Sodium Nitrate Concentration Research Articles

A new method to quantify particulate sodium and potassium salts (nitrate, chloride, and sulfate) by thermal desorption aerosol mass spectrometry

Abstract. The reaction of sea salt (or biomass burning) particles with sulfuric acid and nitric acid leads to the displacement of chloride relative to sodium (or potassium). We have developed a new particle mass spectrometer to quantify non-refractory and refractory sulfate aerosols (referred to as refractory aerosol thermal desorption mass spectrometer: rTDMS). The combination of a graphite particle collector and a carbon dioxide laser enables high desorption temperature (blackbody equivalent radiation temperature of up to 930 ∘C). Ion signals originating from evolved gas molecules are detected by a quadrupole mass spectrometer. Here we propose a new method to quantify the mass concentrations of sodium nitrate (NaNO3: SN), sodium chloride (NaCl: SC), sodium sulfate (Na2SO4: SS), potassium nitrate (KNO3: PN), potassium chloride (KCl: PC), and potassium sulfate (K2SO4: PS) particles by using the rTDMS. Laboratory experiments were performed to test the sensitivities of the rTDMS to various types of particles. We measured ion signals originating from single-component particles for each compound and found a good linearity (r2>0.8) between the major ion signals and mass loadings. We also measured ion signals originating from internally mixed SN + SC + SS (or PN + PC + PS) particles and found that the temporal profiles of ion signals at m/z 23 (Na+) (or 39; K+) were characterized by three sequential peaks associated with the evolution of the desorption temperature. We tested potential interferences in the quantification of sea salt particles under real-world conditions by artificially generating “modified” sea salt particles from a mixture of diluted seawater and SN (or SS) solution. The SS/SC ratios estimated from the ion signals at m/z 23, 36 (H35Cl+), and 48 (SO+) agreed well with those predicted from the solution concentrations to within ∼10 %. The SN/SC ratios estimated from the ion signals at m/z 30 (NO+) and 36 also agreed with those predicted from the solution concentrations to within ∼15 %, whereas the SN/SC ratios estimated from m/z 23 were significantly lower than the predicted values. Based on these experimental results, the applicability of the rTDMS to ambient measurements of sea salt particles is discussed.

Metarhizium robertsii protease and conidia production, response to heat stress and virulence against Aedes aegypti larvae

Nutritional factors exert significant influence on the growth of entomopathogenic fungi, one of the main agents employed commercially in the biological control of arthropods. Thus, the objective of this work is to optimize the culture medium and solid fermentation time for production of proteases and conidia of Metarhizium robertsii ARSEF 2575 and to evaluate the interference of riboflavin and salts on virulence and resistance to abiotic stress factors. In the first step, nine groups were separated: negative control, positive control, and seven supplementation groups: ammonium nitrate, ammonium chloride, potassium nitrate, sodium nitrate, ammonium sulfate, ammonium phosphate, urea. Sodium nitrate showed significant difference in protease production at the time of 20 days of solid fermentation. Then, different concentrations of sodium nitrate and riboflavin as supplement were evaluated. Response surface methodology demonstrated that riboflavin and sodium nitrate influence proteolytic activity and conidia production, but without synergism. Supplementation of the medium with the optimal concentration of sodium nitrate and riboflavin did not interfere with the germination of conidia without exposure to abiotic stress, but did increase the thermotolerance of conidia. The presence of riboflavin and sodium nitrate at optimal concentrations in the culture medium did not alter fungal virulence with and without exposure to heat stress, varying according to the presence or absence of the supernatant during exposure, evidencing that resistance to heat exposure is multifactorial and dependent on intra- and extracellular factors. Moreover, the supplementation increased the larvicidal activity of the supernatant against Aedes aegypti.

Acclimation and Characterization of Marine Cyanobacterial Strains Euryhalinema and Desertifilum for C-Phycocyanin Production.

This study involves evaluation of two native cyanobacterial strains Euryhalinema and Desertifilum isolated from a mangrove pond in Haikou (China) for their possible phycocyanin (C-PC) production. Maximal growth rate with highest chlorophyll and C-PC accumulation were observed at 28°C and 60 μmol photons m−2 s−1 photon flux density for Euryhalinema sp., while for Desertifilum sp. at 32°C and 80 μmol photons m−2 s−1. Nitrogen and iron concentration trails revealed that double strength concentration of sodium nitrate and ferric ammonium citrate in original BG11 media increased growth rate and accumulation of C-PC for both strains. Three different C-PC extraction methods were tested. The combined extraction protocol of freeze–thaw and ultrasonication markedly increased the C-PC extraction efficiency and attained the food grade purity (A 620/A 280 ratio >0.7), whereas a higher C-PC yield was found with Na-phosphate buffer. Furthermore, the clarified crude extract was used to purify C-PC by fractional ammonium sulfate [(NH₄)₂SO₄] precipitation, Sephadex G-25 gel filtration chromatography, and DEAE-sephadex ion exchange chromatography and attained analytical grade purity (A 620/A 280 ratio >3.9). Taken together, both strains showed their potential to be domesticated for valuable phycocyanin production.

Baseline sodium nitrate and nitrite concentrations in fresh and processed meats

Curing salts composed of sodium/potassium nitrate and nitrite mixtures are widely used preservatives in processed meats. Despite many desirable technological effects, their use in meat products has been linked to methemoglobinemia and the formation of nitrosamines. Therefore, an increasing “anti-nitrite feeling” has grown among meat consumers, who search for clean label products. Several analytical results have showed low concentrations of sodium nitrate in meat products whose labels do not mention curing salts. Such results may be interpreted as non-compliance according to current Brazilian regulation. In this work, 120 samples of fresh meats and preservative-free labeled processed meats were analyzed in order to assess the natural presence of nitrate and nitrite salts and to estimate their baseline concentrations. Concentrations of sodium nitrate, ranging from 7.8 to 25.2 mg kg−1 and from 8.7 to 32.3 mg kg−1 were quantitated by capillary zone electrophoresis in some samples of fresh pork and meat products, respectively. Sodium nitrite was not quantitated in any product. Thus, positive analytical results for nitrate in these kinds of samples should be interpreted with caution, because of the risk of them being mistakenly characterized as non-compliant results.

Graphene/PVA coated D-shaped fiber for sodium nitrate sensing

A graphene/Polyvinyl alcohol (PVA) coated D-shaped fiber structure for sensing sodium nitrate solutions is proposed in this paper. D-shaped single mode fiber (SMF) coated with graphene/PVA was used as a sensor for sodium nitrate liquid solutions with the concentration range of 1–7%. After monitoring the output power and spectral transmission characteristics of the sensor, the graphene/PVA coated sensor showed an improved performance over the uncoated structure. The evanescent mode of the side-polished fiber and the interaction between the nitrate ions and the coating graphene improved the sensor’s performance. The graphene/PVA coated sensor had sensitivity and linearity of 0.390 dBm/% and 99% compared to the uncoated sensor sensitivity and linearity of 0.117 dBm/% and 98% respectively. This shows the advantage of using D-shaped fiber coated with graphene and PVA to detect sodium nitrate concentrations.

Assessment of Nitrate Removal Capacity of Two Selected Eukaryotic Green Microalgae

Eutrophication is a leading problem in water bodies all around the world in which nitrate is one of the major contributors. The present study was conducted to study the effects of various concentrations of nitrate on two eukaryotic green microalgae, Chlamydomonas sp. MACC-216 and Chlorella sp. MACC-360. For this purpose, both microalgae were grown in a modified tris-acetate-phosphate medium (TAP-M) with three different concentrations of sodium nitrate, i.e., 5 mM (TAP-M5), 10 mM (TAP-M10) and 15 mM (TAP-M15), for 6 days and it was observed that both microalgae were able to remove nitrate completely from the TAP-M5 medium. Total amount of pigments decreased with the increasing concentration of nitrate, whereas protein and carbohydrate contents remained unaffected. High nitrate concentration (15 mM) led to an increase in lipids in Chlamydomonas sp. MACC-216, but not in Chlorella sp. MACC-360. Furthermore, Chlamydomonas sp. MACC-216 and Chlorella sp. MACC-360 were cultivated for 6 days in synthetic wastewater (SWW) with varying concentrations of nitrate where both microalgae grew well and showed an adequate nitrate removal capacity.

Regulation of the Tpo, Tg, Duox2, Pds, and Mct8 genes involved in the synthesis of thyroid hormones after subchronic exposure to sodium nitrate in female Wistar rats.

Nitrates are natural compounds present in soil and water; however, the intense use of fertilizers has increased their presence in groundwater with deleterious effects on human health. There is evidence of nitrates acting as endocrine disruptors; however, the underlying molecular mechanisms have not been fully described. Here, we investigated the effect of subchronic exposure to different concentrations of sodium nitrate in female Wistar rats, evaluating thyroid hormonal parameters, such as Nis transporter (Na+ /I- symporter, Slc5a5) and Tsh-R receptor protein expression, as well as transcription of the Tpo (thyroperoxidase), Tg (tiroglobulin), Duox2 (dual oxidase 2), Pds (pendrin), and Mct8 (Mct8 transporter, Slc16a2) genes. Hematological and histochemical changes in the liver and thyroid were also explored. Significant differences were found in platelet and leukocyte counts; although a significant increase in the weight of the thyroid gland was observed, no differences were found in the levels of the hormones Tsh, T3, and T4, but a modulation of the mRNA expression of the Tg, Tpo, Duox2, Mct8, and Pds genes was observed. Morphological changes were also found in liver and thyroid tissue according to the exposure doses. In conclusion, subchronic exposure to sodium nitrate induces leukocytosis consistent with an inflammatory response and upregulation of Sod2 in the liver and increases the expression of genes involved in the synthesis of thyroid hormones, keeping thyroid hormone levels stable. Histological changes in the thyroid gland suggest a goitrogenic effect.

Glucosidase Inhibitors Screening in Microalgae and Cyanobacteria Isolated from the Amazon and Proteomic Analysis of Inhibitor Producing Synechococcus sp. GFB01.

Microalgae and cyanobacteria are good sources for prospecting metabolites of biotechnological interest, including glucosidase inhibitors. These inhibitors act on enzymes related to various biochemical processes; they are involved in metabolic diseases, such as diabetes and Gaucher disease, tumors and viral infections, thus, they are interesting hubs for the development of new drugs and therapies. In this work, the screening of 63 environmental samples collected in the Brazilian Amazon found activity against β-glucosidase, of at least 60 min, in 13.85% of the tested extracts, with Synechococcus sp. GFB01 showing inhibitory activity of 90.2% for α-glucosidase and 96.9% against β-glucosidase. It was found that the nutritional limitation due to a reduction in the concentration of sodium nitrate, despite not being sufficient to cause changes in cell growth and photosynthetic apparatus, resulted in reduced production of α and β-glucosidase inhibitors and differential protein expression. The proteomic analysis of cyanobacteria isolated from the Amazon is unprecedented, with this being the first work to evaluate the protein expression of Synechococcus sp. GFB01 subjected to nutritional stress. This evaluation helps to better understand the metabolic responses of this organism, especially related to the production of inhibitors, adding knowledge to the industrial potential of these cyanobacterial compounds.

The kinetics of tempeh wastewater treatment using Arthrospira platensis.

The microalga Arthrospira platensis (Spirulina) was used for tempeh wastewater treatment. Microalga growth and the kinetics of chemical oxygen demand (COD) degradation under different light intensities (2,100 and 4,300 lux), tempeh wastewater concentrations (0, 0.5, 1, 1.5% v/v), and sodium nitrate concentrations (0, 0.75, 1, 2, 2.5 g/L) were studied. Improved cell growth in wastewater indicated that mixotrophic growth was preferred. The addition of sodium nitrate up to 2 g/L increased COD removal. The highest COD removal was 92.2%, which was obtained from cultivation with 1% v/v tempeh wastewater, 2 g/L sodium nitrate, 2,100 lux, and the specific growth rate of 0.33 ± 0.01 day-1. The COD removal followed a pseudo-first-order kinetic model with the kinetic constant of 0.3748 day-1 and the nitrate uptake rate of 0.122 g/L-day. The results can be used to design a pilot-scale tempeh wastewater treatment facility using A. platensis for tertiary treatment. Based on the kinetic model, a 20 m3 reactor can treat tempeh wastewater to reduce the COD from 400 to 100 ppm in 4 days and produces approximately 32.8 kg of dried microalgae.

Formation and evolution of brown carbon during aqueous-phase nitrate-mediated photooxidation of guaiacol and 5-nitroguaiacol

Light absorbing organic aerosols, which are commonly referred to as brown carbon (BrC), have important climate impacts. Phenolic compounds are a class of aromatic compounds that are known BrC precursors. Inorganic nitrate is a ubiquitous component of atmospheric aerosols, clouds, and fog. The photolysis of inorganic nitrate in atmospheric aqueous phases generates a variety of reactive oxygen species and reactive nitrogen species that can facilitate the photooxidation of organic compounds to form BrC. In this study, we investigated the formation and evolution of BrC from the aqueous-phase photooxidation of guaiacol and 5-nitroguaiacol initiated by inorganic nitrate photolysis. Guaiacol and 5-nitroguaiacol are two water-soluble phenolic compounds that are commonly found in fossil fuel and biomass burning emissions. Upon illumination in the presence of sodium nitrate, guaiacol and 5-nitroguaiacol reacted rapidly to form BrC. The reaction rates and quantities of BrC formed depended on the initial sodium nitrate concentration. The reaction rates of guaiacol were substantially faster than those of 5-nitroguaiacol. The electron-withdrawing nitro functional group on 5-nitroguaiacol's aromatic ring likely had a deactivating effect on the ring's reactivity, which contributed to 5-nitroguaiacol's lower reactivity compared to guaiacol. The major products produced during the initial stages of photooxidation were formed by the addition of nitro and/or nitroso groups to guaiacol and 5-nitroguaiacol. These products likely strongly absorbed near-UV and/or visible light, which led to an observed increase in light absorption (i.e., photo-enhancement) in the near-UV and visible range. Greater photo-enhancement was observed during the nitrate-mediated photooxidation of guaiacol. This indicated that the presence of nitro functional group(s) on the aromatic ring of phenolic compounds will impact the extent of photo-enhancement during BrC formation. Further photooxidation caused the initial products to fragment into smaller molecules that do not absorb near-UV and visible light. This resulted in an observed decrease in light absorption (i.e., photo-bleaching). These results highlight how aqueous-phase inorganic nitrate photolysis can drive the formation of BrC by facilitating the photooxidation of organic compounds.

Predicting Runoff Chloride Concentrations in Suburban Watersheds Using an Artificial Neural Network (ANN)

Road salts in stormwater runoff, from both urban and suburban areas, are of concern to many. Chloride-based deicers [i.e., sodium chloride (NaCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2)], dissolve in runoff, travel downstream in the aqueous phase, percolate into soils, and leach into groundwater. In this study, data obtained from stormwater runoff events were used to predict chloride concentrations and seasonal impacts at different sites within a suburban watershed. Water quality data for 42 rainfall events (2016–2019) greater than 12.7 mm (0.5 inches) were used. An artificial neural network (ANN) model was developed, using measured rainfall volume, turbidity, total suspended solids (TSS), dissolved organic carbon (DOC), sodium, chloride, and total nitrate concentrations. Water quality data were trained using the Levenberg-Marquardt back-propagation algorithm. The model was then applied to six different sites. The new ANN model proved accurate in predicting values. This study illustrates that road salt and deicers are the prime cause of high chloride concentrations in runoff during winter and spring, threatening the aquatic environment.

Determination of Extractable and Bound Organochlorine in Sediment by Instrumental Neutron Activation Analysis

Extractable organochlorine (EOC) and bound organochlorine (BOC) compositions in sediments from Lake Bosomtwi have been determined with instrumental neutron activation technique. Within the limit of experimental errors, the precision and accuracy of the method for the determination were within 3% and 4% respectively. The mean levels of EOC and BOC were in the range of 1.71 mg/kg to 5.18 mg/kg and 0.31 mg/kg to 0.68 mg/kg respectively. Analysis of organochlorine data showed the EOC content on the average was about seven times more than those of BOC. Washing of chloride from sediment fortified with an insoluble chloride, thus PbCl2, with various concentrations of sodium nitrate (NaNO3) solutions was investigated and washing with 0.1 M solution of NaNO3 gave the optimum yield of chloride. Organic carbon (OC) and BOC compositions in the sediments were subjected to correlation analysis and results showed that the two correlated very well with corrected coefficient of 0.65. OC in sediments could therefore, be one of the carrier phases of BOC in sediments.

Coupling effect of NaOH and NaNO3 on the solidified fly ash-cement matrices containing Cs+: Reaction products, microstructure and leachability

The low- and intermediate-level radioactive waste liquid is a solution with high concentration of sodium nitrate (100–500 g/L). In order to immobilize the radioactive waste effectively, a certain content of sodium hydroxide (0.82–10%) would be added into the solidified fly ash-cement matrices as alkali activator. This study was aimed to investigate the coupling effect of sodium nitrate and sodium hydroxide on the reaction products, microstructure and leachability of solidified fly ash-cement matrices. The results indicated that a rather high content of sodium hydroxide (above 5%) was necessary for the crystallization of zeolite Na–P1 and sodium nitrate had participated in the formation of zeolite of chabazite and acted as a source of Na. Sodium hydroxide promoted the enhancement of pore structure and increased the compressive strength while sodium nitrate generated an opposite effect. The absorption performance for Cs+ was that: chabazite > zeolite Na–P1 > N-A-S-H gel. The cumulative leaching rate of Cs+ decreased with the increasing content of sodium hydroxide and the increasing concentration of sodium nitrate. However, on the contrary, an excessive amount of sodium nitrate (500 g/L) would accelerate the cumulative leaching rate of Cs+ because of the extreme degradation of the pore structure.

Effects of Irradiance and Different Nitrogen and Carbon Concentrations on the Minerals Accumulation in Scenedesmus obliquus Biomass

Microalgae are capable of absorbing and concentrating constituent elements that have a wide variety of applications in agriculture, food industry, and medicine. Microalgae chemical composition change according to internal and external factors. In this study, the effect of irradiance, sodium nitrate and sodium acetate concentration on the accumulation of essential minerals in Scenedesmus obliquus biomass were evaluated using 23 factorial screening designs. The simultaneous effect of the three experimental factors was studied using three levels for each parameter (irradiance: 36.71, 69.50, 102.30 μE m-2 s-1, sodium nitrate: 0.27, 44.00, 87.73 g L-1 and sodium acetate: 0.00, 2.50, 5.02 g L-1). The response variables were the minerals concentration of Na, K, Ca, Mg, Fe, Zn and Mn. Results show that each mineral has an optimal operation condition in order to improve its concentration in the microalgae biomass. A significant interaction between the variables was observed, which has direct effects on the minerals accumulation in the microalgae biomass. Under these conditions, the maximum concentration of K (1515.77 [mg (100gdw)-1]), Ca (2744.24 [mg (100gdw)-1]), Mg (9697.65 [mg (100gdw)-1]), Fe (2932.42 [mg (100gdw)-1]), Mn (38.48 [mg (100gdw)-1]), Zn (324.00 [mg (100gdw)-1]) and the minimum concentration of Na (5607.20 [mg (100gdw)-1]) were obtained from the microalga biomass. Thus, Scenedesmus obliquus biomass was characterized as good essential mineral source and confirmed to be potentially valuable ingredient for utilization in the food industry.

Use of Seawater/Brine and Caliche’s Salts as Clean and Environmentally Friendly Sources of Chloride and Nitrate Ions for Chalcopyrite Concentrate Leaching

A less harmful approach for the environment regarding chalcopyrite concentrate leaching, using seawater/brine and caliche’s salts as a source of chloride and nitrate ions, was investigated. Different variables were evaluated: sulfuric acid concentration, sodium nitrate concentration, chloride concentration, source of water (distilled water, seawater, and brine), temperature, concentrate sample type, nitrate source (analytical grade and industrial salt), and pre-treatment methods in order to obtain maximum copper extraction. All tests were performed at moderate temperatures (≤45 °C) and atmospheric pressure. The leaching system using distilled water, seawater, and brine base media resulted in copper extraction of 70.9%, 90.6%, and 86.6% respectively. The leaching media, with a concentration of 20 g/L Cl−, obtained a maximum Cu extraction of 93.5%. An increase in the concentration of H2SO4 and NaNO3 from 0.5 to 0.7 M, led to an increase in the copper extraction. The use of an industrial salt compared to the analytical salt did not show great variations in the percentage of extraction achieved, which would be a good and cost effective alternative. The increase in temperature from 25 to 45 °C showed a great effect on the copper leaching (of 60% until 90.6%, respectively). The pre-treatment is suggested to increase copper extraction from 60.0% to 71.4%.

Sodium nitrate sensor based on D-shaped fiber structure

Abstract This paper demonstrates a low-cost robust refractive index (RI) sensor based on a sensing structure realized with graphene-coated D-shaped fiber structure. The proposed sensing structure is of 5-dB insertion loss single mode fibers fabricated by means of side polishing; drop casting is used for the graphene coating that would act as a sensing layer to enhance the sensitivity of the sensing probe. Observations showed that the output power decreased from 7.17 dBm to 5.85 dBm with sensitivity of 0.223 %/dBm and linearity of 99 % as six different concentrations of sodium nitrate that varies from 1 to 7 % were tested on the sensor probe. These results came from the interaction of propagating light in the evanescent wave with the external changing environment. The resonant peak shifted to longer wavelength with increasing refractive index. The sensing structure was embedded onto a fiber ring laser as this combination offers high measurement resolution and increase their remote sensing capability.

Improving effect of combined inorganic nitrate and nitric oxide synthase inhibitor on pancreatic oxidative stress and impaired insulin secretion in streptozotocin induced-diabetic rats.

The aim of this study was to evaluate the effect of dietary nitrate on secretory function of pancreatic islet and oxidative stress status in streptozotocin (STZ) induced type 1 diabetes in absence or presence of nitric oxide synthase inhibitor (L-NAME). Fifty adult male sprague-dawly rats were divided into 5 groups: controls (C), diabetes (D), diabetes+nitrate (DN), diabetes +L-NAME (D + Ln), and diabetes+nitrate+L-NAME (DN + Ln) for 45days. The concentrations of sodium nitrate and L-NAME were respectively 80mg/L in drinking water and 5mg/kg intraperitoneally. Body weight gain, plasma levels of glucose and insulin, islet insulin secretion and content, lipid peroxidation and antioxidant status in the pancreas of rats were determined. Compared to control group, the body weight gain and plasma insulin level were significantly decreased and plasma glucose and pancreatic NO and MDA concentrations and antioxidant enzymes activities were significantly increased in the STZ diabetic rats. In the diabetic rats, nitrate alone significantly reduced plasma glucose and increased pancreatic SOD and GPx activity. Reduced plasma glucose, pancreatic MDA and NO concentrations and increased plasma insulin level and pancreatic islet insulin secretion were observed in D + Ln and DN + Ln groups. Antioxidant enzymes activities were increased in diabetic rats which received combination of nitrate and L-NAME. Our results showed that nitrate without effect on pancreatic islet insulin content and secretion decreased the blood glucose and slightly moderate oxidative stress and its effects in the presence of L-NAME on glucose hemostasis and pancreatic insulin secretion higher than those of nitrate alone.

Fabrication and Characterization of Polysorbate/Ironmolybdophosphate Nanocomposite: Ion Exchange Properties and pH-responsive Drug Carrier System for Methylcobalamin

Background: Nanocomposites are of great interest due to their competency to show multifunctional properties. They have been recently given much attention due to their credibility to offer the synergistic feature of organic material with those of inorganic constituents. Different types of nanocomposites have been prepared to date and are being used for different applications. The delivery of drugs in the human body at a particular site was one of the major problems in the medicinal field. The nanocomposite formulations can be used to provide controlled release and they can be combined with ligands for targeted drug delivery. Applications of the nanocomposites as ion exchangers are also increasing at a faster rate. Due to this, they help in the softening of the water. They can also be easily recharged by washing them with a solution containing a high concentration of sodium ions. In the present paper, we have worked on the synthesis and applications of the polysorbate/ironmolybdophosphate (PS/FMP) nanocomposite. Methods: Polysorbate/ironmolybdophosphate (PS/FMPS) was synthesized by co-precipitation method in the presence of polysorbate. The material was well characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy, (FTIR) scanning transmission microscopy (SEM), and transmission electron microscopy (TEM). Physicochemical properties of material were studied in detail. Drug delivery behavior of polysorbate/ironmolybdophosphate was investigated by using methylcobalamin as a test drug. Results: The polysorbate/ironmolybdophosphate nanocomposite show enhanced Na+ ion exchange capacity of 2.1 meq/g. It has been revealed that PS/FMP nanocomposite was thermally stable as it retained the ion exchange capacity of 40.4 % at 400°C. An optimum concentration of sodium nitrate (eluent) was found to be 1.0 M for the complete removal of H+ ions from the PS/FMP column. The optimum volume of sodium nitrate (eluent) was found to be 230 mL. The FTIR spectra showed the changes in intensities of characteristic peaks in PS/FMP and in drug loaded on PS/FMP nanocomposite. The characteristic peak at 1043-1061 cm-1 was observed for ionic phosphate stretching, 560-567 cm-1 for iron group and 959 cm-1 due to molybdate present in the material. The additional peak at 3390 cm-1 and 1711 cm-1 were due to -OH and C=O stretching due to the presence of these groups in the structure of polysorbate. The peak present at 430 cm-1 might be due to the presence of Co-O stretching of methylcobalamin. The XRD results confirmed the semicrystalline structure of FMP and PS/FMP. Scanning electron micrographs results revealed the beaded surface of FMP changes to fibrous surface in case of PS/FMP nanocomposite. The TEM images indicate the appearance of smooth surfactant layer on the surface of FMP. The size of the nanocomposite is between 10- 70 nm. The drug loading efficiency and encapsulation efficiency were found to be 35.2%. and 60.4%, respectively. The cumulative drug release of methylcobalamin was studied for the PS/FMP nanocomposite. The order of drug release was found to be pH 9.4 (54.6%) > pH 7.4 (46.4%) > saline (pH 5.7) (36.2%) > pH 2.2 (33.9%). The release at pH 9.4 was higher. As the pH of medium changes from acidic to basic i.e. 2.2 - 9.4, there is an appreciable increase in drug release from the PS/FMP nanocomposite due to the presence of more OH- ions resulting in neutralization of cationic nanocomposite and thus increasing the rate of drug release by ion exchange process and matrix deterioration. : The novel nanocomposite PS/FMP has been synthesized by a simple co-precipitation method. The increase in Na+ ion exchange capacity for nanocomposite is due to the binding of organic part (Polysorbate) with inorganic ironmolybdophosphate. The physiochemical properties of PS/FMP were found to be superior. Fourier transform infrared spectra of PS/FMP and drug loaded PS/FMP confirmed the formation of materials. The SEM results indicated the surface of synthesized FMP is bead-like appearance whereas the beaded surface of FMP changes to fibrous surface on the addition of polysorbate thus indicated the fabrication of nanocomposite. The cumulative drug release of methylcobalamin was studied and the order of drug release was found to be pH 9.4 > pH 7.4 > saline (pH 5.7) > pH 2.2. Thus PS/FMP is a promising multifunctional nanocomposite.

Extraction of Organic Compounds from Aqueous Solutions by the Nanofiltration Method

Extraction from aqueous solutions of oxalate and ethylenediaminetetraacetate (EDTA) ions, anionic (ASF) and nonionogenic (NSF) surfactants, and a complex of Co(III) with EDTA by the nanofiltration (NF) method was studied. It was shown that 98–99% of NSFs and EDTA, 85–90% of ASFs and oxalate ions, and 76–79% of the Co(III)–EDTA complex can be extracted with the use of a polymeric NF membrane. The possibility is demonstrated of effectively extracting EDTA and oxalate ions with an NF membrane at solution pH varied within the range 1–13 and sodium nitrate concentrations of 0 to 159 g/dm3. A conclusion is made that using the nanofiltration method is promising for effective removal of various organic complexing and surface-active substances and the Co(III)–EDTA complex from solutions with complex salt composition.

Highly efficient and selective pillararene-based organic materials for Hg2+ and CH3Hg+ extraction from aqueous solution

Pillararenes, a rising star in macrocyclic chemistry, are recognized as promising organic materials for metal ion separation. Herein, three novel pillar[5]arenes (1a-c) appended with N,N-dimethyldithiocarbamoyl groups were designed for highly efficient extraction of aqueous mercury. This work represents the first case of using pillararene-based materials for organic mercury removal, and rather low Hg(II) residue (3.45 ppb) was found in the extraction raffinate of mercury spiked river water after being treated with the as-prepared extractants, which is a rare example of solvent extraction systems that meet the waste water discharge standard (<5 ppb). The extraction performance of the extractant materials was evaluated under different acidities, equilibrium time and sodium nitrate concentrations. High extraction efficiency (>99%) and selectivity (SFHg/M > 690) were achieved under the optimum condition, and the near quantitative stripping after two contacts enable regeneration of the ligands as well as mercury recovery. The stoichiometric ratio between ligands and Hg2+ was ascertained to be 1:1 from the slope analysis method and mass spectroscopy. Investigation of the extracted species by NMR, IR, EXAFS techniques and DFT simulation reveals that the C=S moieties of the ligands play a crucial role in metal complexation. It is noted that the as-prepared extractants show excellent recovery and removal ability towards mercury using simulated samples. After extraction by 1c, the total Hg(II) in spiked river samples was reduced to lower than 5 ppb, the maximum tolerable concentration set by China for industrial waste water. This study demonstrates the potential application of N,N-dimethyldithiocarbamoyl modified pillararenes as functional materials for aquatic mercury remediation.