Ammonium Sulfate Solution Research Articles

High Purity Grade Phycocyanin Recovery by Decupling Cell Lysis from the Pigment Extraction: an Innovative Approach

Phycocyanin, a phycobiliprotein, is one of the few natural blue pigments available as food colourant, and it is largely used in food industry. We have devised an innovative two-step extraction process which allowed to obtain bright blue phycocyanin crude extracts with high purity grade P (within 2.5 and 3.5) directly from fresh biomass of Arthrospira platensis Gomont 1892 (commonly named Spirulina). We found out and for the first time exploited ammonium sulphate capability to minimize the release of water soluble phycobiliproteins in aqueous medium during ultrasound-assisted cell lysis/purification phase. The conventional sequence which is, extraction followed by purification, was reversed. The extraction phase was decoupled from biomass cell lysis. Cell lysis, accomplished by ultrasonication in ammonium sulphate solution, was merged with purification in a single step, before the pigment extraction/recovering phase. The process was entirely carried out in aqueous solutions. No downstream purification was required to obtain products suitable for the most common phycocyanin applications (i.e. foods, nutraceuticals). Production time, hours instead of days, was reduced to the advantage of the product quality. The process has the great advantages of (1) direct use of extracting solutions that cannot be used in the ordinary ultrasound-assisted extraction of phycocyanin (because of the extensive simultaneous extraction of contaminant molecules), (2) gain of high commercial value phycocyanin due to the elevated purity grade and (3) direct production of highly concentrated bright blue pigment crude extracts (up to about 5 mg mL−1) immediately in hand to the market.Graphical

Statistical Study of Extract Keratin Protein from Waste Chicken Feather Based on Response Surface Methodology

The feathers contain a significant amount of keratin protein, which is used in cosmetics, shampoos, hair treatment creams, and skin creams. Dissolving chicken feathers with reducing agent and then separating the protein from chemicals are the key steps involved. However, in order to enhance the amount of recovered keratin as much as possible, the best conditions for extracting keratin from chicken feathers are required. In this study, Response Surface Methodology (RSM) was used in order to simulate and optimize the operating parameters for extracting keratin from waste chicken feathers in order to increase the amount of keratin protein compared to previous studies. Dissolving chicken feathers using sodium sulphide as a reducing agent at various periods, temperatures, and concentrations is the first step in the fundamental technique. After the feathers have been dissolved with a reducing agent, the fluid is treated with an ammonium sulfate solution to precipitate the protein. As determined by a biuret test and UV-Vis analysis, the keratin protein had a maximum wavelength of 290 nm. Finally, the statistical optimization of the extraction conditions provided a better understanding of the reaction parameters. The optimum yield of keratin was achieved at 3.7 hours at 30.07°C with 0.05 M sodium sulfide.

Cathodic Boronitrocarburising and Anodic Polishing of Mild Steel 20 in Electrolitic Plasma

The paper discusses a possibility of increasing the wear and corrosion resistance of a low carbon steel surface after cathodic plasma electrolytic boronitrocarburising in a solution of boric acid, glycerin, and ammonium chloride, with the subsequent anodic plasma electrolytic polishing in an ammonium sulfate solution due to the formation of a modified structure consisting of a dense oxide layer and a diffusion layer below it, which contains up to 0.87% carbon, 0.80% nitrogen, and 0.87% boron upon reaching microhardness up to 970±20 HV. The competitive influence of the surface erosion under the action of discharges and high-temperature oxidation on the morphology and roughness of the surface is revealed. A positive effect of reducing the surface roughness during the formation of a dense oxide layer on the surface and a hardened diffusion layer under it on reducing the friction coefficient and mass wear, as well as reducing the roughness and additional oxidation of the surface during polishing on reducing the corrosion current density, has been established.

Investigating purification and activity analysis of urease enzyme extracted from jack bean source: A green chemistry approach

Urease is an enzyme of historical importance in the field of biochemistry, generally microbial and plant urease is the primary sources of urease. The significant applications of urease enzyme are found to be foremost in food industry, medical equipment's and biosensors. In this work, urease has been extracted from Jack bean meal using ammonium sulphate and acetone precipitation. A significant amount of urease was precipitated and concentrated at 60% saturated solution of ammonium sulphate. The obtained precipitates were dissolved in 50 mM phosphate buffer (pH 8) after centrifugation, and subjected to sodium dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to determine the molecular weight of urease. Results obtained from the SDS-PAGE were validated using Zymography. Anion exchange chromatography was used to separate the desired protein at different pH (7.0, 7.5 and 8.0). The eluted fractions were assessed for urease activity using phenol-nitroprusside dependent ammonia release assay. Under these assay conditions, one unit of urease activity was calibrated as the amount of enzyme liberating 1 μM of NH3 from urea per unit time. The eluted fraction and Zymography analysis show the purified urease observed at 90 kDa and activity of purified urease, respectively. The obtained results for specific activity (173.67Units mg) and % purification (99.71%) for urease has been compared with the available literature, which are found to be in close relation with existing results. The proposed method is a novel approach which has recorded highest % purification and specific activity. Furthermore, it can be suitable for extracting urease from jack bean source for various industrial applications.

Separation of Phycobiliprotein from Nostoc Commune by Using Ion-Exchange Membrane with Quaternary Amine

ABSTRACT Phycobiliprotein (PB), which is produced by cyanobacteria, has potential applications as a valuable pharmaceutical product. In this study, PB was separated by using a nonwoven-fabric membrane (Rx-1) that contained quaternary amino groups. PB was extracted from a Nostoc commune, which is a type of microalga, by disrupting the cell walls by a freeze–thaw method. Two types of biomolecules, namely PB and other biomolecules X, were identified by gel permeation chromatography. Permeation of the PB-containing solution through Rx-1 increased the purity of the PB in the filtrate from 0.25 to 0.45. The adsorption constant (K p) and maximum adsorbed amount of each protein on Rx-1 (q max) were determined by fitting the experimental data to a mathematical model. The obtained values for K p and q max were used to simulate scaled-up treatment of a PB-containing solution. Permeation of a PB-containing solution (3.0 L at 1.2 × 10−3 m3/h) through Rx-1 (volume of scale-up membrane, 8.0 × 10−4 m3) enabled PB separation for 26 h. Further PB purification could be achieved by using the Rx-1 membrane in combination with precipitation with ammonium sulfate solution and an ultrafiltration membrane.

An Electrolyte Life Indicator for Plasma Electrolytic Polishing Optimization

This work shows that electrolyte current-density as an indicator can assist in the optimized timing of the addition of the electrolyte to plasma electrolytic polishing (PEP) to keep it active and in operation. In this experiment, 2 wt% ammonium sulfate was used as an electrolyte to polish 1 cm × 1 cm stainless steel SUS304. The hot-bath heating method was successfully used to heat it from 60 to 90 °C, followed by suction filtration. The cathode was fixed at the beaker edge in the electrolyte and the input voltage was 340 volts. Once the gas-phase layer formed stably around the workpiece, the plasma went through the electrolyte to polish the workpiece surface. Then, the anode was slowly immersed into the electrolyte and the current-density measured. It was found that based on the current-density–temperature curve, for the timing of the addition of the electrolyte, the current-density difference could be used to decide whether it needed to be supplemented or not. When the temperature was from 75 to 80 °C and 85 to 90 °C, it was found that the 2 wt% ammonium sulfate solution should be supplemented. The result showed that the electrolyte life indicator, using the current-density, is a feasible method of practical technology for PEP.

Design of novel temperature-resistant and salt-tolerant acrylamide-based copolymers by aqueous dispersion polymerization

ABSTRACT Development of polymer-based flooding technology to improve oil recovery efficiency, water dispersion copolymerization of acrylamide, cationic monomer methacryloxyethyltrimethyl ammonium chloride (METAC), and anionic monomer acrylic acid (AA) were carried out in aqueous ammonium sulfate solution with polyvinyl pyrrolidone (PVP) as the stabilizer. The copolymers were characterized by 1H-NMR, FT-IR, TG, and SEM to confirm that they were prepared successfully and exhibited excellent salt-resistant property. Moreover, the effect of the aqueous solution of ammonium sulfate (AS) concentration, stabilizer concentration, and initiator concentration on the viscosity and size were systematically investigated. To further improve the thermal endurance properties of copolymer, hydrophobic monomers with different alkyl chain lengths were added to the above system. The acrylamide-based quadripolymer possessed prominent thermal and salt endurance properties by utilizing the advantages of zwitterionic structure and hydrophobic monomer. With the temperature rising, the viscosity retention could reach 70.2% in the water and 63.8% in the saline. This work had expected to provide a new strategy to design polymers with excellent salinity tolerance and thermal-resistance performances.

Development of a Biochar-Based Substrate Added with Nitrogen from a Mining Effluent for the Production of Picea mariana Seedlings

Ammoniacal nitrogen (N-NH3) is one of the pollutants that has adverse effects on the environment and is present in most effluents generated by mining operations. Therefore, mining companies must manage it to keep it below the regulated discharge criteria to avoid environmental contamination. In this context, the present study aims to valorize N-NH3 in the form of ammonium sulphate ((NH4)2SO4) for the manufacture of biochar pellets used as growth substrates for the production of forest seedlings. The biochar was first produced by fast pyrolysis, at 320 °C, and different recipes of pellets were then prepared to evaluate their hardness, binder type and content, humidity and durability. The optimal granule chosen was composed of biochar, corn starch and canola oil. Six combinations of different compositions were then prepared as substrates for black spruce growth: (1) Peat (P); (2) Peat and bulk biochar (PB); (3) Peat and bulk biochar impregnated with ammonium sulfate (PBAS); (4) Peat and biochar pellets impregnated with water (PBPeW); (5) Peat and biochar pellets impregnated with an ammonium sulfate solution (PBPeAS); (6) Peat, biochar pellets impregnated with ammonium sulfate and perlite (PBPeASPer). The effects of these substrates on the growth of black spruce seedlings, as well as fertilizer leaching, were measured. The results show that seedling biomass is equivalent to the control for the granular treatment, but higher biomass was obtained with bulk biochar (PB). This shows that a quarter of peat could be replaced by biochar to obtain similar or even better results of biomass yield and, consequently, solve part of the supply issue. As to plant nutrition, no tendency was observed for the experiments apart from the higher proportion of Ca in spruce needles. The prepared biochar-based pellet substrate appears to not only be advantageous for spruce production but also for other uses such as golf courses, forestry producers and horticultural nurseries using conventional fertilizers and peat as growing media. In addition, these approaches could help the Abitibi-Témiscamingue region in Québec, Canada to build a local circular economy.

Fertiliser Effect of Ammonia Recovered from Anaerobically Digested Orange Peel Using Gas-Permeable Membranes

The manufacture of mineral N fertilisers by the Haber–Bosch process is highly energy-consuming. The nutrient recovery technologies from wastes through low-cost processes will improve the sustainability of the agricultural systems. This work aimed to assess the suitability of the gas-permeable membrane (GPM) technology to recover N from an anaerobic digestate and test the agronomic behaviour of the ammonium sulphate solution (ASS) obtained. About 62% of the total ammonia nitrogen removed from digestate using GPM was recovered, producing an ASS with 14,889 ± 2324 mg N L−1, which was more than six-fold higher than in digestate. The ASS agronomic behaviour was evaluated by a pot experiment with triticale as a plant test for 34 days in a growth chamber. Compared with the triticale fertilised with the Hoagland solution (Hoag), the ASS provided significantly higher biomass production (+29% dry matter), N uptake (+22%), and higher N agronomic efficiency 3.80 compared with 1.81 mg DM mg−1N in Hoag, and a nitrogen fertiliser replacement value of 133%. These increases can be due to a biostimulant effect provided by the organic compounds of the ASS as assessed by the FT-Raman spectroscopy. The ASS can be considered a bio-based mineral N fertiliser with a biostimulant effect.

Fermentation-Inspired Gelatin Hydrogels with a Controllable Supermacroporous Structure and High Ductility for Wearable Flexible Sensors.

Supermacroporous hydrogels have attracted wide concern due to their comfort and breathability in wearable health-monitoring applications. Size controllable supermacroporous structure and excellent mechanical properties are the most important for its application. However, they are normally fabricated by the cryogelation method, which is difficult to control pore size and maintain flexibility. Here, yeast fermentation-inspired gelatin hydrogels with a controllable supermacroporous structure and excellent mechanical properties were fabricated for the first time. The pore size can be controlled by adjusting the content of glucose and yeast, the ratio of glucose to yeast, fermentation time, and gelatin content during fermentation. The hydrogels demonstrated a controllable pore size range from 100 to 400 μm and rapid swelling characteristics. The mechanical properties were maintained by soaking ammonium sulfate solution for 12 h, showing maximum tensile and compressive strains over 300 and 99%, respectively. This novel approach can be easily applied to the preparation of supermacroporous and high ductility hydrogels under mild conditions. Furthermore, conductive hydrogels combined supermacroporous structures with conductive polyaniline and reduced oxidized graphene, and silver nanowires were prepared as wearable flexible sensors. The obtained sensors maintain well-distributed porosity, breathability, and mechanical flexibility, also showing excellent conductivity of 2.4 S m-1. Finally, the sensors were successfully applied to detect physiological signals and human-computer interaction.

Potentials of Breast Milk Antibodies as a Therapeutic for COVID-19

Since the explosion of pneumonia-like symptoms in the province of Hubei, Wuhan in December 2019 over 200 countries have gotten a share of this disease caused by the novel coronavirus disease 2019 (COVID-19). Till date, there exists no modest therapeutic agent to combat this virus. Antibodies in the breast milk of convalescent lactating mothers could be the silver bullet that would deflate the ballooning morbidity and mortality rate caused by the COVID-19 pandemic. Coupled with the fact that breast milk contains a very high amount of Immunoglobulin A which has a desirable higher in vivo stability than other antibodies. This novel approach of purifying antibodies from the breast milk of convalescent lactating mothers is a non-invasive technique relative to the conventional method of using convalescent plasma which had proven effective for generating passive immunity against the seasonal flu. Purified Immunoglobulins would be obtained by adding an equal volume of ammonium sulphate solution to the breast milk sample to induce a lyotropic effect and thereafter passing the partially purified solution through a column chromatographic system impregnated with a Jaclin –lectin, Protein A, L and G. Neutralizing antibodies would by assayed using the Enzyme-Linked Immunosorbent Assay technique. Various statistical tools will be used to analyze a double-blinded randomized clinical trials to ascertain the efficacy of the purified antibodies as it is expected to have clear cut effectiveness over the control and potentially become the invaluable in containing the pandemic.

Isolation of napin from Brassica nigra seeds and coagulation activity to turbid pond water

Abstract Approach to fresh water is limited due to the growing world population and supply of clean drinking water is a global challenge. Pond water is widely used for drinking in developing countries and it has higher turbidity during rainy seasons. This purpose requires a large number of chemical coagulants that lead to a high cost of treatment. Therefore there is a need to find an economical and natural coagulant to treat turbid water. Coagulation activity is an ability of a liquid, changing to a solid or semi-solid state after sometime period of time. This study focuses on the isolation of coagulant proteins from Brassica nigra seeds responsible for water clarification. The coagulant protein (napin) was purified, quantified and identified. Napin protein was precipitated with 70% saturation of ammonium sulfate solution combined with dialysis and size-exclusion chromatography. SDS-PAGE showed that isolated napin has a molecular weight of 16 kDa. Protein quantification was done by using a NanoDrop spectrophotometer. The coagulation activity of the napin protein was measured against synthetic clay solution and turbid pond water. The coagulation assay results showed that napin protein from Brassica nigra has 85% and Moringa seeds extract has 87% coagulation activity against the synthetic clay solution after 120 min. However, the coagulation activity of napin protein against the turbid pond water was higher 85% compared to Moringa seed extract of 80%. The active coagulant napin protein would be helpful in establishing cheaper methods in scaling up the coagulant protein from the Brassica nigra seeds acting as a potential agent for water treatment.

Pilot demonstration of nitrogen removal from municipal wastewater by vacuum membrane distillation

Nitrogen in municipal wastewater must be removed prior to discharge to the environment. However existing energy intensive aerobic processes used for nitrogen removal currently do not capture this important resource. Instead, nitrogen capture in the form of ammonia using a lower energy technology such as the membrane distillation; so far mostly tested in lab-scale, could be a significant improvement. This study reports a vacuum membrane distillation (VMD) pilot trial conducted at a municipal wastewater treatment plant to uniquely demonstrate ammonium removal and recovery to meet effluent discharge targets. The pilot plant was located in two streams on-site in the plant's anaerobic digester liquor handling facilities. The first trialed stream was on the existing phosphorus removal lime dosed effluent, and the second stream was effluent from an experimental struvite phosphorous recovery operation. In the post-lime scenario, VMD recovered N as ammonium sulphate solution and achieved up to 93% reduction. In the post struvite scenario, the VMD system achieved up to 85% reduction within the duration of the demonstration. With VMD driving force derived from volatility of the compound of interest, which is reliably calculated via Henry's law, the ammonia mass transfer coefficient across the membrane was 0.16 kg/m2/h/bar (±37% RSD) over the trial period, being lower than typical best case laboratory test results. Overall, the nitrogen removal and recovery process via VMD was proven technically viable on actual plant effluent leaving existing lime dosed and potential future struvite phosphorus removal systems. However, further studies are required to assess the economics of VMD for nitrogen removal compared with other nitrification-denitrification methods used in wastewater treatment.

Development of an environmental-friendly durable self-compacting concrete.

In this experimental study on self-compacting concrete (SCC), the Manufactured sand (M-sand) and Fly ash (FA) were utilised for partial replacement of Natural sand (N-sand) and Ordinary Portland Cement (OPC), respectively. N-sand was partially replaced by M-sand at various percentage levels, after the dose of FA in the mix was optimised. In terms of compressive strength, the optimum replacement level of OPC by FA was 20%, whilst for replacement of N-sand by M-sand it was 50%. Two types of mixes were prepared to compare the macro and micro level properties of SCC, i.e., SCC-I (100%OPC + 100%N-sand) and SCC-II (80%OPC + 20%FA + 50%N-sand + 50%M-sand). The characteristics of fresh concrete mixes were determined using Slump flow, T50 time, V-funnel, L-box, U-box, and J-ring tests. After 28days of curing in tap water, both types of specimens were exposed to a solution of ammonium sulphate [(NH4)2SO4] containing sulphate salt concentration of 2.0g/l for 360days to test their durability. Loss in compressive strength, weight change, sorptivity, and micro-structural changes (XRD, SEM, and EDS) all were evaluated for up to 360days. It was found that the use of FA and M-sand in concrete makes it more environmental-friendly and durable, as well as have better performance in a sulphate environment.

Detection of atomoxetine and its metabolites in the urine by thin-layer chromatography and mass spectrometry

The aim of the study was the detection of atomoxetine and its biotransformation products in the urine under TLC screening conditions and identification of the metabolites using mass spectrometry method. Materials and methods. The volunteer’s urine samples after taking a single therapeutic dose of atomoxetine (2 capsules of 60 mg each of Strattera®) were studied. Sample preparation included diluting acid hydrolysis followed by the native compound and metabolites extraction with chloroform from the saturated solution of ammonium sulfate at pH of 11–12. Thin-layer chromatography studies of the extracts were carried out in 18 mobile phases including those proposed by The International Association of Forensic Toxicologists for general drug screening, and those widely used in forensic toxicological studies. The color reactions were carried out using a range of chromogenic reagents. A Varian 1200 L mass spectrometer (Netherlands) equipped with a dual quadrupole mass analyzer was applied for analysis of the eluates from chromatograms. Identification was undertaken at the direct introduction of the sample into the ion chamber, electron-impact ionization (70 eV), and full ion scanning mode. Results. The spot of the native drug on the chromatogram was identified by the Rf, value. Two atomoxetine biotransformation products were identified by the molecular weights that correspond to the molecular ion peaks in the mass spectra. Conclusions. Atomoxetine and its biotransformation products were detected in the urine under TLC screening conditions and identified using mass spectrometry method. Chromatographic mobility of the native compound, hydroxyatomoxetine, and dihydroxyatomoxetine in the TLC screening systems as well as the results of their visualization using chromogenic reagents applied for toxicological drug screening in the systematic toxicological analysis have been determined.

Optimized sample pre-treatment procedure for the simultaneous UPLC-MS/MS quantification of ipilimumab, nivolumab, and pembrolizumab in human serum

Ipilimumab, nivolumab, and pembrolizumab are immune checkpoint inhibiting monoclonal antibodies. Their efficacy has been proven to be correlated with clearance, and hence, bioanalytical assays to study their pharmacokinetics are of pivotal importance. We present the first kit-free sample pre-treatment procedure of only three hours for the Ultra-Performance Liquid Chromatography - tandem Mass Spectrometry (UPLC-MS/MS) simultaneous quantification of ipilimumab, nivolumab, and pembrolizumab in human serum. The conventional bottom-up sample pre-treatment steps for protein MS bioanalysis including pre-digestion purification, denaturation, reduction, alkylation, and digestion were optimized in terms of sensitivity and reproducibility. In the final, optimal sample pre-treatment procedure, samples were purified by protein precipitation with saturated ammonium sulfate solution, reduced with dithiothreitol, denatured with methanol, and digested with trypsin. The method was then validated according to European Medicines Agency (EMA) and the United States Food and Drug Administration (FDA) guidelines for bioanalytical method validation, and 4–6-20 acceptance criteria were applied. This method was selective, accurate, and precise within the range of 3–200 µg/mL for all analytes. The validated developed assay was applied to determine ipilimumab, nivolumab, and pembrolizumab concentrations in patient serum, and the results were compared to enzyme-linked immunosorbent assay (ELISA) results.

Coimmobilization of lipases exhibiting three very different stability ranges. Reuse of the active enzymes and selective discarding of the inactivated ones

Lipase B from Candida antarctica (CALB) and lipases from Candida rugosa (CRL) and Rhizomucor miehei (RML) have been coimmobilized on octyl and octyl-Asp agarose beads. CALB was much more stable than CRL, that was significantly more stable than RML. This forces the user to discard immobilized CALB and CRL when only RML has been inactivated, or immobilized CALB when CRL have been inactivated. To solve this problem, a new strategy has been proposed using three different immobilization protocols. CALB was covalently immobilized on octyl-vinyl sulfone agarose and blocked with Asp. Then, CRL was immobilized via interfacial activation. After coating both immobilized enzymes with polyethylenimine, RML could be immobilized via ion exchange. That way, by incubating in ammonium sulfate solutions, inactivated RML could be released enabling the reuse of coimmobilized CRL and CALB to build a new combi-lipase. Incubating in triton and ammonium sulfate solutions, it was possible to release inactivated CRL and RML, enabling the reuse of immobilized CALB when CRL was inactivated. These cycles could be repeated for 3 full cycles, maintaining the activity of the active and immobilized enzymes.

Low-temperature green synthesis of nanocrystalline La2O2S:Pr3+ powders and investigation of photoluminescence

Calcining an amorphous precursor in flowing hydrogen at 900 °C directly produced nanocrystalline La2O2S:Pr3+ powder (LOS:Pr3+; average size ∼35 nm) of a unimodal distribution of particle size (mean diameter ∼90 nm). The precursor, precipitated by titrating an aqueous solution of rare-earth nitrate and ammonium sulfate with ammonia water, was deduced to have an approximate composition of (La,Pr)2(OH)2.6(CO3)0.7SO4·2H2O. Aside from simplicity, the synthesis method reported herein has the obvious advantage of environmental friendliness, as it did not involve any harmful sulfidizing agent. The products were characterized in detail by XRD, FTIR, TG/DTA, and SEM/TEM to reveal the process of phase/morphology development and fine microstructure. Photoluminescence study found that the LOS:Pr3+ nanopowder exhibited strong luminescence at ∼508 nm (3P0,1 → 3H4 transition), with a fluorescence lifetime of ∼4.22 ± 0.03 μs, either through exciting the LOS host (∼263 nm, more efficient) or directly exciting the Pr3+ activator (∼304 nm), and retained ∼45% of its room-temperature intensity at 150 °C. Aside from phosphor application, the thus-synthesized powder would be useful for the fabrication of ceramic scintillators because of its nanosized crystallites and narrow distribution of particle size.

Screen-Printed Structures from a Highly Conductive Mildly Oxidized Graphene Suspension for Flexible Electronics.

In this study, the screen-printed flexible humidity sensor and supercapacitor structures from a suspension of mildly oxidized graphene (MOG) was obtained. MOG suspension with a low atomic oxygen content (~20%) was synthesized by electrochemical exfoliation of natural graphite in an aqueous solution of ammonium sulfate. MOG films (average thickness 5 μm) with a surface resistance of 102–103 kΩ/sq were obtained by screen printing on a flexible substrate. The thermal reduction of MOG films at 200 °C reduced the surface resistance to 1.5 kΩ/sq. The laser reduction with a 474 nm and 200 mW solid-state laser reduced the surface resistance to ~0.065 kΩ/sq. Various structures were screen-printed on a flexible substrate for a variety of flexible electronics applications. The structures representing a flat supercapacitor had an average specific capacitance of ~6 μF/cm2. The tensile deformations occurring during bending reduced the capacitance by 40% at a bending radius of 2 mm. Humidity sensing structures with sensitivity of 9% were obtained.

Recovery of Ammonium Sulfate Solution by Regeneration of Loaded Clinoptilolite.

The zeolite clinoptilolite (CLI) is known to be a very good ion exchanger, as it consists of a three-dimensional structure formed of AlO4− and SiO4 tetrahedral, which are connected by a common oxygen atom. The micropores formed by this structure (with free diameters in the range of 0.40 nm and 0.72 nm) are fine enough to allow cations and water molecules to enter and be exchanged. CLI is a suitable, inexpensive, and globally available material for removing ammonium from highly-concentrated wastewater and is proven to be selective in ammonium uptake and regeneration since no effect of the provenance of the ammonium (matrix-free NH4Cl solution or sludge water) could be found. However, regeneration of the clinoptilolite is necessary to recover the adsorbed ammonium for further use and restore its capability for ion exchange. Within this work, the method by which clinoptilolite, loaded with ammonium (q = 8.1–16.6 mg/g) from different sludge waters and ammonium chloride solution, can be regenerated to yield a stoichiometric ammonium sulfate solution (ASS), that could be used, e.g., as a fertilizer, was investigated. A regeneration solution containing Na2SO4 (0.25 n(Na2SO4)/n(NH4+ads)) with a varying NaOH ratio (0–2.14 n(NaOH)/n(NH4+ads)) was tested. To obtain a high ammonium concentration in the eluate, a large mass fraction ω of 284 g/kg of CLI in the regeneration solution was applied. The effects of different ammonium loads, different origins of the ammonium, and residual moisture on the necessary components of the regeneration solution, in which an ASS is obtained within a contact time of 10 min at 22 °C, were studied. A stoichiometric ASS from CLI loaded up to a maximum of 13.5 mg/g was obtained with a mixture of 0.25 n(Na2SO4)/n(NH4+ads) together with 0.8–1.0 n(NaOH)/n(NH4+ads) for dry CLI, and 0.75 n(NaOH)/n(NH4+ads) for CLI with residual moisture.