Addition Of HCl Research Articles

B-035 Maintaining the Analytical Performance of Calcium and Phosphorus in 24-hour Urine Without Addition of 6n hcl in the Pre-Analytical Process

Abstract Background The measurements of Calcium (Ca) and Phosphorus (P) in 24-hour urine samples are associated with the evaluation of hyperparathyroidism, renal tubular acidosis, and monitoring of Falconi Syndrome and Nephrolithiasis. The aim is to demonstrate the maintenance of analytical performance without the addition of 6N hydrochloric acid (HCl) in the pre-analytical process. Methods The study was divided into stages and carried out for both analytes. In the first stage, correlation tests were performed on 40 samples with and without HCl within the range of linearity. Imprecision was processed at 3 clinically relevant concentrations for 5 days, repeated 5 times. In the second stage, stability testing of Ca and P was performed on 7 samples over 5 days, without HCl (pH 5–6.7), with HCl (pH < 3), alkalized (pH > 8), and neutral (pH 7–7.5). In the last stage, interferent testing was performed on 286 samples, where pH was measured after collection and after acidification with 200uL of HCl. A pH meter and pH strips were used to measure pH, and a Siemens® - Advia 2400 equipment was used for analytical measurement of Ca and P. Results In the correlation results, the variance test for both analytes resulted in F-test: 1.01 < 1.69, the difference analysis was less than 2.02, correlation coefficient and Bias% of 1.00 and 0.55 for Ca and 0.99 and 0.27 for P, respectively. Total error (TE) obtained for Ca was 9.69 and 9.41, lower than the allowed TE for both analytes. The repeatability and intralaboratory imprecision of the three levels of each analyte were less than 13.8% for Ca and 9.0% for P. There was 100% correlation of the results when the analyses were performed with samples at pH up to 7; at pH values > 7, the concentrations decreased by 60%. All 268 samples with different pH values, subjected to 200uL of HCl, were suitable for Ca and P measurement with pH below 5.7. Conclusions Samples with a pH greater >or = to 7 necessarily need to be acidified with HCl 6N. There is no analytical alteration if all samples in the routine of urinary Ca and P are submitted to 200uL of HCl 6N, even the most alkaline samples. The non-provision of preservative containers to patients reduces the risk of accidents, costs, and the need for legal licenses for handling in healthcare facilities.

Wood Decay Resistance Employing Nanoparticle Protective Systems

In this paper, nanoparticle dispersions (nanosilver, copper nano oxide, nanozinc, and nanosilica) have been formulated to be used as protective impregnants. Since all the components of the formulations could be charged according to the pH of the medium, the solutions were formulated with the two profiles of pH=3 and pH=8 (pH changes were handled with the addition of HCl or NH4OH at the time of application), and the interaction capacity has been analyzed. The nanoparticle dispersion medium was alcohol, and the concentrations ranged from 1 to 3% m/v. Impregnations have been performed by immersion. All formulated systems generated good protection against biotic agents due to chemical and structural modifications of the cell wall. It has been observed that the best performances were given with the presence of nanoparticles, which allowed inferring that the composite formed by nano-wood is bioactive. An issue that is also important is that the systems are easy to apply and very low concentrations are required, which translates into low costs.

A handbook for graphitic carbon nitrides: revisiting the thermal synthesis and characterization towards experimental standardization

Graphitic carbon nitrides (g-C3N4s) have continued to attract attention as metal-free, low-cost semiconductor catalysts. Herein, a systematic synthesis and characterization of g-C3N4s prepared using four conventional precursors (urea (U), dicyandiamide (DCDA), semicarbazide hydrochloride (SC-HCl), and thiosemicarbazide (TSC)) and an unexplored one (thiosemicarbazide hydrochloride (TSC-HCl)) is presented. Equal synthesis conditions (e.g. heating and cooling rates, temperature, atmosphere, reactor type/volume etc) mitigated the experimental error, offering fair comparability for a library of g-C3N4s. The highest g-C3N4 amount per mole of the precursor was obtained for D-C3N4 (∼37.85 g), while the lowest was for S-C3N4 (∼0.78 g). HCl addition to TSC increased the g-C3N4 production yield (∼5-fold) and the oxygen content (T-C3N4 ∼ 3.17% versus TCl-C3N4 ∼ 3.80%); however, it had a negligible effect on the level of sulphur doping (T-C3N4 ∼ 0.52% versus TCl-C3N4 ∼ 0.45%). S-C3N4 was the darkest in color (reddish brown), and the band gap energies were S-C3N4(2.00 eV) < T-C3N4(2.74 eV) < TCl-C3N4(2.83 eV) ≤ D-C3N4(2.84 eV) < U-C3N4(2.97 eV). The experimentally derived conduction band position of S-C3N4(−0.01 eV) was closer to the Fermi energy level than the others, attributable to high oxygen atom doping (∼5.11%). S-C3N4 displayed the smallest crystallite size (∼3.599 nm by XRD) but the largest interlayer distance (∼0.3269 nm). Furthermore, BET surface areas were 138.52 (U-C3N4), 22.24 (D-C3N4), 18.63 (T-C3N4), 10.51 (TCl-C3N4), and 9.31 m2 g−1 (S-C3N4). For the first time, this comprehensive handbook gives a glimpse of a researcher planning g-C3N4-based research. It also introduces a novel oxygen-sulphur co-doped g-C3N4 (TCl-C3N4) as a new halogen-free catalyst with a relatively high production yield per mole of precursor (∼24.09 g).

The water fraction of Cantigi (Vaccinium varingiaefolium Bl. Miq.) fruits demonstrate the highest antimetabolic syndrome properties on enzyme assay

Vaccinium varingiaefolium, Cantigi (local name), is a member of the berries family that has various benefits to human health. It contains numerous biological compounds, including polyphenols, flavonoids, and anthocyanin. Although many studies reported the pharmacological activity of berries families, the pharmacological Cantigi’s activity is still limited. The research aims to examine the antimetabolic, inhibition of lipase, alpha-glucosidase (αGIA), and angiotensin-converting enzyme (ACE) of Cantigi. The fractionation process originates from a 70% ethanol extract that underwent treatment with the addition of HCl until reaching a pH of 3. To comprehensively analyze the diverse array of compounds present in the Cantigi water fraction, we employ non-targeted screening through HPLC-Q-TOF-MS. Additionally, the brine shrimp lethality test (BSLT) was applied to check the acute toxicity. The results clearly indicate that the water fraction of Cantigi’s extract exhibits the highest activity against Lipase, ACE, and αGIA with values of 27.74±3.66 μg/mL, 19.33±2.86 μg/mL, and 15.90±1.82 μg/mL, respectively. Furthermore, we found delphinidin was the major anthocyanin of the water fraction. Finally, the toxicity assay showed 196.56±14.8 mg/ml. In conclusion, the water fraction of Cantigi extract demonstrated the highest antimetabolic activity, and we propose that delphinidin contributes significantly to this observed activity as it serves as a major component.

Study on the optimization of hydrothermal liquefaction performance of tobacco stem and the high value utilization of catalytic products

The major objective of this paper was to explore the hydrothermal liquefaction (HTL) characteristics of tobacco stem (TS) and increased the possibility of using TS. The optimum reaction conditions were determined by discussing the reaction temperature, initial pressure and residence time. HCl, KOH and Na2CO3 catalysts were added to compare and analyze the products of bio-oil, biochar and gas (Characterized and analyzed via GC-MS, FT-IR, SEM and GC). Research has found that the best bio-oil yield was 14% under the conditions of reaction temperature 300 °C, initial pressure 6Mpa and residence time 30min. However, the relative content of phenolic compounds in bio-oil was the highest at 320 °C, which is 17.46%. The relative yield of nicotine was the maximum at 280 °C, which was 9.21%. With the increased of reaction temperature, the nicotine content gradually reduced. The addition of HCl could completely decompose nicotine, so that the relative yield of phenolic compounds increased to 24.01% in bio-oil, and valeric acid could be found in bio-oil. Through the investigation of HTL of TS, it was found that TS have a wide application prospect in the preparation of high-value nitrogen-containing compounds and phenolic compounds.

Investigation of the viscoelastic evolution of reactive magnesia cement pastes with accelerated hydration mechanisms

Viscoelasticity of reactive magnesia cement (RMC) pastes containing 3 different hydration agents (HCl, Mg(CH3COO)2 and MgCl2) were investigated. Amplitude sweep, frequency sweep and time sweep of RMC pastes were examined within 3 h of hydration. Time-dependent evolution of storage modulus, loss modulus, phase angle, and shear stress were recorded. Measurements of pH, isothermal calorimetry, XRD, TG-DTG and FTIR were used to analyze hydration reaction and products. Addition of hydration agents (HAs) accelerated the growth rate of storage modulus/loss modulus over time. MgCl2 demonstrated the greatest acceleration influence, also reflected in non-destructive structural build-up and buildability related to 3D printing applications. Addition of MgCl2 and HCl advanced the initial setting time of RMC pastes to 100–110 min, during which yield stress reached maximum, and decreased afterwards. Within 3 h of hydration, pastes containing MgCl2 revealed lowest pH, highest heat release and brucite concentration. HAs inclusion precipitated brucite away from MgO particles in the bulk solution, creating a bridge between MgO particles and enabling denser microscopic network structure.

Physicochemical properties of sodium alginate from brown algae Sargassum aquifolium and Sargassum cinereum

Synthesis and characterization of sodium alginate from Sargassum aquifolium dan Sargassum cinereum have been successfully performed. S. aquifolium and S. cinereum were collected from the Dompu Islands, West Nusa Tenggara, Indonesia. Extraction was performed by acid pathway, due to cell disruption and the addition of Na2CO3 for extraction. The addition of HCl was to convert acid alginate into alginate, then transformed acid alginate into sodium alginate using NaOH. NaOCl and IPA were used for purification. Physicochemical properties were characterized using SEM-EDS, FTIR, and TG/DTG. The morphological structure of synthetic sodium alginate shows layer structure and fiber fibrils. Sodium alginate contained C, O, Na, and Cl elements. FTIR spectrum indicated the presence of functional groups at the following wavelengths: OH at 3343 cm−1, CH2 at 2915 cm−1, CO double bonds at 1614 cm−1, and fingerprint indicated by the presence of uronic acid, which functioned as the CH group stretched at 935 cm−1. The sodium alginate sample shows a three-step thermal degradation pattern. The first step was starting at 41.7 °C associated with dehydration and was followed by 206.4 and 241 °C associated with decomposition. TGA/DTG results showed a reduction in thermal stability at 250–300 °C. It is suitable for modification and application.

Ancient parasite infections from the main Pampean-Patagonian cemetery of hunter-gatherer of prehistoric times: Archaeological site Chenque I (Parque Nacional Lihué Calel, La Pampa Province, Argentina)

Paleoparasitological studies of human sediment samples from prehistoric times of Argentina are scarce. The objective of the present study is to enhance the knowledge of parasitic infections affecting hunter-gatherer populations inhabiting the Pampean region of Argentina in prehistoric times. A total of 33 samples from 12 inhumation structures of archaeological site Chenque I, the unique cementery studied in Argentina until now from a paleoparasitological point of view, were studied. Chenque I constitute the greater repository of human archaeological remains of La Pampa province. Thirty-one samples came from human burials, and 2 samples from a dog retrieved in a burial, associated with a child. By humans, 11 samples correspond to males, 13 to females, and 7 to undifferentiated individuals. A total of 5 samples corresponds to control samples and were taken under the skull. Paleoparasitological examination revealed that 8 of the 33 sediment samples resulted positive for parasite remains applying the rehydration and spontaneous sedimentation technique with or without addition of HCl (10%). The pre-treatment of samples with HCl as a preliminary step allowed a greater recovery of parasitic remains compared to standard spontaneous sedimentation procedure. The most common parasite species found was Trichuris trichiura being probably one of the parasites that commonly affect human populations inhabiting the region. The low preservation evidenced by the parasite remains recovered indicate a taphonomic interference in the data of parasite assemblages, which probably produce a bias in the recovery of other parasite species that could infect these ancient populations. Proceed in the study of new human samples to improve the knowledge of parasitic infections affecting ancient populations inhabiting the studied region is necessary.

A comparative study of chlorine and bromine species addition on the explosion limits of hydrogen-oxygen mixtures

In this work, we investigate the effects of chlorine (Cl) and bromine (Br) containing species additions on the pressure-temperature explosion limits of hydrogen-oxygen (H2-O2) mixtures computationally. It is shown that, with the addition of HCl, Cl2, HBr and Br2, the explosion limit evolves from being a non-monotonic Z-shaped curve to monotonic or maintains its non-monotonic response depending on the different types of additives. Specifically, with the addition of HCl to the mixtures, the limit always maintains the non-monotonic structure, while with the addition of around 18% of Cl2, it loses its Z-shaped structure. Compared with HCl and Cl2, more sensitive responses were found for HBr and Br2. With the addition of around 1% of HBr and 0.7% of Br2 to the H2-O2 mixtures, the limit's non-monotonic feature disappears rapidly, and becomes a monotonic curve. Further detailed kinetics analysis explains that after the addition of the halogen species, the radical competitions are different at the low- (P = 1.0 × 102 Pa), intermediate- (P = 1.0 × 104 Pa) and high- (P = 1.0 × 106 Pa) pressures respectively, resulting in the change of the dominant reactions. These findings enhance the understanding of Cl and Br containing species sensitization for the explosion limits of the H2-O2 mixtures and help to understand the kinetic interaction between the H2-O2 system and halogen.

Effect of Cation Chloride Concentration on the Dissolution Rates of Basaltic Glass and Labradorite: Application to Subsurface Carbon Storage

The steady-state dissolution rates of basaltic glass and labradorite were measured in the presence of 10 to 700 × 10−3 mol·kg−1 aqueous NaCl, KCl, CaCl2, and MgCl2 at 25 °C. All rates were measured in mixed flow reactors, and at pH~3.6 by the addition of HCl to the reactive fluids. The steady-state basaltic glass dissolution rates, based on Si release, increased by ~0.3 log units in the presence of 10−3 mol·kg−1 of either CaCl2 or MgCl2 compared to their rates in 10−3 mol·kg−1 of NaCl or KCl. In contrast, the steady-state dissolution rates of labradorite decreased by ~0.4 log units in the presence of 10−3 mol·kg−1 of either CaCl2 or MgCl2 compared to their rates in 10−3 mol·kg−1 of NaCl or KCl. These contrasting behaviours likely reflect the varying effects of these cations on the stability of rate controlling Si-rich activated complexes on the surface of the dissolving solids. On average, the Si release rates of these solids are similar to each other and increase slightly with increasing ionic strength. As the pH of water charged with 10 to 30 bars CO2 is ~3.6, the results of this study indicate that both basaltic glass and labradorite dissolution will likely be effective at increasing the pH and adding Ca to the aqueous phase in saline fluids. This observation supports potential efforts to store carbon through its mineralization in saline aquifers containing Ca-bearing feldspar and in submarine basalts.

Effet of hematite (Fe2O3) from natural iron ore as a catalyst in MgH2 as hydrogen storage materials

The main obstacle that hinders the application of fuel cell fuels for vehicles today is the hydrogen storage tube. Therefore, this paper will report the results of a study on MgH2-based hydrogen storage materials with Fe2O3 catalyst inserted (5 wt%, 10 wt%, 15wt%) and prepared by mechanical alloying technique for 10 hours. Fe2O3 samples were obtained from the Lhoong Setia Mining site in Jantang Village, Lhoong, Aceh Besar. The initial sample separation process was carried out manually using a bar magnet. Furthermore, hematite extraction was carried out with the addition of 1M HCL and NaOH each. Then the milling process of MgH2-Fe2O3 samples was carried out using a planetary ball mill. The results of the X-ray diffraction test showed that the MgH2 phase was the most dominant/mainstream phase. Thermal testing with DSC showed that the H2 desorption process experienced a decrease in temperature from 194.56 °C with a milling time variation of 7 hours.

Comparison of Nutrient-Release Strategies in Hydrothermally Treated Digested Sewage Sludge

This work studies the fate of nutrients (N, P, and K) during the hydrothermal treatment of anaerobically digested sewage sludge to raise their concentrations in the liquid phase and facilitate their recovery as solid minerals by chemical precipitation. The hydrothermal process has been optimized by evaluating the temperature (170–230 °C) and reaction time (5–60 min) in an acid-free medium or with the addition of HCl (0.1–0.5 M). In the acid-free hydrothermal reactions, nutrients were mainly concentrated in the hydrochar, which were extracted with 0.5 M HCl (10% w/v). Following this route, 6.9 g N/kg, 13.8 g P/kg, and 8.8 g K/kg contained in the feedstock were extracted from the hydrochar produced at 230 °C, which, considering direct nutrient solubilization to process water by acid-free hydrothermal treatments, accounts for 82, 83, and 78% N, P, and K release, respectively. In the HCl-assisted hydrothermal treatment, the release of nutrients directly into the process water was improved and depended mainly on the acid concentration used and to a lesser extent on the reaction temperature. Operating at 230 °C and 0.5 M HCl, the release of 98% N (more than 45% as NH4–N), 87% P (as PO4–P), and 70% K contained in the feedstock was achieved in the process water. Chemical precipitation of phosphorus and nitrogen from the process water allowed the recovery of a solid identified as crystalline struvite, with high contents in P, Mg, and NH4–N and negligible heavy-metal content. The estimated cost of digested sewage sludge treatment could reach 13.7 euros per tonne, considering the energy inputs required in the hydrothermal treatment.

Zeta Potential of Nanosilica in 50% Aqueous Ethylene Glycol and in 50% Aqueous Propylene Glycol.

A sufficient amount of ionic surfactants may induce a zeta potential of silica particles dispersed in water-glycol mixtures of about 100 mV in absolute value. Nanoparticles of silica were dispersed in 50-50 ethylene glycol (EG)-water and 50-50 propylene glycol (PG)-water mixtures, and the zeta potential was studied as a function of acid, base, and surfactant concentrations. The addition of HCl had a limited effect on the zeta potential. The addition of NaOH in excess of 10-5 M induced a zeta potential of about -80 mV in 50% EG, but in 50% PG the effect of NaOH was less significant. The addition of CTMABr in excess of 10-3 M induced a zeta potential of about +100 mV in 50% EG and in 50% PG. The addition of SDS in excess of 10-3 M induced a zeta potential of about -80 mV in 50% EG and in 50% PG. Long-chained analogs of SDS were even more efficient than SDS, but their application is limited by their low solubility in aqueous glycols.

Influence of pH variation on structural, optical, and superparamagnetic behavior of Ni-doped ZnO (X=0.02) using a solvothermal method

Zn1-xNixO nanoparticles at a concentration (2%) with pH variation (4, 5, 8 and 9) are successfully synthesized using the solvothermal method. ZnO nanoparticle has a hexagonal wurtzite structure when synthesized at acidic and basic conditions. In pH, the solution is calculated from 4 to 9 by the composed addition of NaOH and HCl. The structural properties are studied from XRD and TEM. The average particle size is found to be 13.2 nm using the Debye Scherrer formula and optical properties are analyzed through UV–Visible, FTIR, & PL. From the absorption spectra, it is observed that the bandgap energy is inversely proportional to the particle size. UV–Vis and PL are used to study the optical behavior of the samples. The magnetic behavior of Zn1-xNixO exhibit changing behavior from paramagnetic to superparamagnetic structure with increases in their pH values.

Efficient Removal of Heavy Metals from Contaminated Sunflower Straw by an Acid-Assisted Hydrothermal Process.

The removal of heavy metals is crucial to the utilization of contaminated biomass resources. In this study, we report an efficient process of hydrothermal conversion (HTC) of sunflower straw (Helianthus annuus L.) to remove heavy metals. The effect of different HTC temperatures and concentrations of HCl additives on heavy metal removal efficiency was investigated. The results revealed that increasing the temperature or concentration of HCl promoted the transfer of heavy metals from hydrochar to liquid products during HTC. The heavy metals removed to the liquid products included up to 99% of Zn and Cd, 94% of Cu, and 87% of Pb after hydrothermal conversion with a temperature of 200 °C and HCl 2%. The species of heavy metals in hydrochars converted from unstable to stable with an increase in temperature from 160 °C to 280 °C. The stable fractions of heavy metals in the acidic condition decreased as the acid concentration increased. This aligns well with the high transfer efficiency of heavy metals from the solid phase to the liquid phase under acidic conditions. The FTIR indicated that the carboxy and hydroxy groups decreased significantly as the temperature increased and the concentration of HCl increased, which promoted the degradation of sunflower straw. A scan electron microscope showed that the deepening of the destruction of the initial microstructure promotes the transfer of heavy metals from hydrochars to liquid phase products. This acid-assisted hydrothermal process is an efficient method to treat biomass containing heavy metals.

BIOFILM FORMATION AND CALCIUM PRECIPITATION IN BACILLUS LICHENIFORMIS AND ALCALIGENES FAECALIS FOR SOIL IMPROVEMEN

&#x0D; &#x0D; &#x0D; Calcium precipitation and biofilm formation in halophilic bacteria were investigated in the current study. The strain SMK (Bacillus licheniformis) was isolated from plant rhizosphere and and AQ-1 (Alcaligenes faecalis) from marble crushing soil in Lahore. Bacterial growth, biofilm formation and CaCO3 precipitation of both strains was determined under varying stress (pH, temperature, agitation and salinity). Soil aggregation was investigated under salt stress (NaCl and MgSO4). Results showed that pH 8.0, temperature 42°C, 1.5 M salt (NaCl and MgSO4) stress without agitation was favorable for biofilm formation. Both strains were able to precipitate CaCO3 in media specially at margins of colonies in AQ-1. Effervescence of crystals with addition of concentrated HCl showed confirmatory results. Stereomicroscopic analysis of aggregates in inoculated soil and sand showed precipitation under salt stress. SMK (Bacillus licheniformis) showed high aggregation in soil. From the results, it was concluded that these indigenous strains have potential for sustainable agriculture by improving disturbed soil.&#x0D; &#x0D; &#x0D;

Stability of mesoporous silica using ricinoleic methyl ester as a template with the addition of HCl and application of Cd2+ adsorption optimized by Box-Behnken design.

Mesoporous silica is restricted to organic solvents or other acidic media. The application of mesoporous silica depends on the medium's chemical stability and mechanical properties. It is necessary to stabilize the mesoporous silica material under acidic conditions. The results of the nitrogen adsorption characterization show that MS-50 has a large surface area and porosity, resulting in good mesoporous silica. Using variance analysis (ANOVA) to compare the collected data, the best conditions were found at a pH of 6.32, a Cd2+ concentration of 25.30 ppm, an adsorbent dose of 0.06 g, and a time of 70.44 min. The Cd2+ adsorption experiment data best fit the Langmuir isotherm model with the maximum amount of Cd2+ that MS-50 could absorb being 103.10 mg g-1.

Oxygen Vacancy Defect Engineering of Heterophase Junction TiO2: Interfacial/Surface Oxygen Vacancies Coadjust the Photocatalytic ROS Production

In this study, TiO2 samples are synthesized through two stages including hydrolysis and calcination. It is found that the addition of HCl in the hydrolysis stage could facilitate the formation of heterophase junction TiO2. By annealing at 300 °C in an argon atmosphere, interfacial oxygen vacancies (Vo) and surface Vo (distributed in the anatase phase) can be constructed in the heterophase junction TiO2. After photocatalytic experiments, it can be found that surface Vo and interface Vo have a synergistic effect in the production of photocatalytic reactive oxygen species (ROSs). Surface Vo can enrich O2 and transmit electrons to O2 on the surface of anatase. Therefore, the enriched O2 can be converted into •O2– and 1O2 easily. The interfacial Vo not only facilitate the electron transmission between the two phases but also change the electron transfer mode from I-scheme to Z-scheme. Thus, interfacial Vo make photogenerated electrons transfer to anatase and photogenerated holes leave in the rutile. These holes in the rutile part have high oxidation potential and can better oxidize H2O (or OH–) molecules to •OH. They can also oxidize •O2– to 1O2. This work promotes the further development of defect design and application in photocatalytic materials.

Effect of pH Change on the Microalgae-Based Biogas Upgrading Process

An alternative way to remove CO2 from biogas is the use of photosynthetic microorganisms, such as microalgae. This can be achieved by the operation of an open photobioreactor, connected with a mass transfer column, such as a counterflow column. This technology provides up-graded biogas with high quality. The microalgal uptake of CO2 from the biogas in counterflow columns generates pH changes in microalgae culture. To clarify the potential effect of these dynamic pH conditions in the culture, the effect of pH change on the photosynthetic activity and PSII quantum yield was studied for microalgae Chlorella sorokiniana. Thus, assays were carried out, where the pH drop reported in the counterflow columns was replicated in batch microalgae culture through HCl addition and CO2 injection, moving the culture pH from 7.0 to 5.0 and from 7.0 to 5.8, respectively. Moreover, the effect of light/darkness on photosynthetic activity was tested when the pH decreased. The results obtained in this research showed that the photosynthetic activity decreased for the light conditions when the pH was shifted by HCl addition and CO2 injection. Despite this, the value of the PSII quantum yield remained at 0.6–0.7, which means that the microalgae culture did not suffer a negative effect on the photosynthetic system of cells because a high value of PSII efficiency remained. In the same way, the results indicated that when the pH change was corrected, the photosynthetic activity recovered. Moreover, the apparent affinity constant for dissolved inorganic carbon (KDIC) was 0.9 µM at pH 5 and 112.0 µM at pH 7, which suggests that the preferred carbon source for C.sorokniana is CO2. Finally, all the results obtained indicated that the pH drop in the counter-flow column for biogas upgrading did not cause permanent damage to the photosynthetic system, and the decrease in the photosynthetic activity as a result of the pH drop can be recovered when the pH is corrected.

Assessment of catalytic thermal hydrolysis of swine manure slurry as liquid fertilizer: Insights into nutrients and metals

The recovery of nutrients from livestock manure has generated a lot of interest in biosolids value-adding. There is now more research on manure with high solids content but less study on manure with lower solids content. This study used swine manure slurry as the research object and comprehensively examined the characteristics of organic matter conversion, nitrogen, phosphorus, and metals release during the catalytic-thermal hydrolysis (TH) process. It was found that ammonia nitrogen showed a continuous increase with increasing temperature while inorganic phosphorus showed a rising and then decreasing trend. The addition of HCl and H2O2 (TH-HCl-H2O2) promoted the hydrolysis of organic matter, showing the best nitrogen and phosphorus release performance, releasing 62.2% of inorganic phosphorus and 50.8% of nitrogen. The release characteristics of nutrients and metals from the TH process were significantly affected by the addition of HCl and H2O2, according to structural equation modelling study. The data analysis demonstrated that the liquid fertilizer produced by TH did not surpass the environmental risk associated with nutrients or the ecological risk associated with heavy metals. This study would offer theoretical justification for biowaste conversion for agricultural applications.