Aqueous Caustic Soda Research Articles

Long-lasting antistatic hydrophilic polyethylene terephthalate fabric using greener reagents

AbstractPolyethylene terephthalate (PET) is the most common synthetic polymer used in the textile sector by virtue of its unique superior performance attributes. However, the comfort characteristics of PET fabrics, such as their inadequate sweat-absorbing capability, low affinity for most dyestuff classes, and susceptibility to the accumulation of electrostatic charge, make them unfavorable compared to natural fibers. Rendering PET fabrics with hydrophilic and antistatic properties is difficult due to the lack of reactive functional groups. Herein, a long-lasting eco-friendly strategy to impart some desirable properties to PET fabrics was developed. The PET fabric was saponified in an aqueous caustic soda solution, followed by treatment with an amino acid, namely lysine, aspartic acid, serine, tyrosine, or cysteine, as a coupling agent, and eventually, the fabric was finished with the protein biopolymer gelatin using the pad-dry-cure method. The effects of treatment of PET fabric with the aforementioned reagents on its surface hydrophilicity, roughness, antistatic, thermal stability, ultraviolet protection, air permeability, yellowness, bending stiffness, and tensile properties were monitored. The discrepancy between the chemical structures of the untreated and finished fabrics was determined using Fourier transform infrared spectroscopy as well as by determining the carboxylic and nitrogen contents. The morphological and crystal structures of the treated fabrics were examined using scanning electron microscopy and X-ray diffraction pattern, respectively. The results indicate that a maximum add-on was obtained upon treatment of the saponified PET fabrics with 0.5 M lysine followed by 7.5% (on the weight of the fiber) gelatin using the pad-dry-cure method.The finished PET fabrics exhibited improved hydrophilic and antistatic properties with adequate protection against UV rays.Ingeneral, treatment of PET fabrics with gelatin, using a bi-functional amino acid as a coupling agent, is an effective and durable method to improve some performance and comfort features of PET fabric without having a remarkable negative effect on the fabric’s mechanical properties.

Analysis of parameters technological gas emissions neutralization during the sintering process of phosphorite agglomerate

This study analyzes the specific properties and technological parameters of gas emissions from chemical-energy processes [1], considering the volume and content of toxic components, as well as the operating experience of gas emission purification systems at existing phosphate plants. A three-stage system of apparatuses is studied for gas purification: an ensemble of single cyclones, foam aggregates irrigated with aqueous caustic soda solution. It is established that cyclones are the most suitable apparatus for dry gas cleaning, and that their diameter should be no more than one meter to increase the efficiency of cleaning. It has been demonstrated through scientific research that when cleaning phosphorite sintering gases, which have a volume exceeding the capacity of a single cyclone, it is necessary to use group cyclones. These are several cyclones combined into one group with a common hopper. It is recommended that the cyclone speed be increased by approximately 50% in comparison to the standard speed, which contributes to an increase in the efficiency of the separation of impurities in the purified gas.

Simulation of the Effect of Various Operating Parameters for the Effective Separation of Carbon Dioxide into an Aqueous Caustic Soda Solution in a Packed Bed Using Lattice Boltzmann Simulation

Nowadays, reduction of the carbon footprint in the environment is one of the most challenging issues, and thus several technologies have been adopted for the effective arrest of carbon dioxide (CO2...

이온성액체 기반 SO2흡수제 개발 동향

지구온난화에 대한 해결방향으로 배가스 중 이산화탄소를 분리 및 저장하는 연구가 활발하게 진행되고 있다. 이산화탄소 흡수액은 주로 MEA와 같은 아민계 화합물이 사용되는데 이때 배가스에 함께 포함된 이산화황 (<TEX>$SO_2$</TEX>)은 <TEX>$CO_2$</TEX> 흡수액의 성능을 저하시키는 원인이 되거나 공기중으로 배출될 경우 산성비의 원인이 된다. 지금까지의 <TEX>$SO_2$</TEX> 흡수제로는 Ca계 고체 흡수제가 주로 사용되었는데 최근 액체 흡수액으로 이온성액체가 주목받고 있다. 이온성액체는 이온으로 이루어진 특징으로 인하여 넒은 액체 범위 및 극성가스에 대하여 높은 용해성을 갖고 있다. 본 총설에서는 최근 발표된 <TEX>$SO_2$</TEX> 흡수제로 이온성액체에 대하여 그 구조 변화에 따른 <TEX>$SO_2$</TEX> 흡수량 변화 그리고 흡수 메커니즘에 대하여 살펴보았다. Separation of <TEX>$SO_2$</TEX> from the flue gases of fossil fuel power plants are important issue because of its strong environmental impact. Industrially, <TEX>$SO_2$</TEX> is being removed with a slurry of limestone, lime or aqueous caustic soda. However, these scrubbing processes possess several drawbacks such as the generation of huge amount of wastewater and the production of metal salts. Recently, ionic liquids have gained increasing interest as an absorbent for acid gas, <TEX>$CO_2$</TEX> and <TEX>$SO_2$</TEX>. In this review, we have introduced the recent progress of ionic liquids as a <TEX>$SO_2$</TEX> absorbent.

Recent Sodium Technology Development for the Decommissioning of the Rapsodie and Superphénix Reactors and the Management of Sodium Wastes

The Commissariat à l’Energie Atomique (CEA) has recently developed and/or conducted experiments on several processes in support of the decommissioning of two French liquid-metal fast reactors (LMFRs), Rapsodie and Superphénix, as well as on the treatment of CEA sodium wastes. CEA has demonstrated that it is possible to define appropriate and efficient processes to meet the different situations encountered in decommissioning LMFRs. Mechanical techniques derived from standard technologies have been successfully applied to fast reactor decommissioning to complete primary vessel draining from sodium. In addition, specific chemical processes have been developed to deal safely with metallic sodium reactivity. Sodium-contaminated equipment has been successfully cleaned by reacting sodium with water mist in an atmosphere with carbon dioxide to form inert sodium carbonate. Bulk sodium has been successfully converted into aqueous caustic soda by injection of liquid-metallic sodium into sodium hydroxide solution. Several processes were also defined to deal with specific sodium wastes. In all cases the principle is based on a sodium/water chemical reaction where the released hydrogen and heat are controlled. With the development of a wide variety of processes, all steps in the decommissioning of LMFRs are assumed to be now properly mastered.

Extraction of Naphthenic Acid from Kerosene Using Porous and Nonporous Polymeric Membranes

Abstract A systematic study of membrane-assisted extraction of naphthenic acids from hydrocarbon fractions by aqueous caustic soda using both porous and nonporous membranes is reported. The effects of hydrodynamic factors, concentration of naphthenic acids and caustic soda, and temperature on the transmembrane flux are discerned. The film model is used to determine the intrinsic mass transfer characteristics of the membranes. ∗ Present address: Scientist Fellow, Environmental Bitechnology Division, National Environmental Engineering Institute, Nehru Marg, Nagpur, India.

Production of New Cellulosic Filament Spun from Cellulose/aqueous NaOH Solution. (part 3). Spinning of Alkali Soluble Cellulose-Caustic Soda Solution System Using Sulfuric Acid as Coagulant.

Novel cellulose filaments from aqueous caustic soda solution were spun by sulfuric acid coagulation method on bench scale. In this spinning, the concentration of sulfuric acid was found to seriously affect on the structure and tensile properties of the yarn obtained. When draft ratio is constant, both degree of orientation and packing density which are measured as the degree of swelling of never dried yarn increase with an increase of the sulfuric acid concentration and the time of coagulation. It was inferred that dehydration effect of the sulfuric acid markedly increases with an increase of its concentration. The dehydration of the sulfuric acid gives rise to high shrinking stress in the coagulating yarn, leading to high orientation and packing density. Consequently, the yarn obtained showed high tensile strength and high initial Young's modulus. The shrinking stress due to the dehydration effect was calculated and it was found that the stress drastically increases when sulfuric acid concentration was 40-50wt%. Based on these facts, cellulose filament with tensile strength in dry state higher than that of regular viscose rayon was successfully obtained using sulfuric acid with concentration of 50-65wt%.

The hydrolysis of polyester-ether homologs by an alkali.

The rate of hydrolysis of aromatic polyester-ether homologs in an aqueous caustic soda solution was investigated at temperatures of 60°C to 90°C, and the activation energy for the reaction was determined. The results indicate that the polyester-ether homologs have higher alkali resistances than poly(ethylene terephthalate). The activation energy for hydrolysis of poly (ethylene 1, 2-diphenoxyethane-p, p′-dicarboxylate) [B type polyester-ether] was estimated as high as 22.6kcal/mole.

PREPARATION OF FIBROUS WEAK ACIDIC CATION EXCHANGER

A preparation of fibrous weak acidic exchanger is carried out by chemically modifying acrylic fiber as follows:1) Acrylic fibers, as raw material, are treated with aqueous hydrazine hydrate solution for the crosslinking.2) Then the fibers are treated with aqueous caustic soda solution to introduce carboxyl group on the hydrolysis of residual nitrile groups. The results thus obtained are as follows.a) The fibrous ion exchanger obtained is an amphotenic ion exchanger. However, since much more cation exchange groups than anion exchange groups can be introduced, it can practically be used as a cation exchanger.b) The ion exchange capacity of the fibrous ion exchanger obtained is about 6-9 meq/g and the weaker hydrazine treatment gives the higher ion exchange capacity and water swelling ratio. On the contrary, the mechanical strength of the fibrous ion exchanger goes down.c) After the hydrazine hydrate treatment the color of the fiber becomes light yellow and subsequently changes into orange in the air. Immediately after the caustic soda treatment, the color is light yellow but it changes into light red in the air.

Reaction kinetics for the saponification of oxidized paraffin with aqueous caustic soda

1. A study has been made of the reaction kinetics in the saponification of oxidized paraffins with aqueous sodium hydroxide solutions. It has been shown that, for the case of irreversible saponification reactions, a sixth-order equation is applicable; this order is a timewise order. The true order of the reaction is equal to unity. Analytical expressions have been proposed for the rate constants in the saponification of oxidized paraffins by aqueous sodium hydroxide solutions.

Cellulose xanthate dissolution in aqueous caustic soda solutions

Cellulose xanthate dissolution in aqueous caustic soda solutions

A new physicochemical technique for studying native and modified structures of polymer fibers: The continuous measurement of length variations, under tension, in a swelling medium of continuously variable concentration

AbstractA device for linear variation of the concentration of a binary mixture in function of time is described. This device is used to study the dimensional variations of cotton yarns immersed in an aqueous caustic soda solution under a fixed tension while the concentration is increased from 0 to 10N. This method is very sensitive and seems of particular interest for the study of fibrous polymer structures.

Improved Abrasion Resistance Through Internal Lubrication

, The cross-linking reaction of cellulose with lauroyl and stearoyl ester is described. With increasing number of carbon atoms in the ester substituent, the reactivity and wet crease recovery decreased. There is an improvement in tear and abrasion resistance and, with stearoyl ester, a remarkable improvement (5 to 20 times) in flex abrasion resistance. The tear resistance, however, is improved only to the extent of 10% to 50%. By using a modified microscopic count technique and a polarizing microscope, it is shown that the cellulose is cross-linked. The degree of insolubility in cuprithylene diamine is proportional to the degree of cross-linking. Bulk scale application of stearoyl dichloropropanol (DCP) to two fabrics, viz, medium and superfine poplins, has been done. An improvement in abrasion resistance of about 500% to 800% and tear resistance of 20% to 50% has been recorded. The finish is stable to mild laundering, boiling 0.5 N aqueous caustic soda, and boiling 0.5% non-ionic detergent. However, boiling solutions of soap (0.5%) and soda (0.2%) hydrolyze the ester-link, though the cross-linking is still unaffected. The treated fabrics are suitable base materials for wash-wear treatment and it is possible to obtain wash-wear fabrics with abrasion resistance equivalent to or higher than the starting material. Some data on field wear trials of SDCP-treated fabrics are presented and discussed. It is concluded that the idea of providing internal or built-in lubrication by the use of three carbon cross links, with a bulky substituent at the center, may open up a new approach to enhance the abrasion resistance of cotton and other cellulosic textiles.

Preparation of trans-Difluorodiazine

Abstract : Pure trans-difluorodiazine can readily be prepared in about 45% yield from commercially available tetrafluorohydrazine and aluminum chloride: 3N2F4 + 2AlCl3 yields 3N2F2 + 3Cl2 + 2AlF3. Consistent yields of 45-48% trans-N2F2 were obtained from both batch and flow reactions involving excess AlCl3 and N2F4 at 15-20 mm. and -80 with contact times ranging from 0.5 to 5 min. Because of the necessarily low pressures, flow systems are strongly recommended. A convenient reactor can be prepared by subliming anhydrous AlCl3 (15-20 g. for 30-50 mmoles of N2F4) onto the side-arm walls of a conventional Pyrex U-tube (16 mm. o.d.) by heating the material in the bottom of the vessel with a bunsen burner. It is necessary to activate the AlCl3 before use by keeping it in contact with a small quantity of N2F4 at room temperature for 30 min. The product is purified by washing with aqueous caustic soda followed by trap-to-trap vacuum distillation. (Extracted)

THE DEFATTING OF NATURAL RUBBER MILKING MACHINE LINERS

SUMMARYIt has been shown that detergents in general are relatively poor fat removal agents from used liners. Alcohols and alcoholic alkalis are more efficient as cleaning agents judged by their power of removing fats and they are generally better than the commonly used aqueous caustic soda solution. Limited farm tests have in general confirmed laboratory test results. Liners are kept in good condition for periods longer than previously obtained when using other cleaning methods.

ACCESSIBILITY OF HYDROGEN BONDS IN CELLULOSE

Cellulose derives most of its functional properties from its hydroxyl groups: derivatives are formed by reactions with the hydroxyl groups, when cellulose is dissolved it is usually as a complex of the hydroxyl groups with ions or polar groups, and the physical properties of cellulose in the solid state are to a large extent a function of the hydroxyl groups.It is known from infrared analysis that practically all hydroxyl groups in dry solid cellulose, both native and regenerated, are not free but engaged in hydrogen bonds of some kind. The proton donor group is always a hydroxyl group with another hydroxyl group or an oxygen group as acceptor. The accessibility of the hydrogen bonded hydroxyl groups has been measured by a combination of deuterium exchange (OH to OD groups) in heavy water and infrared analysis. Accessible OH groups are largely in amorphous (disordered) cellulose. The OH groups in crystalline (well ordered) cellulose are gradually made accessible by swelling with caustic soda solutions of increasing strength.In regenerated cellulose a large fraction (usually about 80%) of the hydroxyl groups is accessible to the exchange in heavy water. Complete accessibility is obtained with 12 to 16% aqueous caustic soda. Intrachain hydrogen bonds along the cellulose chains are more resistant than interchain bonds between adjacent chains. By certain treatment the crystallinity of regenerated cellulose can be increased substantially. It has been found that the packing density of amorphous cellulose also can be increased by these treatments. Special crystallization processes from dilute solution give cellulose crystals of high order and low accessibility.Native cellulose has a morphology of rather well defined microfibrils, containing parallel and partly crystallized cellulose chains. The accessibility is usually much lower (30 to 50%) than in regenerated accessible, we calculate an accessibility value for holocellulose from spruce of about 57%. Reported accessibilities for purified wood pulp from softwood are about 58% (8). If our measured data are accepted as given here, they would indicate that hemicellulose in the native state in wood, although X-ray amorphous, is only partially accessible to tritium exchange in tritiated water. There are, however, some difficulties in the interpretation of these measurements, and the data will be further treated elsewhere.

ALKALI TREATMENT OF POLYESTER FIBERS

Fibers, made from polyesters of β-hydroxyethoxy aromatic acids, and their copolyester, and those from polyethylen terephthalate (PET), were treated with aqueous caustic soda solutions.Rate constants of solution, k (g/hr/cm2), are calculated from the equationwhere x is the loss of weight by solution, d0 (cm) the initial diameter of a fiber, t (hr) the treatment time, and ρ (g/cm3) the density of the fiber.At room temperature, k of fibers from polyester A and coplyester are much smaller than those from polyethylen terephthalate, but higher the temperature, they become closer. Draw ratio and heat-treating temperature have some influence on k, but chemical constitution of polyesters have much more.We conclude that k, rate constants of solution, are most influenced by the rate of hydrolysis of ester combination of the molecular chains on the surface of fibers. The differences of k, caused by chemical constitution of polyesters, may be explained by Hammet's Law.

How to minimize the movement of tools being hardened

1. To decrease their deformation in quenching, tools of carbon steels U8 to U12 should be hardened in 35–45% aqueous caustic soda at 120°C (250°F). Tools of steel KhVG should be quenched with isothermal holding in the martensite range at 160°C (320°F) in alkalis or in saltpeter for 3–6 minutes or at 110°C (230°F) in 75% aqueous caustic soda for 10–15 minutes. 2. Tools of high-speed steels, which tend to distort, should be marquenched at 170–180°C (340–355°F) and held for 4–12 minutes in a saltpeter or alkali bath.

IMPROVEMENT OF LIGHT RESISTANCE OF NYLON

Light resistance and alkali exhaustion of nylon treated with aqueous alkali solution were measured.(1) Nylon taffeta, when treated in aqueous caustic soda solution, was improved in light resistance. The higher the temperature of the solution, the earlier the improvement was observed.(2) LiOH, KOH as well as NaOH had good effects on the light resistance of nylon, but Na2CO3 and NaHCO3 had only poor effects.(3) The treatment reduced the OH- concentration of the solution, that is, alkali was exhausted by nylon. As the OH- concentration of the solution and the time of the treatment increased, alkali exhaustion approached a saturation value, which was approximately equal to the carboxyl group content of nylon.Alkali is probably exhausted to neutralize the carboxyl group of nylon, but it is still in doubt why neutralization of the carboxyl group can improve the light resistance of nylon.

The colorimetric determination of benzene hexachloride in insect tissues

AbstractBenzene hexachloride may be determined by hydrolysing it to trichlorobenzene, nitrating to trichlorodinitrobenzene and converting this into chlorodinitroresorcinol by hydrolysis with aqueous caustic soda. Under these conditions the main colour‐producing compound is 6‐chloro‐2: 4‐dinitroresorcinol, but 2‐chloro‐4: 6‐dinitroresorcinol and 5‐chloro‐2: 4‐dinitroresorcinol may also contribute to the colour. Benzene hexachloride is separated from fats in insect tissues by percolating through a column packed with kieselguhr and a mixture of carbon tetrachloride and oleum.