and X-ray diffraction. The inclusion of HACC improved the color stability and antioxidant and antibacterial properties of the PAH-2.0 film. When applied to pork for freshness monitoring at 4 °C, three freshness stages, including fresh, sub-fresh, and spoiled, could be clearly distinguished based on the color variations of the PAH-2.0 film. The distinct hierarchical color change from purple to blue-violet and finally to grayish-blue was highly correlated with the indicators of pork freshness: pH values, total volatile basic nitrogen, and total viable count. This study provides a simple and promising approach for fabricating meat freshness indicator films with high color recognition accuracy, thereby offering new possibilities for visual meat freshness monitoring.

Study on the changes and transformation characteristics of intermediate liquid products in hydrogen sulfide production from lignite degraded by sulfate-reducing bacteria.

The changes and transformation laws of intermediate liquid-phase products during the anaerobic degradation of lignite by sulfate-reducing bacteria in the formation of hydrogen sulfide play an important role in supplementing and improving the existing theories on the genesis of hydrogen sulfide gas in coal mines. In this paper, H2S gas and key intermediate liquid-phase products produced during the anaerobic degradation of lignite by sulfate-reducing bacteria were detected and analyzed by gas chromatography and gas chromatography-mass spectrometry. The results showed that the process of hydrogen sulfide production from lignite degradation by sulfate-reducing bacteria can be roughly divided into four stages: slow production phase, rapid growth phase, steady production phase, and slight decline phase. In this reaction system, the SO42- concentration showed a decreasing trend, the pH value showed an increasing trend, and the ORP value decreased and then slightly increased with time. Ten volatile component types were detected during the experiment: straight-chain alkanes, branched-chain alkanes, alcohols, aldehydes, ketones, olefins, amines, lipids, acids and phenols. The key components in the intermediate liquid phase products were straight chain alkanes, straight chain alkanes, acids, alcohols, phenols and amines. PAHs, alkanes, and phenols are closely related to H2S production, while amides stimulate nitrogen production. The process is divided into three stages: hydrolysis stage, H2S gas production stage, and decay stage. Liquid-phase intermediates play an important role in the formation process of coal mine BSR hydrogen sulfide and the mechanism of coal mine H2S genesis.

Unraveling the role of black soldier fly larvae in chicken manure conversion: Facilitating maturation and enhancing humification

Black soldier fly larvae (BSFL) have garnered considerable attention for their efficacy in mitigating waste management challenges. However, their potential in treating antibiotics contaminated chicken manure remains uncertain. This study investigates the physicochemical properties changes and nutrient dynamics during the composting of contaminated-chicken manure using BSFL. The results indicate that BSFL treatment reduces electrical conductivity (by 6.01–58.09 %), organic matter, and dissolved organic carbon content in chicken manure throughout the composting process, while maintaining a more stable pH value (pH ∼ 6.0–8.0). This is attributed to the consumption of organic matter by BSFL and the subsequent promotion of organic acid formation. Additionally, BSFL treatment improves the degree of aromatization of dissolved organic matter (DOM) in chicken manure and increases the proportions of fulvic acid (up to 48.77 %) and humic acid (maximally 14.27 %) within the DOM. The germination index and pot experiments indicated improved compost maturity and plant growth in BSFL-treated composts. Furthermore, BSFL meal demonstrated high protein and essential fatty acid content, highlighting its potential as a protein supplement in animal feed. This study underscores the efficacy of BSFL in enhancing compost quality and nutrient availability, offering a sustainable solution for waste management and animal feed production.

Preparation of composite superhydrophobic coatings for mortar utilizing polydimethylsiloxane as a hydrophobic interconnection

Cement-based materials are prone to various contamination problems in aqueous environments, and superhydrophobic coatings are an effective solution to solve this problem. Polydimethylsiloxane (PDMS) is a low surface energy polymer with good mechanical properties, which has a wide range of applications in the field of superhydrophobic coatings. In this study, isobutyltriethoxysilane (IBTES) was employed to hydrophobically modify nano- SiO2, resulting in the modified particles with a core-shell structure to enhance the interfacial effect between the inorganic particles and organosilanes. Simultaneously, the organic-inorganic composite superhydrophobic coatings were prepared using PDMS as a hydrophobic interconnection. The waterproofing performance, self-cleaning performance, aging resistance, mechanical stability, and chemical durability of the coatings were investigated. The results indicate that the water contact angle of the IBTES@SiO2/PDMS composite coating can reach 163°, showing good resistant to contamination, self-cleaning, and mechanical stability. The IBTES@SiO2/PDMS composite coating can maintain the superhydrophobicity after the UV-accelerated aging and immersion in different pH values solutions.

A high-throughput spectroscopic method for pH determination in lactic acid bacteria screening

In this study, a colorimetric method was developed to enable the rapid determination of lactic acid bacteria (LAB) acidification ability by assessing the pH drop during juice fermentation. The proposed method used spectrophotometry to track pH variations induced by LAB, utilizing bromophenol blue as a pH indicator. This colorimetric method demonstrated linearity within the pH range of 2.50–5.70. Optimal performance was achieved with 5.0 % bromophenol blue, yielding a linear equation of y = 1.25x-0.78, with an R2 value of 0.99 upon regression analysis. The method's high accuracy, repeatability and reproducibility were validated through comparisons of pH values obtained using different matrices with those measured using glass electrodes/pH meters. Several Lactiplantibacillus plantarum strains with excellent acid-producing properties were identified through this method. Specifically, the growth of L20, L2 and L6 in MRS medium with a glucose concentration of 200 g/L for 24 h led to a pH decrease of 1.00 unit, while the growth of L20 and L21 in MRS with an ethanol concentration of 12 % (v/v) for 24 h resulted in a similar pH decrease. Strains L12, L14, and L18 could lower the pH of banana and lychee juices by more than 0.30 units at both 25 and 36°C. These results highlight the effectiveness of the method for rapidly screening LAB acidifying activity.

Fe-MOFs nanosheets for photo-Fenton degradation of carbamazepine

Iron(II)-based metal organic framework (Fe(II)-MOF) nanosheets have emerged as promising candidates for photo-Fenton catalysis. However, efficiently synthesizing Fe(II)-MOF nanosheets remains a significant challenge. Here, a bottom-up synthesis strategy is proposed to prepare two-dimensional Fe-MOF nanosheets (TFMN) with micrometer lateral dimensions and nanometer thickness, featuring Fe(II) as the metal nodes. The application of TFMN in the photo-Fenton degradation of carbamazepine (CBZ) demonstrates remarkable CBZ degradation performance and excellent efficiency across a wide range of pH values. The electron density and density of states are further calculated by density functional theory. Mechanism analysis identifies h+, •OH and •O2− as the predominant active species contributing to the catalytic oxidation process in the Vis/TFMN/H2O2 system.

Machine learning-assisted optimization of food-grade spirulina cultivation in seawater-based media: From laboratory to large-scale production

The shortage of food and freshwater sources threatens human health and environmental sustainability. Spirulina grown in seawater-based media as a healthy food is promising and environmentally friendly. This study used three machine learning techniques to identify important cultivation parameters and their hidden interrelationships and optimize the biomass yield of Spirulina grown in seawater-based media. Through optimization of hyperparameters and features, eXtreme Gradient Boosting, along with the recursive feature elimination (RFE) model demonstrated optimal performance and identified 28 important features. Among them, illumination intensity and initial pH value were critical determinants of biomass, which impacted other features. Specifically, high initial pH values (>9.0) mainly increased biomass but also increased nutrient sedimentation and ammonia (NH3) losses. Both batch and continuous additions could decrease nutrient losses by increasing their availability in the seawater-based media. When illumination intensity exceeded 200 μmol photons/m2/s, it amplified the growth of Spirulina by mitigating the light attenuation caused by a high initial inoculum level and counteracted the negative effect of low temperature (<25 °C). In large-scale cultivation, production efficiency would be reduced if illumination was not maintained at a high level. High salinity and sodium bicarbonate (NaHCO3) addition promoted carbohydrate accumulation, but suitable dilution could keep the required protein content in Spirulina with relatively low media and production costs. These findings reveal the interactive influence of cultivation parameters on biomass yield and help us determine the optimal cultivation conditions for large-scale cultivation of Spirulina-based seawater system based on a developed graphical user interface website.

Development of Spray Drying of Powdered Oolong Tea Incorporated with Chinese Jujube Beverage

One useful economic crop which is utilized worldwide is Chinese jujube. It offers both nutritional and therapeutic benefits. Meanwhile, Oolong tea is a semi-oxidized form of tea which has a flavour that falls somewhere between black tea and green tea. Finally, spray-drying is an important technique used in food preservation. This current study sought to assess the most suitable use of Chinese jujube along with appropriate levels of maltodextrin when creating a mixed Oolong tea which incorporates Chinese jujube and is subsequently processed via spray-drying. Oolong tea served as the control sample, while evaluations were carried out on 60%, 70% and 80% blends of Chinese jujube with maltodextrin which served as a carrier agent at concentrations of 20 g, 30 g, 40 g and 50 g. These solutions underwent spray-drying where the respective inlet and outlet temperatures were 190°C and 80°C. An evaluation of the physico chemical, microbiological and sensory evaluation were performed. There was evidence of an increase in the total phenolic compounds, whereas in contrast there was a decline in antioxidant activity. L* and +a* showed no statistically significant difference, although for +b* a statistically significant difference was found. For products with mixed Chinese jujube and Oolong tea, the moisture, water activity and pH values were shown to be lower, although there was an increase in total soluble solids. In the evaluation, flavour and overall acceptability for Treatment 4 (80% Chinese jujube) achieved the highest respective ratings at 8.17 and 8.13 on the 9-point scale. This demonstrates that spray-drying can be beneficial in the context of powdered particles. The combination of Chinese jujube and powdered Oolong tea provides good antioxidant properties and offers strong potential for applications in the food sector.

Reorientation of interfacial water molecules during melting of brain sphingomyelin is associated with the phase transition of its C24:1 sphingomyelin lipids

Melting of brain sphingomyelin (bSM) manifests as a broad feature in the DSC curve that encompasses the temperature range of 25 – 45 °C, with two distinguished maxima originating from the phase transitions of two the most abundant components: C24:1 (Tm,1) and C18:0 (Tm,2). While C24:1/C18:0 sphingomyelin transforms from the gel/ripple phase to the fluid/fluid phase, the dynamics of water molecules in the interfacial layer remain completely unknown. Therefore, we carried out a calorimetric (DSC), spectroscopic (temperature-dependent UV-Vis and fluorescence) and MD simulation study of bSM in the absence/presence of Laurdan® (bSM ± L) suspended in Britton-Robinson buffer with three different pH values, 4 (BRB4), 7 (BRB7) and 9 (BRB9), and of comparable ionic strength (I = 100 mM). According to DSC, T̅m, 1 (≈ 34.5 °C/≈ 32.1 °C) and T̅m, 2 (≈ 38.0 °C/≈ 37.2 °C) of bSM suspended in BRB4, BRB7, and BRB9 in the absence/presence of Laurdan® are found to be practically pH-independent. Turbidity-based data (UV-Vis) detected both qualitative and quantitative differences in the response of bSM suspended in BRB4/BRB7/BRB9 (T̅m: ∼ 35 °C/32.0 ± 0.2 °C/36.4 ± 0.4), suggesting an intricate interplay of weakening of van der Waals forces between their hydrocarbon chains and of increased hydration in the polar headgroups region during melting. The temperature-dependent response of Laurdan® reported a discontinuous, pH-dependent change in the reorientation of interfacial water molecules that coincides with the melting of C24:1 lipids (on average, T̅m (LTC/HTC): ≈ 31.8 °C/30.6 °C/30.5 °C). MD simulations elucidated the impact of Laurdan® on a change in the physicochemical properties of bSM lipids and characterized the hydrogen bond network at the interface at 20 °C and 50 °C.

De Novo Design and Characterization of Amphiphilic Peptides with Basic Side Chains for Tailored Interfacial Chemistries.

Lysine-leucine (LK) peptides have been used as model systems and platforms for 2D material design for decades. LK peptides are amphiphilic sequences designed to bind and fold at hydrophobic surfaces through hydrophobic leucine side chains and hydrophilic lysine side chains extending into the aqueous subphase. The hydrophobic periodicity of the sequence dictates the secondary structure at the interface. This robust design makes them ideal candidates for controlling interfacial chemistry. This study presents the de novo design and characterization of two novel peptides: LRα14 and LHα14, which substitute lysine with arginine and histidine, respectively, in the helical LKα14 sequence. This modification is intended to expand the LK peptide platform to a new basic interfacial chemistry. We explore the stability of the new LRα14 and LHα14 designs with respect to changes in pH and salt concentration in bulk solution and at the interface using circular dichroism (UV-CD) and vibrational sum-frequency generation spectroscopy, respectively. Notably, the structural stability of the peptides remains unaffected across a wide range of pH and ionic strength values. At the same time, the variation of side-chain chemistry leads to a wide spectrum of interfacial water structures. By extension of the LK platform to include arginine and histidine, this study broadens the toolbox for designing tailored interfacial chemistries with applications in material and biomedical sciences.

Petroleum spills and assessment of heavy metals in water, sediment, soil from Afiesere River, Ughelli, Delta State, Nigeria

The study which was to determine the concentrations of heavy metals in water, sediment and soil of Afiesere river because of the anthropogenic activities of petroleum exploration and attendant spills in the area. Surface water, sediment, surface soil and sub-surface soil samples were collected from Afiesere River, Ughelli, Delta State. Some physiochemical parameters of water were analysed using standard methods and Hanna water quality checker. The concentrations of five heavy metals, namely; lead (Pb), cadmium (Cd), zinc (Zn), copper (Cu) and nickel (Ni) were determined in water, sediment, surface soil, and sub-surface soil using Flame Atomic Absorption Spectrophotometer (Flame-AAS). The results obtained show the mean values of pH, temperature, total dissolved solid, conductivity, dissolved oxygen, biological oxygen demand, phosphate, nitrate, and sulphate as follows: 6.87 ± 0.18, 27.40 ± 0.28oC, 4.00 ± 0.00 mg/L, 8.67 ± 0.25 µs/cm, 4.23 ± 0.08 mg/L, 0.65 ± 0.17 mg/L, 0.01 ± 0.00 mg/L, 0.01 ± 0.03 mg/L, and 2.17 ± 0.18 mg/L respectively. The heavy metals; Pb, Cd, Zn, Cu and Ni mean concentrations are as follows: in water, 0.06 ± 0.02, 0.02 ± 0.01, 0.46 ± 0.01, 0.03 ± 0.01 and 3.56 ± 0.07 mg/L; in sediment, 0.52 ± 0.03, 0.02 ± 0.00, 0.21 ± 0.02, 0.07 ± 0.01 and 0.26 ± 0.01 mg/kg; in surface soil, 0.50 ± 0.03, 0.02 ± 0.00, 0.07 ± 0.01, 0.03 ± 0.00 and 2.91 ± 0.03 mg/kg; in sub-surface soil, 0.55 ± 0.02, 0.02 ± 0.01, 0.26 ± 0.02, 0.06 ± 0.01 and 0.36 ± 0.08 mg/kg respectively. The results showed a significant difference at P&lt;0.05. The results obtained in this study were within and above the set standard for water, sediment and soil by World Health Organization (WHO). The metals are toxic, can bio-accumulate and are potential carcinogens; therefore treatment of water is very important. Periodic medical examination of the inhabitants of the area must be a top priority.

Natural deep eutectic solvents: A paradigm of stability and permeability in the design of new ingredients

Ascorbic Acid (AA) is a crucial component in the food industry, serving as both a quality and safety criterion. It is used to fortify foods due to its significant role in human health, acting as an antioxidant. Its benefits extend to both product quality and consumer health in the food and cosmetic industry. Due to their physicochemical properties, Natural Deep Eutectic Solvents (NADES) have the potential to be used for the extraction and stabilization of bioactive compounds. The objective of this study is to characterize various NADES, simulate the solubility of AA, evaluate the antioxidant and protective capacity of NADES, and investigate the permeability of this vitamin through the skin and gastrointestinal membrane. Antioxidant capacity was measured using three methods: TEAC, DPPH, and ORAC. The solubility of AA in NADES systems was simulated using the COSMOTherm software. The degradation of AA was monitored by HPLC/UV–Vis for 30 days at two different storage temperatures. Additionally, the membrane solubility was measured using the PAMPA method in both skin and gastrointestinal. The results indicate that organic acid-based NADES are more polar than sugar and polyalcohol-based NADES. The solubility prediction shows that reduced ln(γ) in Choline chloride-based NADES results in low AA solubility, which positively correlates with higher pH values. AA degradation increased at lower pH, and its half-life time was longer at 4 °C, being the best choline chloride (ChChl):xylose. Moreover, betaine:malic acid, ChChl:tartaric acid, and ChChl:lactic acid gave worse stabilizing results than control. According to the PAMPA study, AA in lactic acid:glucose had the highest Pe (permeability coefficient) for both gastrointestinal (Log Pe: −4.99) and skin (Log Pe: −4.78). Malic acid:glucose, on the other hand, had the lowest LogPe value (−6.9). In this study, some NADES can play a protective role in the preservation of ascorbic acid. This statement could be extended to other bioactive compounds found in NADES extracts that may be impacted by oxidative processes. Moreover, not all NADES stabilized equally AA. These findings could be applied to the formulation of ascorbic acid-containing drugs, cosmetics, and food products.

Physio-chemical and bacteriological quality of well water from Kottayam district, Kerala

This study focused on determining of physio-chemical, Biological and Weighed water quality index of well water samples from twelve different stations in Kottayam district, Kerala. The water samples analyzed for physio-chemical parameters including pH, Electrical conductivity, TDS (Total Dissolved Solids), Total iron, Bacterial contamination and water quality index was calculated. All 120 samples were analyzed separately and were compared with the water quality standard prescribed by the APHA and IS 3025. It was found that the mean pH values showed slight variations ranging from 5.85±0.72- 7.19±2.09. The electrical conductivity showed variations ranging from 64.9±46.34- to 366.4±561.8. The well water samples were shown the TDS value under the permissible limit with a range of 42±39.8-248.2±393.03. A significant variation in total iron value was obtained from the Neendoor station and the range is 0.0033±0.0069-0.5525±1.703. Weighted water quality index was calculated based on physiochemical parameters and it is evident that the water from Neendoor station is unsuitable for drinking purposes. The bacterial concentrations of Pampady station showed 90% contamination and 65.8% of water samples were showed Indicator organism Escherichia coli.