Sodium Citrate Concentration Research Articles

Advancements in on-site heavy metal detection: Characterizing and sensitive Hg2+ sensing of silver spheroid nanoparticles obtained by laser ablation synthesis in solution

Heavy metal detection in water bodies is crucial to prevent potential harm to the environment, animals and humans. While powerful techniques such as atomic absorption spectrometry exist, they often require extensive sample preparation and are typically confined to laboratory settings. As a result, alternative detection methods such as optical sensors, are under development to provide a simpler, faster, and on-site detection solution. In the present work spheroidal silver nanoparticles (AgNPs) with a mean size of 14.7 ± 0.6 nm were synthesized by laser ablation in a sodium citrate solution. These nanoparticles exhibit a localized surface plasmon resonance (LSPR), which is profoundly dependent on the size, morphology and composition of the nanoparticles and the refractive index of the surrounding media. The detection capabilities of these nanoparticles were assessed by exposing them to various metal ions, revealing a distinctive sensitivity to Hg2+ ions. Notably, this particular ion had a significant impact on the extinction curve of the AgNPs. The impact of synthesis parameters, including sodium citrate and NaCl concentration, as well as pH, on the efficacy of Hg2+ detection was systematically studied. Characterization techniques such as Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), High-Resolution TEM (HRTEM), and Scanning Transmission Electron Microscopy (STEM) were employed to determine the size, morphology, distribution, crystalline structure, and elemental composition of the AgNPs. The results indicated that AgNPs synthesized through laser ablation in a sodium citrate solution exhibited sensitive detection capabilities for Hg2+ ions, reaching an LOD and LOQ of 0.9355 μM and 2.8350 μM respectively.

Rheology and Printability of a Porcelain Clay Paste for DIW 3D Printing of Ceramics with Complex Geometric Structures.

The modeling of ceramics with complex geometric structures currently depends on the handcrafted mode, with long cycles, high costs, and low efficiency; additive manufacturing (AM) technology can solve this problem well. Herein, the porcelain clay paste was successfully prepared for the direct ink writing (DIW) 3D printing process of ceramics with complex geometric structures, and the effects of sodium citrate (SC) content on the rheological properties and DIW 3D printability of the porcelain clay paste were investigated in detail. The SC has a vital role in the rheological behavior of porcelain clay paste. Adding SC increases the absolute zeta potential and decreases the viscosity of the paste, while a high SC content will lead to a low storage modulus of the paste. The porcelain clay paste with an SC content of 0.05% and a paste solid content of 75% possesses suitable rheological properties and a storage modulus for DIW 3D printing. The as-prepared porcelain clay paste has high DIW 3D printability at a pressure of 0.5 MPa, and a 3D-printed green body with a well-densified structure can be achieved. After being sintered, the 3D-printed ceramic exhibits high densification and mechanical properties. A green body with complex geometric structures is quickly and precisely modeled by the DIW 3D printing process with the resultant porcelain clay paste as the raw material. This work provides a practical approach to rapidly fabricating ceramics with complex geometrical structures.

Enhancing casein micelle dissociation in diluted skim milk systems using combined processing techniques

The present work aims to evaluate the dissociation of casein micelles in diluted skim milk (SM) systems after undergoing solvent- or emulsifying salt-based dissociation coupled with ultra-high-pressure homogenization (UHPH). Specifically, part I evaluated dilute SM solutions combined with varying ethanol concentrations (0%-60%) at varying temperatures (5-65°C) in combination with UHPH (100-300 MPa), and part II evaluated dilute SM solutions combined with varying concentrations (0-100 mM) of either sodium hexametaphosphate (SHMP) or sodium citrate (SC) in combination with UHPH (100-300 MPa). In part I, high concentrations of ethanol (40%-60% vol/vol) at elevated temperatures (45-65°C) achieved extensive dissociation of casein micelles, especially in combination with UHPH at ≥200 MPa, as shown by a reduction in sample absorbance and in casein particle size compared with the control (dilute SM, 65°C) under optimum conditions (dilute SM, 60% ethanol, 65°C, ≥200 MPa). In part II, the level of casein micelle dissociation using emulsifying salts (ES) was dependent on the ES type and concentration. Considerable casein micelle dissociation in dilute SM systems was achieved with SHMP concentrations ≥1 mM and SC concentrations ≥10 mM, resulting in decreased sample absorbance, bimodal casein size distributions, and increased hydrophobicity (∼2-fold increase in intrinsic fluorescence) compared with the control (dilute SM). This dissociation was further enhanced with UHPH (≥200 MPa). These results indicate that both solvent- and ES-based casein dissociation techniques can be optimized when used in combination with UHPH. Together, these processing techniques can be used to extensively dissociate casein micelles with the potential to use these altered systems for value-added applications such as functional ingredients or encapsulation agents.

Preparation and activity study of Ruoqiang jujube polysaccharide copper chelate.

Background: Polysaccharide metal chelate exhibit both immunoregulatory activity and metal element supplementation effects. Methods: In this study, Ruoqiang jujube polysaccharide copper chelate (RJP-Cu) was prepared and the preparation conditions were optimized using the response surface method. Subsequently, RJP-Cu was administered to lambs to evaluate its impact on growth performance, copper ion (Cu2+) supplementation, immune enhancement, and intestinal flora was evaluated. Results: The results indicated that optimal RJP-Cu chelation conditions included a sodium citrate content of 0.5 g, a reaction temperature of 50°C, and a solution pH of 8.0, resulting in a Cu2+ concentration of 583°mg/kg in RJP-Cu. Scanning electron microscopy (SEM) revealed significant structural changes in RJP before and after chelation. RJP-Cu displaying characteristic peaks of both polysaccharides and Cu2+ chelates. Blood routine indexes showed no significant differences among the RJP-Cu-High dose group (RJP-Cu-H), RJP-Cu-Medium dose group (RJP-Cu-M), RJP-Cu-low dose group (RJP-Cu-L) and the control group (p > 0.05). However, compared with the control group, the RJP-Cu-H, M, and L dose groups significantly enhanced lamb production performance (p < 0.05). Furthermore, RJP-Cu-H, M, and L dose groups significantly increased serum Cu2+ concentration, total antioxidant capacity (T-AOC), catalase (CAT), and total superoxide dismutase (T-SOD) contents compared with control group (p < 0.05). The RJP-Cu-H group exhibited significant increases in serum IgA and IgG antibodies, as well as the secretion of cytokines IL-2, IL-4, and TNF-α compared to the control group (p < 0.05). Furthermore, RJP-Cu-H group increased the species abundance of lamb intestinal microbiota, abundance and quantity of beneficial bacteria, and decrease the abundance and quantity of harmful bacteria. The RJP-Cu-H led to the promotion of the synthesis of various Short Chain Fatty Acids (SCFAs), improvements in atrazine degradation and clavulanic acid biosynthesis in lambs, while reducing cell apoptosis and lipopolysaccharide biosynthesis. Conclusion: Thus, these findings demonstrate that RJP-Cu, as a metal chelate, could effectively promote lamb growth performance, increase Cu2+ content, and potentially induce positive immunomodulatory effects by regulating antioxidant enzymes, antibodies, cytokines, intestinal flora, and related metabolic pathways.

Influence of Sodium Citrate Concentration on the Formation of Silver Nanoparticles and Acti Bacterials Studies

Silver nanoparticles (AgNPs) have been frequently studied in the scientific field due to their physical, chemical and biological properties. These characteristics are influenced by the nanomaterials' size, morphology and composition , allowing the application of AgNPs in the biomedical area due to their antimicrobial action. This work studied the influence of sodium citr ate concentration on the size of silver nanoparticles. Characterization techniques such as DLS and UV visible spectr oscopy were applied to analyze nanoparticle stability, size and polydispersity index. Characterization was carried out using a UV Vis Spectrophotometer and TEM (Transmission Electron Microscope). Analysis of the UV Vis spectra shows that the relatively sta ble nanoparticles at the maximum wavelength measurement of 417 to 418 nm are synthesized using 35, 55 and 100 mmol/L of sodium citrate. Characterization using TEM and XRD analysis shows that silver nanoparticles synthesized based on sodium citrate concentr ation have the smallest size in the 15.5 34.56 nm range with a face centred cubic (FCC) crystal structure. The nanoparticles utilized in this study demonstrated greater antimicrobial activity against Gram positive bacteria than Gram negative bacteria.

Improved-sensitivity sodium citrate concentration sensor using modified thin-diameter polarization maintaining fiber

Sodium citrate, as strong alkali and weak acid salt, play an essential role in the food and pharmaceutical industries. However, lack of detection method selectivity, limited biocompatibility and complexity of the manufacturing process are challenges that hinder the practical application of the sensors. In this paper, a improved-sensitivity sodium citrate concentration sensor with simple and compact interrogation setup is proposed. The sensor is fabricated by fusion splicing the sandwich structure of modified thin-diameter polarization-maintaining fiber, two pieces of multimode fiber, and single-mode fiber. In theoretical modeling, the properties of the structure are investigated. In the experiment, the evanescent field generated by the modified thin-diameter polarization-maintaining fiber plays a vital role in the detection of different sodium citrate concentrations. The sodium citrate concentration sensor exhibits a high linear sensitivity response up to 4.65 nm/%. The sensor provided refractive index sensitivity of 3173.2 nm/RIU. In addition, the response, repeatability, and stability are also evaluated by the experiments. Our results show that the sodium citrate concentration sensor holds great promise for serving as a soft and biocompatible probe for monitoring sodium citrate in situ.

A genetic selection for Mycobacterium smegmatis mutants tolerant to killing by sodium citrate defines a combined role for cation homeostasis and osmotic stress in cell death.

Mycobacteria can colonize environments where the availability of metal ions is limited. Biological or inorganic chelators play an important role in limiting metal availability, and we developed a model to examine Mycobacterium smegmatis survival in the presence of the chelator sodium citrate. We observed that instead of restricting M. smegmatis growth, concentrated sodium citrate killed M. smegmatis. RNAseq analysis during sodium citrate treatment revealed transcriptional signatures of metal starvation and hyperosmotic stress. Notably, metal starvation and hyperosmotic stress, individually, do not kill M. smegmatis under these conditions. A forward genetic transposon selection was conducted to examine why sodium citrate was lethal, and several sodium-citrate-tolerant mutants were isolated. Based on the identity of three tolerant mutants, mgtE, treZ, and fadD6, we propose a dual stress model of killing by sodium citrate, where sodium citrate chelate metals from the cell envelope and then osmotic stress in combination with a weakened cell envelope causes cell lysis. This sodium citrate tolerance screen identified mutants in several other genes with no known function, with most conserved in the pathogen M. tuberculosis. Therefore, this model will serve as a basis to define their functions, potentially in maintaining cell wall integrity, cation homeostasis, or osmotolerance. IMPORTANCE Bacteria require mechanisms to adapt to environments with differing metal availability. When Mycobacterium smegmatis is treated with high concentrations of the metal chelator sodium citrate, the bacteria are killed. To define the mechanisms underlying killing by sodium citrate, we conducted a genetic selection and observed tolerance to killing in mutants of the mgtE magnesium transporter. Further characterization studies support a model where killing by sodium citrate is driven by a weakened cell wall and osmotic stress, that in combination cause cell lysis.

Research on the Promotion of Sludge Anaerobic Fermentation with Sodium Citrate under Low Concentrations of Polyaluminum Chloride

Polyaluminum chloride (PAC) is used widely and increasingly in wastewater treatment plants, resulting in its inevitably high production in sludge. Previous studies have indicated that the production of short-chain fatty acids (SCFAs) is inhibited by the existence of PAC in sludge anaerobic fermentation, so it is necessary to study how to promote sludge anaerobic fermentation under low concentrations of PAC. In this study, sodium citrate (SC) was first used to improve the efficiency of anaerobic fermentation under low concentrations of PAC. The results showed that the production of SCFAs increased with SC, especially when the ratio of PAC to SC was 1:2, and the maximum production of SCFAs reached 2890 mg/L, which is 2.5 times more than when PAC only exists. The mechanism studies showed that SC could remove the Al3+ in the sludge floc, which led to deflocculation of the sludge floc, accelerated the destruction of extracellular polymers (EPS), and released soluble substances in the sludge. At the same time, the key enzymes that were bound and hidden originally in the sludge were also released, which promoted the further degradation of organic matter and shortened the anaerobic fermentation period. However, the higher concentration of SC was not conducive to sludge dehydration. Therefore, the optimal distribution ratio of PAC to SC should be 1:1. This study provides a new idea for the research and practical application of sludge anaerobic fermentation.

Pengaruh Konsentrasi Natrium sitrat dan Variasi Prapemasakan Terhadap Karakteristik Multigrain Rice Instan

&#x0D; &#x0D; &#x0D; &#x0D; Instant multigrain rice is instant rice with a combination of more than one type of rice, beans and grains. The study aimed to determine the effect of variations in precooking and the addition of sodium citrate on the physicochemical characteristics of instant multigrain rice. The research method used a combination of two factors, namely a combination of preprocessing (roasting and steaming) and sodium citrate concentration (2% and 5%). Data analysis used ANOVA at the 0.05% level. This study included preparation of ingredients, weighing of ingredients, size reduction of edamame and kidney beans, washing, soaking (Na3C6H5O7 2% and 5%), washing, precooking (roasting and steaming), cooking, cooling, freezing, thawing, drying, and rehydration. Variations in the preprocessing method and the addition of sodium citrate concentration had a significant effect on the value of water content, fiber content, protein content, fat content, color and rehydration time. The value of water content obtained ranges from 3.47%-5.03%, fat, 3.53%-4.09%, fiber 5.07%-5.51%, protein 12.23%-12.79, rehydration time 5.07-5.51 minutes and color obtained brightness value (L*) of 53.22%-53.79%, reddish value (a*) 7.08%-6.53%, and yellowish value (b*) 14.22%-14.81%.&#x0D; &#x0D; &#x0D; &#x0D;

Extraction of Bovine Serum Albumin by Aqueous Two-Phase System Using PEG4000/Sodium Citrate and PEG8000/Sodium Phosphate

Aqueous Two Phase System (ATPS) or liquid-liquid extraction is used in biotechnology to recover valuable compounds from raw sources. In Aqueous Two-Phase Systems, many factors influence the Partition coefficient, K, (which is the ratio of protein concentration in the top phase to that in the bottom phase) and the Recovery percentage (Rec%). In this research, two systems of ATPS were used: first, polyethylene glycol (PEG) 4000/Sodium citrate (SC), and the second, PEG8000/ Sodium phosphate (SPH), for the extraction of Bovine Serum Albumin (BSA). The behavior of Rec% and K of pure (BSA) in ATPS has been investigated throughout the study by the effects of five parameters: temperature, concentration of polyethylene glycol (PEG4000 and PEG8000), the concentration of Sodium citrate or Sodium phosphate, pH, and the addition of sodium chloride as a supporting agent. The recovery percentage of BSA and its partition coefficient are significantly influenced by these factors to various degrees. The most influential variable in this study is PEG concentration for both systems. In addition to the PEG concentration, the stabilizing impact of NaCl is a crucial factor. The interaction between biomolecules and PEG gets more hydrophobic as the PEG concentration is raised. In the first system (PEG4000/SC), the maximum recovery percentage and partition coefficient were 98.99% and 97.69, respectively, at 31°C, PEG4000 concentration 1.5g/10 ml, Sodium citrate concentration 2.7 g/10 ml, pH 10, and 0.5 M NaCl concentration. While in the second system (PEG8000/SPH), the maximum recovery percentage and partition coefficient was 98.93% and 92.12, respectively, at 31oC, PEG8000 concentration 1.5 g/10 ml, Sodium phosphate concentration 2.4 g/10 ml, pH 10, and concentration of NaCl 0.5 M.

Gelatinization Properties of Parboiled Siramog Varieties Black Rice with Variation of Immersion Time and Sodium Citrate Concentration

Black rice still contains epidermis which is composed of several layers, including pericarp, lemma, aleuron and testa so that cooking takes a long time. To speed up the cooking time on rice can be modified by parboiling process so that it changes the character of gelatinization. The research aims to find out the effect of the concentration of sodium citrate solution and immersion time on the process of black rice parboiled Sirampog varieties on its gelatinization properties. Soaking in sodium citrate solution at a certain time is expected to accelerate the cooking time of black rice. The research using Completely Randomized Factorial design consisting of concentration of sodium citrate solution (0, 3, 5 and 7%) and immersion time (20, 30 and 40 minutes). The variables observed were gelatinization properties including gelatinization temperature, peak viscosity, final viscosity, breakdown viscosity, trough viscosity and setback viscosity. The results showed that the setback viscosity and peak viscosity of Sirampog rice were affected by the concentration of sodium citrate. The sodium citrate solution of 5% as a marinade produces Sirampog varieties of parboiled rice with high trough viscosity and lowest setback viscosity, which means it is easier to cook and more resistant to retrogradation during cooling.

Development of chondrocyte-laden alginate hydrogels with modulated microstructure and properties for cartilage regeneration.

Alginate hydrogel is an attractive biomaterial for cell microencapsulation. The microarchitecture of hydrogels can regulate cellular functions. This study aims to investigate the applicability of sodium citrate buffer (SCB) as a culture medium supplement for modulating the microstructure of alginate microbeads to provide a favorable microenvironment for chondrogenic induction. The chondrocyte-laden microbeads, with and without TGF-β3 incorporation, were produced through an encapsulator. The obtained small-sized microbeads (~300 μm) were exposed to a treatment medium containing SCB, composed of varied concentrations of sodium citrate (1.10-1.57 mM), sodium chloride (3.00-4.29 mM), and ethylenediaminetetraacetic acid (0.60-0.86 mM) to partially degrade their crosslinked structure for 3 days, followed by culture in a normal medium until day 21. Scanning electron microscope micrographs demonstrated a loose hydrogel network with an enhanced pore size in the SCB-treated microbeads. Increasing the concentration of SCB in the treatment medium reduced the calcium content of the microbeads via a Na+ /Ca2+ exchange process and improved the water absorption of the microbeads, resulting in a higher swelling ratio. All the tested SCB concentrations were non-cytotoxic. Increases in aggrecan and type II collagen gene expression and their corresponding extracellular matrix accumulation, glycosaminoglycans, and type II collagen were vividly detected in the TGF-β3-containing microbeads with increasing SCB concentrations in the treatment medium. Our findings highlighted that the combination of SCB treatment and TGF-β3 incorporation in the chondrocyte-laden microbeads is a promising strategy for enhancing cartilage regeneration, which may contribute to a versatile application in cell delivery and tissue engineering.

Physicochemical Characteristics of Instant Boiled Rice: Study of Sodium Citrate Concentration and Soaking Time

Cooked rice (nasi liwet) is a typical rice dish of Java Island which is cooked using spices so that it has a unique taste and aroma. Making nasi liwet takes a long time, so this dish is only served at certain times. Therefore, a fast rice processing technique is needed but still has a distinctive taste and aroma. The purpose of this study is to analyze the physicochemical analysis of instant liwet rice based on the concentration and soaking time of sodium citrate. The physicochemical analysis tested were rehydration time, volume expansion, bulk density, texture, yield, ash content, and water content. The study was conducted by soaking sodium citrate (0, 2, 5, and 8% w/v) and soaking time (2, 4, and 6 hours) on rice. The results showed that the fastest rehydration time for instant nasi liwet was 4.55 minutes. The range of observation parameters such as expansion volume is 66.26-91.24%; bulk density is 0.413-0.581 g/ml; the texture is 431-1496 g/mm; yield is 89.64-92.26%; ash content is 4.11-4.45% and water content is 5.83-7.03%wb. Variations in sodium citrate concentration and immersion time increased the swelling volume and ash content, while water content, bulk density, texture, and yield tended to decrease. The best treatment based on the multiple attribute Zeleny method was immersion of 5% sodium citrate for 4 hours of immersion. Keywords: Immersion Time, Instant Rice, Nasi Liwet, Physicochemical, Sodium Citrate

Purification of pectin by ultrafiltration in combination with sodium citrate

Ultrafiltration is an effective method to improve the purity of pectin, but membrane fouling is an urgent problem to overcome. In this work, trisodium citrate, sodium caseinate and calcium caseinate were combined with ultrafiltration to separate and purify pectin extract. The molecular weight cutoff (MWCO) of the ultrafiltration membrane and the sodium citrate concentration were optimized using the color and clarity of the pectin extract as indices, and the influence of sodium citrate on the pectin particle size and zeta potential was further studied. Finally, the pectin extraction yield, some physicochemical indices, including galacturonic acid (Gal A) content, esterification degree, and ash content, and the surface morphology of the pectin particles were measured. The results showed that the ultrafiltration membrane fouling was effectively controlled and that the steady-state flux increased by 2-fold when the pectin extract was treated with a polyether sulfone (PES) UF membrane (100 kDa) in combination with sodium citrate at a concentration of 0.25 mg/ml. The pectin extraction yield increased to 16.4%, and the resulting pectin was a higher-ester refined pectin with a Gal A content of 89.7%, DE content of 77.42%, and ash content of 0.63%. The combination of sodium citrate and ultrafiltration was beneficial not only for improving the permeability and separation performance of the ultrafiltration process but also for providing an example of a monovalent salt as a precipitation agent.

Detailed Investigation of Factors Affecting the Synthesis of SiO2@Au for the Enhancement of Raman Spectroscopy.

The reaction time, temperature, ratio of precursors, and concentration of sodium citrate are known as the main factors that affect the direct synthesis process of SiO2@Au based on the chemical reaction of HAuCl4 and sodium citrate. Hence, we investigated, in detail, and observed that these factors played a crucial role in determining the shape and size of synthesized nanoparticles. The significant enhancement of the SERS signal corresponding to the fabrication conditions is an existing challenge. Our study results show that the optimal reaction conditions for the fabrication of SiO2@Au are a 1:21 ratio of HAuCl4 to sodium citrate, with an initial concentration of sodium citrate of 4.2 mM, and a reaction time lasting longer than 6 h at a temperature of 80 °C. Under optimal conditions, our synthesis process result is SiO2@Au nanoparticles with a diameter of approximately 350 nm. In particular, the considerable enhancement of Raman intensities of SiO2@Au compared to SiO2 particles was examined.

Effects of methanol, sodium citrate, and chlorella powder on enhanced anaerobic treatment of coal pyrolysis wastewater

To better promote environment friendly development of the coal chemical industry, this study investigated effects of methanol, sodium citrate, and chlorella powder (a type of microalgae) as co-metabolic substances on enhanced anaerobic treatment of coal pyrolysis wastewater with anaerobic sludge. The anaerobic sludge was loaded into four 2 L anaerobic reactors for co-metabolism enhanced anaerobic experiments. Anaerobic reactor 1 (R1) as control group did not add a co-metabolic substance; anaerobic reactor 2 (R2) added methanol; anaerobic reactor 3 (R3) added sodium citrate; and anaerobic reactor 4 (R4) added chlorella powder. In the blank control group, the removal ratios of total phenol (TPh), quinoline, and indole were only 12.07%, 42.15%, and 50.47%, respectively, indicating that 50 mg/L quinoline, 50 mg/L indole, and 600 mg/L TPh produced strong toxicity inhibition function on the anaerobic microorganism in reactor. When the concentration of methanol, sodium citrate, and chlorella was 400 μg/L, the reactors with co-metabolic substances had better treatment effect on TPh. Among them, the strengthening effects of sodium citrate (TPh removal ratio: 44.87%) and chlorella (47.85%) were better than that of methanol (38.72%) and the control group (10.62%). Additionally, the reactors with co-metabolic substances had higher degradation ratios on quinoline, indole, and chemical oxygen demand (COD). The data of extracellular polymeric substances showed that with the co-metabolic substances, anaerobic microorganisms produced more humic acids by degrading phenols and nitrogen-containing heterocyclic compounds (NHCs). Compared with the control group, the reactors added with sodium citrate and chlorella had larger average particle size of sludge. Thus, sodium citrate and chlorella could improve sludge sedimentation performance by increasing the sludge particle size. The bacterial community structures of reactors were explored and the results showed that Aminicenantes genera incertae sedis, Levinea, Geobacter, Smithella, Brachymonas, and Longilinea were the main functional bacteria in reactor added with chlorella.

Tuning magnetic heating efficiency of colloidal dispersions of iron oxide nano-clusters by varying the surfactant concentration during solvothermal synthesis

Magnetic fluid hyperthermia (MFH) is being actively sought as a supplementary cancer therapy, where enhancing the MFH efficiency is essential for reducing dosage and field exposure. Owing to the superior magnetic properties, magnetic nano-clusters (MNCs) are being developed as MFH agents, where the role of synthesis routes, colloidal stability and magneto-structural properties on MFH efficiency requires further attention. In this article, we report the tuning of MFH efficiency of water and diethylene glycol-based magnetic nanofluids containing iron-oxide MNCs of sizes ∼ 125 to 539 nm, obtained by varying the surfactant concentration. Magnetite MNCs are prepared via solvothermal route, where the primary nano-crystallite (MNP) size is varied from 7.4 ± 0.7 to 25.0 ± 0.8 nm by reducing the sodium citrate (surfactant) concentration from 29 to 0.29 mg/mL. With decreasing surfactant concentration, the amount of sodium citrate absorbed on the surface of the freshly formed nano-seeds reduces, which lowers the electrostatic stabilization in polar media and favours the growth of larger MNPs that results in comparatively larger MNCs. Transmission electron microscopy and atomic force microscopy based studies indicate the monodisperse spherical morphology of the MNCs, consisting of several primary nano-crystallites. Room temperature isothermal magnetization measurements indicate high saturation magnetization and superparamagnetic nature of the MNCs, which are beneficial for MFH applications. Magneto-calorimetry experiments are performed for the accurate estimation of the MFH efficiency of the colloidal dispersions of the MNCs. Experimental findings indicate that the heating efficiency increases from 15.24 ± 1.22 to 193.8 ± 5.2 W/gFe (i.e., an enhancement of ∼ 12.7 times), at a field exposure condition of 33.1 kA/m and 126 kHz, when the primary nano-crystallite size is increased by ∼ 3.4 times by reducing the surfactant concentration. It is observed that the heating efficiency decreases linearly with the logarithm of surfactant concentration in all the cases, which is attributed to the variations in primary nano-crystallite sizes and the resultant magnetic losses. Magneto-calorimetric experiments, using MNCs immobilized in high viscosity agar matrix, indicate insignificant contributions from the whole-scale Brownian relaxation, and the heating efficiency is found to be solely dependent on the magnetic losses of the primary nano-crystallites. With increasing primary nano-crystallite size, augmentation of heating efficiency is due to the increase in magnetization and dynamic coercivity, which is confirmed from theoretical calculations using the high frequency hysteresis loops and sweeping rate modified Stoner Wohlfarth model. The obtained results indicate the possibility of tuning hyperthermia efficiency of MNCs by varying the surfactant concentration, which is beneficial for designing colloidally stable dispersions of MNCs with improved MFH efficiency.

Anaerobic digestion of waste activated sludge to produce volatile fatty acids and release nutrients using sodium citrate with sodium hydroxide pretreatment

AbstractThis study investigated the synergistic effect of sodium citrate (SC) and sodium hydroxide (NaOH) on the anaerobic digestion (AD) efficiency of waste activated sludge (WAS). Using the amount of SC as the control variable, changes in sludge cell cracking and AD performance under different pretreatment conditions was investigated. The optimum treatment conditions were a NaOH input of initial pH 10 and an SC concentration of 0.20 g/g total suspended solids. The pretreatment was monitored in 150 min. And the changes in soluble chemical oxygen demand (SCOD), soluble polysaccharide, soluble protein, volatile fatty acids (VFAs), PO43−‐P and NH4+‐N during the pretreatment stage and fermentation process were studied. Results show a significant disintegration effect on WAS under optimal pretreatment conditions, with the peak concentration of SCOD, soluble protein, and soluble polysaccharide being 2059.5, 114.86, and 190.97 mg/L, respectively, which means that large amounts of intracellular carbon sources were released. The production of VFAs included acetic acid, propionic acid, isobutyric acid, n‐butyric acid, isovaleric acid, and n‐valeric acid, with a peak concentration of 9555.89, 1779.12, 608.84, 805.7, 777.91, 184.86 mg·COD/L, respectively. The content of PO43‐P and NH4+‐N were great in fermentation liquid, 71.82 and 320.75 mg/L, respectively. These results indicate that the synergistic process improve VFAs production and contribute to nutrients reuse.

Improving the Chemical Stability of Al Alloy through the Densification of the Alumina Layer Assisted by SiF62- Anion Hydrolysis.

In this work, a high-density alumina layer with high chemical stability was successfully developed by controlling the hydrolysis of hexafluorosilicate (SiF62−) anions through the addition of various concentrations of sodium citrate (SCi) into the electrolyte of plasma electrolysis (PE). To achieve this aim, the substrate samples were anodized in alkaline aluminate–SiF62−-based electrolytes with 0, 5, and 10 g/L of SCi. The presence of SCi anions in the electrolyte led to the formation of a thick adsorbed electrochemical double layer (EDL) on the substrate surface. The EDL not only affected the movement of SiF62− anions towards the anode but also influenced their hydrolysis reaction, which in turn led to a controllable sealing of structural defects with the hydrolysis products, namely SiO2 and AlF3. Among three different oxide layers, the oxide layer obtained from the electrolyte with 5 g/L SCi showed the highest chemical stability in a corrosive solution, which was linked to the fact that a considerable increase in the compactness of the oxide layers was obtained by the incorporation of SiO2 and AlF3. The mechanism underlying the effects of SCi on triggering the hydrolysis of SiF62− anions and factors affecting chemical stability are discussed based on the experimental data and computational analysis.

Hydrogen Inhibition as Explosion Prevention in Wet Metal Dust Removal Systems

Hydrogen energy attracts an amount of attention as an environmentally friendly and sustainable energy source. However, hydrogen is also flammable. Hydrogen fires and explosions might occur in wet-dust-removal systems if accumulated aluminum dust reacts with water. Hydrogen inhibition is a safe method to address these issues. For this purpose, we used sodium citrate, a renewable and nontoxic raw material to inhibit H2 formation. Specifically, hydrogen inhibition experiments with sodium citrate were carried out using custom-built equipment developed by our research group. When the concentration of sodium citrate solution was in the range of 0.4–4.0 g/L, a protective coating was formed on the surface of the Al particles, which prevented them from contacting with water. The inhibitory effect was achieved when the concentration of sodium citrate was in a certain range, and too much or too little addition may reduce the inhibitory effect. In this paper, we also discuss the economic aspects of H2 inhibition with this method because it offers excellent safety advantages and could be incorporated on a large scale. Such an intrinsic safety design of H2 inhibition to control explosions in wet-dust-removal systems could be applied to ensure the safety of other systems, such as nuclear reactors.