High Alkali Resistance Research Articles

Barrier functionality of SiO x layers and their effect on mechanical properties of SiO x /PLA composite films

Silicon oxide (SiO x ) films are widely used as barrier layers in different types of commodity packaging and have caught the interest of manufacturers and researchers alike owing to their high barrier functionality, good acid and alkali resistance, ability to withstand high-temperature and microwave treatments, and good transparency. In this study, we first synthesized polylactic acid (PLA) films by extrusion calendaring and then deposited a SiO x layer on the PLA films by plasma-enhanced chemical vapor deposition to prepare SiO x /PLA composite films. We then evaluated the barrier functionality of the SiO x layer and elucidated its underlying mechanism. We also analyzed its effect on the mechanical properties of the composite films by comparing the oxygen and water vapor transmission rates, soil degradation performances, and surface morphologies of the two types of synthesized films (uncoated and coated with SiO x ). The results showed that, because of the SiO x layer, the barrier properties and mechanical properties of the SiO x /PLA composite films were better than those of the uncoated films. In particular, the oxygen and water vapor transmission rates of the composite films were approximately 8–10 and 6–8 times lower, respectively, than those of the uncoated PLA films. In addition, the SiO x layer lowered the rate of soil degradation of the composite films, owing to which the weight-loss rates of the composite films were also lower than those of the uncoated films. Further, the tensile strengths and elongations at break of the composite films were higher because of the SiO x layer.

UV-initiated polymerization of acid- and alkali-resistant cationic flocculant P(AM-MAPTAC): Synthesis, characterization, and application in sludge dewatering

Abstract Cationic polyacrylamide (CPAM) has been the focus of research in environmental engineering field, particularly in sludge dewatering. However, poor stability of the existing cationic polyacrylamide has limited its application. In the face of the current complex sewage/sludge environment, CPAM with high efficiency, good stability and economy is remarkably desired in this field. In this study, a CPAM (PAMA) with high acid and alkali resistance was synthesized through copolymerization of acrylamide (AM) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) under ultraviolet (UV) radiation. The structure, morphology as well as the thermal decomposition property were analyzed through instrumental analysis. Furthermore, influencing factors of the copolymerization reaction were investigated and discussed in detail. The dewatering performance of PAMA was also evaluated by measuring the supernatant residual turbidity (RT), moisture content of the filter cake (FCMC), and specific resistance to filtration of the sludge (SRF). The RT, FCMC, and SRF reached 4.70 NTU, 71%, and 3.94 (1012 m Kg−1), respectively, at 40 mg L−1 of PAMA-25-15.1 and pH of 6.0. Furthermore, these indices did not increase with the pH changes of the original sludge, and which indicated a high acid and alkali resistance of PAMA.

Omics analysis and industrial application prospects of lignocellulose-degrading actinomycetes

Actinomycetes , a group of Gram-positive bacteria with high GC contents, play important roles in hyperthermal lignocellulose degradation in terrestrial habitats. A functional genomics analysis revealed that lignocellulose-degrading actinomycetes have more cellulases than hemicellulases and pectinases. Additionally, the enzymes capable of degrading cellulose were mainly cellobiohydrolases belonging to glycoside hydrolase family 6, with a small number of cellulases belonging to glycoside hydrolase families 9 and 48. In addition to glycoside hydrolases, large numbers of polysaccharide monooxygenases from auxiliary activity family 10 were also identified. Therefore, actinomycetes can efficiently degrade crystalline cellulose by continuous hydrolysis and oxidation mechanisms. Furthermore, some of these enzymes with multiple structural domains can be secreted quickly into the extracellular environment through the twin-arginine translocation system. These lignocellulolytic enzymes have excellent properties, such as high enzyme activity and high temperature and alkali resistance. Therefore, the characteristics and advantages of these actinomycetes in lignocellulose degradation and secondary metabolite production make them well suited for industrial applications.

Outdoor Growth Characterization of an Unknown Microalga Screened from Contaminated Chlorella Culture.

Outdoor microalgae cultivation process is threatened by many issues, such as pest pollution and complex, changeable weather. Therefore, it is difficult to have identical growth rate for the microalgae cells and to keep their continuous growth. Outdoor cultivation requires the algae strains not only to have a strong ability to accumulate oil, but also to adapt to the complicated external environment. Using 18S rRNA technology, one wild strain Scenedesmus sp. FS was isolated and identified from the culture of Chlorella zofingiensis. Upon contamination by Scenedesmus sp., the species could quickly replace Chlorella zofingiensis G1 and occupy ecological niche in the outdoor column photobioreactors. The results indicated that Scenedesmus sp. FS showed high alkali resistance. It also showed that even under the condition of a low inoculum rate (OD680, 0.08), Scenedesmus sp. FS could still grow in the outdoor raceway pond under a high alkaline environment. Even under unoptimized conditions, the oil content of Scenedesmus sp. FS could reach more than 22% and C16–C18 content could reach up to 79.68%, showing that this species has the potential for the biodiesel production in the near future.

Assembly of a high stable POM-based Cu(I) coordination polymer with visible-light-driven photocatalytic properties

A new coordination polymer (CP), [(PW12O40)2CuI6(trz)6]·H2O (1), has been prepared by hydrothermal method. Six Cu(I) ions are bridged by six trz molecules and six surface oxygen atoms of PW12 to generate a wheel-type CuI6 cluster, and each CuI6 cluster was capped with two PW12 anions to form a dumbbell-like second building block (SBB). 1 can remain intact in solution with pH range from 1 to 10, boiling water and boiling organic solvents, which shows the high heat stability, acid and alkali resistance. It also shows efficient visible-light-driven photocatalytic activities in the degradation of organic dyes.

Studies on Chemical Resistance of Sol-Gel Derived TiO2-Fe2O3 Thin Film Coatings on Glazed Ceramic Wall Tiles

ABSTRACTPresent study reports improvement in chemical resistance of glazed wall tile by solgel derived TiO2-Fe2O3 thin film coatings on the glazed surface. Effect of firing temperature on the chemical resistance of the coating was estimated after firing at different temperatures (600°, 700° and 800°C). The chemical durability of the coated substrate in comparison to the uncoated was tested against acidic attack by immersing them in 3% (v/v) hydrochloric acid solution and 10 wt% citric acid solution and basic attack by immersing them in 20 wt% potassium hydroxide solution in accordance with IS: 13630 (Part 8): 2006 standard. Further, the coated surface was also tested against basic attack in 1 N sodium hydroxide and 2.5 wt% detergent solution for seven days. The chemical durability was quantitatively estimated by measuring gloss at the surface at regular time intervals. Acid resistance was found to be good for coated substrate fired at all test temperatures. The coated substrate fired at 800°C showed high alkali resistance as compared to the uncoated substrate. FESEM and IR studies substantiate the corrosion resistance of the coated surface fired at 800°C.

Assembly of three stable POM-based pillar-layer CuI coordination polymers with visible light driven photocatalytic properties

Three new 3D POM-based CuI coordination polymers have been successfully prepared by a hydrothermal reaction. Compounds 1–3 show remarkably high heat stability, acid and alkali resistance, and effectively degrade methylene blue within visible light range.

Evaluation of Operational Properties of Composite Reinforcement Used in Concrete Structures

The paper is devoted to the study of composite reinforcement made of glass fiber and basalt fiber, in particular their operational properties under the aggressive alkaline lightweight aggregate concrete environment. Their thermal resistance being sufficiently less than that of the regular steel composites they may be used in three-layered building envelopes to provide enhanced thermal properties. However there is lack of data and experimental results on the topic. Previous research indicated high alkali resistance of basalt fiber reinforcement, but there is a need in further studies. For the objective of the composite reinforcement that is used as flexible connectors for layer wall panels, a series of experimental studies. Research data have shown satisfactory performance study of flexible links.

Effect of intermetallic diffusion between Pd and Ti–Al alloy on the performance of Pd/Ti–Al alloy composite membranes

The Ti–Al alloy possesses very desirable properties such as having a low density, high specific strength, good oxidation resistance at high temperatures, good acid or alkali resistance, and easy to process. Therefore, the use of porous Ti–Al alloys for the support of palladium composite membranes is an attractive alternative compared to stainless steel and ceramics. However, information on the intermetallic diffusion between Pd and the Ti–Al alloy at high temperatures is not yet available. In this work, the intermetallic diffusion between Pd and the Ti–Al alloy at high temperatures was studied using backscattered electron microscopy (BSE), EDX cross-sectional line scans, and electron probe microanalysis (EPMA). The results showed that neither diffusion of palladium nor diffusion of titanium and aluminum was observed after 40 h of treatment at 500 °C in hydrogen, which proved that the Ti–Al alloy effectively avoided the diffusion of metals compared to stainless steel. However, extensive intermetallic diffusion occurred between the Pd and the Ti–Al alloy after 40 h of treatment at 700 °C in hydrogen. Ti and Al atoms diffused from the metal-support interface into the Pd membrane layer. Pd also diffused into the Ti–Al alloy support. Significantly, the flux decline and the formation of pinholes on membrane surface correlated to the degree of intermetallic diffusion, and intermetallic diffusion would intensify leak formation.

A novel salt-tolerant endo-β-1,4-glucanase Cel5A in Vibrio sp. G21 isolated from mangrove soil

Although cellulases have been isolated from various microorganisms, no functional cellulase gene has been reported in the Vibrio genus until now. In this report, a novel endo-beta-1,4-glucanase gene, cel5A, 1,362 bp in length, was cloned from a newly isolated bacterium, Vibrio sp. G21. The deduced protein of cel5A contains a catalytic domain of glycosyl hydrolase family 5 (GH5), followed by a cellulose binding domain (CBM2). The GH5 domain shows the highest sequence similarity (69%) to the bifunctional beta 1,4-endoglucanase/cellobiohydrolase from Teredinibacter turnerae T7902. The mature Cel5A enzyme was overexpressed in Escherichia coli and purified to homogeneity. The optimal pH and temperature of the recombinant enzyme were determined to be 6.5-7.5 and 50 degrees C, respectively. Cel5A was stable over a wide range of pH and retained more than 90% of total activity even after treatment in pH5.5-10.5 for 1 h, indicating high alkali resistance. Moreover, the enzyme was activated after pretreatment with mild alkali, a novel characteristic that has not been previously reported in other cellulases. Cel5A also showed a high level of salt tolerance. Its activity rose to 1.6-fold in 0.5 M NaCl and remained elevated even in 4 M NaCl. Further experimentation demonstrated that the thermostability of Cel5A was improved in 0.4 M NaCl. In addition, Cel5A showed specific activity towards beta-1,4-linkage of amorphous region of lignocellulose, and the main final hydrolysis product of carboxymethylcellulose sodium and cellooligosaccharides was cellobiose. As an alkali-activated and salt-tolerant enzyme, Cel5A is an ideal candidate for further research and industrial applications.

Demineralisation for beet sugar solutions using an electrodialysis pilot plant to reduce melassigenic ions

Alkali metal cations were suspected of being highly melassigenic by holding sugar in molasses and preventing it from being recovered as crystalline sugar. An electrodialysis operation using a pilot plant equipped with an improved stack with a high alkali, temperature and organic resistance was conducted on Moroccan beet sugar syrup, juice and mother liquor B. The good performances of electrodialysis for each solution were shown. The quality of the three solutions was improved. On the basis of the running industrial conditions and on the electrodialysis results, a discussion was conducted concerning the better step to introduce electrodialysis.

Water-Repellent Thin Film with High Alkali Resistance Using the Sol–Gel Method for Ink Jet Printer Head

Water-repellent thin films from silane coupling agents have been widely used for inducing hydrophobicity on various surfaces. However, films obtained by conventional methods have poor durability against alkaline solutions. A new water-repellent thin film with high alkali resistance has been obtained for the first time by the sol–gel method using fluoroalkylmethoxysilane and 1,4-bis(trimethoxysilylethyl)benzene (BTB). The film maintained its hydrophobicity after soaking in alkaline ink with pH=8.9 at 70°C for 500 h. While the film maintained alkali resistance after being heat-treated at temperatures up to 300°C, that heat-treated at 400°C lost its alkali resistance. Fourier transform infrared measurements of the film indicated that ethyl groups in BTB molecules burn or oxidize at 400°C. It is speculated that the ethyl groups in the vicinity of siloxane bonds and the three-dimensional BTB polymer network prevent OH-ions from approaching and breaking the siloxane bonds in the film, and thus the film has high alkali resistance. We demonstrate that the new water-repellent film is applicable to the ink jet printer head.

Characterisation of dissolving pulp using designed process variables, NIR and NMR spectroscopy, and multivariate data analysis

Two processability variables, filter clogging and alkali resistance, were measured in a series of laboratory‐cooked viscose pulps. The pulps were also characterised by 13C‐CP/MAS solid state nuclear magnetic resonance (NMR) and near infrared (NIR) spectroscopy. Partial least squares (PLS) regression was used to investigate the information provided by the spectroscopic methods with respect to the processability measurements. The study showed that the alkali resistance, R18, of the pulp and the filter clogging value, Kw, of the laboratory‐prepared viscose can be modelled by NIR and multivariate data analysis (MVA). The alkali resistance, R18, of the pulp can also be calculated by NMR and partial least squares (PLS) regression. Analysis of the loading values in the PLS model showed that pulps with high alkali resistance have higher crystallinity than pulps with low alkali resistance. Analysis of variables of the cooking conditions showed that the chemical charge (Na2O) and pH should be kept low to give high alkali resistance, whereas high Na2O gives low filter clogging values.

Development of polymer concrete with polybutadiene matrix

Composite materials based on polymer binders and mineral fillers are widely used as structural chemically resistant, vibration and impact proof materials for industrial construction and chemical machinery. Up to the present hetero-chain polymers, unsaturated polyesters, polyepoxy and polyuretanes are applied as binders of such concrete-polymer composites. A new type of conglomerate composites-polymer concrete based on polybutadiene belonging to the liquid rubbers (RubCon—Rubber Concrete) has been enveloped and investigated. Such a rubber is used as a binder hardened by sulphur in the presence of special admixtures. Quartz sand and fly ash may be used as fillers and fine grained granites and basalt chipping as coarse aggregate. The resulting material has high acid and alkali resistance, toughness and adhesion to metal reinforcements, low water absorption and remarkable compression strength (80–90 MPa). A series of RubCon compositions are presented and industrial production technology for chemically resistant items and structures is worked out. The experimental samples of the material were successfully applied in real plant conditions at constant action of concentrated solutions of sulphuric acid and caustic potash.

Novel alkali-resistant porous glass prepared from a mother glass based on the SiO2-B2O3-RO-ZrO2 (R = Mg, Ca, Sr, Ba and Zn) system

The alkali-resistant porous glass was prepared from the Si02-B203-RO (R=Mg, Ca, Sr, Ba and Zn) system containing Zr02. The porous glass skeleton contained 2–3 mass% Zr02 and the alkali resistance was greatly improved over that of ordinary Vycor-type porous glass. Because of the high alkali resistance, the elimination of the colloidal Si02 and Zr02 gelated during the acid leaching of the phase-separated glass, was promoted and as a result, a very sharp pore-size distribution of porous glass was attained. In addition, the limit of the available pore size of porous glass was widely expanded.

Determination of glassfibre-reinforced cement durability

This paper deals with accelerated and long-term durability tests of glassfibre-reinforced cement composites. AR glassfibres REZAL, ESAP and SVUS 16, developed in Czechoslovakia, and Cem-FIL 1 fibres developed in the United Kingdom were applied. REZAL and ESAP fibres are of a low zirconium dioxide content, SVUS 16 and Cem-FIL 1 fibres are of a high zirconium dioxide content. The accelerated and the long-term ageing process were studied. The modulus of rupture was determined after 28, 90, 180, 360, 720 and 1080 days, and 6 years of ageing. The investigated glassfibre types have shown a high alkali resistance, mostly when dry curing was applied. Within the testing period of six years, glassfibres of low as well as high zirconium dioxide content show similar behaviour in the cement matrix.

4414183 Phenolic chelate resin, process for producing the same, and method of recovering heavy metal ions with the same

The phenolic chelate resin has a chelate-forming group wherein part or all of the hydrogen atoms in a primary and/or secondary alkylamino group introduced in a phenol nucleus are replaced by a methylenephosphonate group. Also disclosed is a process for producing such a chelate resin, and a method for recovering heavy metal ions with such a resin. The resin has particularly high selectivity for adsorbing uranium ions, as well as high heat, acid and alkali resistance as well as dimensional stability. The resin is very effective for recovering uranium from various uranium-containing solutions such as sea water, crude phosphoric acid fertilizer solutions, lowgrade uranium ore, waste water from uranium refining, and uranium mine water.

Peculiarities in the copolymerization of trioxane and epichlorohydrin under the influence of EtB⊖F3 A⊕lEt2

AbstractThis study deals with the copolymerization of trioxane (TO) and 1‐chloro‐2, 3‐epoxypropane (epichlorohydrin, ECH) catalyzed by EtB⊖F3 A⊕lEt2 in toluene. The rate of exhaustion of monomers during copolymerization was measured by gas chromatography. It was established that no homopolymers were formed. The copolymers obtained show a high alkali resistance, indicating a statistical distribution of the ECH in the polymer chain. During the first stages of the copolymerization the ECH is exhausted almost instantaneously, whereas TO is gradually exhausted, finally reaching a certain equilibrium depending both on the quantity of the initial ECH and on the temperature at which the process was carried out. Copolymerization is inhibited at increased ECH levels, and only homopolymerization occurs at a certain critical concentration of ECH.

Studies on the Relation between the Types of Soil and the Palatability of Paddy Rice : II. On the relation between chemical characters of rice grains and taste of cooked rice

Paddy rice was cultivated on several types of soil, and the relation between the taste and physicochemical properties of rice grains were studied. the results are summarized as follows. Peat soil and severely lodged plants grown on diluvial soil produced rice grains low in starch content and also those grains were low in alkali resistance. Owing to these characters of rice grains the gelatinization upon cooking was depressed and resulted in inferior taste of boiled rice. These properties of rice grains are considered to be resulted by the over-luxuriant growth caused by excess nitrogen in later stage of the growth of the rice plants as reported in the previous paper. Alluvial and tertiary soil on the contrary produced rice grains with high starch content and high alkali resistance and cooked rice showed good palatability. The lodged plants on diluvial soil produced rice grains high in total nitrogen and proteins, and the latter might have induced the collapse of outer layer and promoted the depression of softening of inner layer at cooking. The rice grains prduced on peat soil was next to the lodged rice grown on diluvial soil in the amount of globulin and had cosiderable amounts of other proteins. Owing to these characters, the rice grains grown on the peat soil showed depression of the amounts of dissolved materials and swelling at cooking under higher temperature and ultimately became inferior in softness. The rice grains prduced on alluvial soil was poor in their nitrogen content and the amounts of dissolved materials at low cooking temperature was high and both the high amounts of dissolved materials and good swelling at high cooking temperature resulted in the high softnese of the cooked rice. The rice grains on tertiary soil was high in proteins other than globulin and proved to be gelatinized easily in cooking at high temperature. As to the effect of nitrogen, the cases of lodged plants and rice grown on peat soil, the proteins especially globulin in rice grains appeared ot depress the amounts of dissolved materials and swelling. Globulin might do so more severely at higher temperature. The rice grains produced on volcano ash soil was deficient in phosphate especially in rice bran, and both starch content and alkali resistance were low, the depression of dissolved material and swelling in cooking were found to occur ultimately resulting to the considerably inferior in taste. In these rice grains, the mal-effects of proteins at cooking as stated above was probably negligible because of the low content of total nitrogen and globulin. The main factors of rice grains produced on different types of soils to be cooked soft, sticky and palatable are considered to be the content and alkali resistance of starch, and high content of proteins especially that of globulin might promote the inferiority of boiled rice. Amylose contents had little influence in these cases.

The structure and characteristics of Polynosic fibres

Abstract