Acidic Conditions pH Research Articles

Environmental Influences on Seed Germination and Seedling Emergence in Four Echinochloa Taxa

Echinochloa species are troublesome weeds that cause serious problems in paddy fields. Due to the fact that the genus Echinochloa comprises numerous species and subspecies, research on its seed germination and emergence ecology is still insufficient. In this study, the influence of varying temperatures; light, osmotic, and saline conditions; and depth of seed burial on the germination of Echinochloa seeds and the emergence of seedlings was determined through laboratory and pot tests: E. crus-galli var. crus-galli, E. crus-galli var. mitis, E. crus-galli var. praticola, and E. caudata. Seed germination of the constant temperatures in the four Echinochloa taxa was examined between 15 and 40 °C, and optimum germination occurred over the following temperature ranges: 25‒35 °C for E. crus-galli var. crus-galli; 15‒25 °C for E. crus-galli var. mitis; 15‒40 °C for E. crus-galli var. praticola; and 15‒35 °C for E. caudata. Fluctuating temperatures were conducive to seed germination in all four Echinochloa taxa. Except for E. crus-galli var. crus-galli and E. crus-galli var. mitis exposed to very acidic conditions (pH = 4), germination of seedlings from the four taxa of Echinochloa was not evidently affected by pH or light. Seed germination of the four Echinochloa taxa decreased as water stress decreased (<−0.2 MPa); however, it occurred across a wide spectrum of salt concentrations (0–320 mM NaCl). The seeds that were placed 0–0.5 cm below the surface had the highest rate of seedling emergence, which declined gradually as burial depth increased. This result demonstrates that deep tillage is an efficient management method for decreasing the seedling emergence of various weed species. This study’s findings will enhance our comprehension of the conditions necessary for the germination and emergence of Echinochloa seeds, as well as furnish information that may assist in managing its growth.

Deciphering adsorption behaviour and mechanisms of enhanced phosphate removal via optimized cetyltrimethylammonium bromide-modified nanofibrillated cellulose.

To combat the persistent environmental issues resulting from eutrophication, it is necessary to scavenge excess phosphorous levels from aquatic ecosystems. In response, a cationic adsorbent was prepared by modifying agrowaste-derived natural biomacromolecule; nanofibrillated cellulose (NFC) using cetyltrimethylammonium bromide (CTAB) surfactant. Comprehensive characterization through XRD, FTIR, HR-SEM, SEM-EDX, BET and XPS demonstrated that quaternizing NFC significantly improved its surface chemistry by introducing substantial quaternary ammonium groups. This modification imparted positive ζ potential across broad pH range, underscoring a strong affinity for negatively charged phosphate ions. Enhanced roughness and improved spatial dispersion led to nearly threefold increase in phosphate removal efficiency compared to pristine NFC, attributable to a higher number of available active sites. The adsorption process followed pseudo-second-order kinetic and Sips isotherm model, with a maximum adsorption capacity of 21.78 mg P/g, reaching equilibrium within 120 min. Besides, the prepared adsorbent demonstrated pH-dependent adsorption and displayed stable adsorption capacity particularly at weakly acidic or neutral pH conditions. Furthermore, it exhibited excellent retention capacity with only 12.61 % desorption rates over three cycles. Both XPS and FTIR results revealed that electrostatic adsorption (based on Lewis acid-base principle) and hydrogen bonding were primary adsorption mechanism.

Acidosis overrides molecular heterogeneity to shape therapeutically targetable metabolic phenotypes in colon cancers.

Colorectal cancer (CRC) represents a prototypical example of a cancer type for which inter- and intra-tumor heterogeneities remain major challenges for the clinical management of patients. Besides genotype-mediated phenotypic alterations, tumor microenvironment (TME) conditions are increasingly recognized to promote intrinsic diversity and phenotypic plasticity and sustain disease progression. In particular, acidosis is a common hallmark of solid tumors, including CRC, and it is known to induce aggressive cancer cell phenotypes. In this study, we report that long-term adaptation to acidic pH conditions is associated with common metabolic alterations, including a glycolysis-to-respiration switch and a higher reliance on the activity of phosphoglycerate dehydrogenase (PHGDH), in CRC cells initially displaying molecularly heterogeneous backgrounds. Pharmacological inhibition of PHGDH activity or mitochondrial respiration induces greater growth-inhibitory effects in acidosis-exposed CRC cells in 2D and 3D culture conditions, and in patient-derived CRC organoids. These data pave the way for drugs targeting the acidic tumor compartment as a "one-size-fits-all" therapeutic approach to delay CRC progression.

Effects of whey protein aggregates with different sizes on the gelatinization and retrogradation behavior of wheat starch.

Starch retrogradation leads to undesirable changes in the texture and taste of starchy foods. The fibrous aggregates of whey protein fibrils (WPF) formed by heating under acidic conditions possess enhanced emulsification and foaming properties, but their effect on the retrogradation behavior of starch is unclear. WPFs with various molecular sizes were obtained by heating at 85 °C under acidic conditions (pH 2.0) for different times (0, 0.5, 2.5, 5, 7.5, and 10 h). Their effects on the gelatinization and retrogradation of wheat starch were investigated. Particle size distribution and confocal laser scanning microscopy confirmed the formation of WPFs. Compared to native starch, WPFs reduced swelling, lowered the storage modulus (G') peak, and increased the gelatinization temperature, indicating inhibition of starch gelatinization. High molecular weight WPF (WPF5) had the strongest inhibitory effect, significantly enhancing G' during cooling after gelatinization, suggesting a stronger gel network. Moreover, all WPFs reduced retrogradation and crystallinity of starch gels over 14 days, with WPF5 showing the most significant effect, reducing retrogradation by 35.85% and relative crystallinity by 5.53%. Whey protein fibrous aggregates, especially those with high molecular weight (WPF5), inhibit starch gelatinization and retrogradation. This study presents a novel approach to improve starch-based food quality by reducing retrogradation and enhancing gel structure. © 2025 Society of Chemical Industry.

Beta‐Lactoglobulin for Water‐Based and Tunable Nanostructure Templating of Printed Titania Thin Films: The Influence of pH Value and Protein Concentration

AbstractAn environmentally friendly as well as scalable synthesis route of nanostructured titania thin films is of interest for many state‐of‐the‐art devices, from solar cells to battery materials. Beta‐lactoglobulin (ß‐lg) enables water‐based and tunable titania thin film templating, allowing for different domain sizes, porosities, and morphologies. When printed with a slot‐die coater, the titania films can be tailored to specific applications with simple changes to the solution chemistry. Films printed at acidic pH conditions form significantly different final morphologies than films printed at a neutral pH value. The protein concentration plays a more limited role in the final nanostructure. With in situ grazing incidence small‐angle/wide‐angle X‐ray scattering (GISAXS/GIWAXS), the structure formation is followed with an excellent time resolution during the printing process. From the GISAXS measurements, the size evolution of the titania clusters is understood, showing significant differences for different pH values. Crystal phases and corresponding crystal orientations are investigated with GIWAXS. The combination of a water‐based titania synthesis with the scalable film deposition via slot die coating makes the presented results interesting for potential environmentally friendly mass production of nanostructured titania films.

Novel Piperazine Derivatives as Selective Antagonists of GluN2B-Containing NMDARs under Acidic pH Conditions

Novel Piperazine Derivatives as Selective Antagonists of GluN2B-Containing NMDARs under Acidic pH Conditions

Chemical design of metal complexes for electrochemical water oxidation under acidic conditions.

The development of viable, stable, and highly efficient molecular water oxidation catalysts under acidic aqueous conditions (pH < 7) is challenging with Earth-abundant metals in the field of renewable energy due to their low stability and catalytic activity. The utilization of these catalysts is generally considered more cost-effective and sustainable relative to conventional catalysts relying on precious metals such as ruthenium and iridium, which exhibit outstanding activities. Herein, we discussed the effectiveness of transition metal complexes for electrocatalytic water oxidation under acidic conditions. We focus on important aspects of 3d first-row metal complexes as they relate to the design of water oxidation systems and emphasize the importance of the fundamental coordination chemistry perspective in this field, which can be applied to the understanding of catalytic activity and fundamental structure-function relationships. Finally, we identified the scientific challenges that should be overcome for the future development and application of water oxidation electrochemical catalysts.

Enhanced targeted treatment of cervical cancer using nanoparticle-based doxycycline delivery system

This study investigates a nanoparticle-based doxycycline (DOX) delivery system targeting cervical cancer cells via the CD44 receptor. Molecular docking revealed a strong binding affinity between hyaluronic acid (HA) and CD44 (binding energy: -7.2 kJ/mol). Characterization of the HA-Chitosan nanoparticles showed a particle size of 284.6 nm, a zeta potential of 16.9 mV, and a polydispersity index of 0.314, with SEM confirming smooth surface morphology. The encapsulation efficiency of DOX-loaded nanoparticles was 89.32%, exhibiting a sustained release profile, with 67.45% released over 72 h in acidic conditions (pH 5.5). Cytotoxicity assays demonstrated a significant reduction in HeLa cell viability to 22% at 72 h, compared to 67% in normal HEK cells. Stability tests confirmed the maintenance of nanoparticle integrity and a consistent drug release profile over three months. Cell migration was reduced by 45%, and RT-PCR analysis revealed a 53% downregulation of TNF-α expression, suggesting effective targeting of inflammatory pathways. These results underscore the potential of HA-Chitosan-based DOX nanoparticles in improving cervical cancer treatment through enhanced targeted delivery and inhibition of tumor-promoting mechanisms.

Approaches and applications in transdermal and transpulmonary gene drug delivery.

Gene therapy has emerged as a pivotal component in the treatment of diverse genetic and acquired human diseases. However, effective gene delivery remains a formidable challenge to overcome. The presence of degrading enzymes, acidic pH conditions, and the gastrointestinal mucus layer pose significant barriers for genetic therapy, necessitating exploration of alternative therapeutic options. In recent years, transdermal and transpulmonary gene delivery modalities offer promising avenues with multiple advantages, such as non-invasion, avoided liver first-pass effect and improved patient compliance. Considering the rapid development of gene therapeutics via transdermal and transpulmonary administration, here we aim to summarize the nearest advances in transdermal and transpulmonary gene drug delivery. In this review, we firstly elaborate on current delivery carrier in gene therapy. We, further, describe approaches and applications for enhancing transdermal and transpulmonary gene delivery encompassing microneedles, chemical enhancers, physical methods for transdermal administration as well as nebulized formulations, dry powder formulations, and pressurized metered dose formulations for efficient transpulmonary delivery. Last but not least, the opportunities and outlooks of gene therapy through both administrated routes are highlighted.

Controlled Nitrogen Release by Hydroxyapatite Nanomaterials in Leaves Enhances Plant Growth and Nitrogen Uptake.

Nitrogen fertilizer delivery inefficiencies limit crop productivity and contribute to environmental pollution. Herein, we developed Zn- and Fe-doped hydroxyapatite nanomaterials (ZnHAU, FeHAU) loaded with urea (∼26% N) through hydrogen bonding and metal-ligand interactions. The nanomaterials attach to the leaf epidermal cuticle and localize in the apoplast of leaf epidermal cells, triggering a slow N release at acidic conditions (pH 5.8) that promote wheat (Triticum aestivum) growth and increased N uptake compared to conventional urea fertilizers. ZnHAU and FeHAU exhibited prolonged N release compared to urea in model plant apoplast fluid pH in vitro (up to 2 days) and in leaf membranes in plants (up to 10 days) with a high N retention (32% to 53%) under simulated high rainfall events (50 mm). Foliar N delivery doses of up to 4% as ZnHAU and FeHAU did not induce toxicity in plant cells. The foliar-applied ZnHAU and FeHAU enhanced fresh and dry biomass by ∼214% and ∼161%, and N uptake by ∼108% compared to foliar-applied urea under low soil N conditions in greenhouse experiments. Controlled N release by leaf-attached nanomaterials improves N delivery and use efficiency in crop plants, creating nanofertilizers with reduced environmental impact.

Bifunctional adsorbents based on hyper-cross-linked polymers containing carbonyl and amine species for the efficient removal of diclofenac from water in a broad pH range.

Development of new adsorbents for the efficient removal of organic pollutants from water is one of the most emerging environmental issues. Current studies in this field focus on improving the adsorption capacity of various materials and/or broadening the pH range in which the adsorbents can efficiently remove target pollutants. In this study, we designed bifunctional hyper-cross-linked polymers (HCPs) containing both carbonyl and amine species to investigate the effect of amine functional groups on the efficiency of adsorptive removal of non-steroidal anti-inflammatory drugs (NSAIDs) from water. We revealed that post-synthesis functionalization of carbonyl-rich HCPs with amine species does not have a significant impact on the adsorption capacity of these polymers under strongly acidic conditions (pH < 4; qe ∼ 544 mg/g), but significantly extends the pH range in which bifunctional polymers can adsorb diclofenac. For example, at native pH (pH ∼ 6), bifunctional HCP-based adsorbents exhibited an adsorption capacity approximately 8 times higher than that of pristine materials (qe = 191 vs. 24 mg/g, respectively). Furthermore, it was revealed that the adsorbents designed in this study can efficiently remove diclofenac from complex water matrices and exhibit high stability in several adsorption-desorption cycles. Moreover, we demonstrated that selecting a cross-linker with a longer chain results in a polymer with a lower surface area and smaller average pore size, while enabling higher efficiency in amine incorporation via post-synthesis functionalization. This latter feature was crucial for ensuring the high adsorption capacity of HCP-based adsorbents in the removal of NSAID at neutral pH.

Growth Characteristics of Sheep-Derived Bacteroides fragilis and Preliminary Research on Effects in Mice and Lambs.

With the growing demand for sheep, the sheep farming industry has developed rapidly. However, lamb diarrhea, a disease with high mortality rates, significantly hampers the industry's growth. Traditional antibiotic treatments often disrupt the Intestinal microbiota, induce antibiotic resistance, and cause adverse side effects, highlighting the urgent need to develop alternative therapies. Bacteroides fragilis, a candidate next-generation probiotic, has been closely associated with intestinal health. This study investigated the growth characteristics and probiotic effects of a sheep-derived Bacteroides fragilis isolate, focusing on its efficacy in alleviating lamb diarrhea and infectious intestinal diseases. The experiments demonstrated that the Bacteroides fragilis isolate grows well under mildly acidic conditions (pH 6-8), exhibits some tolerance to bile salts, and has survival rates of 38.89% and 92.22% in simulated gastric and intestinal fluids, respectively, indicating its potential as a probiotic. In a mouse model, Bacteroides fragilis intervention significantly alleviated colonic inflammation caused by Enterohemorrhagic Escherichia coli infection, enhanced tight junction protein expression, mitigated oxidative stress, and improved intestinal barrier function, with high-dose interventions showing superior effects. In lamb trials, Bacteroides fragilis intervention stopped diarrhea in four out of five lambs, partially restored intestinal microbiota diversity, and reduced the abundance of potential pathogens such as Aerococcus suis and Corynebacterium camporealensis. Therefore, Bacteroides fragilis exhibited remarkable effects in regulating intestinal homeostasis, alleviating inflammation, and promoting recovery from diarrhea.

A novel carbazole-pyrimidine-based dual mode fluorescent probe for detection of acidic and basic pH in biological systems.

pH balance is an important factor in regulating the internal environment of body and maintaining the normal physiological activities, but pH cannot be detected in vivo without damaging the tissue. It is important to develop a pH probe with low toxicity, high sensitivity and targeting of organelles. In this research, a novel carbazole-pyrimidine-based probe PKZP was designed from 2-hydroxyl-3-pinanone which was derived from natural monoterpene α-pinene for detecting both acidic and basic pH in vivo. Probe PKZP demonstrated a response characterized by ratiometric fluorescence under acidic pH conditions, while exhibiting a quenching fluorescence effect under alkaline pH conditions. In addition, the two different assay performances demonstrated that probe PKZP possessed the outstanding merits including fast response (within 1s), good photostability and excellent anti-interference performance. Furthermore, probe PKZP can be used as an efficient tool to detect exogenous acidic and basic pH in living organisms.

Facile construction of polyoxometalate-polymer hybrid nanoparticles with pH/redox dual-responsiveness.

Responsive nanomaterials have emerged as promising candidates for advanced drug delivery systems (DDSs), offering the potential to precisely target disease sites and enhance treatment efficacy. To fulfil their potential, such materials need to be engineered to respond to specific variations in biological conditions. In this work, we present a series of pH/redox dual-responsive hybrid nanoparticles featuring an amphiphilic shell polymer and a pH-responsive core polymer. These nanoparticles incorporate a polyoxometalate (POM), specifically the cobalt(iii)-substituted borotungstate ([BIIIW11O39CoIII]6-), loaded through coordination chemistry between the encapsulated CoIII ions of the POM and pyridyl functional groups on the core polymer. The resulting hybrid nanoparticles show potential for controlled release with excellent stability at physiological pH, and efficient particle disassembly in response to the combination of pH and redox stimuli. Disassembly is proposed to occur following a two step mechanism. Structural rearrangement of the nanoparticle occurs on acidification followed by destabilization of the coordination bond between the polyanion and the pyridyl functionality in the core polymer following reduction. In this system, the POM acts in a novel role as a redox active structural cross-linker. These hybrid dual-responsive nanoparticles, featuring superior colloidal stability under extracellular conditions and controllable disintegration in response to the dual stimuli of acidic pH and redox conditions, provide a novel platform for the controlled intracellular release of therapeutics.

Stability of lead immobilization by Aspergillus niger and fluorapatite under different pH conditions.

The combination of Aspergillus niger (A. niger) and fluorapatite (FAp) has been applied in lead (Pb) immobilization. However, the different pH can affect the stability of the immobilized Pb minerals. This experiment explored the stability of Pb immobilization by A. niger and FAp under different pH conditions. A. niger can grow normally in a pH range from 2.5 to 6.5 conditions. Meanwhile, more than 99 % of Pb cations were removed by A. niger and FAp under a pH range from 3.5 to 6.5. More importantly, only less than 1.23 % Pb was released again under pH 3.5-5.5. The strong acidic conditions (pH 1.5) inhibited the growth of A. niger and caused a lower Pb removal ratio of 37.86 %. In addition, the formed minerals of lead oxalate and lead/calcium oxalate coprecipitate dominate the Pb remediation by A. niger and FAp. The pH > 5.5 condition could decrease the stability of Pb immobilization via the low calcium/lead ratios. The combination of A. niger and FAp shows great potential in Pb remediation at a pH range from 3.5 to 5.5, suitable for fungal growth and Pb minerals stability. This research provides new insight into Pb remediation by phosphate-solubilizing fungi and FAp in various acidic environments.

Study on the absorption characteristics of euscaphic acid and tiliroside in fruits of Rosa laxa Retz.

The fruits of Rosa laxa Retz. (FRL) have a long history of medicinal use, known for their rich composition of flavonoids, polyphenols, amino acids, sugars, and other bioactive compounds. FRL exhibits pharmacological effects such as antioxidant, antiviral, antibacterial, and antitumor activities, making it a valuable resource with significant development potential in both the food and pharmaceutical industries. This study employed a response surface methodology combined with ultra-high-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-TQ-MS) to optimize FRL extraction. Reflux extraction was determined to be the most effective method with the following optimized parameters: 65% ethanol extraction solvent, material-to-liquid ratio of 1:35 (g/mL), and extraction time of 140 min, resulting in the FRL extract (FRLE). Under these optimized conditions, the extracted amount was extract was 51.00 ± 1.07%, the average content of total polyphenols was 126.55 ± 2.61 mg/g, and the average content of euscaphic acid was 2.90 ± 0.08 mg/g, demonstrating the efficiency of the extraction method. Using the Caco-2 cell model, the study investigated the absorption characteristics of euscaphic acid and tiliroside within FRLE. Results indicated that with increasing time, the absorbed amount (Qr) of euscaphic acid and tiliroside gradually increased, with an efflux ratio (RB→A/A→B) of less than 1.5, suggesting bidirectional drug transport with no significant directionality. Upon the addition of P-glycoprotein (P-gp) inhibitors Verapamil (Ver) and Ciclosporin A (CsA), as well as the chelating agent ethylenebis (oxyethylenenitrilo) tetraacetic acid (EGTA), Qr and Papp values notably increased, indicating that these two components are P-gp substrates with cellular basolateral efflux transport. Additionally, optimal absorption efficiency was observed under weakly acidic conditions (pH 6.0). In conclusion, euscaphic acid and tiliroside in FRLE demonstrated good membrane permeability, primarily relying on passive diffusion for absorption. This study offers experimental insights into the intestinal absorption of FRL in vivo.

Computational Simulation Study-Based Formulation Development and Characterization of MethylprednisoloneLoaded Nanoparticles Containing Chitosan and Pectin to Treat Nocturnal Asthma.

Nocturnal asthma (NA) is a high-prevalence disease that causes severe respiratory issues, leading to death from early midnight to early morning. In this research, nanoparticulate drug delivery system of methylprednisolone (MP) was developed using chitosan (CH) and pectin (PEC). MP is a synthetic corticosteroid medication widely used for its potent anti-inflammatory activity. Computational simulation study (AI-based blend analysis algorithm) was used to identify a better-mixing polymer with MP. MP nanoparticles were formulated by the ionic gelation method with the combination of CH and PEC. To modify the drug release properties, the formed beads were coated with chitosan succinate (CSSC). The morphological characteristics of the beads were determined by SEM analysis. The X-ray radiographic imaging study was used to observe the intactness of MP beads. Histopathological studies were also carried out to find out the toxicity of the beads in the organs of rats. Pectin and chitosan polymers were selected based on the computational simulation study. SEM analysis revealed that the beads had a spherical shape with a rough outer surface. CSSC-coated beads achieved sustained drug release for up to 24 h. X-ray imaging demonstrated the stability of the beads in acidic pH conditions. In vivo pharmacokinetic studies showed that CSSC-coated beads were more stable in the gastrointestinal tract (GIT) than PEC-CH beads and the pure drug. Histological evaluation confirmed that the beads are nontoxic and safe for use in rats. Based on the findings, it was concluded that CSSC-coated beads of MP exhibited superior release properties, making them suitable for a chronomodulated drug delivery system.

Role of Aspartate 42 and Histidine 79 in the aiPLA2 activity and oligomeric status of Prdx6 at low pH.

Peroxiredoxin 6 (Prdx6), a unique non-seleno peroxidase, is a bifunctional protein with GSH peroxidase at pH 7.4 and calcium independent phospholipase A2 (aiPLA2) activities at pH 4.0. Changes in pH brings about alteration in the conformational and thermodynamic stability of Prdx6. For instance, under acidic condition (pH 4.0), Prdx6 forms higher oligomers with concommittant gain in aiPLA2 activity that is resistant to thermal denaturation. However, there has been no molecular level understanding of how low pH induces formation of oligomers. In the present study, site directed mutagenesis of two conserved amino acid residues, Asp42 and His79, was used to study the molecular basis for the influence of pH on the oligomeric state of Prdx6. We observed that mutation at Asp42 and His79 residues by Ala did not result in a significant change in its peroxidase activity at neutral pH 7.4 but its aiPLA2 activity at low pH 4.0 decreased significantly. At this pH condition, both mutants exhibit highly conserved alpha-helix content but fluctuating tryptophan micro-environment with partly exposed hydrophobic patches that renders the formation of oligomers. DLS measurements and analytical SEC revealed that Wt Prdx6 forms oligomers at low pH but not the mutan proteins suggesting the importance of these residues in pH sensing and oligomerization. These results suggest that Asp42 and His79 interact each other to induce conformational change of Prdx6 that triggers the oligomerization of Prdx6 at low pH.

Removal of cetirizine dihydrochloride from different matrices waters using Bi2O3/TiO2 photocatalyst under simulated solar irradiation: Kinetics, mechanism, and effect of environmental media.

In this study, the photodegradation of cetirizine dihydrochloride (CET) by Bi2O3/TiO2 heterojunctions under simulated solar light irradiation (300-800nm) was examined in detail for the first time. A hydrothermal synthesis of the photocatalyst was carried out, and several analytical techniques were used to characterize the product. The resulting Bi2O3/TiO2 photocatalyst effectively removed CET from an aqueous solution. The Bi2O3/TiO2 (5.0%/95.0%) ratio exhibited the highest photocatalytic performance for CET degradation, degrading 75.85% of CET after 60 min of irradiation, with a high pseudo-first-order rate constant (kapp = 0.022 min-1; t1/2 = 31.50 min; natural pH). Moreover, TOC decreased by 40.45% after 420 min of irradiation. The Bi2O3/TiO2 photocatalyst has also been proven effective in degrading CET in different real aqueous matrices (Seawater (99.89%) > spring water (68.44%) > tap water (52.62%)), and the degradation under natural solar irradiation is more effective and faster than under artificial irradiation. Additionally, the Bi2O3/TiO2 photocatalyst demonstrated excellent photo-stability in a five-cycle photocatalytic experiment. The influence of various parameters showed that the removal of CET was heightened with a dose of 1 g/L of the Bi2O3/TiO2 and enhanced under acidic conditions (pH = 2.3). Moreover, the involvement of different reactive species was investigated by introducing diverse scavengers, revealing that hydroxyl radicals and photo-holes were the main reactive species involved in the CET photodegradation process over the Bi2O3/TiO2 photocatalyst. The primary photodegradation byproducts were identified using HPLC-MS analysis, and a possible mechanism was proposed.

Blooming Chemistry: Vinca as Your Pocket-Friendly pH Indicator

This study reveals the potential of Vinca flowers (in hues of red, purple, violet, pink, light pink, and white) as vibrant and effective natural acid-base indicators for titration experiments. By employing a cold extraction method with 70% ethanol, we successfully isolated anthocyanin pigments from these flowers and explored their pH sensitivity across a broad range (pH 1-14). The extracts displayed striking color changes: red/pink in acidic conditions (pH 1-3), colorless at pH 5, green hues in the mid-range (pH 7-9), and yellow in basic solutions (pH 11-14). Notably, the purple, red and violet extracts showed the most distinct color shifts. UV-vis spectroscopy confirmed that anthocyanins are the principal pigments, with additional sugar content also identified. In practical titration experiments, including NaOH vs. HCl, HCl vs. NH4OH, and NaOH vs. CH3COOH, the Vinca flower extracts provided clear and reliable color transitions, comparable to synthetic indicators like methyl red, methyl orange, and phenolphthalein. The pH endpoints observed with these natural indicators matched those obtained with synthetic counterparts, underscoring the accuracy and reliability of Vinca flowers as pH indicators. This innovative approach not only offers a sustainable alternative to synthetic indicators but also highlights the valuable application of plant-based pigments in both educational and practical settings for acid-base titrations.