Acidic pH Values Research Articles

Efficient removal of Cr(VI) by mechanochemically modified pyrites: Self-regulated neutralization behaviors

The pH of the aqueous environment commonly occurs during the application of natural/modified pyrite in water/soil remediation. In this study, mechanochemical modification of natural pyrite (M−pyrite) was employed to remove Cr(VI) over a wide pH range. Self-regulated neutralization was observed during Cr(VI) removal by M−pyrite in the initial pH range of 2.0–12.3. The reductive immobilization of total Cr occurred effectively when the solution self-regulated to a circumneutral pH (pH 5.0–9.0), but only efficient Cr(VI) reduction occurred under strongly acidic or alkaline conditions. Three pathways, i.e., Fe(II) removal, surface sulfide reduction and both combinations, could be revealed for Cr(VI) removal by M−pyrite at circumneutral pH and under strongly alkaline and acidic conditions. As Cr(VI) is reduced by ferrous and sulfide species, the protons generated from pyrite oxidation by O2 are consumed, causing neutral restoration to resist the initial sharp decrease in pH. Effective immobilization of the reduced Cr(VI) was confirmed at an initial pH of 5.0–9.0, but this immobilization did not occur at more acidic and alkaline pH values due to strong Fe(II) dissolution or surface precipitation. The M−pyrite was successfully applied in treating four types of saline industrial Cr(VI) wastewaters, demonstrating the advantage of self-regulated neutralization resistance in complex wastewater matrices.

Enhance the physicochemical properties of the citronella oil -SLNPs to improve the insecticidal activity against Spodoptera littoralis (Boisd) (Lep. Nactuidae)

The Nano-formulation of citronella essential oil (Cymbopogon nardus (L.) and their mixtures of three adjuvants (Provecta®, Top film®, and PEG600-dioleate) were studied to enhance physico-chemical properties of the Nano-formulation and improve the insecticidal effect against Spodoptera littoralis (Boisd). Characterisation of physicochemical properties of Nano-formulation was studied by calculating droplet size, polydispersity index (PDI), and Zeta-potential parameters. The results showed that the Solid Lipid Nanoparticles (SLNs) mixtures of three adjuvant mixtures had more toxic activity and stability than the Nano-formulation alone. Before storage the acidity, alkalinity (pH), and viscosity exhibited an acidic pH value in the range (4.11–5.34), whereas after three months of storage was recorded high pH, a shift in the pH on storage can indicate the instability of active substances or product under semi field-laboratory conditions. Nano-formulation of the citronella oil mixed with the three adjuvants increased the mortality percentage of S. littoralis larvae.

Leachability of hexavalent chromium from fly ash-marl mixtures in Sarigiol basin, Western Macedonia, Greece: environmental hazard and potential human health risk

Hexavalent chromium (Cr (VI)) is an environmental contaminant brining high concerns due to its higher toxicity and mobility in comparison with trivalent chromium Cr(III). Cr (VI) has been linked with several adverse health effects, including respiratory diseases, lung cancer, and skin irritation. The primary sources of it in the environment are industrial activities.Most of the time, fly ash made of lignite can release Cr(VI) when it comes into contact with water in an aquatic environment. The objective of this study is the investigation of Cr (VI) concentration in leachates of fly ash and marl mixtures and the determination of its solubility under different pH conditions. Samples of fly ash were collected from the Power Plant of Agios Dimitrios. Additionally, samples of marl were collected from the mine of South Field, and both samples were mixed and prepared in in different proportions (% w.t.). The leaching experiments were carried out according to the EN-12457/1-4 (2003) standard under different pH conditions and chemical analysis of the leachates were performed by spectrophotometry with diphenylcarbazide (DPC). The environmental footprint of Cr (VI) in the study area was significant, especially in mixtures containing higher concentrations of fly ash. A critical pH range between 6 to 12 is observed. At acidic pH values, a high release of Cr (VI) was observed, while at the mentioned critical values (pH 10–12), a gradual decrease in its leachability was noticed. The high concentrations of Cr (VI) in the industrial area studied require immediate actions in terms of managing and limiting the potential hazardous impacts on the environment and by extension on the public health by developing appropriate prevention strategies.Graphical abstract

Template-free efficacious morphology of electrosynthesized polyaniline/β-cyclodextrin host-guest complex on Au/rGO modified electrode for removal and recovery of rare-earth and heavy elements from seawater

Global water pollution and scarcity of water resources are turning increasingly into serious threats to the survival of all living organisms on Earth. This study offers an influent strategy for the electrosynthesis of reduced graphene oxide/polyaniline/β-cyclodextrin (rGO/PAni/βCD) nanocomposite and its application to the removal/recovery of heavy elements (HEs) and rare-earth elements (REEs). Besides physicochemical and electrochemical studies, the surface morphological and statistical properties of fabricated nanocomposite electrode were examined. The textural and morphological characteristics of nanocomposite electrode were investigated via AFM data based on statistical, stereometric, and fractal theory. The cohesive, porous, and well-developed morphology of fabricated nanocomposite electrode has enabled the electrodeposition technique to achieve significant simultaneous removal/recovery efficiency of HE and REE ions such as Pb(II), Cu(II), Cd(II), Hg(II), Ce(IV), and Nb(V). Therefore, using rGO/PAni/βCD, considerable removal of HEs and REEs was achieved under optimized pH, 0.1 M KNO3, and 35 mg L−1 metal ion initial concentration during 20 min. Removal capacity of the nanocomposite electrode is preserved subsequent to 10 cycles of electrodeposition/desorption, according to the desorption investigation through eluted adsorbent at time intervals in deionized water and adjusted acidic pH values. Then, using rGO/PAni/CD nanocomposite, simulated seawater remediation was accomplished successfully. This interdisciplinary approach reveals that the removal/recovery efficiency enhance linearly along with the improvement of well-developed morphology for electrosynthesized composites. Thus, these results suggest how the morphological features of the polymer composites could improve remediation of water resources.

Effect of cassava pulp treated with Lactobacillus casei TH14, urea, and molasses on gas kinetics, rumen fermentation, and degradability using the in vitro gas technique

This study focused on examining the gas dynamics, rumen fermentation, and digestibility of ensiled cassava pulp (CSVP) using Lactobacillus casei TH14, urea, and molasses in the context of a laboratory experiment. All data in this study were analyzed using treatments arranged in 2 × 2 × 2 factorial arrangements using a completely randomized design. The L.casei TH14 additive (L) was factor A. Factor B was the molasses additive (M), while factor C was urea (U). There was no interaction effect of L, U, and M on gas production, volatile fatty acid (VFA) content, pH value, or ammonia-nitrogen level (P<0.05). The interaction of L, U, and M influenced in vitro dry matter digestibility (IVDMD) at 12 h (P < 0.05), and the CSVP fermented with the additions of L, U, and M together (LUM) was higher than the additions of CON, M, U, UM, and L on IVDMD (P < 0.05). However, the IVDMD values of adding LUM were higher in the control group (CON), M, U, UM, and L additive groups (P < 0.05). There was an interaction effect of L, U, and M on the protozoal count at 8 h (P<0.05), which had a lower protozoal count in the control group. In addition, acetic acid and butyric acid concentrations at 4 h and 8 h (P<0.05) were increased during the fermentation of CSVP using L and M combinations. Furthermore, the combination of U and M enhanced (P<0.05) average acetic acid, propionic acid, and pH at 4 h and 8 h while reducing (P<0.05) the gas generation from the insoluble portion (b). It was suggested that utilizing L. casei TH14 together with urea and molasses can enhance nutrient contents and improve the in vitro dry matter digestibility of CSVP, although it has no effect on ruminal fermentation or gas production.

Self-Amplified pH/ROS Dual-Responsive Co-Delivery Nano-System with Chemo-Photodynamic Combination Therapy in Hepatic Carcinoma Treatment.

Chemo-photodynamic combination therapy has demonstrated significant potential in the treatment of cancer. Triptolide (TPL), a naturally derived anticancer agent, whencombined with the photosensitizer Chlorin e6 (Ce6), has shown to provide enhanced anti-tumor benefits. However, the development of stimuli-responsive nanovehicles for the co-delivery of TPL and Ce6 could further enhance the efficacy of this combination therapy. In this study, we synthesized a pH/ROS dual-responsive mPEG-TK-PBAE copolymer, which contains a pH-sensitive PBAE moiety and a ROS-sensitive thioketal (TK) linkage. Through a self-assembly process, TPL and Ce6 were successfully co-loaded into mPEG-TK-PBAE nanoparticles, hereafter referred to as TPL/Ce6 NPs. We evaluated the pH- and ROS-sensitive drug release and particle size changes. Furthermore, we investigated both the in vitro suppression of cellular proliferation and induction of apoptosis in HepG2 cells, as well as the in vivo anti-tumor efficacy of TPL/Ce6 NPs in H22 xenograft nude mice. The mPEG-TK-PBAE copolymer was synthesized through a one-pot Michael-addition reaction and successfully co-encapsulated both TPL and Ce6 by self-assembly. Upon exposure to acid pH values and high ROS levels, the payloads in TPL/Ce6 NPs were rapidly released. Notably, the abundant ROS generated by the released Ce6 under laser irradiation further accelerated the degradation of the nanosystem, thereby amplifying the tumor microenvironment-responsive drug release and enhancing anticancer efficacy. Consequently, TPL/Ce6 NPs significantly increased PDT-induced oxidative stress and augmented TPL-induced apoptosis in HepG2 cells, leading to synergistic anticancer effects in vitro. Moreover, administering TPL/Ce6 NPs (containing 0.3 mg/kg of TPL and 4 mg/kg of Ce6) seven times, accompanied by 650 nm laser irradiation, efficiently inhibited tumor growth in H22 tumor-bearing mice, while exhibiting lower systemic toxicity. Overall, we have developed a tumor microenvironment-responsive nanosystem for the co-delivery of TPL and Ce6, demonstrating amplified synergistic effects of chemo-photodynamic therapy (chemo-PDT) for hepatocellular carcinoma (HCC) treatment.

Expression and Characterization of a Thermostable α-Glucuronidase from Geobacillus kaustophilus

Fossil fuels are a crucial resource for the global economy, but they also contribute to greenhouse gas emissions and environmental pollution. Lignocellulosic biomass, which includes cellulose, hemicellulose, and lignin obtained from plants, is a promising alternative to fossil fuels. It can help address these problems while reducing environmental impact. Enzymatic pre-treatment is used to degrade lignocellulosic biomass into subunits. The degradation of the hemicellulose structure involves accessory enzymes of industrial importance, such as α-glucuronidase. α-glucuronidases (EC 3.2.1.139) catalyze the hydrolysis of the α-1,2-glycosidic bond between α-D-glucuronic acid (GlcA) or its 4-o-methyl ether form (MeGlcA) and d-xylose units in the structure of xylooligosaccharides. The aim of this study was cloning, heterologous expression and biochemical characterization of the α-glucuronidase enzyme from the thermophilic bacterium Geobacillus kaustophilus. With this aim, the codon optimized α-glucuronidase gene was cloned into pQE-30 vector, overexpressed in E. coli BL21 (DE3), and purified with nickel affinity chromatography. The biochemical characterization of the purified α-glucuronidase revealed that the enzyme has activity at elevated temperatures between 65-90 °C. Additionally, Geobacillus kaustophilus α-glucuronidase enzyme showed higher activity at acidic pH values from pH 4.0 to 6.5. This is the first study to report the gene cloning, recombinant expression and biochemical characterization of α-glucuronidase which could be used as accessory enzyme from a thermophilic bacterium Geobacillus kaustophilus.

Spatial distribution of Pb and Zn in soils under native vegetation in Southeast Brazil.

Heavy metals can play an important biological role as micronutrients but also as potentially toxic elements (PTEs). Understanding the natural concentrations of PTEs-Pb and Zn included-in soils allows for the identification and monitoring of contaminated areas and their role in environmental risk assessment. In this study, we aim to determine semi-total or natural and available concentrations of Pb and Zn in topsoils (0-20 cm depth) from 337 samples under native vegetation in the State of Minas Gerais, Brazil. Additionally, we sought to interpret the spatial geochemical variability using geostatistical techniques and quality reference values for these elements in soils were established. The semi-total concentrations were determined by flame and graphite furnace atomic absorption after microwave-assisted nitric acid digestion method. The available concentrations were extracted using the Mehlich-I extractor and determined by atomic absorption spectrometer. Spatial variability was modeled using semivariance estimators: Matheron's classic, Cressie and Hawkins' robust, and Cressie median estimators, the last two being less sensitive to extreme values. This allowed the construction of digital maps through kriging of semi-total Pb and Zn contents using the median estimator, as well as other soil properties by the robust estimator. The dominance of acidic pH and low CEC values reflects highly weathered low-fertility soils. Semi-total Pb contents ranged from 2.1 to 278 mg kg-1 (median: 9.35 mg kg-1) whereas semi-total Zn contents ranged from 2.7 to 495 mg kg-1 (median: 7.7 mg kg-1). The available Pb contents ranged from 0.1 to 6.92 mg kg-1 (median: 0.54 mg kg-1) whereas available Zn contents ranged from 0.1 to 78.2 mg kg-1 (median: 0.32 mg kg-1). The highest Pb and Zn concentrations were observed near Januária, in the northern part of the territory, probably on limestone rocks from the Bambuí group. Finally, the QRVs for Pb and Zn in natural soils were lower than their background values from other Brazilian region and below the prevention values suggested by Brazilian environmental regulations.

Bi2Fe4O9/rGO nanocomposite with visible light photocatalytic performance for tetracycline degradation

Bismuth-iron semiconductor materials have been widely studied in the photocatalytic field due to their excellent light responsiveness. Among them, the potential and mechanism regarding photocatalytic degradation of organic pollutants by Bi2Fe4O9 are seriously ignored. In this research, Bi2Fe4O9/reduced graphene oxide (BFO/rGO) was successfully synthesized for tetracycline (TC) removal. Under visible light irradiation, the TC degradation efficiency reached 83.73% within 60 min, which was much higher than that of pure BFO or rGO. The impacts of crucial factors (TC initial concentration, humic acid concentration, pH value and inorganic anions) were systematically analyzed. The photoelectric performance experiments indicated that the addition of rGO decreased the electron-hole pair recombination efficiency and improved the charge transfer efficiency, thus significantly enhancing the photocatalytic performance. According to quenching experiments and EPR (Electron Paramagnetic Resonance) analysis, superoxide radical (•O2−) and hole (h+) were determined as the main active species during degradation reactions. Eventually, the possible degradation routes of TC were presented by identifying intermediates.

Chemical stability of Hg-adsorbed pyrite under different pH and redox conditions: A fundamental study for stable management of Hg-bearing wastes

Along with the worldwide awareness of mercury (Hg) toxicity, safe disposal and preservation of Hg-bearing waste becomes a matter of concern. In this study, Hg adsorbed pyrite, which is a type of Hg-bearing wastes, was synthesized and subjected to leaching tests at different pH (2, 6, and 10) and dissolved oxygen concentrations (aerobic and anaerobic) for 168 h in order to evaluate the chemical stability of the adsorbed Hg. Hg solubilization after 168 h leaching was negligibly small (0.13 µmol/L) at pH 10 under aerobic conditions while robust sulfur solubilization here (29.4 mmol/L), resulting from oxidative dissolution of pyrite, was expected to trigger the Hg desorption. Under anaerobic conditions, 35 times more Hg was released at pH 10 than pH 2, which was the opposite trend from aerobic conditions. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) analyses found that Fe (oxy)hydroxides were formed on the pyrite surface through its oxidative dissolution, contributing to the re-immobilization of once-desorbed Hg via the formation of surface complexation. Little Fe (oxy)hydroxide formed under anaerobic conditions, thus leading to the enhanced Hg release at alkaline than acidic pH values. Numerical calculation with a geochemical modeling confirmed that this hypothesis was valid and allowed the Hg distribution during the leaching of Hg-bearing pyrite to be quantified. Overall, we developed some suggestions for the stable management of Hg-bearing waste at the final waste disposal site based on the findings of this study.

Towards sustainable battery recycling: selective dynamic adsorption of nickel(II) and cobalt(II) in an adsorbent fixed-bed reactor at elevated temperature

Caused by the scarce resources of critical heavy metals which are in high demand, e.g., for lithium-ion batteries, processes for the recovery of such materials for recycling are of high interest. Adsorption is an effective method in order to selectively separate metal ions from aqueous solutions. Unfortunately, the prerequisites in battery recycling, like acidic pH-value and high temperature, are in general impairing the adsorption process. In this study, the competitive dynamic adsorption of nickel(II) (Ni(II)) and cobalt(II) (Co(II)) by a silica adsorbent functionalized with amino-polycarboxylate derivative ligands (designated as HSU331) under recycling process conditions, (pH = 3.5, T = 20 °C, and T = 50 °C, respectively) and varying concentrations (Ni(II):Co(II) 1:1 (5.0, and 10 mmol·L−1, respectively), Ni(II):Co(II) 3:1 and 1:3 (3.0 mmol·L−1 and 1.0 mmol·L−1 vice versa)) were investigated. A displacement desorption of Co(II) in favor of the binding of Ni(II) was observed, achieving maximum loadings of 0.95 µmolNi(II)·µmolLigand−1 (28.3 mgNi(II)·gAdsorbent−1), and 0.48 µmolCo(II)·µmolLigand−1 (14.3 mgCo(II)·gAdsorbent−1) at T = 20 °C and 1.0 µmolNi(II)·µmolLigand−1 (29.9 mgNi(II)·gAdsorbent−1) and 0.18 µmolCo(II)·µmolLigand−1 (5.38 mgCo(II)·gAdsorbent−1) at T = 50 °C, respectively. These results demonstrate a distinctly selective separation of Ni(II) in the presence of Co(II) by HSU331, achieving an even higher efficiency at elevated temperatures.

Speciation of the proton in water-in-salt electrolytes.

Water-in-salt (WiS) electrolytes are promising systems for a variety of energy storage devices. Indeed, they represent a great alternative to conventional organic electrolytes thanks to their environmental friendliness, non-flammability, and good electrochemical stability. Understanding the behaviour of such systems and their local organisation is a key direction for their rational design and successful implementation at the industrial scale. In the present paper, we focus our investigation on the 21 m bis(trifluoromethanesulfonyl)imide (LiTFSI) WiS electrolyte, recently reported to have acidic pH values. We explore the speciation of an excess proton in this system and its dependence on the initial local environment using ab initio molecular dynamics simulations. In particular, we observe the formation of HTFSI acid in the WiS system, known to act as a superacid in water. This acid is stabilised in the WiS solution for several picoseconds thanks to the formation of a complex with water molecules and a neighboring TFSI- anion. We further investigate how the excess proton affects the microstructure of WiS, in particular, the recently observed oligomerisation of lithium cations, and we report possible notable perturbations of the lithium nanochain organisation. These two phenomena are particularly important when considering WiS as electrolytes in batteries and supercapacitors, and our results contribute to the comprehension of these systems at the molecular level.

Strategies based on nido-carborane embedded indole fluorescent polymers: their synthesis, spectral properties and cell imaging studies.

The continuous preparation scheme EPO-Poly-indol-nido-carborane (E-P-INDOLCAB), L100-55-Poly-indol-nido-carborane (L-P-INDOLCAB), RS-Poly-indol-nido-carborane (S-P-INDOLCAB), and RL-Poly-indol-nido-carborane (R-P-INDOLCAB) were used to prepare the four types of acrylic resin-coated nido-carborane indole fluorescent polymers. After testing their spectral properties and the fluorescence stability curve trend at various acidic pH values (3.4 and 5.5, respectively), L-P-INDOLCAB and S-P-INDOLCAB were determined to be the best polymers. The stable states of the two polymers and the dispersion of the nanoparticles on the system's surface during Atomic Force Microscope (AFM) test are shown by the zeta potentials of -23 and -42mV. The dispersion of nanoparticles on the system's surface and the stable condition of the two polymers were examined using zeta potential and atomic force microscopy (AFM). Transmission electron microscopy (TEM) can also confirm these findings, showing that the acrylic resin securely encases the interior to form an eyeball. Both polymers' biocompatibility with HELA cells was enhanced in cell imaging, closely enclosing the target cells. The two complexes displayed strong inhibitory effects on PC-3 and HeLa cells when the concentration was 20ug/mL, as validated by subsequent cell proliferation toxicity studies.

The adsorption of direct red 23 as a toxic pollutant in aqueous solution by using surface modified metal-organic framework containing tricarboxylic acid benzene ligand

In this research, Cu-BTC (C-BTC) metal-organic framework (MOF) was prepared and characterized. The synthesized C-BTC was modified with 3-aminopropyltrimethoxysilane to synthesize C-BTC-NH2. The ability to remove the direct red 23 (DR-23) dye by the synthesized materials (C-BTC and C-BTC-NH2) as adsorbents was investigated. The effect of operational parameters on dye removal was investigated. The results showed that the ability of the modified adsorbent (C-BTC-NH2) to adsorbed dye is more than the raw adsorbent (C-BTC). The amount of dye adsorption is high in acidic pH values. Increasing the amount of adsorbent and decreasing the pH of solution causes an increase in the percentage of dye adsorption and enhance in the DR-23 concentration causes a decrease in the percentage of DR-23 removal. The results of dye adsorption were matched with different isotherms and removal process followed the Langmuir isotherm. The experimental data exhibited a good fit with the Langmuir isotherm model (R2 = 0.9637), with the maximum adsorption capacity (Q0) of the calculated as 89.2857 and 2500 mg/g for DR-23 removal by C-BTC and C-BTC-NH2, respectively. Dye adsorption follows pseudo-second-order kinetics and k2 is PSO rate constant 0.0028 and 0.010 for by C-BTC and C-BTC-NH2, respectively. The data presented that C-BTC-NH2 as a modified adsorbent has high removal ability and is appropriate adsorbent for dye adsorption from aqueous solution.

Comparing microbial populations from diverse hydrothermal features in Yellowstone National Park: hot springs and mud volcanoes.

Geothermal features, such as hot springs and mud volcanoes, host diverse microbial life, including many extremophile organisms. The physicochemical parameters of the geothermal feature, such as temperature, pH, and heavy metal concentration, can influence the alpha and beta diversity of microbial life in these environments, as can spatiotemporal differences between sites and sampling. In this study, water and sediment samples were collected and analyzed from eight geothermal sites at Yellowstone National Park, including six hot springs, a mud volcano, and an acidic lake within the same week in July 2019, and these geothermal sites varied greatly in their temperature, pH, and chemical composition. All samples were processed and analyzed with the same methodology and taxonomic profiles and alpha and beta diversity metrics determined with 16S rRNA sequencing. These microbial diversity results were then analyzed with respect to pH, temperature, and chemical composition of the geothermal features. Results indicated that predominant microbial species varied greatly depending on the physicochemical composition of the geothermal site, with decreases in pH and increases in dissolved heavy metals in the water corresponding to decreases in alpha diversity, especially in the sediment samples. Similarly, sites with acidic pH values had more similar microbial populations (beta diversity) to one another than to relatively neutral or alkaline pH geothermal sites. This study suggests that pH and/or heavy metal concentration is a more important driver for microbial diversity and population profile than the temperature for these sites and is also the first reported microbial diversity study for multiple geothermal sites in Yellowstone National Park, including the relatively new mud volcano Black Dragon's Caldron, which erupted in 1948.

PH responsive curcumin released from urea-amine group functionalized mesoporous organosilica nanoparticles.

Studies on natural products with anticancer properties have gained more importance in recent years in order to not damage healthy tissues during cancer treatments or to perform the treatment causing the least damage. Curcumin is a common natural product with anticancer properties, but its low solubility, instability, and bioavailability have limited its use in clinical applications in cancer research. As a proposed solution to this problem, a new mesoporous organosilica nanocarrier (MON-A) functionalized with a 1,2-diphenylethane-1,2-diamine structure capable of pH-controlled release was prepared in this study. MON-A was characterized by TGA, BET, XRD, FT-IR, and SEM-EDS analyses. Dispersion of MON-A into curcumin stock solution in ethanol afforded a curcumin-loaded MON-A-Cur system. Elevated loading capacity and pH-controlled release were provided by the Schiff base reaction that occurred during loading of curcumin with 1,2-diphenylethane-1,2-diamine placed on the silica wall of the nanocarrier system. The encapsulation efficiency was 25% for MON-A-Cur. In in vitro release experiments, curcumin release from the MON-A-Cur system was 0.5% at physiological and endosomal pH values. The resulting low release percentage indicates the presence of very strong interactions between the nanocarrier MON-A and curcumin. This strong interaction showed that MON-A nanocarrier could carry 99.5% of the curcumin without leakage under physiological and endosomal pH conditions without using pore capping agents. At a lower acidic pH value (pH 4.5), 26.3% curcumin release was obtained. These findings showed that the cumulative release of curcumin from the MON-A-Cur system can be achieved in a long-term and pH-controlled manner.

Improving the Anaerobic Digestion Process of Wine Lees by the Addition of Microparticles

Wine lee generation, a by-product of the wine industry, implies economic challenges for producers in terms of management due to its high organic load and low pH value. Biological treatment based on controlled anaerobic digestion may emerge as a viable management alternative given its promising potential for biogas production thanks to the organic content of the substrate. However, the complex properties of wine lees may lead to microbial activity inhibition and process kinetics failure. Various solutions have already been explored, including co-digestion with other substrates, or the application of different pretreatments, to mitigate the effects of the accumulation of phenolic compounds, volatile fatty acids, antioxidants, or the acidic pH value of the medium. In this study, laboratory-scale batch reactors were established, adding iron- (magnetite) or carbon (graphite)-based microparticles to assess their impact on the kinetics of the process. The results demonstrate a significant improvement of 35% in the potential production of biomethane after four days of operation with graphite particles and 42% after five days using magnetite particles. Methane production rates, as determined by the Gompertz model, were 45.38 and 46.54 mL CH4∙gVS−1∙d−1 for the application of graphite and magnetite microparticles to the medium, respectively, compared to the value of 33.46 mL CH4∙gVS−1∙d−1 for the control trial, confirming kinetic process improvements of 36% and 39%, respectively. Evidences of the acceleration of the methanogenesis phase were detected along the essays; however, the strong inhibition mediated by the carboxylate accumulation was not avoided in any of the tested conditions.

Microbiological quality and efficacy of preservatives in marigold-based skin care products

&amp;lt;p&amp;gt;The microbiological stability of cosmetic products is crucial, especially in products with high water content, such as creams. Therefore, preservatives are used in order to protect consumers from harmful pathogens that would otherwise invade the cosmetics. Despite their function, the addition of preservatives can be considered controversial in the cosmetics industry. Parabens are frequently used synthetic preservatives in various industries. According to regulatory directives concerning cosmetics (Cosmetic Directive by the European Commission) usage of some parabens (methylparaben, propylparaben, butylparaben, and ethylparaben) is safe and permitted in allowed concentrations. On the other hand, the European Commission prohibited the use of isopropylparaben, isobutylparaben, phenylparaben, benzylparaben and pentylparaben. Therefore, a comprehensive stability study was conducted to evaluate the influence of paraben-based preservative (Gujsol-1&amp;lt;sup&amp;gt;&amp;amp;reg;&amp;lt;/sup&amp;gt;, INCI name: Phenoxyethanol, Methylparaben, Ethylparaben, Propylparaben, Butylparaben) and potassium sorbate in order to preserve plant extracts-based skin-care products, Day and Night creams with marigold extract. Previously, mentioned skin-care products were preserved with the preservative Dekaben C&amp;lt;sup&amp;gt;&amp;amp;reg;&amp;lt;/sup&amp;gt;, which contained paraben mixture with banned isobutylparaben. All tested formulations showed favorable texture and sensory characteristics, desirable mild acidic pH values, satisfactory physical stability and appropriate microbiological quality at the initial point, as well as after storage at elevated temperature or at cyclic stress test conditions and at room temperature during two years. In addition, both preservatives significantly reduced the number of inoculated microorganisms during the challenge test. It can be concluded that potassium sorbate in plant-based creams could be an efficient alternative to paraben-based preservatives.&amp;lt;/p&amp;gt;

Electro-Oxidation of Diols in Polymer Recycling: Facilitating Separation and Refining Products

Increasing environmental awareness has highlighted the importance of plastic recycling and rightfully so, considering plastic pollution and an ever-increasing consumption of plastic products. Currently, numerous recycling strategies are being investigated with varying approaches depending on the type of polymer [1]. One attractive process is the chemical recycling of polyesters via alkaline hydrolysis which produces the dicarboxylic acid salts and diols of the respective polyester. The dicarboxylic acids can be separated by crystallization, while the diol separation remains a challenge. A process concept is proposed that utilizes two electrochemical separation technologies to process the polyester hydrolysis solution. A selective electro-oxidation of diols is proposed to mediate and simplify the challenging diol separation. The dicarboxylic acids can be crystalized using an electrochemical pH shift crystallization, which can simultaneously provide the base required for the alkaline hydrolysis of polyesters.The electrochemical pH shift crystallization utilizes water electrolysis in a membrane-separated parallel plate electrolyzer. The pH of the anode and cathode chambers is shifted towards acidic and basic pH values, respectively [2]. The acidification of the anolyte shifts the dissociation equilibrium of the respective dicarboxylic acid salt to the less water-soluble, fully protonated dicarboxylic acid. Crystallization is carried out within the electrolyzer, while the alkaline catholyte solution may be applied in the polyester hydrolysis.To circumvent the challenging removal of diols from aqueous solution [3], a selective electro-oxidation of said diols is proposed. The oxidation towards hydroxycarboxylic acids or dicarboxylic acids facilitates simplified separation processes such as pH shift extraction or crystallization, respectively. Rather than a closed-loop recycling towards both monomers, the proposed process suggests an upgrading of the diols to value-added molecules and crystallization of the dicarboxylic acid, which facilitates and simplifies separation.The study investigates the selective electro-oxidation of diols from three different polyesters: polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polybutylene succinate (PBS). A three-electrode setup utilizing plate electrodes as working electrodes is used in a custom cyclic voltammetry cell. Electro-oxidation is carried out in 1M KOH as electrolyte with diol concentrations ranging from 0.2 to 1M. Following the electrocatalyst activity studies, the selectivity of the electro-oxidation utilizing the most promising catalyst is studied in membrane-separated parallel plate electrolyzer experiments. A custom Luggin-Haber capillary setup monitors and controls the oxidation potential during the experiment. This presentation features the preliminary results of plate electrode catalysts’ electro-oxidation of three different diols in alkaline media. Selectivity studies for the oxidation of the three diols (ethylene glycol, 1,3-propane diol, and 1,4-butane diol) in the membrane-separated parallel plate electrolyzer are presented.[1] Hamad, K., Kaseem, M., & Deri, F. (2013). Recycling of waste from polymer materials: An overview of the recent works. Polymer Degradation and Stability, 98(12), 2801–2812. DOI: 10.1016/j.polymdegradstab.2013.09.025[2] Kocks, C., Wall, D., & Jupke, A. (2022). Evaluation of a Prototype for Electrochemical pH-Shift Crystallization of Succinic Acid. Materials (Basel, Switzerland), 15(23), 8412. DOI: 10.3390/ma15238412[3] Garcia-Chavez, L. Y., Hermans, A. J., Schuur, B., & Haan, A. B. de (2012). COSMO-RS assisted solvent screening for liquid–liquid extraction of mono ethylene glycol from aqueous streams. Separation and Purification Technology, 97, 2–10. DOI: 10.1016/j.seppur.2011.11.041

Evaluation of Physicochemical Properties of Yogurt Fortified with Four Verities of Common Bean Whey (Phaseolus vulgaris)

Background: In recent years, the role of novel foods in public health has rapidly grown due to increased life expectancy, rising medication costs and consumers’ focus on obtaining health benefits. Methods: This study evaluates the acid production, microbial growth, physicochemical and textural properties of common bean-fortified yogurt (CBWFY) during 28 days of cold storage. Result: All varieties of CBWFY showed higher acidity and lower pH value, resulting in a higher microbial population after production and during 28-day storage. The color values “a” and “L” did not vary significantly in all samples and remained steady after 28 days, while the “b” value increased. The highest syneresis (14.86%) was found in white bean whey, while the lowest syneresis (1.81%) was observed in kidney bean whey. In terms of texture, the cohesiveness of CBWFY and the control sample decreased, while the hardness, springiness and gumminess improved during cold storage. Remarkably, cranberry bean whey had higher values (cohesiveness, springiness and gumminess) despite the hardness found in white bean whey.