Salt Ionic Strength Research Articles

Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties.

A method to synthesize stable, raspberry-like nanoparticles (NPs), using surface grafting of poly(glycidyl methacrylate) (PGMA) brushes on a polystyrene (PS) core with varying grafting densities, is reported. A two-step functionalization reaction of PGMA epoxide groups comprising an amination step first using ethylene diamine and then followed by a quaternization using glycidyltrimethylammonium chloride generates permanently and positively charged polyelectrolyte brushes, which result in both steric and electrostatic stabilization. The dispersion stability of the brush-bearing NPs is dramatically improved compared to that of the pristine PS core in salt solutions at ambient (25 °C) and elevated temperatures (60 °C). Additionally, the grafted polyelectrolyte chains undergo a reversible swelling in the presence of different ionic strength (IS) salts, which modulate the surface properties, including roughness, stiffness, and adhesion. An atomic force microscope under both dry and wet conditions was used to image conformational changes of the polyelectrolyte chains during the swelling and deswelling transitions as well as to probe the nanomechanical properties by analyzing the corresponding force-sample separation curves. The quaternized polyelectrolyte brushes undergo a conformational transition from a collapsed state to a swelled state in the osmotic brush (OB) regime triggered by the osmotic gradient of mobile ions to the interior of the polymer chain. At IS ∼ 1 M, the brushes contract and the globules reform (salted brush state) as evidenced by an increase in the surface roughness and a reduction in the adhesion of the brushes. Beyond IS ∼ 1 M, quartz crystal microbalance with dissipation monitoring measurements show that salt uptake continues to take place predominantly on the exterior surface of the brush since salt adsorption is not accompanied by a size increase as measured by dynamic light scattering. The study adds new insights into our understanding of the behavior of NPs bearing salt-responsive polyelectrolyte brushes with adaptive swelling thresholds that can ultimately modulate surface properties.

Optimization of emulsion properties of chickpea protein and its application in food

AbstractAs a leguminous plant, chickpea has been widely concerned by researchers because of its high yield, low production cost, and high protein content. Compared with soy protein, chickpea protein has lower allergenicity, better solubility, and foaming properties. Therefore, chickpea protein is considered a good alternative to animal protein. Currently, chickpea protein is used in products made from flour, such as cookies, breads, and noodles. Chickpea protein emulsion also has many potential applications in food, such as delaying lipid oxidation, transporting nutrients, and serving as a substitute for animal fat. However, the physical, chemical stability and biological activity of chickpea protein emulsion are easily affected by many factors, including salt ionic strength, pH, temperature, and so forth in food processing. In order to better apply chickpea protein emulsions to more real food substrates, it is necessary and meaningful to study the factors that affect the characteristics of the emulsion. The properties of chickpea protein emulsion can be improved by pretreatment of chickpea protein, including pH adjustment, cross‐linking by glutaminase, hydrolysis of by protein hydrolase, formation of complex with glycosides or polysaccharides and acetylation modification. In the future, the optimized and stable chickpea protein emulsion will be more widely used in the food field.

Folic Acid Adjustive Polydopamine Organic Nanoparticles Based Fluorescent Probe for the Selective Detection of Mercury Ions.

Polydopamine fluorescent organic nanomaterials present unique physicochemical and biological properties, which have great potential application in bio-imaging and chemical sensors. Here, folic acid (FA) adjustive polydopamine (PDA) fluorescent organic nanoparticles (FA-PDA FONs) were prepared by a facile one-pot self-polymerization strategy using dopamine (DA) and FA as precursors under mild conditions. The as-prepared FA-PDA FONs had an average size of 1.9 ± 0.3 nm in diameter with great aqueous dispersibility, and the FA-PDA FONs solution exhibit intense blue fluorescence under 365 nm UV lamp, and the quantum yield is ~8.27%. The FA-PDA FONs could be stable in a relatively wide pH range and high ionic strength salt solution, and the fluorescence intensities are constant. More importantly, here we developed a method for rapidly selective and sensitive detection of mercury ions (Hg2+) within 10 s using FA-PDA FONs based probe, the fluorescence intensities of FA-PDA FONs presented a great linear relationship to Hg2+ concentration, the linear range and limit of detection (LOD) were 0-18 µM and 0.18 µM, respectively. Furthermore, the feasibility of the developed Hg2+ sensor was verified by determination of Hg2+ in mineral water and tap water samples with satisfactory results.

Nitrogen, sulfur, and phosphorus Co-doped carbon dots-based ratiometric chemosensor for highly selective sequential detection of Al3+ and Fe3+ ions in logic gate, cell imaging, and real sample analysis

Heteroatom-doped photoluminescent (PL) carbon dots (CDs) have recently gained attention as optical sensors due to their excellent tunable properties. In this work, we propose a one-pot hydrothermal synthesis of PL nitrogen (N), sulfur (S), and phosphorus (P) co-doped carbon dots (NSP-CDs) using glutathione and phosphoric acid (H3PO4) as precursors. The synthesized NSP-CDs were characterized using different spectroscopic and microscopic techniques, including ultraviolet–visible (UV–Vis) spectroscopy, fluorescence spectroscopy, Fourier-transform infrared (FTIR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. The NSP-CDs exhibited excellent PL properties with green emission at 492 nm upon excitation at 417 nm, a high quantum yield of 26.7%, and dependent emission behavior. The as-prepared NSP-CDs were spherical with a well-monodispersed average particle size of 5.2 nm. Moreover, NSP-CDs demonstrate high PL stability toward a wider pH, high salt ionic strength, and various solvents. Furthermore, the NSP-CDs showed a three-state “off–on–off” PL response upon the sequential addition of Al3+ and Fe3+ ions, with a low limit of detection (LOD) of 10.8 nM for Al3+ and 50.7 nM for Fe3+. The NSP-CD sensor can construct an INHIBIT logic gate with Al3+ and Fe3+ ions as the chemical inputs and emissions as the output mode. Owing to an excellent tunable PL property and biocompatibility, the NSP-CDs were applied for sensing Al3+ and Fe3+ ions as well as live cell imaging. Furthermore, NSP-CDs were designed as PL sensors for detecting Al3+ and Fe3+ ions in real water show their potential application.

Removal of tetracycline onto KOH-activated biochar derived from rape straw: Affecting factors, mechanisms and reusability inspection

A porous biochar (BC) was prepared using the recycled agricultural waste rape straw as resources by combining high temperature carbonization with KOH activation procedure, and applied into tetracycline hydrochloride (TC) adsorption. The multiple characteristic techniques were adopted to investigate the structures and properties of as-prepared BC. The results demonstrated that the BC activated by KOH would possess the more graphite-like structures, more abundant oxygen-containing functional groups, and larger specific surface area (1531 m2/g) comparing with unactivated BC, which were favorable for the TC adsorption. The effects of initial TC concentration, solution pH value, salt ionic strength and adsorption temperature on the adsorption performances were explored in detail. The adsorption data could be well fitted by the pseudo-second-order kinetic model and Freundlich isothermal model. The maximum adsorption capacity of KOH activation BC could reach 325.07 mg/g at 30 °C. The endothermic and spontaneous properties of the adsorption system was implied by thermodynamic study. The adsorption TC mechanism of KOH activation BC was involved in the pore filling, π-π electron donor-acceptor interaction, hydrogen bonding and electrostatic action. Regeneration experiments showed that the TC removal efficiency could still attain 97.0% even after six cycling experiment, suggesting that the BC had the excellent reusability and stability. These results indicate the feasibility of a win-win strategy for the application of agricultural waste to water remediation.

Kaolin based protective barrier in municipal landfills against adverse chemo-mechanical loadings

In this work, we assess the self-sealing and swelling ability of the compacted granular bentonite (GB) under an inorganic salt environment and induced overburden stresses from the landfill waste. The laboratory permeation tests with high ionic strength salt solutions reveal that the GB fails to seal and exhibits a significant mechanical collapse under different applied stresses. The applicability of GB in the form of geosynthetic clay liners as the bottom liner facilities in landfills that produce high ionic strength salt leachates, therefore, remains a serious concern. We propose an additional barrier system based on kaolin, for the first time, to address this problem. The proposed kaolin-GB layered system performs satisfactorily in terms of its sealing and swelling ability even in adverse saline conditions and low overburden stresses. The kaolin improves the osmotic efficiency of the self and also helps the underlying GB layer to seal the inter-granular voids. The estimated design parameters by through-diffusion test suggest that the kaolin-GB layered system effectively attenuates the permeant flux and suitable as a landfill liner.

Interaction of tetradecyltrimethylammonium bromide with bovine serum albumin in different compositions: Effect of temperatures and electrolytes/urea

Herein, the interaction of a protein, bovine serum albumin (BSA), with tetradecyltrimethylammonium bromide (TTAB, a cationic surfactant), has been investigated using the conductivity measurement technique in pure water and some sodium salts (NaCl, Na2SO4, Na2CO3, and Na3PO4) solutions at temperature range of 295.15–320.15 K. Results reveal that, in the plot of specific conductivity versus the concentration of TTAB, only a single critical micelle concentration (cmc) was found for the TTAB + BSA mixed system in all solvents media studied. The addition of BSA in aqueous TTAB solution, the value of cmc undergoes a change from its pure form, which indicates the presence of strong interaction operating between the BSA and TTAB molecules. In aqueous system, the cmc values of the TTAB + BSA mixtures are obtained higher compared to the values found for single TTAB surfactant. However, the addition of salt decreases the cmc value of mixed TTAB + BSA system. The values of cmc of the BSA + TTAB mixed system at 310.15 K and 1.00 mmol·kg−1 ionic strength of salt followed the order: cmcNa2CO3 > cmcNa3PO4 > cmcNaCl > cmcNa2SO4. The cmc values of TTAB + BSA mixture were found to be lowered in urea solution within the concentrations studied. The values of degree of dissociation (α) and fraction of counter ion binding (β) were found to be dependent on additives and temperature. The free energy of micellization (∆ Gmo) is negative for all the systems, which manifests that the micellization phenomenon is energetically spontaneous. The enhancement of the negative value of ∆ Gmo in aqueous salt solutions reveals an increase of spontaneity of the TTAB + BSA micellization process. The values of ∆ Gmo also reveal that the spontaneity of micelle formation is enhanced at higher temperatures in all media studied. The values of free energy of transfer (∆ Gm, to) were also determined for numerous solvent media used in the present study and described with appropriate reasoning.

Enhanced removal of Eriochrome Black T in wastewater by zirconium-based MOF/graphene oxide

The zirconium-based MOF/graphene oxide (UiO-66-NH2/GO) composites were prepared by ultrasonic dispersing different amounts of graphene oxide (GO) in a well-dissolved zirconium tetrachloride/H2BDC-NH2 mixture, obtaining 2 wt% (UiO-66-NH2/GO-1), 5 wt% (UiO-66-NH2/GO-2), and 10 wt% (UiO-66-NH2/GO-3) GO composites. The products were characterized by XRD, FTIR, SEM, BET, Raman, UV, XPS, and Zeta potential. Adsorption experiments on simulated Eriochrome Black T (EBT) printing and dyeing wastewater were carried out using UiO-66-NH2/GO, and the optimal conditions for adsorption were obtained by exploring the effects of initial EBT concentration, time, pH, and salt ionic strength. Adsorption isotherms, kinetics, mechanism, and regeneration were also researched. The adsorption behavior was consistent with the Langmuir isotherm and fully compliant with pseudo secondary dynamics model. The adsorption capacity of UiO-66-NH2/GO-2 was found to be the highest of the three products, which was 263.158 mg/g. Therefore, the UiO-66-NH2/GO-2 composite was considered to be an excellent adsorbent for the adsorption of EBT from organic dye wastewater.

High-efficiency adsorption of methylene blue dye from wastewater by a thiosemicarbazide functionalized graphene oxide composite

With the aim of developing an improved adsorbent material for the treatment of printing and dyeing wastewater, we prepared a novel thiosemicarbazide functionalized graphene oxide (GO-TSC-GO) adsorbent by condensation reaction of the thiosemicarbazide amino group with the graphene oxide carboxyl group. This material was characterized by SEM, XPS, FTIR, Raman, XRD, UV–Vis, TGA, and BET then used to conduct adsorption experiments on simulated printing and dyeing wastewater containing methylene blue (MB). We investigated the effects of temperature, time, pH, salt ionic strength, initial MB solution solubility, and the activation and regeneration of the adsorbent on adsorption performance. The adsorption behavior was consistent with the pseudo-second-order adsorption kinetic model and the Langmuir adsorption isotherm model. Thermodynamic analysis indicated an exothermic chemical adsorption reaction. In addition, the GO-TSC-GO exhibited excellent reusability. The maximum adsorption capacity of GO was 196.8 mg/g whereas the maximum adsorption capacity of GO-TSC-GO was 596.642 mg/g, verifying that the GO-TSC-GO composite has important applications for the treatment of printing and dyeing wastewater.

Application of Amberlite XAD-7HP resin impregnated with Aliquat 336 for the removal of Reactive Blue - 13 dye: Batch and fixed-bed column studies

Adsorption studies were performed in both batch and column mode for the removal of Reactive Blue-13 (RB-13) dye using Amberlite XAD-7HP resin impregnated with Aliquat 336. In batch mode, the effect of adsorbent dosage (1–4 g/L), initial dye concentrations (50–100 mg/L) at various temperatures (293–333 K), pH (2–12), contact time (0–60 min), and ionic strength of salt (NaCl & Na2SO4: 1–50 mg/L) solution were studied. The Langmuir isotherm showed the best-fitted correlation for the equilibrium data at all temperatures. Adsorption kinetics followed both the pseudo-second-order (RRB2 = 0.997) and Elovich model (RRB2 = 0.998). The average values of ΔGo, ΔHo, and ΔSo were found to be -30.828 kJ/mol, −68.07 kJ/mol, and −98.19 kJ/mol, respectively, showing that the adsorption process is exothermic, feasible and spontaneous. 4 g/L of impregnated resin gave effective removal (∼99 %) of RB-13 dye (50 mg/L) within 60 min, and change in solution pH did not affect removal percent significantly. The resin could be regenerated up to 2 cycles. In fixed bed column studies, the bed height (2–4 cm), flow rate (2.5–5 mL/min), initial dye concentration (20–50 mg/L) and bed temperature (303–323 K) were changed to see their effect. All breakthrough curves were well fitted by Thomas model. A column with 0.1127 m ID, 0.0199 m height and 0.066 kg impregnated resin will be sufficient to treat 10,000 L/day of RB-13 dye solution.

Cholinium chloride effect on ethanol-based aqueous biphasic systems: Liquid-liquid equilibrium and biomolecules partition behavior

Alcohols-based aqueous biphasic systems (ABS), such as ethanol-based ABS, are of great interest to the industry due to its low viscosity and suitability in separation and purification of biomolecules. Ethanol-based ABS using several salts were well described in the literature. In this work, the cholinium chloride ([N111(2OH)]Cl) was combined with the salts (NaH2PO4, K2HPO4, K3PO4, K2CO3, and K3C6H5O7) to obtain ions at equivalent concentrations. The cholinium chloride influence was evaluated on the ABS formation and biomolecules partition. For all systems, the [N111(2OH)]Cl affects the liquid-liquid equilibrium, and a decrease of the biphasic region was observed due to the reduction of the salt ionic strength when part of this was replaced by the cholinium chloride. Moreover, the top and bottom phases properties were properly described using analytical techniques to quantify all the phases’ components. Concerning the [N111(2OH)]Cl effect on biomolecules separation and purification process, several biomolecules namely alkaloids (caffeine and nicotine), amino acids (l-tryptophan, l-phenylalanine and l-tyrosine) and phenolic compounds (gallic acid and vanillic acid) were used as molecular probes. The partition coefficient (K) showed a strong influence of the [N111(2OH)]Cl presence on the partition behavior. Besides, in some cases, specific interaction between the [N111(2OH)]Cl and the biomolecules overcome the electrostatic interactions as the main driving force to the partition behavior. The obtained results suggest that [N111(2OH)]Cl can act in ABS to modulate the phases properties and partition behavior.

Physicochemical properties and interfacial dilatational rheological behavior at air-water interface of high intensity ultrasound modified ovalbumin: Effect of ionic strength

High intensity ultrasound (HIUS), as an efficient modification method, generally improves the interfacial properties of globular proteins. Herein, to better understand the intrinsic relationship between the foaming property and the interface behavior of HIUS-treated ovalbumin (OVA). The main purpose of this work was to investigate the correlation between the physicochemical properties of high intensity ultrasound (HIUS)-treated ovalbumin (OVA) and interfacial dilatational rheological behavior at air-water interface with different salt ionic strength. The results showed that HIUS treatment resulted in aggregation of OVA dominated by hydrophobic interaction. The size of HIUS-treated OVA gradually increased due to the charge shielding effect caused by the increase of salt ionic strength, while the surface net potential and free sulfhydryl content of the OVA particle were progressively reduced. As a result, the HIUS treated-OVA exhibited the highest diffusion rate and the amount of protein adsorbed at the air-water interface with salt ionic concentrations of 50 mM and 100 mM, respectively. On the other hand, the modified-OVA contact with the air-water interface led to an exposure of aromatic residues, the content of α–helix, β-helix, and β-turn decreased by 6.3%, increased by 10.3%, and decreased by 5.5%, respectively, and there was no salt ion strength dependence. Moreover, the conformational changes resulted in a thiol-disulfide interchange reaction between the OVA molecules at the interface, which was the main contribution to the viscoelastic properties of OVA absorbed layer. These findings provide better insights for an in-depth understanding of the foaming mechanism of ultrasound treated OVA.

One-step DNA purification and amplification on an integrated plastic microdevice for on-site identification of foodborne pathogens

In this study, we demonstrate a simple and facile method to enable DNA purification and amplification in a continuous step inside a thermoplastic microdevice. The innate property of thermoplastics was adopted to simplify DNA purification because negatively charged DNA can electrostatically interact with the induced positively charged surfaces of thermoplastics as a sample flows inside a microchannel; thus, the DNA purification step can be eliminated. We report the use of natural plastics for the selective adsorption of DNA and conduct a subsequent flow-through polymerase chain reaction (PCR) using a thermoplastic microdevice. Four thermoplastics—poly(methyl methacrylate) (PMMA), polycarbonates (PC), polystyrene (PS), and polypropylene (PP)—were selected as analytical models, and DNA adsorption phenomena on their pristine surfaces were examined. DNA was successfully immobilized onto the pristine thermoplastic surfaces, and the results were confirmed by fluorescent measurement and contact angle measurement and by performing PCR using a thermocycler. The electrostatically attached DNA was subsequently released from the pristine thermoplastic surface using a PCR reagent, which contained a low ionic strength salt as a component that could be used for DNA elution. The eluted DNA was then seamlessly amplified in the subsequent microchannel designed to perform flow-through PCR. The PCR products were collected by a microchamber connected at the end of the microchannel for on-site fluorescence detection. The PMMA microdevice was used to successfully purify and amplify a 210 bp target amplicon from a foodborne pathogen, Escherichia coli O157:H7, within 35 min. This study is expected to pave the way for developing an integrated monolithic thermoplastic microdevice suitable for rapidly identifying foodborne pathogens with reduced operation, decreased manufacturing cost, and enhanced device disposability.

Design and Validation of an Assay for Isotope Ratio Mass Spectrometry Analysis of Biologically Relevant Dissolved and Heat-Extracted Organic Carbon with Neutral Potassium Phosphate Buffer

ABSTRACTLabile soil dissolved organic carbon (DOC) and heat-extracted carbon (HEC) are sensitive indicators of changing soil organic carbon (SOC) stocks. Isotope ratio mass spectrometry (IRMS) is an important tool for studying SOC turnover and soil biological function. Several complications are involved in measuring DOC/HEC, for example salt ionic strength; solution pH; and anionic damage to elemental analyzer-IRMS. We evaluated a method for DOC/HEC analysis with 0.1 M potassium phosphate buffer (PPB). This method was strongly correlated with commonly used carbon (C) extractants for C quantification. Carbon-13 comparisons between DOC/HEC extracted with Milli-Q water and PPB were similar. The δ13C (‰) values of particulate OC and DOC were similar, whereas the relationship between humic OC and HEC was soil specific. An incubation experiment demonstrated that DOC/HEC δ13C (‰) successfully explained respired microbial carbon dioxide over 90 days. We conclude that this method represents an alternative for DOC/HEC quantification and δ13C (‰) analyses.

Synthesis, characterization, properties of N-succinyl chitosan-g-poly (methacrylic acid) hydrogels and in vitro release of theophylline

Although there was great interest in the biocompatible and stimuli responsive polymeric materials in oral drug delivery systems in recent years. The stimuli sensitive and swellable hydrogels have got striking attention as promising materials for site specific controlled drug delivery. In the present study, unique biodegradable, biocompatible, swellable, and pH responsive N-succinyl chitosan-g- Poly (methacrylic acid) hydrogels were prepared through free radical mechanism for oral administration of theophylline. In this method, ammonium persulfate (APS) and N, N′-methylenebisacrylamide (MBA) were used as initiator and crosslinking agent, respectively. The physical properties characterization was performed by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), field emission scanning electron microscope (FESEM), and rheometer. The results clearly confirmed the successful formation of N-succinyl chitosan-g- Poly (methacrylic acid) gel. In vitro degradation of hydrogels was found dependent on the ratio of monomers to crosslinking concentration. The effect of concentration of monomers, initiator, and crosslinking agent, pH and ionic strength of salts on swelling behavior was investigated. The results revealed the strong influence of these parameters, on swelling properties. Hydrogel prepared with high concentration of initiator and low crosslinking agent showed maximum swelling. The swelling showed good fitting to second order rate equation and the swelling kinetics data demonstrated the swelling behavior followed non-Fickian anomalous transport mechanism. Furthermore, theophylline loading and encapsulation efficiency (EE %) were found to be 14.5–23.5% and 58–94%, respectively. However, the in vitro release profile of theophylline was found dependent on pH, concentration of monomers, initiator, and crosslinking agent. The maximum release was found to be 90% in simulated intestinal fluid (SIF). The drug release data showed good fitting to Ritger-Peppas model. Moreover, the chemical activity of theophylline was also investigated and found that the drug maintained its chemical activity after in vitro release.

Adsorption of Cu(II) ion from aqueous solutions on hydrogel prepared from Konjac glucomannan

A novel adsorbent, biodegradable Konjac glucomannan-poly(acrylic acid) (KGMP) hydrogel, is prepared by Konjac glucomannan grafting with acrylic acid. The adsorption properties of the KGMP for Cu(II) ion removal from aqueous solutions are investigated. The experiments are performed under various impact factors such as initial Cu(II) ion concentration, pH, contact time, temperature and salt ionic strength. The Langmuir and Freundlich isotherm are employed to discuss the adsorption behavior. The result shows the equilibrium data obtained at different temperatures are represented perfectly by Langmuir isotherm model compared to the Freundlich isotherm models. The monolayer saturation adsorption capacities of KGMP for Cu(II) ion is found to be 27.1739, 30.2115, 34.1297 and 41.6667 mg g−1 at 298, 303, 308 and 313 K, respectively. Thermodynamic parameters such as ΔG, ΔH and ΔS are calculated. The kinetics studies show that adsorption process follows the pseudo-second-order model and the adsorption process is mainly controlled by both surface reactivity and intra-particle diffusion. FT-IR analysis shows that a large number of carbonyl, ester, and hydroxyl groups are included in the external surface of the KGMP, SEM indicates that the rough, irregular and pores of different size and shapes on surfaces of the KGMP are observed before adsorption. The present study indicates that the KGMP is an effective adsorbent for the removal of Cu(II) ion from aqueous solutions.

Biosorption of methylene blue from aqueous solution by natural Osmanthus fragrans powder

The potential of Osmanthus fragrans powder as a natural biosorbent was investigated for the removal of methylene blue (MB) from aqueous solution. The effects of various experimental conditions including contact time, adsorbent dose, initial MB concentration, solution pH, salt ionic strength, and temperature on the adsorption properties of O. fragrans powder were discussed. The adsorption kinetic data were modeled using pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics equations, indicating that the pseudo-second-order and intraparticle diffusion models could better describe the adsorption kinetics. Furthermore, adsorption equilibrium data were analyzed by Langmuir and Freundlich models, suggesting the Langmuir model presented a better correlation with the experimental data. The maximum adsorption capacities (qm) of O. fragrans powder for MB obtained from the Langmuir model were 155.52, 165.02, and 172.71 mg g−1 at different temperatures of 288.15, 298.15, and 308.15 K, respectively. Thermodynamic parameters such as standard free energy changes (ΔG°), standard enthalpy changes (ΔH°), and standard entropy changes (ΔS°) were also calculated. The results showed that the adsorption process was spontaneous and endothermic in nature. In addition, the possible adsorption mechanism of O. fragrans powder as adsorbent was proposed. The present study implies that O. fragrans powder were a promising candidate as novel biosorbents for the removal of MB from aqueous solution.

2015 4thTERMIS World CongressBoston, MassachusettsSeptember 8–11, 2015

2015 4^thTERMIS World CongressBoston, MassachusettsSeptember 8–11, 2015

Preparation of a new charged nanofiltration membrane based on polyelectrolyte complex by forced fouling induction for a household water purifier

A new technique is introduced for the preparation of composite membranes based on the salting-out effect. The concept of this new technique consists of three parts: (i) polymer precipitation by the salting-out effect, (ii) blocking the pore structure by pressurizing the precipitated polymer particles (polyelectrolyte), and (iii) deposition of opposite charged polyelectrolyte through ionic cross-linking (polyelectrolyte complex). The pore blocked polyelectrolyte has the role of a membrane, and we called this membrane preparation technique by forced fouling induction “precipitated solute pressurization” (PSP). In this study, water-soluble polymers that are all polyelectrolytes were used as coating materials, namely polyethylenimine (PEI), poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA), and poly(vinyl sulfonic acid) (PVSA). The polymer particles formed by the addition of Mg(NO3)2·6H2O were pressurized and flown to the surface of microporous polyvinyledene fluoride (PVDF) to prepare composite membranes under varying conditions of polyelectrolyte concentration, ionic strength of salt, pressure, annealing temperature, etc. The resulting membranes were characterized in terms of the flux and rejection for 100 ppm NaCl at 4 atm to determine their suitability for application in a household water purifier. A combination of PVSA and PEI polyelectrolyte complex produced by the PSP method showed the best performance of flux of 43 LMH and salt rejection rate of 83%, and this performance was maintained without loss of flux or rejection rate in a durability test carried out for 10 days.

Potential of alginate fibers incorporated with drug-loaded nanocapsules as drug delivery systems.

A major problem related to the fabrication of drug-loaded fibers by wet spinning is the significant loss of load when the drugs and spinning dopes are directly mixed together. We report a novel method to fabricate drug-loaded alginate fibers by spinning an aqueous mixture containing alginate and alginate nanocapsules incorporated with drugs. The alginate fibers exhibit spotty features of nanocapsules located close to the surface of the fibers. Adsorption experiments demonstrate the superabsorbent properties of the fibers, as well as the dependence of adsorption profiles on salt ionic strength. The adsorption processes of all the fibers are well-described by the pseudo-second-order kinetics model. Drug release tests show that the cumulative release amount increased with an increase in the proportion of nanocapsules present in the fiber. In addition, the burst release behaviors of the fibers incorporated with the nanocapsules were also diminished dramatically. This work suggests that adding nanocapsules containing drugs into the spinning dopes is a promising strategy to fabricate novel drug-loaded fibers for immediate drug delivery for wound dressing.