Increase In pH Research Articles

Characterization and application of biochar derived from greenhouse crop by-products for soil improvement and crop productivity in South Korea

AbstractThe study examined the optimal production conditions and application rates of biochar derived from greenhouse crop by-products to enhance soil improvement and increase crop yield, thereby promoting sustainable agriculture in South Korea. The expansion of greenhouse cultivation has resulted in significant waste management challenges, and biochar production has emerged as a promising recycling solution for these by-products. Biochar was produced from red pepper stalks through pyrolysis at 200 to 600 °C, and its chemical properties, including pH, EC, T-C, and T-N, were analyzed. In this study, the chemical properties of biochar showed a significant increase in pH (from 5.8 to 10.3), EC (from 46.0 to 119.5 dS m⁻¹), and T-C (from 47.7 to 63.1%) with rising pyrolysis temperatures, while T-N decreased due to nitrogen volatilization above 300 °C. In the lettuce cultivation experiment, biochar application significantly improved fresh weight yield, with the biochar-treated group achieving a maximum of 83.3 g pot− 1 in the first cropping season, compared to 62.8 g pot− 1 in the NPK-only treatment group. However, excessive biochar application rates (≥ 800 kg ha⁻¹) led to yield reductions in the second cropping season, likely due to increased soil pH and EC. These results suggest the potential of recycling greenhouse crop residues into biochar to enhance soil fertility and crop productivity while indicating the need to manage application rates to minimize negative impacts from excessive use.

Modified Biochar Adsorption Combined with Alkaline Solution Absorption for Sulfur-Containing Odor Gases Removal from Domestic Waste Transfer Stations

Odor emission has become a major issue in waste transfer stations. Hydrogen sulfide, methyl mercaptan (MM), and dimethyl disulfide (DMDS) are the main odorous gases. They have a low odor threshold and are difficult to remove. In this study, pine bark biochar was produced and modified with metal ions, including Ni2+, Ti2+, Mn2+, Zn2+, Mg2+, and Cu2+. It was then used for the removal of hydrogen sulfide, methyl mercaptan, and dimethyl disulfide. Among all modifications, the Cu2+ modified biochar showed the best sorption capacity, and the maximum sorption amounts were 20.50 mg/g for H2S, 36.50 mg/g for MM, and 57.98 mg/g for DMDS. To understand the adsorption, BET, SEM, and XPS of the original and modified biochar were performed. This illustrated that modification with Cu2+ increased the surface area and porosity, thus enhancing the adsorption capacity. In the alkaline absorption study, it was found that the removal of the three odor gases increased with the pH increase. Based on the results, a combined process called absorption–adsorption was established to treat the odor gas generated in a local waste transfer station. Thirty-one gas components were detected in the odor gas of the waste transfer station. The process proceeded for 30 days, and these gas components were not found in the effluent during treatment. Regarding H2S, MM, and DMDS, they were not detected even after 90 days. This indicates the high adsorption capacity of the modified biochar toward the three odor gases. In addition, the process is simple and easy to operate. This suggests that it is suitable for treating odor in places where there is no technician, and the odor needs efficient treatment. The study provides a feasible alternative for domestic waste transfer stations to control the odor problem.

Impact of HPMCAS Grade on the Release of Weakly Basic Drugs from Amorphous Solid Dispersions.

Oppositely charged species can form electrostatic interactions in aqueous solution, and these may lead to reduced solubility of the interacting components. Herein, insoluble complex formation between the lipophilic weakly basic drugs, cinnarizine or loratadine, and the enteric polymer, hydroxypropyl methylcellulose acetate succinate (HPMCAS), was studied and used to better understand drug and polymer release from their corresponding amorphous solid dispersions (ASDs). Surface area normalized release experiments were performed at various pH conditions for three different grades of HPMCAS, LF, MF and HF, as well as their ASDs. Both polymer and drug release rates were measured for the ASDs. Complexation tendency was evaluated by measuring the extent of polymer loss from the aqueous phase in the presence of the drug. Results showed that release from ASDs with HPMCAS-LF was less impacted by the presence of a cationic form of the drug than ASDs prepared with the HF grade. Furthermore, an increase in pH, leading to a reduction in the extent of ionized drug also led to an improvement in release rate. These observations provide a baseline to understand the role of drug-polymer electrostatic interactions on release from ASDs formulated with HPMCAS. Future studies should focus on adding complexity to media conditions by employing simulated intestinal fluids with solubilizing components.

Changes in the Composition and Properties of Cultured Bacterial Strains of Ginseng Rhizosphere According to Soil Characteristics in the Forest and Plots

The cultivation of Panax ginseng C.A. Meyer, a valuable medicinal plant, presents a number of challenges due to its physiology and life cycle. The composition of the soil and the microbiome living in it are important for plant growth and root quality. Modern analytical methods were used to identify differences in the rhizosphere soils of plants in the forest and in the plots. Microbiological and molecular genetic methods were used to isolate and identify bacterial isolates from these soils, allowing for the establishment of a working collection of potentially useful bacterial strains. Increases in soil pH in the plots and changes in the amount of macronutrients partially explained the changes in the activity of the forest and plot isolates and the composition of the cultivated strains. The cultivated strains belonged to the rhizosphere-dominant phyla Pseudomonadota, Bacillota, and Actinomycetota of the main functional groups of soil potassium, phosphorus, and nitrogen transformations. The ratio of bacteria functional groups was comparable in the forest and in the plots. The most common phylum of cultured microorganisms was Bacillota, while the main differences were observed in the functional group of potassium-solubilizing bacteria belonging to the phyla Pseudomonadota.

Gamma-aminobutyric acid fermentation and its fermented extracts on α-glucosidase inhibition and anti-obesity effect.

Levilactobacillus brevis KCL010 was fermented in a simple medium containing 8% (w/v) of rice bran extract. We modified the carbon, nitrogen, and initial pH conditions using 10g/L of sucrose, 10g/L of yeast extract, and 5.0 of pH, respectively. To minimize the pH increase due to decarboxylation, we fermented 100mL of modified synthetic medium containing citrate-phosphate buffer (CPB, pH 5.0) of 25-200mM in 250mL Erlenmeyer flasks. After 72h of fermentation with 50mM CPB, the maximum GABA concentration and conversion efficiency were 3.42g/L and 22.39%. Furthermore, the potential α-glucosidase inhibitory activity, MTT assay, and oil red O staining were determined by fermented extracts of L. brevis KCL010. At the highest concentration of 500μg/mL, the α-glucosidase inhibition percentages for non-fermented rice bran (NFRB), rice bran fermented by L. brevis (RBFL), and GABA (analytical standard) extracts were 55.03%, 58.37%, and 59.48%, respectively. All extracts exceeded 80% viability, suggesting that there was no cytotoxic to 3T3-L1 adipocytes. The rice bran fermented by L. brevis (RBFL) extract shows a high inhibition of lipid accumulation by 29.33% compared to those of extracts.

A Comparative Account of the Sugarcane Bagasse and Rice Husk Biochar on the Physicochemical and Biological Properties of Soils from Heterogeneous Agroecosystems

ABSTRACT Biochar optimal use reduces agricultural waste and promotes sustainability in farming systems. Its production and characterization are crucial for carbon sequestration in agroecosystems. The present study elucidated the properties of Sugarcane Bagasse Biochar (SBB) and Rice Husk Biochar (RHB), synthesized under varying experimental conditions, and revealed that a pyrolytic temperature of 400°C and a duration of 90 min was optimum for the production of both biochars in terms of pH, electrical conductivity, total dissolved solids, total organic carbon, cation exchange capacity, and water holding capacity. The effect of varying concentrations of SBB and RHB (0.5%, 1%, and 1.5%) in response to control on the physicochemical and biological properties of soils revealed that 1.5% SBB had a significant increase in the soil pH and conductivity. Application of SBB increased the soil organic carbon due to its higher carbon content (64.24%) than RHB (46.04%). Also, the water-holding capacity of heterogeneous soil samples was higher with the SBB application of 1.5%. The THB was positively and significantly correlated with pH (r = 0.50, p < .05), EC (r = 0.60, p < .01), TDS (r = 0.48, p < .05), SOM (r = 0.55, p < .01), moisture content (r = 0.63, p < .01) and WHC (r = 0.90, p < .01) but negatively correlated with THF (r = -0.84, p < .01). At the same pyrolytic temperature, SBB had the highest surface area (266.51 m2/g) and pore volume (0.195 cm3/g) than RHB (39.06 m2/g and 0.095 cm3/g respectively). It is concluded that the application of SBB at 1.5% level can successfully improve the soil properties, thereby aiding in carbon sequestration.

The safety and efficacy of regional citrate anticoagulation for multiple consecutive therapeutic plasma exchanges with fresh frozen plasma as a replacement solution.

Therapeutic plasma exchange (TPE) is an important blood purification technology and most patients require multiple consecutive TPEs. Regional citrate anticoagulation (RCA) could be used for membrane therapeutic plasma exchange (mTPE). However, there is no research on the metabolic complications of the RCA for patients receiving multiple consecutive mTPEs with fresh frozen plasma (FFP) as a replacement solution. We retrospectively included patients who used RCA for multiple consecutive mTPEs with FFP as a replacement solution in Xijing Hospital from 2020 to 2022. We collected blood gas analysis and electrolyte results before and after mTPE treatment and analysed the anticoagulation effectiveness and metabolic complications of the RCA. A total of 33 patients who underwent 131 mTPE sessions were included, and 129 (98.5%) sessions were successfully completed. Severe hypocalcemia (19.1%) and metabolic alkalosis (58.5%) were frequently observed. In single mTPE sessions, there was a significant decrease in ionized calcium levels and significant increases in serum sodium, potassium, pH, bicarbonate, and base excess (BE) levels compared to pretreatment values. When comparing the values after the last treatment to the baseline values in all 33 patients, the serum sodium, pH, bicarbonate, and BE levels increased significantly, while the ionized calcium decreased significantly. The levels of pH, bicarbonate, and BE increased with the number of mTPE sessions, and the cumulative incidence of metabolic alkalosis reached 95.2% after the fifth treatment according to the Kaplan-Meier survival analysis. RCA is an effective anticoagulation method for patients undergoing mTPE with FFP as a replacement solution. However, the metabolic complications associated with RCA, especially hypocalcemia and metabolic alkalosis, frequently develop in patients who undergo multiple consecutive mTPEs with FFP.

Improving cold resistance and shelf life of Carica papaya Linn through 1- methylcyclopropene and geranium oil applications

The perishability and susceptibility to chilling of Carica papaya Linn have impeded its long-distance exportation, posing challenges to international trade investments. This study explores the efficacy of 1-MCP and geranium oil (GO) treatments in enhancing papaya's cold tolerance. Designated concentrations for 1-MCP were 300 and 600 mg/L, and for GO, 2% and 4% (v/v), with exposure times set at 30 and 60 mins. Subsequently, the fruits were stored at 4°C for 16 days, and various parameters such as chilling injury (CI), weight loss (WL), respiratory rate (RR), firmness, colour, total soluble solids (TSS), titratable acidity (TA), pH, and ripening index (RI) were assessed at 4-day intervals. The results demonstrated a significant reduction in chilling damage in treated fruits. Specifically, the 60-minute exposure to 600 mg/L 1-MCP (MCP600+60) delayed the development of CI symptoms by at least 4 days compared to the control. At day 16, MCP600+60 exhibited the least WL (1.93%), O2 consumption (4.19±0.25 mL/kg/hr), and CO2 production (4.05±0.17 mL/kg/hr). Treated fruits, especially MCP600+60 and 30-minute exposure to 4% (v/v) GO (GO4+30), preserved firmness and colour. In GO treatments, GO4+30 showed the least increase in TSS (1.69-fold) and pH (1.09-fold). The highest TA and RI were reported in MCP600+60 and GO4+30. Overall, MCP600+60 emerged as the most effective treatment for enhancing papaya's cold tolerance and storage quality based on our study.

Unlocking Novel Functionality: Pseudocapacitive Sensing in MXene-Based Flexible Supercapacitors

Extensively explored for their distinctive pseudocapacitance characteristics, MXenes, a distinguished group of 2D materials, have led to remarkable achievements, particularly in the realm of energy storage devices. This work presents an innovative Pseudocapacitive Sensor. The key lies in switching the energy storage kinetics from pseudocapacitor to electrical double layer capacitor by employing the change of local pH (-log[H+]) in MXene-based flexible supercapacitors during bending. Pseudocapacitive sensing is observed in acidic electrolyte but absent in neutral electrolyte. Applied shearing during bending causes liquid-crystalline MXene sheets to increase in their degree of anisotropic alignment. With blocking of H+ mobility due to the higher diffusion barrier, local pH increases. The electrochemical energy storage kinetics transits from Faradaic chemical protonation (intercalation) to non-Faradaic physical adsorption. We utilize the phenomenon of capacitance change due to shifting energy storage kinetics for strain sensing purposes. The developed highly sensitive Pseudocapacitive Sensors feature a remarkable gauge factor (GF) of approximately 1200, far surpassing conventional strain sensors (GF: ~ 1 for dielectric-cap sensor). The introduction of the Pseudocapacitive Sensor represents a paradigm shift, expanding the application of pseudocapacitance from being solely confined to energy devices to the realm of multifunctional electronics. This technological leap enriches our understanding of the pseudocapacitance mechanism of MXenes, and will drive innovation in cutting-edge technology areas, including advanced robotics, implantable biomedical devices, and health monitoring systems.

Synergistic Effects of Unmodified Tea Leaves and Tea Biochar Application on Remediation of Cr-Contaminated Soil

Hexavalent chromium (Cr(VI)) contamination in soil presents significant risks due to its high toxicity to both the environment and human health. Renewable, low-cost natural materials offer promising solutions for Cr(VI) reduction and soil remediation. However, the effects of unmodified tea leaves and tea-derived biochar on chromium-contaminated soils remain inadequately understood. In this study, tea tree pruning waste was converted into biochar at various temperatures, and the impacts of both unmodified tea leaves and tea biochar on soil Cr(VI) content, chromium fractionation, and soil biochemical properties were assessed using a soil incubation experiment. The results showed that the combined treatment of tea and tea biochar produced at 500 °C reduced Cr(VI) content by up to 49.30% compared to the control. Chromium fractionation analysis revealed a significant increase in the residual chromium fraction, accounting for 32.97% of total chromium, substantially reducing its bioavailability and mobility. Soil properties were markedly improved, with notable increases in pH (14.89%), cation exchange capacity (CEC; up to 100.24%), and organic matter content (up to 167.12%) under the combined treatments. Correlation analysis confirmed that Cr(VI) content reductions were positively correlated with increases in pH, nutrient retention, and enzyme activities, highlighting their role in chromium stabilization. This study underscores the synergistic potential of unmodified tea leaves and tea biochar as an innovative, eco-friendly strategy for Cr(VI) remediation, enhancing both soil quality and heavy metal stabilization.

Behavior of PGS/apatite foam scaffolds during incubation in SBF, PBS, Ringer's solution, artificial saliva, and distilled water.

Poly(glycerol sebacate) is a polymeric material with potential biomedical application in the field of tissue engineering. In order to act as a biodegradable scaffold, its incubation study is vital to simulate its behavior. This study explores the degradation of porous poly(glycerol sebacate)/hydroxyapatite scaffolds subjected to incubation in various physiological solutions. The research involved monitoring pH and conductivity values over a 14-day period, as well as analyzing the swelling capacity and mass alterations of the scaffolds. In simulated body fluid (SBF) and phosphate-buffered saline (PBS), the pH levels remained relatively stable, whereas Ringer's solution caused a pH decrease. Conversely, artificial saliva demonstrated an increase in pH, and distilled water caused a slight decrease. The conductivity values remained stable in SBF and Ringer's solution, slightly decreased in PBS, increased in artificial saliva, and significantly increased in distilled water. The swelling capacity of the scaffolds varied depending on the solution used, with the lowest equilibrium swelling observed in SBF and PBS. The effect of the presence of ceramics on this parameter was also observed. The mass changes of the scaffolds indicated deposition of particles or salts from the incubation solutions, and subsequent rinsing in distilled water led to a decrease in mass. Scanning electron microscopy (SEM) imaging and elemental analysis confirmed the presence of crystallized salts on the scaffold surfaces after incubation in SBF. Surface roughness measurements revealed changes in roughness depending on the solution, with deposition of additional layers in SBF and degradation in artificial saliva. In summary, the scaffolds exhibited biodegradation in physiological solutions, with variations in pH, conductivity, swelling capacity, mass changes, and surface morphology depending on the specific solution and scaffold composition.

A novel agrosinters support growth, photosynthetic efficiency and reduce trace metal elements accumulation in oilseed rape growing on metalliferous soil

Soil conditioners to fertilize, improve soil structure and support the phytostabilization of trace metal elements (TMEs) are being used more and more frequently. One of the options are agrosinters – slow-release ceramic fertilizers consisting mainly of SiO2, CaO, P2O5 and K2O, with an alkaline pH and high impact strength. The effect of two different agrosinters, A1 and A2, on the growth and physiological condition of Brassica napus grown in uncontaminated and Pb-, Cd- and Zn-contaminated soil was investigated in a pot experiment. In vivo data were collected using an infrared gas analyzer, a fluorimeter, a pigment content meter and a thermal camera. Elemental composition of the biomass was also investigated. The tested agrosinters promote biomass yield and have an effect on improving leaf chlorophyll content, phenomenological energy fluxes and plant gas exchange. The effect of the agrosinters on the plants was dose- and amendment-specific. An immobilization effect was observed not only in the soil but also in the plants. A reduction in the Cd (22%) and Zn (40%) content in the biomass was measured. All this was related to the effect of increasing the available form of P (50%), K (300%) and Ca (50%) in the soil, which improves soil fertility and reduces the bioavailable forms of the studied TMEs, due to the increase in soil pH and/or the complexation of these with phosphate compounds. The multidimensional analysis of A2 agrosinter shows the most positive effects on plant conditions, indicating that fly ash as a mixed substrate benefits the plants.

Amorphous pectin/calcium magnesium carbonate @ konjac glucomannan for recovery phosphate from aqueous

To safeguard water quality and sustainable phosphorus cycling, it is imperative to recover phosphorus from high-content wastewater, particularly livestock wastewater, considering the low tolerance threshold for phosphate in surface water (below 0.5mg/L). Calcium carbonate and magnesium carbonate possess considerable potential for phosphate adsorption; however, their crystalline nature diminishes the reactivity of calcium and magnesium, resulting in the limited phosphate adsorption capacity. In this study, a novel phosphate adsorbent (PCCM@K) was synthesized through co-precipitation involving Ca, Mg, and pectin, followed by direct coating with konjac glucomannan, which eliminated the need for separation and cleaning steps. Pectin macromolecules interact with Ca and Mg to yield amorphous minerals, thereby enhancing the pore structure. The assessment of the phosphate adsorption performance of PCCM@K reveals robust alkali release, stable adsorption across a broad pH range (3-12), high adsorption capacity (61.9 mg-P/g), minimal interference from coexisting ions, and effective phosphate recovery in the actual biogas slurry. The primary mechanism underlying phosphate adsorption is chemisorption. During the adsorption process, ligand exchange takes place between carbonate and phosphate, leading to an increase in solution pH and the immobilization of phosphate via inner-sphere complexation with Ca and Mg. Overall, PCCM@K exhibits considerable potential for phosphorus recovery from wastewater, highlighting its significance in promoting environmentally sustainable practices.

TMT-based quantitative proteomics reveals the effects of electromagnetic field and freezing preservation techniques on mutton quality

This study investigated the effects of electromagnetic field preservation (EP) and freezing storage (FS) on the quality of northern Qianbei Ma mutton. Using tandem mass tagging (TMT)-labeled quantitative proteomics and bioinformatics, it was observed that EP more effectively inhibited pH increase and maintained a* and b* values compared to FS. Furthermore, the EP group was able to better maintain the water-holding capacity and tenderness of the mutton under prolonged storage. Proteomics analysis identified 397 differentially expressed proteins (DEPs) between the two storage methods at the same storage duration. GO and KEGG enrichment analyses indicated that proteins such as A0A452DSW4, A0A452E8M7, and D3JYV6 were involved in energy metabolism and redox processes, while A0A452EJ66, A0A452DSW4, and A0A452FJE8 played significant roles in protein binding. Overall, EP technology demonstrated superior benefits for maintaining mutton quality, suggesting a novel approach for mutton preservation.

Enhancing simultaneous nitrogen and phosphorus removal using partial nitritation/anammox with an airlift inner-circulation partition bioreactor

The partial nitritation/anammox (PNA)-hydroxyapatite (HAP) process for synchronized nitrogen (N) and phosphorus (P) removal has attracted much attention; however, its use has been restricted by the limited availability of optimal bioreactor configuration and its operational conditions. In the present study, a new single-stage PNA reactor, the airlift inner-circulation partition bioreactor (AIPBR), was continuously operated for 261 days at a fixed hydraulic retention time of 6 h. The results showed that the optimal removal performance (ammonia, 92.77 ± 0.72 %; total N, 76.92 ± 1.78 %; %, total P, 86.57 ± 2.84 %) was achieved at a Ca/P ratio of 4.0 during the operation period; the influent ammonia and P concentrations were maintained at 250 mg/L and 20 mg/L, respectively. The P removal efficiency was 10 % higher than that reported in similar studies, indicating that a highly efficient PNA-HAP process can be successfully achieved using the AIPBR. By enhancing the circulation of the mixture between the inner and outer layers, accelerating the accumulation of ammonia-oxidizing and anaerobic ammonia-oxidizing bacteria, and promoting simultaneous biological autotrophic denitrification and phosphorization, the sludge granulation and HAP crystallization were gradually strengthened by the pH increase inside the sludge particles. Our findings provide a scientific basis for developing next-generation technologies for synchronized N and P removal from wastewater.

The Impact of an Edible Composite Coating Formulated with Farsi Gum and Iranian Black Cumin Essential Oil Emulsion or Nanoemulsion, Alongside Low-Dose Gamma Irradiation, on the Quality of Chilled Turkey Breast

Background: Hurdle technology is an effective method for preserving muscle food products and extending their shelf life. Objectives: This study evaluated the combined effect of Farsi gum (FG) coating impregnated with black cumin essential oil (BCEO) emulsion or black cumin nanoemulsion (BCNE) and low-dose gamma irradiation (GIR) at 2 kGy on the quality of turkey breast over 21 days of chilled storage. Methods: Turkey breast samples were divided into eight groups: Control, FG, GIR, FG + GIR, FG + BCEO, FG + BCNE, FG + BCEO + GIR, and FG + BCNE + GIR. The samples were assessed for microbial, physicochemical, and sensory attributes throughout 21 days of chilled storage. Results: The growth of mesophilic and psychrotrophic bacteria, Enterobacteriaceae, and lactic acid bacteria (LAB) was inhibited in all treated groups compared to the control and FG groups during the storage period. The treatments also curbed the increase in pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and protein carbonyls in the turkey breast. The most effective treatment for controlling microbial growth, minimizing physicochemical changes, and extending the storage life of turkey breast was the combination of FG + BCNE + GIR. Conclusions: The combination of active FG coating containing BCNE and low-dose GIR offers effective long-term preservation of turkey breast during chilled storage.

Hydrogen underground storage potential in sandstone formation: A thorough study utilizing surface complexation modelling

This research focuses on the geochemical aspects of hydrogen underground storage, with particular emphasis on surface complexation modelling and its impact on surface potential and surface charge. The primary objective is to develop the first comprehensive surface complexation model specifically tailored for sandstone rocks, emphasizing key minerals such as quartz, kaolinite, and calcite, which are suitable for hydrogen underground storage applications. This model is intended to serve as a benchmark for more research in this field, providing a solid foundation for investigating and improving predictions related to wettability alteration. Additionally, the model has been integrated with hydrogen solubility to accurately capture changes in surface charge. The study identified six brine compositions with various minerals to examine the effect of monovalent and divalent ions. The results showed an increase in solubility with an overall reduction in salinity, and a decrease in divalent ions. The homogeneous surface complexation model demonstrated a neutral surface potential, attributed to an increased mole fraction of positively charged >SiOH+and a decreased in negatively charged >SiO-. Similar trends were observed in kaolinite and calcite minerals. The influence of pH was also explored, revealing a significant impact on the homogeneous quartz case, where an increase in pH shifted the surface potential from neutral to more negative. The heterogeneous cases exhibited less negative behavior as the quartz content increased per case, mainly due the increasing presence of positively charged species such as >SiOH+ and >AlOH+, and the reduction of the negatively charged >AlO-. Increasing the salinity of the solution resulted in less negative surface potential, attributed to the abundance of positive divalent and monovalent ions boosted by increasing salinity, thus the formation of positive surface complexes.

Enhanced peracetic acid activation under Far-UVC Radiation: Micropollutant degradation and radical assessment

Traditional ultraviolet/peracetic acid process (UV/PAA) was limited by energy utilization. Herein, an efficient advanced oxidation process (AOP) for activating PAA by the far-ultraviolet of 222 nm (UV222/PAA) was established for micropollutant degradation. UV222/PAA system can effectively degrade various kinds of micropollutants, and the degradation rate of naproxen (NAP) in UV222/PAA system were about 2.61, 3.50 and 4.92 times higher than that in UV222/H2O2, UV222 and UV254/PAA systems within 300 s, respectively. The innate quantum yields of molecular state PAA (PAA0) and dissociated state PAA (PAA−) photolysis under UV222 irradiation were determined to be 0.51 and 0.84 mol Einstein−1 at pH 5.0 and pH 9.6, respectively. Based on an established kinetic model, the second-order rate constants of acetylperoxyl radical (CH3(O)OO•) and acetyloxyl radical (CH3(O)O•) with NAP were determined to be 1.74 × 107 and 1.08 × 106 M−1s−1, respectively. UV222, hydroxyl radical (HO•) and CH3(O)OO• were mainly responsible for the degradation of NAP, and their relative contributions were 33.00 %, 8.15 %, and 58.83 %, respectively. The increase of pH showed a promoting effect on NAP degradation, and the steady-state concentration of radicals increased with the increase of pH in UV222/PAA system. Cl– and HCO3– have inconspicuous impact on NAP degradation, while HA inhibits the degradation of NAP. The degradation pathway of NAP was proposed on the basis of product identification and theoretical calculation analysis. Finally, the effectiveness of the UV222/PAA system for NAP degradation was also verified in real water. This work develops an efficient PAA activation AOP with high radical yield for micropollutant degradation in practical applications.

The influence of pH on the liquid-phase transformation of phenolic compounds driven by nitrite photolysis: Implications for characteristics, products and cytotoxicity

The aqueous-phase conversion of phenolic compounds (PhCs) driven by nitrite photolysis has been recognized as a significant source of secondary brown carbon (BrC). However, the influence of pH on the conversion kinetics and product distribution of PhCs remains unclear. In this study, three representative PhCs with varying functional groups were selected to examine their aqueous-phase conversion kinetics in the presence of nitrite under different pH conditions and simulated sunlight conditions. The results indicate that as the pH increases, the decay rates of PhCs decrease, following first-order reaction kinetics. These varying decay rates also suggest that different substituents on the benzene ring significantly impact the reactivity of PhCs. The molecular composition of the products is pH-dependent, with 4-nitrocatechol (4NC) emerging as the primary reaction product. A range of conversion products were detected across different pH values: nitrification dominated at low pH, while hydroxylation products increased with rising pH, and polymerization products appeared prominently at high pH. Due to the electron-withdrawing effect of the nitro group on the benzene ring, fewer products formed from 4-nitrophenol were observed, and the visible absorption spectrum also showed a decreasing trend as the reaction progressed across various pH conditions. Toxicity assays on human non-small cell lung cancer cells (A549) revealed that the toxicity of the reaction products decreased with increasing pH. Correspondingly, the accumulation of reactive oxygen species (ROS) and apoptosis rates in cells also declined. This may be due to the fact that at lower pH levels, nitrophenols (NPs), which tend to promote ROS accumulation and cell death, dominate the product mix. This study provides valuable insights into the toxicological properties of secondary organic aerosols (SOA) formed from the photo-oxidation products of PhCs under different pH conditions. These findings contribute to a deeper understanding of the environmental and health impacts of SOA in atmospheric chemistry.

High cell density cultivation by anaerobic respiration

BackgroundOxygen provision is a bottleneck in conventional aerobic high cell density culturing (HCDC) of bacteria due to the low O2 solubility in water. An alternative could be denitrification: anaerobic respiration using nitrogen oxides as terminal electron acceptors. Denitrification is attractive because NO3− is soluble in water, the end-product (N2) is harmless, and denitrification is widespread among bacteria, hence suitable organisms for most purposes can be found. The pH must be controlled by injection of an inorganic acid to compensate for the pH increase by NO3−-consumption, resulting in salt accumulation if feeding the bioreactor with NO3− salt. We avoid this with our novel pH–stat approach, where the reactor is supplied with 5 M HNO3 to compensate for the alkalization, thus sustaining NO3−-concentration at a level determined by the pH setpoint. Here we present the first feasibility study of this method, growing the model strain Paracoccus denitrificans anaerobically to high densities with glucose as the sole C-source and NO3− as the N-source and electron acceptor.ResultsOur fed-batch culture reached 20 g cell dry weight L−1, albeit with slower growth rates than observed in low cell density batch cultures. We explored reasons for slow growth, and the measured trace element uptake indicates it is not a limiting factor. Bioassays with spent medium excluded accumulation of inhibitory compounds at high cell density as the reason for the slow growth. The most plausible reason is that high metabolic activity led to CO2/H2CO3 accumulation, thus suppressing pH, leading to a paucity in HNO3-feeding until N2-sparging had removed sufficient CO2. The three free intermediates in the denitrification pathway (NO3− → NO2− → NO → N2O → N2) can all reach toxic concentrations if the electron flow is unbalanced, and this did occur if cells were glucose-limited. On the other hand, accumulation of polyhydroxyalkanoates occurred if the cells were NO3−-limited. Carefully balancing glucose provision according to the HNO3 injected is thus crucial.ConclusionsThis work provides a proof of concept, while also identifying CO2/H2CO3 accumulation as a hurdle that must be overcome for further development and optimization of the method.