CHARACTERISTICS OF FLOCCULES OF CLAY-SALT SLUDGE FORMED BY POLYACRYLAMIDE AND ITS COPOLYMERS

The main characteristics of aggregates formed during the flocculation of clay-salt slurry using polyacrylamide-based polymers with various types of charge and molecular weights were studied using a laser analyzer of particle size Lasentec D600L of the FBRM system. The effect of the polymer type on the size of the floccules formed and their density was shown. It has been established that when using non-ionic polyacrylamide and its anionic copolymers floccules with a size of 500-600 mm are formed, and when flocculated with a cationic reagent, the floccules do not exceed 300 mm It was shown that an increase in the molecular weight of the cationic polymer does not contribute to an increase in the size of the aggregates of the clay slurry particles. It has been proven that with the use of non-ionic polyacrylamide and its anionic copolymers, the density of floccules significantly decreases with increasing their size, which is an important property of fractal aggregates. If the charge density of anionic polymers increases, the aggregates density decreases, due to electrostatic repulsion between the negatively charged polymer and the negatively charged surface of the sludge. Analysis of the kinetics of the clay sludge flocculation process showed that when using non-ionic and anionic polymers, fast flocculation occurs, and the number of primary particles in the aggregate does not exceed several units. When using a cationic polymer, the filling of the intraflouclear volume with primary particles occurs due to the displacement of the liquid phase, which contributes to the formation of dense and compact floccules. The results obtained can be used for the selection of flocculant in order to improve the process of thickening clay-salt sludge in the production of potash fertilizers.

Optimizing the Dyeing of Silk Fabric with Gemstone Powder using Exhaustion Process

The silk fabrics were modified by a cationic reagent, N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride in order to prepare the fiber to be dyed with gemstone powder (i.e. malachite, lapis lazuli and jasper) by an exhaustion process. The effect of dyeing conditions such as temperature, dyeing time, pH and gemstone powder concentration on colour strength were investigated. Optimum results were achieved when dyeing at a liquor ratio of 1:100 at pH 3 (for malachite and jasper) or pH 5 (for lapis lazuli), at 90 ºC for 60 min. The color fastness to crocking of cationic treated silk fabric dyed with gemstone powder was fair to good, whereas the color fastness to washing was poor to fair. However, the colour fastness to light was very good. This study demonstrated that cationic treated silk fabric can dyed with gemstone powder by exhaustion process.

Homogeneous Synthesis of Cationic Chitosan via New Avenue

Using a solvent formed of alkali and urea, chitosan was successfully dissolved in a new solvent via the freezing–thawing process. Subsequently, quaternized chitosan (QC) was synthesized using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) as the cationic reagent under different incubation times and temperatures in a homogeneous system. QCs cannot be synthesized at temperatures above 60 °C, as gel formation will occur. The structure and properties of the prepared QC were characterized and quaternary groups were comfirmed to be successfully incorporated onto chitosan backbones. The degree of substitution (DS) ranged from 16.5% to 46.8% and the yields ranged from 32.6% to 89.7%, which can be adjusted by changing the molar ratio of the chitosan unit to CHPTAC and the reaction time. QCs inhibits the growth of Alicyclobacillus acidoterrestris effectively. Thus, this work offers a simple and green method of functionalizing chitosan and producing quaternized chitosan with an antibacterial effect for potential applications in the food industry.

Adsorption of Cr(VI) onto the Cross-Linked Cationic Starch and the Establishment of the Adsorption Isotherm and Kinetic Equation

Glycidyl trimethyl ammonium chloride (GTA) has been synthesized and used as cross-linked cationic reagent to prepare modified starch. The adsorption behavior of Cr(VI) onto the cross-linked cationic starch was studied systematically. The adsorption time and the temperature took great effects on the adsorption performance of the adsorbent. After a suitable time the adsorption could reach an equilibrium state and the adsorption capacity increased with the decrease of the temperature. The adsorption isotherm and the kinetic equation were established and they fit well with the Freundlich and Lagergren models, respectively. The used adsorbent was regenerated with acid medium and the recycling of the regenerated adsorbent has also been investigated.

Study on Structure of Amphoteric Starch and Its Reinforcing Effect on Secondary Fiber

In the presented work, a series of the phosphate amphoteric cassava starch were synthesized by a two-step semi-dry process with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CTA) as the cationic reagent and phosphate mixture as the anionic reagent. The structure of the amphoteric starch was characterized by FTIR and XRD. The reinforcing effects of the amphoteric starch on the secondary fiber were also studied. The results indicated that the reaction occurred not only in the amorphous region, but also in its crystalline region. When the cationic starch reacted with different amount of phosphates, the degree of cation substitution (DSc) of products was decreased with the dosage of the phosphates. When cationic starch with different DSc reacted with the same amount of phosphates, the degree of anion substitution (DSa) of products was decreased with the DSc. All the amphoteric starch showed reinforcing effect on the secondary fiber. The No. 7 sample showed better reinforcing effects on paper strength due to its higher total degree of substitution (0.095), proper DSa/DSc ratio (DSc = 0.067, DSa = 0.028) and interior modification of the starch granule. Compared with the control sample, the secondary fiber paper with 1.0 wt % (relative to dried pulp) of 7# modified starch showed 23.5%, 20.3% and 29.4% increases in tensile index, tearing index, and burst index, respectively.

Synthesis of Cationic Starch of High DS Using Metal Sodium in Place of Sodium Hydroxide

Cationic starch was prepared from maize starch, with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride used as cationic reagent, by our specific solvent process, which was different from dry procedure. In conventional solvent process, the solvents were hydrophilic and sodium hydroxide was employed as catalyst. Metal sodium as a substitute for sodium hydroxide in the synthesis of high DS (degree of substitution) cationic starch could be obtained using dioxane as solvent. A L9(34) orthogonal analysis was used in this work and results suggested the best combination of the reaction condition was A2B2C1, where the reaction time, temperature and weight of metal sodium were 2 h, 80 °C and 0.5 g, respectively. FTIR spectra revealed a special peak (1450 cm-1) of cationic starch confirming the existence of cationic groups in cationic starch. In a model of neutralizing the anionic groups, it revealed that the content of 0.8% (w/w) cationic starch was the optimum dosage.

Improvement of lysine effect on aldehyde-ruthenium red preservation and staining of the staphylococcal glycocalyx

The cationic reagent ruthenium red (RR) has been used to enhance ultrastructural preservation and staining of the bacterial glycocalyx. Lysine was needed in prefixation to preserve the polysaccharide glycocalyx material for the gram-positive, coagulase-negative staphylococci species. The inclusion of lysine in the prefixative of glutaraldehyde (GA)-RR enhanced observation of elaborate and extensive glycocalyx material. However, prefixation in 75 mM lysine in GA-RR is restricted to 20 minutes because gelling or solidification frequently occurs at longer intervals resulting in loss of sample. To improve the utility of this approach, the effect of the Karnovsky ratio of 2% paraformaldehyde to 2.5% GA was investigated.Cells of gram-positive, coagulase-negative staphylococci species, Staphylococcus epidermidis RP62, a polysaccharide producer, and Staphylococcus epidermidis M187-SN3, a polysaccharide negative mutant, were recovered from frozen storage and grown on blood agar plates. After 24 hours, cells were transferred to trypticase soy broth for 18 hours, and incubated at 35°C. Half of the cells were prefixed in 75 mM L-lysine, 0.075% RR, 2.5% GA in 0.1 M sodium cacodylate pH 7.2 for 20 minutes.