Coagulant Solution Research Articles

Preparation of chitosan microspheres by ionotropic gelation under a high voltage electrostatic field for protein delivery

Biodegradable microspheres have been widely used in drug/protein delivery system. In this paper, a modified ionotropic gelation method combined with a high voltage electrostatic field was developed to prepare protein-loaded chitosan microspheres. Bovine serum albumin (BSA) was chosen as a model protein. The preparation process and major parameters were discussed and optimized. The morphology, particle size, encapsulation efficiency and in vitro release behavior of the prepared microspheres were investigated. The results revealed that the microspheres exhibited good sphericity and dispersity when the mixture of sodium tripolyphosphate (TPP) and ethanol was applied as coagulation solution. Higher encapsulation efficiency (>90%) was achieved for the weight ratio of BSA to chitosan below 5%. 35% of BSA was released from the microspheres cured in 3% coagulation solution, and more than 50% of BSA was released from the microspheres cured in 1% coagulation solution at pH 8.8. However, only 15% of BSA was released from the microspheres cured in 1% coagulation solution at pH 4. The results suggested that ionotropic gelation method combined with a high voltage electrostatic field will be an effective method for fabricating chitosan microspheres for sustained delivery of protein.

Ionic Liquids in the Preparation of Biopolymer Composite Materials

Preliminary data are shown for the mechanical properties of cellulose and silk composite blends with and without nanomodifiers. Composite strength increases with increasing cellulose concentration for samples created with two different coagulation solutions. In general, samples containing > 30% silk are difficult to handle and test because they are extremely brittle. The addition of nanocomposites may increase overall strength of samples, but is dependent on the morphology of the nanomaterial added.

Strongly differentiable solutions of the discrete coagulation–fragmentation equation

We examine an infinite system of ordinary differential equations that models the binary coagulation and multiple fragmentation of clusters. In contrast to previous investigations, our analysis does not involve finite-dimensional truncations of the system. Instead, we treat the problem as an infinite-dimensional differential equation, posed in an appropriate Banach space, and apply perturbation results from the theory of strongly continuous semigroups of operators. The existence and uniqueness of physically meaningful solutions are established for uniformly bounded coagulation rates but with no growth restrictions imposed on the fragmentation rates.

Mechanically stirred single‐stage column for continuous gelation of colloidal systems

AbstractA continuous and fast gelation unit, referred to as a single‐stage mechanically agitated gelation column has been proposed to perform gelation of colloidal systems. A fluorinated polymer latex, MFA®, has been used. The column is initially filled with a coagulant solution at a concentration that fully destabilizes the colloid. Under agitation, the colloid is fed continuously to the discharging region of the agitator blades where it forms flocs of gel by mixing with the coagulant. If the density of the colloidal particles is larger than that of water, the flocs settle downward to the bottom of the column and flow out of the unit for further treatment or direct applications. Timescale analysis of the phenomena involved in the column has been carried out to understand the complex interplay between gelation and mixing. Various gelation regimes have been identified, which can interpret the observed gelation behavior in the column. © 2008 American Institute of Chemical Engineers AIChE J, 2008

GPE 2007 - Utilization of the Coagulation Diagram in the Evaluation of the Natural Organic Matter (NOM) Removal for Obtaining Potable Water

The natural organic matter (NOM) is a mixture of many organic compounds that can be dispersed in superficial water. The NOM is due to the compounds formed in the biologic degradation process of the vegetable organic matter and its interaction with the clay and the other hydrographic basin soil constituents, besides algae and other microorganism activity. Many researchers have obtained results that indicate that the coagulation/flocculation process is an effective process in the NOM reduction without committing the non-stabilization colloidal particles. So, with the intuit to guarantee a better final water quality in the water treatment plants, different studies were evaluated based on the coagulation diagram for obtaining the best concentration of the chitosan coagulant as function of the pH for the NOM removal for obtaining potable water. The data for the coagulation diagram construction will be obtained by a series of tests in a jar-test apparatus. Different concentrations of the coagulant solution (0.1% w/v of chitosan) will be studied. The pH will be varied (4.0 – 8.5) with sodium hydroxide solution (NaOH) and hydrochloric acid (HCl) 25 and 50%. The rapid mixture gradient, the coagulation time, the slow mixture gradient and the flocculation time will be maintained constant during this experiment. The process efficiency will be evaluated by the color, turbidity and compounds with absorption in UV-254nm removal. The best results of removal were found for the chitosan in the concentration of 1.0mg/L and pH between 4.0-5.0, approximately.

Fibrous poly(chitosan- g- dl-lactic acid) scaffolds prepared via electro-wet-spinning

dl-Lactic acid was grafted onto chitosan to produce poly(chitosan- g- dl-lactic acid)(PCLA) copolymers. These PCLAs were then spun into submicron and/or nanofibers to fabricate scaffolds using an electro-wet-spinning technique. The diameter of fibers in different scaffolds could vary from about 100 nm to around 3 μm. The scaffolds exhibited various pore sizes ranging from about 1 μm to less than 30 μm and different porosities up to 80%. Two main processing parameters, that is, the concentration of PCLA solutions and the composition proportions of coagulation solutions, were optimized for obtaining desired scaffolds with well-controlled structures. The tensile properties of the scaffolds in both dry and hydrated states were examined. Significantly improved tensile strength and modulus for these fibrous scaffolds in their hydrated state were observed. The data collected from in vitro rabbit-fibroblast/scaffold culture showed that there were no substantial differences in the viability, density and distribution of cultured fibroblasts between PCLA scaffolds and pure chitosan scaffolds.

Hydrogel–elastomer composite biomaterials: 4. Experimental optimization of hydrogel–elastomer composite fibers for use as a wound dressing

We report a novel 3-D cavity wound dressing based on a hydrogel-elastomer Interpenetrating Polymer Network (IPN) fabricated into an open-mesh architecture. IPN fibers used to form the dressing were produced by a wet spinning method and optimized in two steps. A factorial experiment was first conducted to identify key parameters that controlled fiber properties. We observed that gelatin wt% played a major role in determining fiber yield, swelling, strength and stability. Other contributing factors included coagulation solution composition, gelatin type, and pre- and post-UV irradiation time. The key factors were then further evaluated individually to achieve a condition that provided a combination of good swelling, mechanical properties and stability. The concentration of the gelatin/HydroThane extrusion solution significantly affected fiber formation and properties, presumably due to the changes in solution viscosity. The effects of pre-UV irradiation were also ascribed to its impact on the solution viscosity and became negligible at higher concentrations when viscosity is mainly controlled by concentration. The composition of the coagulation bath influenced the fiber swelling and wet stress. These results, taken together with our previous studies, suggest that our biomaterial would provide a combination of mechanical and swelling properties suitable for wound dressing applications.

해양심층수를 이용한 다시마 추출물의 두부응고제 특성

We investigated the characteristics of various Tofu coagulants extracted from sea tangle using treated deep ocean water (DOW) as the solvents. The coagulants were typical solutions extracted from sea tangle using raw DOW and strongly electrolyzed acidic (SAC) or alkaline (SAK) water. The total dissolved solids (TDS), NaCl and electric conductivity were increased in the coagulant solution extracted by SAC than the others. In the coagulant solutions extracted by acidic electrolyzed solvent, aspartic acid content (13.5 mg/100 g) was higher than others (11.2 and 12.1 mg/100 g). The Tofu obtained using coagulants extracted with treated DOW had the water contents ranging from 79.55% to 80.04%. The contents of crude protein (12.1 g/100 g) and Na, Ca, K and Mg were relatively higher than general Tofu commercially available. Therefore, coagulant solutions extracted from sea tangle using treated DOW can be used to develop natural high-grade tofu for practical use.

Preparation and characterization of PVDF–PFSA blend hollow fiber UF membrane

Polyvinylidene fluoride (PVDF)–perfluorosulfonic acid (PFSA) blend hollow fiber ultrafiltration (UF) membranes were prepared by wet-spinning method using pure water as an external coagulation solution. Coagulation kinetics of PVDF–PFSA–DMAc system was measured by light transmittance experiment. Using PEG10000 ( M w = 10,000), lysozyme ( M w = 14,400), PEG20000 ( M w = 20,000) and BSA ( M w = 67,000), the separation performances of PVDF–PFSA blend hollow fiber UF membranes were obtained. Based on the experimental results, the delayed demixing process was observed for the dope solution M-1 without PFSA-H while the instantaneous demixing process was observed for the others with PFSA-H in the dope solutions M-2 to M-6. The precipitation rate increased with the increment of the PFSA-H concentration in PVDF–PFSA dope solution. The bore fluid solution with 95:5 DMAc:H 2O resulted in single finger-like voids for PVDF–PFSA-H UF membrane. The pure water permeation flux of PVDF–PFSA-H UF membranes firstly increased from <0.1 × 10 −5 to 119.1 × 10 −5 L m −2 h −1 Pa −1 (<0.1 to 119.1 L m −2 h −1 bar −1) for M-1 to M-4(1) and 137 × 10 −5 L m −2 h −1 Pa −1 (137 L m −2 h −1 bar −1) for M-4(2), and decreased from 119.1 × 10 −5 to 79 × 10 −5 L m −2 h −1 Pa −1 (119.1 to 79 L m −2 h −1 bar −1) for M-4(1), M-5 and M-6 as the PFSA-H concentration changed from 0% to 5% and total PVDF–PFSA-H concentration was 20 wt.%. The molecular weight cut-off (MWCO) of PVDF–PFSA blend hollow fiber UF membranes spun from 20 wt.% PVDF–PFSA-H concentration with 3–5 wt.% PFSA-H was about 20,000 while that spun from 22 wt.% PVDF–PFSA-H or PVDF–PFSA-Na concentration with 5 wt.% PFSA-H or PFSA-Na was about 10,000. As the W PFSA-H/ W PVDF increases from 2/18 to 5/15 for M-3–M-6, J BSA/ J w increases from 0.53 to 0.79. The anti-fouling property of PVDF–PFSA-H blend UF membrane is superior to PVDF–PFSA-Na blend membrane. Based on FTIR spectra, PFSA-H existed in PVDF–PFSA blend hollow fiber UF membranes. There is no obvious variation of the intensity of the characteristic peak at 983 cm −1 assigned to C–O–C group of PFSA-H molecules. This also illustrated that PVDF–PFSA-H blend hollow fiber UF membranes were stable.

Wet spinning of pre-doped polyaniline into an aqueous solution of a polyelectrolyte

We report the preparation of highly conductive polyaniline (PANi) fibers produced via a wet-spinning process into different coagulation solvents or solutions. To the best of our knowledge, this paper shows the first successful spinning of PANi fibers into an aqueous environment where no post-doping of the fiber is needed. Aqueous solutions of different salts, small anionic molecules, small cationic molecules, polycations, and polyanions are studied. Best results are obtained using an aqueous solution of a polyanion as a coagulation bath. The resulting fibers exhibit good length, stability, and morphology. An in depth study of the relationship between the fiber properties and the concentration of a polyanion in the aqueous bath (poly(sodium 4-styrenesulfonate), PSS) is performed. It is shown that PSS solutions stabilize the PANi fibers without dramatically changing the conductivity of the fibers. It is believed that this stabilization is a result of numerous ionic interactions between cationic centers on the PANi and anionic groups on the polyanion. This new preparation method should be industrially viable.

Fabrication of semipermeable hollow fiber membranes with highly aligned texture for nerve guidance

In order to improve the guidance potential of a nerve entubulation bridging device, highly aligned textures were formed on the inner surface of semipermeable hollow fiber membranes (HFMs) during the wet phase inversion process. By precisely controlling the fabrication parameters, such as polymer solution flow rate, coagulant solution flow rate, and the air-gap distance, also called drop height, different-sized aligned grooves can be fabricated on the inner surface of HFMs. Preliminary studies using in vitro dorsal root ganglion (DRG) regeneration assay showed that both the alignment and outgrowth rate of regenerating axons increased significantly on HFMs with aligned textures compared to those on HFMs with a smooth inner surface. Studies in progress are evaluating axonal outgrowth and regeneration using in vivo sciatic-nerve and spinal-cord-injury models.

Preparation and Characterization of Three Dimensions Chitosan Rods with Biomimetic Layered Structure Similar to Annual Ring

Inspired by the annual ring structure of wood, a cylindrical semi-permeable chitosan gel membrane was chosen as a template to separate chitosan solution from NaOH coagulation solution. Three dimensions (3D) chitosan (CS) rods (Φ5×80 mm) with layered structure similar to annual ring of wood were prepared via a novel and simple in-situ intermittently precipitating method. These chitosan rods presented quite good mechanical properties with bending strength and shear strength of 102MPa and 31MPa respectively. The concentric circles layered structure was approved by SEM characterization, the mechanism of preparation and the relationship between structure and properties of chitosan rods were also discussed.

Influence of some additives to aluminium species distribution in aluminium coagulants

Aluminium ions hydrolyse and polymerise into different species in water. Main aluminium species in aluminium coagulant solutions are monomeric Al species (Al 1) and polymeric Al species Al 13 O 4 ( OH ) 24 7 + (Al 13). The aluminium species distribution in coagulant solutions can be influenced by many parameters. This paper studies influences of concentrations of total aluminium species (Al t) and other species—OH −, polysilicic acid and ferric species, which were added in aluminium coagulant solutions, on the aluminium species distribution through 27Al nuclear magnetic resonance (NMR) analysis. Results show that only Al 1 and no Al 13 exist in coagulant solutions at higher Al t concentrations (over 1 mol l −1), while both species exist at lower Al t concentrations (0.1 mol l −1). The increase of OH/Al value (molar ratio) increases the concentration of Al 13 in coagulant solutions, while the addition of polysilicic acid and ferric species decreases the concentration of Al 13.

Development of a rapid titration method for predicting optimal coagulant concentration for filled tofu.

A rapid titration method was developed for predicting the optimal coagulant concentration for making filled tofu. Cooked soymilk (350 mL, 20 degrees C) in a 400 mL beaker was stirred by a magnetic stirrer to form a swirl. The quick-acting coagulant solution (20.0 Brix) was added into the soymilk at 1.0 mL/min. The swirl depth decreased when the soymilk viscosity increased as a result of increasing the concentration of coagulant in the soymilk. At a suitable stirrer speed, the swirl finally disappeared but the soymilk still maintained rotation, and then the swirl reappeared after around 1 min. The critical point of coagulant concentration (CPCC) was calculated on the basis of the volume of coagulant consumed to get the swirl to disappear. The influences of several factors on the CPCC were investigated, including coagulant addition rate, soymilk temperature, soymilk concentration, soymilk volume, stir bar length, and container size. For validation, 33 soybean samples were used to determine their CPCCs and make filled tofus. The results indicated that CPCC was a characteristic parameter of soymilk and could be used as an effective indicator for predicting optimal coagulant concentration.

Effects of raw water conditions on solution-state aluminum speciation during coagulant dilution

The speciation of aluminum in solutions of alum and various prehydrolyzed, aluminum-based water treatment coagulants was investigated by 27Al NMR at 5°C and 25°C. Alum solutions were seen to contain only mononuclear species including an AlSO 4 + complex, while the prehydrolyzed coagulant solutions contained polynuclear aluminum species, as well. The relative proportions of both polynuclear species and AlSO 4 + complex decreased in cold water. The presence of organic matter had little effect on the speciation of aluminum in diluted alum, but markedly reduced the relative proportion of the tridecamer species in the prehydrolyzed coagulant solutions. The relationship between Al speciation in the coagulants and organic matter removal during jar tests was considered, and the possible role of sulfate in both the formation of the tridecamer species and the effect of organic matter on coagulation efficiency was discussed.

Preparation and characterisation of polyaluminium silicate chloride coagulant

To improve the coagulation efficiency for water treatment purposes, a composite aluminium‐silicon coagulant, the polyaluminium silicate chloride was prepared and characterised. The preparation process included the preparation of polyaluminium chloride and polysilicic acid followed by the compounding of the two solutions. The prepared polyaluminium silicate chloride coagulant solution had an aluminium concentration of 0.10 mole per litre, hydroxyl to aluminium molar ratios between 0.5 and 2.0, and silicon to aluminium molar ratios between 0.025 and 0.075. Aluminium‐27 nuclear magnetic resonance spectroscopy, photon correlation spectroscopy, streaming current measurement, jar tests and pilot‐scale coagulation tests were employed to study the aluminium speciation, particle size distribution, electrokinetic and coagulation properties of this composite coagulant. In comparison with polyaluminium chloride, polyaluminium silicate chloride contains less polynuclear aluminium [AlO4Al12(OH)24(H2O)12]7+ and shows smaller charge neutralisation capacity. However, its particle size shows a significant increase, which enhances the coagulation efficiency. The results show that polyaluminium silicate chloride is an efficient composite coagulant for water treatment.

Recovery of Kraft Lignin from Aqueous Solutions with Oxotitanium Sulfate, Aluminum Sulfate, and Their Mixture

Coagulation recovery of kraft lignin from aqueous solutions with oxotitanium sulfate, aluminum sulfate, and a composite coagulant based on their mixture was studied in a wide range of coagulant concentrations and solution pH values.

New application of a traditional analytical method--arsenic removal from water works sludge during iron(III) chloride coagulant production.

The Marsh Test, the original means of determination of arsenic by hydride generation, has been modified to remove arsenic from water works sludge, with iron used instead of zinc as the main agent. Water works sludge (main compound iron(III) oxyhydrate) generated during groundwater treatment can be enriched in arsenic up to several gkg(-1). Acidic dissolution of this sludge to produce FeCl3 coagulant liberates the arsenic. Addition of elemental iron reduces this dissolved As(V) mainly to dispersed elemental As(0) particles, which can be removed by filtration. If the reaction temperature is kept below 50 degrees C, more than 99% of the arsenic can be removed from the coagulant solution and less than 10% will escape as gaseous arsine (AsH3). Severe foaming and silicic acid gel formation occurs during the acidic dissolution, however. For technical and economic reasons the use of the water works sludge for FeCl3 coagulant production is not competitive when compared with other recycling methods.

Preparation and characterization of chitosan/poly(vinyl alcohol) blend fibers

AbstractChitosan and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose‐type spinneret at 25°C into a coagulating bath containing aqueous NaOH and ethanol. The influence of coagulation solution composition on the spinning performance was discussed, and the intermolecular interactions of blend fibers were studied by infrared analysis (IR), X‐ray diffraction (XRD), and scanning electron micrograph (SEM) and by measurements of mechanical properties and water‐retention properties. The results demonstrated that the water‐retention properties and mechanical properties of the blend fibers increase due to the presence of PVA in the chitosan substract, and the mechanical strength of the blends is also related to PVA content and the degree of deacetylation of chitosan. The best mechanical strength values of the blend fibers, 1.82 cN/d (dry state) and 0.81 cN/d (wet state), were obtained when PVA content was 20 wt % and the degree of deacetylation of chitosan was 90.2%. The strength of the blend fibers, especially wet tenacity could be improved further by crosslinking with glutaraldehyde. The water‐retention values (WRV) of the blend fibers were between 170 and 241%, obviously higher than pure chitosan fiber (120%). The structure analysis indicated that there are strong interaction and good miscibility between chitosan and poly(vinyl alcohol) molecular resulted from intermolecular hydrogen bonds. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 80: 2558–2565, 2001

Coagulation Mechanism of Salt Solution-Extracted Active Component in Moringa oleifera Seeds

This study focuses on the coagulation mechanism by the purified coagulant solution (MOC-SC– pc) with the coagulation active component extracted from M. oleifera seeds using salt solution. The addition of MOC-SC- pc tap water formed insoluble matters. This formation was responsible for kaolin coagulation. On the other hand, insoluble matters were not formed when the MOC-SC- pc was added into distilled water. The formation was affected by Ca 2+ or other bivalent cations which may connect each molecule of the active coagulation component in MOC-SC- pc and form a net-like structure. The coagulation mechanism of MOC-SC- pc seemed to be an enmeshment of Kaolin by the insoluble matters with the net-like structure. In case of Ca 2+ ion (bivalent cations), at least 0.2 mM was necessary for coagulation at 0.3 mg C l −1 dose of MOC-SC- pc. Other coagulation mechanisms like compression of double layer, interparticle bridging or charge neutralization were not responsible for the coagulation by MOC-SC- pc.